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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential
Security Level
wwwhuaweicom
LTE Basic Knowledge
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Network Architecture of LTE
bull Compare with traditional 3G network LTE architecture becomes much more simple and flat which can lead to lower networking cost higher networking flexibility and shorter time delay of user data and control signalling
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Network Architecture of LTE
EPC Network Simplification
bull The E-UTRAN consists of e-NodeBs The e-NodeBs are interconnected with each other by means of the X2 interface which enabling direct transmission of data and signaling
bull The EPC (Evolved Packet Core) consists of MME S-GW P-GWHSSPCRF and son on
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Routing mobility charge and
account PDN and QCI
IP address allocation gating
and rate enforcement
Paging handover bearer control idle
state mobility handling
Network Architecture of LTE
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Network Architecture of LTE
bull Compare with traditional 3G network LTE architecture becomes much more simple and flat which can lead to lower networking cost higher networking flexibility and shorter time delay of user data and control signalling
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Network Architecture of LTE
EPC Network Simplification
bull The E-UTRAN consists of e-NodeBs The e-NodeBs are interconnected with each other by means of the X2 interface which enabling direct transmission of data and signaling
bull The EPC (Evolved Packet Core) consists of MME S-GW P-GWHSSPCRF and son on
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Routing mobility charge and
account PDN and QCI
IP address allocation gating
and rate enforcement
Paging handover bearer control idle
state mobility handling
Network Architecture of LTE
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Network Architecture of LTE
bull Compare with traditional 3G network LTE architecture becomes much more simple and flat which can lead to lower networking cost higher networking flexibility and shorter time delay of user data and control signalling
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Network Architecture of LTE
EPC Network Simplification
bull The E-UTRAN consists of e-NodeBs The e-NodeBs are interconnected with each other by means of the X2 interface which enabling direct transmission of data and signaling
bull The EPC (Evolved Packet Core) consists of MME S-GW P-GWHSSPCRF and son on
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Routing mobility charge and
account PDN and QCI
IP address allocation gating
and rate enforcement
Paging handover bearer control idle
state mobility handling
Network Architecture of LTE
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Network Architecture of LTE
EPC Network Simplification
bull The E-UTRAN consists of e-NodeBs The e-NodeBs are interconnected with each other by means of the X2 interface which enabling direct transmission of data and signaling
bull The EPC (Evolved Packet Core) consists of MME S-GW P-GWHSSPCRF and son on
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Routing mobility charge and
account PDN and QCI
IP address allocation gating
and rate enforcement
Paging handover bearer control idle
state mobility handling
Network Architecture of LTE
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Routing mobility charge and
account PDN and QCI
IP address allocation gating
and rate enforcement
Paging handover bearer control idle
state mobility handling
Network Architecture of LTE
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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e-Node hosts the following functions p Functions for Radio Resource Management Radio Bearer
Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs in both uplink and downlink (scheduling)
p IP header compression and encryption of user data streamp Selection of an MME at UE attachmentp Routing of User Plane data towards Serving Gatewayp Scheduling and transmission of paging and broadcast
messages (originated from the MME)p Measurement and measurement reporting configuration for
mobility and scheduling
MME (Mobility Management Entity) hosts the following functions p NAS signaling and security p AS Security controlp Idle state mobility handlingp EPS (Evolved Packet System) bearer controlp Support paging handover roaming and authentication
S-GW (Serving Gateway) hosts the following functions p Packet routing and forwarding Local mobility anchor point
for handover Lawful interception UL and DL charging per UE PDN and QCI Accounting on user and QCI granularity for inter-operator charging
P-GW (PDN Gateway) hosts the following functions p Per-user based packet filtering UE IP address allocation UL
and DL service level charging gating and rate enforcement
Function of LTE Network Element
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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S1 S1
S1 S1X2X2
The main difference between UMTS and LTE the removing of RNC network element and the introduction of X2 interface which make the network more simple and flat leading lower networking cost higher networking flexibility and low latency
UTRAN
Comparison bw UTRANampE-UTRAN
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Radio Frame Structure
bull Radio Frame Structures Supported by LTEsect Type 1 applicable to FDD
sect Type 2 applicable to TDD
bull FDD Radio Frame Structuresect LTE applies OFDM technology with subcarrier spacing ∆f 15kHz and 2048-
order IFFT The time unit in frame structure is Ts=1(2048 ∆f) second
sect FDD radio frame is 10ms shown as below divided into 20 slots which is 05ms One slot consists of 7 consecutive OFDM Symbols under Normal CP configuration
FDDRadio Frame Structure
l Concept of Resource Blockp LTE consists of time domain and frequency domain resources The minimum unit for
schedule is RB (Resource Block) which compose of RE (Resource Element)p RE has 2-dimension structure symbol of time domain and subcarrier of frequency domainp One RB consists of 1 slot and 12 consecutive subcarriers under Normal CP configuration
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Time
System Bandwidth
1 Resource Block 12 Sub-carriers1 Sub-carrier = 15KHz180KHz (Total 200KHz with Guard)
-
Sub-carrier
1 Sub-frame TTI 1ms2 Slots Frequency
-
User 1
User 2
User 3
1 Sub-frame2 Slots2 RBs
7 Symbols
1 Sub-frame = 2 Slots 14 Resource Elements (RE)
D U U D D U U D
DwPTS GP UpPTS
TDD 1
FDD
Time-Frequency Resource Unit
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Frame and Slot Structure (Normal CP)
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Resource Element Mapping (6 RBs 2 Antenna)
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Downlink Channelsp Physical Broadcast Channel (PBCH) Carries system information
for cell search such as cell IDp Physical Downlink Control Channel (PDCCH) Carries the
resource allocation of PCH and DL-SCH and Hybrid ARQ information
p Physical Downlink Shared Channel (PDSCH) Carries the downlink user data
p Physical Control Format Indicator Channel (PCFICH) Carriers information of the OFDM symbols number used for the PDCCH
p Physical Hybrid ARQ Indicator Channel (PHICH) Carries Hybrid ARQ ACKNACK in response to uplink transmissions
p Physical Multicast Channel (PMCH) Carries the multicast information
Uplink Channelsp Physical Random Access Channel (PRACH) Carries the
random access preamblep Physical Uplink Shared Channel (PUSCH) Carries the uplink
user datap Physical Uplink Control Channel (PUCCH) Carries the HARQ
ACKNACK Scheduling Request (SR) and Channel Quality Indicator (CQI) etc
Mapping between downlink transport channels and downlink physical channels
Mapping between uplink transport channels and downlink physical channels
Physical Layer
MAC Layer
Physical Layer
MAC Layer
Introduction of LTE PHY- Physical Channels
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Channel MappingM
AC
PHY
MA
CPH
Y
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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RS (Reference Signal)p Similar with Pilot signal of CDMA Used for downlink physical channel
demodulation and channel quality measurement (CQI)p Three types of RS in protocol Cell-Specific Reference Signal is essential and
the other two types RS (MBSFN Specific RS amp UE-Specific RS) are optional
One
Ant
enna
Por
t
Antenna Port 3
Characteristicsp Cell-Specific Reference Signals are generated from cell-
specific RS sequence and frequency shift mapping RS is the pseudo-random sequence transmits in the time-frequency domain
p The frequency interval of RS is 6 subcarriersp RS distributes discretely in the time-frequency domain
sampling the channel situation which is the reference of DL demodulation
p Serried RS distribution leads to accurate channel estimation also high overhead that impacting the system capacity
MBSFN MulticastBroadcast over a Single Frequency Network
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l
0=l0R
0R
0R
0R
6=l 0=l0R
0R
0R
0R
6=l 0=l
1R
1R
1R
1R
6=l 0=l
1R
1R
1R
1R
6=l 0=l 6=l 0=l
2R
6=l 0=l 6=l 0=l 6=l2R
2R
2R
3R
3R
3R
3R
Cell-Specific RS Mapping in Time-
Frequency Domain
Two
Ante
nna
Ports
Four
Ant
enna
Por
ts
Antenna Port 0 Antenna Port 1 Antenna Port 2
RE
Not used for RS transmission on this antenna portRS symbols on this antenna port
R1 RS transmitted in 1st ant portR2 RS transmitted in 2nd ant port
R3 RS transmitted in 3rd ant port
R4 RS transmitted in 4th ant port
Introduction of LTE PHY- DL Physical Signals(1)
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Synchronization Signalp synchronization signals are used for time-frequency synchronization between UE and E-UTRAN during cell searchp synchronization signal comprise two parts
n Primary Synchronization Signal used for symbol timing frequency synchronization and part of the cell ID detectionn Secondary Synchronization Signal used for detection of radio frame timing CP length and cell group ID
Synchronization Signals Structure
Characteristicsp The bandwidth of the synchronization signal is 72
subcarrier locating in the central part of system bandwidth regardless of system bandwidth size
p Synchronization signals are transmitted only in the 1st and 11th slots of every 10ms frame
p The primary synchronization signal is located in the last symbol of the transmit slot The secondary synchronization signal is located in the 2nd last symbol of the transmit slot
CautionSynchronization signals are sometimes named as Synchronization Channel (P-SCH amp S-SCH) in some documents The meaning should be the same which represents the signals transmitted in the specified time-frequency locations Please donrsquot be confused with Share Channel (SCH)
Introduction of LTE PHY- DL Physical Signals(2)
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Introduction of LTE PHY- UL Physical SignalsReference Signal
p The uplink pilot signal used for synchronization between E-UTRAN and UE as well as uplink channel estimation
p Two types of UL reference signalsn DM RS (Demodulation Reference Signal)
associated with PUSCH and PUCCH transmission n SRS (Sounding Reference Signal) without
associated with PUSCH and PUCCH transmission
Characteristicsp Each UE occupies parts of the system bandwidth since SC-
FDMA is applied in uplink DM RS only transmits in the bandwidth allocated to PUSCH and PUCCH
p The slot location of DM RS differs with associated PUSCH and PUCCH format
p Sounding RSrsquos bandwidth is larger than that allocated to UE in order to provide the reference to e-NodeB for channel estimation in the whole bandwidth
p Sounding RS is mapped to the last symbol of sub-frame The transmitted bandwidth and period can be configured SRS transmission scheduling of multi UE can achieve timefrequencycode diversity
CautionThe SRS mapping will be difference in many documents since the protocol are still under discussion when these document been compiled The mapping shown in this
slide is the result from the latest protocol version
DM RS associated with PUSCH is mapped to the 4th symbol each slot
Time
Freq
Time
Freq
Time
Freq
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the central 3 symbols each slot
DM RS associated with PUCCH (transmits UL ACK signaling) is mapped to the 2 symbols each slot
PUCCH is mapped to up amp down ends of the system bandwidth hopping between two slots
Allocated UL bandwidth of one UE
System bandwidth
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Introduction of LTE PHY- Cell SearchBasic Principle of Cell Search
p Cell search is the procedure of UE synchronizes with E-UTRAN in time-freq domain and acquires the serving cell ID
p Two steps in cell searchn Step 1 Symbol synchronization and acquirement of ID within
Cell Group by demodulating the Primary Synchronization Signal
n Step 2 Frame synchronization acquirement of CP length and Cell Group ID by demodulating the Secondary Synchronization Signal
Caution 170 Cell ID groups are defined in the earlier protocol version So totally 1703=510 Cell IDs exists which is mentioned in some early-written documents
Please be noticed this differences
About Cell IDp In LTE protocol the physical layer Cell ID comprises two parts Cell
Group ID and ID within Cell Group The latest version defines that there are 168 Cell Group IDs 3 IDs within each group So totally 1683=504 Cell IDs exist
p represents Cell Group ID value from 0 to 167represents ID within Cell Group value from 0 to 2
(2)ID
(1)ID
cellID 3 NNN +=
(1)IDN(2)IDN
Initial Cell Searchp The initial cell search is carried on after the UE power on Usually
UE doesnrsquot know the network bandwidth and carrier frequency at the first time switch on
p UE repeats the basic cell search tries all the carrier frequency in the spectrum to demodulate the synchronization signals This procedure takes time but the time requirement are typically relatively relaxed Some methods can reduce time such as recording the former available network information as the prior search target
p Once finish the cell search which achieve synchronization of time-freq domain and acquirement of Cell ID UE demodulates the PBCH and acquires for system information such as bandwidth and Tx antenna number
p After the procedure above UE demodulates the PDCCH for its paging period that allocated by system UE wakes up from the IDLE state in the specified paging period demodulates PDCCH for monitoring paging If paging is detected PDSCH resources will be demodulated to receive paging message
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Introduction of LTE PHY- Random AccessBasic Principle of Random Access
p Random access is the procedure of uplink synchronization between UE and E-UTRAN
p Prior to random access physical layer shall receive the following information from the higher layers
n Random access channel parameters PRACH configuration frequency position and preamble format etc
n Parameters for determining the preamble root sequences and their cyclic shifts in the sequence set for the cell in order to demodulate the random access preamble
p Two steps in physical layer random accessn UE transmission of random access preamble
n Random access response from E-UTRAN
Detail Procedure of Random Access
p Physical Layer procedure is triggered upon request of a preamble transmission by higher layers
p The higher layers request indicates a preamble index a target preamble received power a corresponding RA-RNTI and a PRACH resource
p UE determines the preamble transmission power is preamble target received power + Path Loss The transmission shall not higher than the maximum transmission power of UE Path Loss is the downlink path loss estimate calculated in the UE
p A preamble sequence is selected from the preamble sequence set using the preamble index
p A single preamble is transmitted using the selected preamble sequence with calculated transmission power on the indicated PRACH resource
p UE Detection of a PDCCH with the indicated RA-RNTI is attempted during a window controlled by higher layers If detected the corresponding PDSCH transport block is passed to higher layers The higher layers parse the transport block and indicate the 20-bit grant
RA-RNTI Random Access Radio Network Temporary Identifier
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Introduction of LTE PHY- Power ControlBasic Principle of Power Control
p Downlink power control determines the EPRE (Energy per Resource Element)
p Uplink power control determines the energy per DFT-SOFDM (also called SC-FDMA) symbol
Uplink Power Controlp Uplink power control consists of opened loop power and closed loop
power control
p A cell wide overload indicator (OI) is exchanged over X2 interface for integrated inter-cell power control possible to enhance the system performance through power control
p PUSCH PUCCH PRACH and Sounding RS can be controlled respectively by uplink power control Take PUSCH power control for example
p PUSCH power control is the slow power control to compensate the path loss and shadow fading and control inter-cell interference The control principle is shown in above equation The following factors impact PUSCH transmission power PPUSCH UE maximum transmission power PMAX UE allocated resource MPUSCH initial transmission power PO_PUSCH estimated path loss PL modulation coding factor TF and system adjustment factor f (not working during opened loop PC)
UE report CQI
DL Tx Power
EPRE Energy per Resource ElementDFT-SOFDM Discrete Fourier Transform Spread OFDM
f(i)(i)ΔPLα(j)(j)P(i))(MP(i)P TFO_PUSCHPUSCHMAXPUSCH ++sdot++= 10log10min
Downlink Power Controlp The transmission power of downlink RS is usually constant The
transmission power of PDSCH is proportional with RS transmission power
p Downlink transmission power will be adjusted by the comparison of UE report CQI and target CQI during the power control
X2
UL Tx Power
System adjust parameters
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Introduction of LTE Radio Protocol Stackbull Two Planes in LTE Radio Protocol
sect User-plane For user data transfersect Control-plane For system signaling
transfer
bull Main Functions of User-planesect Header Compressionsect Cipheringsect Schedulingsect ARQHARQ
User-plane protocol stack
Control-plane protocol stack
Main Functions of Control-planep RLC and MAC layers perform the same functions as
for the user planep PDCP layer performs ciphering and integrity
protectionp RRC layer performs broadcast paging connection
management RB control mobility functions UE measurement reporting and control
p NAS layer performs EPS bearer management authentication security control
Layer 1
Layer 2
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Introduction of LTE Layer 2 - OverviewLayer 2 is split into the following layers
p MAC (Medium Access Control) Layer
p RLC (Radio Link Control ) Layer
p PDCP (Packet Data Convergence Protocol ) Layer
Main Functions of Layer 2
p Header compression Ciphering
p Segmentation and concatenation ARQ
p Scheduling priority handling multiplexing and demultiplexing HARQ
Layer 2 Structure for DL Layer 2 Structure for UL
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Introduction of LTE Layer 2 - MAC LayerMain functions of MAC Layer
p Mapping between logical channels and transport channels
p Multiplexingdemultiplexing of RLC PDUs (Protocol Data Unit) belonging to one or different radio bearers intofrom TB (transport blocks ) delivered tofrom the physical layer on transport channels
p Traffic volume measurement reporting
p Error correction through HARQ
p Priority handling between logical channels of one UE
p Priority handling between UEs (dynamic scheduling)
p Transport format selection
p Padding
Logical Channels of MAC Layer
p Control Channel For the transfer of control plane information
p Traffic Channel for the transfer of user plane information
MAC Layer Structure
UL Channel Mapping of MAC Layer
Control Channel
Traffic Channel
DL Channel Mapping of MAC Layer
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Introduction of LTE Layer 2 - RLC LayerMain functions of RLC Layer
p Transfer of upper layer PDUs supports AM or UM
p TM data transfer
p Error Correction through ARQ (no need RLC CRC check CRC provided by the physical)
p Segmentation according to the size of the TB only if an RLC SDU does not fit entirely into the TB then the RLC SDU is segmented into variable sized RLC PDUs no need padding
p Re-segmentation of PDUs that need to be retransmitted if a retransmitted PDU does not fit entirely into the new TB used for retransmission then the RLC PDU is re-segmented
p Concatenation of SDUs for the same radio bearer
p In-sequence delivery of upper layer PDUs except at HO
p Protocol error detection and recovery
p Duplicate Detection
p SDU discard
p Reset
RLC PDU Structurep The PDU sequence number carried by the RLC
header is independent of the SDU sequence number p The size of RLC PDU is variable according to the
scheduling scheme SDUs are segmented concatenated based on PDU size The data of one PDU may source from multi SDUs
RLC Layer Structure
AM Acknowledge ModeUM Un-acknowledge ModeTM Transparent ModeTB Transport BlockSDU Service Data UnitPDU Protocol Data Unit
RLC PDU Structure
Segmentation Concatenation
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Main functions of PDCP Layerp Functions for User Plane
n Header compression and decompression ROHC
n Transfer of user data PDCP receives PDCP SDU from the NAS and forwards it to the RLC layer and vice versa
n In-sequence delivery of upper layer PDUs at handover for RLC AM
n Duplicate detection of lower layer SDUs at handover for RLC AM
n Retransmission of PDCP SDUs at handover for RLC AM
n Cipheringn Timer-based SDU discard in uplink
p Functions for Control Planen Ciphering and Integrity Protectionn Transfer of control plane data PDCP
receives PDCP SDUs from RRC and forwards it to the RLC layer and vice versa
PDCP PDU Structurep PDCP PDU and PDCP header are octet-
aligned
p PDCP header can be either 1 or 2 bytes long
Introduction of LTE Layer 2 - PDCP Layer
PDCP Layer Structure
ROHC Robust Header Compression
PDCP PDU Structure
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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LTE 3GPP Specification Overview
36201 LTE Physical Layer General Description 36211 Physical Channels and Modulation 36212 Multiplexing and Channel Coding 36213 Physical Layer Procedures 36214 Physical Layer Measurements
36300 E-UTRAN Overall Description Stage 236302 E-UTRAN Services Provided by the Physical Layer36304 User Equipment (UE) Procedures in Idle Mode36306 User Equipment (UE) Radio Access Capabilities36321 Medium Access Control (MAC) Protocol Specification36322 Radio Link Control (RLC) Protocol Specification36323 Packet Data Convergence Protocol (PDCP) Specification36331 Radio Resource Control (RRC) Protocol Specification
36401 E-UTRAN Architecture Description36410 S1 General Aspects and Principles36411 S1 Layer 136412 S1 Signalling Transport36413 S1 Protocol Specification36414 S1 Data Transport36420 X2 General Aspects and Principles36421 X2 Layer 136422 X2 Signalling Transport36423 X2 Protocol Specification36424 X2 Data Transport
Physic Layer
Layer 2 and Control Protocol Interfaces and Procedure
TS 36xxx for LTE Specification
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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bull OFDM amp OFDMAsect OFDM (Orthogonal Frequency Division Multiplexing)
is a modulation multiplexing technology divides the system bandwidth into orthogonal subcarriers CP is inserted between the OFDM symbols to avoid the ISI
sect OFDMA is the multi-access technology related with OFDM is used in the LTE downlink OFDMA is the combination of TDMA and FDMA essentially
sect Advantage High spectrum utilization efficiency due to orthogonal subcarriers need no protect bandwidth Support frequency link auto adaptation and scheduling Easy to combine with MIMO
sect Disadvantage Strict requirement of time-frequency domain synchronization High PAPR
bull DFT-S-OFDM amp SC-FDMAsect DFT-S-OFDM (Discrete Fourier Transform
Spread OFDM) is the modulation multiplexing technology used in the LTE uplink which is similar with OFDM but can release the UE PA limitation caused by high PAPR Each user is assigned part of the system bandwidth
sect SC-FDMA(Single Carrier Frequency Division Multiple Accessing)is the multi-access technology related with DFT-S-OFDM
sect Advantage High spectrum utilization efficiency due to orthogonal user bandwidth need no protect bandwidth Low PAPR
sect The subcarrier assignment scheme includes Localized mode and Distributed mode
LTE Key Technology mdash OFDMA amp SC-FDMA
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
User 1
User 2
User 3
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
System Bandwidth
Sub-band12Sub-carriersTime
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
Sub-carriers
TTI 1ms
Frequency
Time
System Bandwidth
Sub-band12Sub-carriers
User 1
User 2
User 3
User 1
User 2
User 3
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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GSM FDM Spectrum
OFDM system spectrumSpectrum Efficiency Improvement
N
eNB
Multi-elementTransmitter
M
UE
Multi-elementReceiver
Easy to co-work with MIMO
Frequency-selective scheduling amp Adaptive modulation and coding
CP resist ISI caused by multipath effect
OFDMA Benefits
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Uplink SC-FDMA for PAR resistance
Oslash The main difference between OFDMA and SC-FDMA is that the latter performs DFT before
performing IFFT for transmission which can be taken as a time-domain precoding operation
l Compared with single carrier system OFDM will cause high peak-to-average ratio (PAR) which will
caused problem for the amplifier design and increase the UE implementation cost accordingly
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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Comparing OFDM and SC-FDMA(QPSK example M=4 subcarriers)
1 1 -1-1 -1 1 1 -1 1 1 -1-1 -1 1 1 -1
15 kHzFrequencyfc
V
CP
OFDMAData symbols occupy 15 kHz for one OFDMA symbol period
SC-FDMAData symbols occupy M15 kHz for 1M SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
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R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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bull Downlink MIMOsect MIMO is supported in LTE downlink to achieve
spatial multiplexing including single user mode SU-MIMO and multi user mode MU-MIMO
sect In order to improve MIMO performance pre-coding is used in both SU-MIMO and MU-MIMO to controlreduce the interference among spatial multiplexing data flows
sect The spatial multiplexing data flows are scheduled to one single user In SU-MIMO to enhance the transmission rate and spectrum efficiency In MU-MIMO the data flows are scheduled to multi users and the resources are shared within users Multi user gain can be achieved by user scheduling in the spatial domain
bull Uplink MIMOsect Due to UE cost and power consumption it is difficult to
implement the UL multi transmission and relative power supply Virtual-MIMO in which multi single antenna UEs are associated to transmit in the MIMO mode Virtual-MIMO is still under study
sect Scheduler assigns the same resource to multi users Each user transmits data by single antenna System separates the data by the specific MIMO demodulation scheme
sect MIMO gain and power gain (higher Tx power in the same time-freq resource) can be achieved by Virtual-MIMO Interference of the multi user data can be controlled by the scheduler which also bring multi user gain
LTE Key Technology mdash MIMO
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
Pre-coding vectors
User k data
User 2 data
User 1 data
Channel Information
User1
User2
User k
Scheduler Pre-coder
S1
S2
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
MU-MIMO Virtual-MIMO
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Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 34
2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 37
2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 33
Transmit Diversity
Laye
r Map
ping
Pre
codi
ng
s0 s2Lay 0
2 Antenna Transmit Diversity (SFBC)
s1s0 s3s2
s1 s3
s1s0 s3s2
-s1 s0
-s3 s2
Pre
codi
ng
Laye
rMap
ping
Lay 1
Ant 0
Ant 1
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 34
2 Antenna MIMO
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 37
2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 41
Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 34
2 Antenna MIMO
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 35
4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 37
2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
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4 Antenna Spatial Multiplexing (Two Codewords Without CDD)D-TxAA (Double Transmit Antenna Array ) Scheme
W0
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
s0 s2Lay 0
s1 s3Lay 1
s0 s2Lay 2
s1 s3Lay 3
Laye
r Map
ping
s1s0 s3s2
s1s0 s3s2
sum
sum
sum
sum
y1y0 Ant 0
Ant 1
Ant 2
Ant 3
y1y0
y1y0
y1y0
y0 = w0s0 + w4s1 + w8s0 + w12s1y1 = w0s2 + w4s3 + w8s2 + w12s3
y0 = w1s0 + w5s1 + w9s0 + w13s1y1 = w1s2 + w5s3 + w9s2 + w13s3
y0 = w2s0 + w6s1 + w10s0 + w14s1y1 = w2s2 + w6s3 + w10s2 + w14s3
y0 = w3s0 + w7s1 + w11s0 + w15s1y1 = w3s2 + w7s3 + w11s2 + w15s3
4 Antenna MIMO
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UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
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2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 36
UE1
Layer 1 CW1 AMC1UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
Layer 1 CW1 AMC1
UE2
Layer 2 CW2 AMC2
MIMO encoder and layer mapping
DL MU-MIMO
DL SU-MIMO
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
User 1 data
Channel Information
User1
User2
User kScheduler
MIMODecoderUser k data
User 1 data
Virtual-MIMO in UL
Spatial Multiplexing boosts capacity
codeword
UE1
User1SFBCMod
Tx Diversity extends coverage
Beamforming extends coverage
codeword
User1
ModBeamforming
Precoding Processing
UE2
UE1
MIMO Operation in LTE
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2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 37
2x2 MIMOeNodeB UE 1
1x2 SIMOeNodeB UE 1
Thro
ughp
ut (M
bps)
2834
1815
ISD500mSpeed3kmh
1388
164
942
1209
1236
1423
1512
MIMOSIMOxxxx Gain
ISD500mSpeed30kmh
ISD1732mSpeed30kmh
Thro
ughp
ut (M
bps)
46404694
Outdoor-to-IndoorSpeed 3kmh
2324
34155668
MIMOSIMOxxxx Gain
2403
3518
1715
2687
Outdoor-to-OutdoorSpeed 3kmh
Outdoor-to-OutdoorSpeed 30kmh
In typical urban area
15~28 gain over SIMO Macro~50 gain over SIMO Micro
LTE
LTE
LTE
Macro
Micro
MIMO the Key to Improve Cell Throughput-- System Gain 2X2 MIMO over SIMO
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 41
Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 38
2 bits per symbol in each carrier
4 bits per symbol in each carrier
6 bits per symbol in each carrier
Adaptive Modulation and Coding
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
PDF created with pdfFactory Pro trial version wwwpdffactorycom
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Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 39
Adjust MIMO mode according to channel quality and userrsquos velocity
Different MIMO modes fit different scenarios
SFBC and CL Tx Diversity (rank=1) increase link reliability and coverage
OL SM and CL-SM (rank=2) increase throughput
10 gain in average cell throughput over non-adaptive MIMO
Adaptive MIMO
Benefits
DLOL-SMULMU-MIMO
DLSFBCULRx Diversity
DLCL-SMULMU-MIMO
DLCL-Tx DiversityULRx Diversity
Channel Quality (SINR)
Open Loop
Closed Loop
Cell Center Cell Edge
Mob
ility
Vel
ocity
(km
h)
Adaptive MIMO Increasing Cell Throughput
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
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HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 41
Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 40
Frequency
Cell 357Power
Frequency
Cell 357Power
Frequency
Cell 246Power
Frequency
Cell 246Power
ICIC(Inter-Cell Interference Coordination)p ICIC is one solution for the cell interference control is essentially a schedule strategy In LTE some
coordination schemes like SFR (Soft Frequency Reuse) and FFR (Fractional Frequency Reuse) can control the interference in cell edges to enhance the frequency reuse factor and performance in the cell edges
SFR Solutionp SFR is one effective solution of inter-cell interference control The system bandwidth is separated into primary
band and secondary band with different transmit power
1
2
3
6
5
7
4
1
2
3
6
5
7
4
The primary band is assigned to the users in cell edge The eNB transmit power of the primary band can be high Secondary
Band
Cell 246 Primary BandFrequency
Cell 1Power
Frequency
Cell 1Power
Cell 1 Primary Band
Secondary Band
Cell 357P Primary Band
Total System BW
The total system bandwidth can be assigned to the users in cell center The eNB transmit power of the secondary band should be reduced in order to avoid the interference to the primary band of neighbor cells
Secondary Band
Secondary Band
Cell Interference Control
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 41
Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 41
Agenda
LTE Protocol
1 LTE Network Architecture
2
LTE Key Technology3
Compsirson bw LTE and UMTS4
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
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Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 42
UMTS (R99) HSPA HSPA+ LTE
Radio Access W-CDMA W-CDMA W-CDMA OFDMA DLSC-FDMA UL
Bandwidth 5 MHz 5 MHz 5MHz or 10MHz (DC) Scalable from 14MHz to 20MHz
Modulation DL QPSK QPSK16QAM QPSK16QAM64QAM QPSK16QAM
64QAM
Modulation UL BPSK QPSK QPSK16QAM QPSK16QAM
64QAM
Antenna Systems Rx Diversity Rx Diversity 2x2 MIMO 2x2 - 4X4 MIMO
Network Structure Node B + RNC Node B + RNC NodeB + RNC
Or eHSPA NodeB eNodeB to EPC
Services Circuit amp Packet Switched
Circuit amp Packet Switched
PS but compatible to CS PS Only
Transport ATM Mixed ATM amp IP
ATM Mixed ATM amp IP Option for All IP All IP
Technology comparison for features
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 43
R8 HSPA(+) LTETime To Market Commercial deployment by 2009 Commercial deployment by 2010
Market Operator adoption
66+ operators commited 54 Mobile BB users by 2015 (HSPAampHSPA+)
~59 operators commitments20 Mobile BB users by 2015
Infrastructure commercial date 2009 2009
1st commercial terminal 2009 2010
Evolution from Legacy Smooth evolution based on Huawei Uni-BTS and One Unified Core
Smooth evolution based on Huawei Uni-BTS and One Unified Core
Backwards compatibility amp roaming with legacy Inherent LTE commercial terminal are multi-mode
GSMUMTSLTE allowing inter-RAT HO
Frequency bandIMT2000 (Technology Neutral)Common trends for 850MHz 900MHz AWS 21GHz
IMT2000 (Technology Neutral)Common trends for DD 1800MHz AWS 21GHz 26GHz
Frequency bandwidth 5MHz ndash 10MHz 14 3 5 10 15 20MHz
LTE vs HSPA+ comparison summary (12)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
HUAWEI TECHNOLOGIES CO LTD Huawei Confidential Page 44
R8 HSPA(+) LTE
Peak ratesbull 42 Mps DL 11 Mpbs UL in 5 MHzbull 84Mbps DL 22Mbps UL in 10 MHz
bull 43 Mps DL 28 Mpbs UL in 5 MHzbull 86 Mbps DL 57 Mbps UL in 10 MHzbull 173 Mbps DL 115 Mbps UL in 20 MHz
Average throughput in a cell
58 Mbps DL MIMO 2X2 16QAM (5MHz-ISD 500m)
78 Mbps DL MIMO 2X2 (5MHz-ISD 500m)(better OFDM orthogonality less interference)
DL Throughput at cell edge with 800 m ISD
multi cell ndash single user
1 Mbps ( 21 GHz 5 MHz MIMO 2X2 16QAM)
58 Mbps ( 26 GHz 20 MHz MIMO 2X2 64QAM)
Latency User plane 40ms User plane 13-20ms
Scalability Multi-carrier (5MHz stepping) Single User MIMO up to 2x2
Single carrier linear scaling in bandwidth from 14 to 20 MHz - Single user MIMO up to 4x4
FadingTime dependent scheduling and frequency diversity gain vs less efficient spreading over carrier bandwidth (5MHz)
Frequency AND Time dependent scheduling mitigates fading impact
InterferenceSoft frequency re-useICIC
LTE vs HSPA+ comparison summary (22)
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
Thank youwwwhuaweicom
PDF created with pdfFactory Pro trial version wwwpdffactorycom
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