umts long term evolution (lte) overview.pdf · 2010-12-14 · -lte 전환시시시시, ... cost...

UMTS Long Term Evolution (LTE)

안안안안수수수수현현현현[email protected]

1ES/GP

Rohde & Schwarz, Korea

Date | Title of presentation | 2

Overview: Market Trend


이동이동이동이동통신통신통신통신기술기술기술기술동향동향동향동향

“LTE”

“UMB”

“WiLAN(802.11n)”“WiMAX(802.16x)”

OFDMA

+MIMO

GSM/(E)GPRSWCDMA/HSPA

CDMA20001xEVDO

802.11x


Overview

GSM

(EDGE)

GSM

(EDGE)WCDMA/

HSPA

WCDMA/

HSPA

EDGE II

HSPA+

EDGE II

HSPA+

LTE or

WiMAX

LTE or

WiMAX

GSM(EDGE)

GSM(EDGE)

WCDMA/HSPA

WCDMA/HSPA

GSM

(EDGE)

GSM

(EDGE)

CDMA2000CDMA2000

NothingNothing

1xEVDO1xEVDO

MIMO 적용적용적용적용 OFDMA 적용적용적용적용

== 요요요요 약약약약 ==

-현재현재현재현재시장시장시장시장 : 63억억억억인구의인구의인구의인구의약약약약 50% 이동통신이동통신이동통신이동통신이용이용이용이용

-현재현재현재현재 3GPP 시장시장시장시장점유율점유율점유율점유율 : 약약약약 80%

- 3GPP에서에서에서에서 LTE 전환전환전환전환시시시시 , 투자투자투자투자비용비용비용비용최소최소최소최소

- LTE 전환전환전환전환시시시시 , 시장시장시장시장점유율점유율점유율점유율유지유지유지유지및및및및향상향상향상향상가능가능가능가능

- LTE 기술이기술이기술이기술이 WiMAX기술기술기술기술대비대비대비대비우위우위우위우위

�� 단단단단 , 2년년년년정도의정도의정도의정도의 lunching gap

- WiMAX의의의의이동통신이동통신이동통신이동통신시장시장시장시장진입의진입의진입의진입의어려움어려움어려움어려움

�� LTE 대비대비대비대비기술력기술력기술력기술력저하저하저하저하

�� 투자투자투자투자비용의비용의비용의비용의과다과다과다과다

- WiMAX기대기대기대기대시장시장시장시장

�� 기존기존기존기존인터넷인터넷인터넷인터넷사업을사업을사업을사업을무선화무선화무선화무선화시시시시시장시장시장시장형성형성형성형성

�� USB, Note-PC 등에등에등에등에탑재된탑재된탑재된탑재된제품제품제품제품시장시장시장시장현재현재현재현재 이동통신이동통신이동통신이동통신현황현황현황현황

802.11x(WiLAN)

802.11x(WiLAN) 802.11n802.11n 802.11n802.11n


UMTS Long Term Evolution (LTE) Ambitious targets

�Significantly increased peak data rate e.g. 100 Mbps (downlink) and 50 Mbps (uplink)

�Significantly improved spectrum efficiency ( e.g. 2-4 x Release 6)

� Improved latency:

� Possibility for a radio access network latency (user plane UE – RNC - UE) below

10 ms

� Significantly reduced control plane latency

�Scaleable bandwidth

� 5, 10, 15, 20 MHz

� Smaller bandwidths to allow flexibility in narrow spectral allocations

�Support for inter-working with existing 3G systems and non-3GPP specified systems

�Reduced CAPEX and OPEX including backhaul

�Cost effective migration from release 6 UTRA radio interface and architecture

�Efficient support of the various types of services, especially from the PS domain

�System should be optimized for low mobile speed but also support high mobile speed

�Operation in paired and unpaired spectrum should not be precluded (FDD and TDD modes)

�Enhanced Multimedia Broadcast Multicast Services (E-MBMS)


UMTS Long Term Evolution(LTE) Deployment scenarios

�Standalone deployment scenario for EUTRAN

�Integrating with existing 2G/3G deployment scenario

� Handover to and from GERAN and UTRAN will be supported

� Study on handover to and from WiMAX and cdma2000 based

networks has been finalized

�LTE as overlay network on another frequency to increase overallcapacity in certain areas

�Narrower LTE carriers can also be introduced in legacy frequency bandssuch as 900 MHz

�LTE interworking with 3GPP2/WiMAX


Network Structure


Network Architecture

IMT-DS(Direct Spread)

UTRA FDD(WCDMA)

3GPP

IMT-TC(Time Code)

UTRA TDD(TD-S/CDMA)

3GPP

IMT-MC(Multi Carrier)

cdma2000

3GPP2

IMT-SC(Single Carrier)

UWC-136(EDGE)

UWCC/3GPP

IMT-FT(Freq. + Time)

DECT

ETSI

IMT-2000 RAT (ITU-R)

IMT-2000 CN

(ITU-T)

UMTS

CN ⇔ RAT Mapping

Gateways and Interworking Functions

GSM

(MAP)

ANSI-41

(IS-634)

IP-Net

v4, v6


Circuit Switched

Packet Switched

Network Architecture – 3GPP


Network Architecture – 3GPP

� VLR (Visitor Location Register)- User의 Ciphering and authentication 정보- 실제 Location Area의정보

� HLR (Home Location Register) - IMSI 기초로단말의위치를지속적으로관리하는데이터베이스- 착신호를받아단말의등록된 VLR 영역의 MSC로해당호전달- 실제 VLR의 Location 정보(단말의실제위치정보)

� EIR (Equipment Identity Register)- IMEI 등록및관리

� MSC (Mobile Switching Center) - location DB와연동

� SGSN (Serving GPRS Support Node)- 서비스지역내에서이동국과의 Packet 전달을담당하는 Node- 단말에대한이동성및보안 기능담당- HLR과연동하여 Mobility 관리(Packet의이동)- SGSN과 GGSN의 Session 관리(WAP,SMS, MMS등)

� GGSN- Packet Data 망(Mobile Network)과외부 Packet Data 망(IP Network)로의 Gateway- SGSN으로부터오는 Packet을적당한 PDP(Packet Data Protocol) 형식으로변환하여전송


Network Architecture – 3GPP+LTE


eNB functions:

l RRM, Radio Bearer Control, Radio Admission Control,

Connection Mobility Control, Scheduling for uplink and downlink

l IP header compression and encryption of user data stream

l Selection of an MME at UE attachment

l Routing of user plane data towards SAE Gateway

l Scheduling and transmissino of paging messages originated from MME

l Scheduling and transmission of broadcast informationoriginated

from MME or O&M

l Measurement and measurement reporting configuration

LTE Protocol ArchitectureNew network elements and functional split

SAE Gateway:

� Termination of user plane packets for paging reasons

� Switching of user plane for support of UE mobility

MME functions:

� Distribution of paging messages to eNBs

� Security Control

� Idle s tate mobility control

� SAE bearer ccontrol

� Ciphering and integrity protection of NAS Signalling


OFDMA


Wideband Signal

Non-Linear System

Fading

SINR

Amp. Design

Scalable BW


Coherence Bandwidth

)(tx

Time domain view

στ delay spread

)( fX

Freq. domain view

High correlation of amplitudebetween two different freq.

components

Range of freq over

which response is flat

Bc

Coherence BW

- Max Frequency for “Flat” with 1 signal

- Max Frequency for “Comparison” with 2 signal


Block Diagram Transmitter Receiver


How to Increase Data Rates: Modulation

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

��

b1

b2

b3

b4

b5

b6

b7

b8

BPSK

1 symbol = 1 bitQPSK

1 symbol = 2 bit

16 QAM

1 symbol = 4 bit

64 QAM

1 symbol = 6 bitoptional for WiMAX

(+1)

(-1)

(+1,+1)

(+1,-1)(-1,-1)

(-1,+1)

bit to symbol mapping

b1 b1 b1 b1b2 b2 b2b3 b3 b4 b5 b6b4


How to reach higher data rates?

Time

Time

1. Possibility: Reduce Symbol Time

S 1

S 2

S 1

S 2

S 1 S 1

S 2 S 2

delay spread

time time


Weak Points & Solution

Time

Symbol 2

copy

cyclicprefix

useful symbol time

OFDMA symbol time

ICI (Inter-Carrier Interference)

ISI (Inter-Symbol Interference)


ISI and ICI: Guard Intervall

lSymbol l-1

L

l+1

L

n

( )h n∗

L

L

L

L

L

L

Delay spread

Receiver DFT

Window

GT Delay Spread>

Guard Intervall guarantees the supression of ISI!

But, there is some week point in the “Amplifier”


Receiver DFT

Window

Guard Intervall as Cyclic Prefix

lSymbol l-1

L

l+1

L

n

( )h n∗

L

L

L

L

L

L

Delay spread

GT Delay Spread>

Cyclic Prefix guarantees the supression of ISI and ICI!

Cyclic Prefix


Degradation due to Frequency Offset

f

f∆

f0 f2Samples

f1 f3f0 f2f1 f3

2j nfe π∆

( )ls n ( )lr n

Channel


Degradation due to Clock Offset

f

f0 f2Samples

f1 f3f0 f2f1 f3

ε( )ls n ( )lr n

Channel

f k∆ ∝


•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

Difference between OFDM and OFDMA

l OFDM allocates users in time

domain only

l OFDMA allocates users in time and

frequency domain

•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

•••••••••

Time domain Time domain

Frequencydomain

Frequencydomain

User

3

User

3User

2

User

2

User

1

User

1


Localized versus Distributed FDMA


OFDMA vs SC-FDMA


MIMO


MIMO (Multiple In Multiple Out)

l Technical Overview for

l DEGE Evolution

l WiMAX

l HSPA+

l LTE

l IEEE 802.11n

l 1xEVDO Rev C (UMB)

UMB = Universal Mobile Broadband


SU-MIMO versus MU-MIMO

s1 s2 sn

… …

UE1

UE2

UEn

� SU (Single User)-MIMO

l Goal: to increase user data rate

l Simultaneous transmission of

different data streams to 1 user

l Efficient when the user

experiences good channel conditions

� MU (Multiple User)-MIMO

l Goal: to increase sector capacity

l Selection of the users

experiencing good channel

conditions

l Efficient when a large number of users have an active data

transmission simultaneously


MIMO & SIMO & MISO

Trans-

mitterReceiver

MIMO 2x2

Trans-

mitter Receiver

SIMO 1x2

Trans-mitter

Receiver

MISO 2x1


MIMO modes

� Transmit diversity (TxD)� 사용사용사용사용목적목적목적목적 : Reliability 향상(Get a higher SNR at the Rx)

� Replicas of the same signal sent on several Tx antennas

� Array gain : Power

� Diversity gain : STBC/SFBC

� No Feedback

� Spatial multiplexing (SM)� 사용사용사용사용목적목적목적목적 : Data Throughput 향상

� Different data streams sent simultaneously on different antennas

� Higher data rate

� No diversity gain

� Limitation due to path correlation

� Beamforming� 사용사용사용사용목적목적목적목적 : Reliability/Data Throughput 향상

� Intelligent Antenna : Switched/Adaptive Antenna

� Some Feedback

� CDD (Cyclic Delay Diversity)� 사용사용사용사용목적목적목적목적 : Reliability 향상(Frequency Selectivity 및 Channel Decoder의 Performance 향상)


� Transmit diversity:� Space Time Block Coding (STBC), Space Frequency Block Coding (SFBC)

� 2TX : STBC / 4TX : STBC+SFBC

� Increasing robustness of transmission

� Spatial Multiplexing에적용가능(2X1 or 3X2 or 4X2 MIMO인경우)

� Beamforming 적용(Adaptive Antenna)

� Indoor=TXD, Outdoor=BF 적합

� Open-SM & RI=1 일때, TXD 적용

� Spatial multiplexing:� Codebook based precoding

� Transmission of different data streams simultaneously over multiple spatial layers

� Beamforming 적용(Adaptive Antenna)

� CDD 적용(Zero, small delay and large delay)

� Closed-SM : 저속 UE, PMI/RI를 Feedback받아 Layer/Codeword/Precodeing결정(Zero, small Delay)

� Open-SM : 고속 UE, RI만이용하여 Layer/Codeword/Precoding 처리(Large Delay &RI>1)

LTE MIMO Downlink modes


RX Diversity = SIMO

Aim:

increase of S/N ratio

�� increase of throughput

Trans-mitter

Recei-

ver

same signal via different paths

=> different fading

SNR

(dB)

Received Signals

Switched Diversity

C = max(A,B)

CA

B

Maximum Ratio Combining

C = (A+B)


Receive Diversity


TX Diversity = MISO

TXData

Proces-

sing

TX

Data

“Intelligence on RX side“

RX

Data Proces-

sing

RXData

“Intelligence on TX side“

Motivation for Alamouti Space-Time-Coding:- increase of range,

- improvement of BER,

- improvement of antenna diversity,

- improvement of signal quality


-s2*

s1 s2

Space Time Coding

time

space

Section of the

input bit-stream

Alamouti Matrix

Matrix A

-s2*

s1 s2

s1*

s1 s2-s2* s1*

s1*

s1 s2-s2* s1*

s1 s2

math.

operation s1 s2

s1 s2=

Receiver

Transmitter


Transmit diversity


Spatial Multiplexing (MIMO 2x2)

TX RXs1 s2 s3 s4

s1

s2

s3

s4

s1 s2 s3 s4

Motivation for Space-Time-Coding with Matrix B:

- increase of data rate by multiplexing (theory by factor 2)


MIMO with the SMU: K74 SW option


The MIMO promise

� Channel capacity grows linearly with antennas ☺☺☺☺

� Assumptions �� Perfect channel knowledge � Spatially uncorrelated fading

� Reality �� Imperfect channel knowledge� Correlation ≠ 0 and rather unknown

Max Capacity ~ min(NTX, NRX)


MIMO channel

know

Singular Value

Decomposition

r = H s + n

s1

s2

r1

r2

channel H

MIMO

wanted

r = D s + n~ ~~

s1

s2

r1

r2

channel D

~

~ ~

~SISO


MIMO channel

s1

s2

r1

r2

channel H

MIMO

s1

s2

r1

r2

channel D

~

~ ~

~SISO

H =h11

h21

h12

h22

D =d1

0

0

d2

h11

h22

h12

h21

d1

d2

This is the reality ��

What we like to have ☺☺☺☺

Mathematical

Wizard: SVD


h11

h21

h12

h22

r = H s + n

r = H s + n

Singular Value Decomposition (SVD)

(U*)T (U*)T(U*)T

h11

h21

h12

h22

U (V*)Td1

0

0

d2

r = D s + nU (V*)Td1

0

0

d2

(U*)T (U*)T(U*)T U (V*)Tr = D s + nd1

0

0

d2

~~ ~


Downlink spatial multiplexing - precoding

l The signal is “pre-coded” at Node B side before transmission

l Optimum precoding matrix is selected from predefined “codebook” known at Node B and UE side

l UE estimates the channel, selects the best precoding matrix at the

moment and sends back its index


MIMO: avoid inter-channel interference

Idea: F adapts transmitted signal to current channel conditions

Link adaptation

Transmitter

F

H+

+

Space time

receiver

xk yk

V1,k

VM,k

Feedback about H

e.g. linear precoding:

Y=H*F*S+V

S


d(0)d(1)

MIMO Precoding in LTE (DL)Tx diversity (2 antennas)

Tx 1

d(0)d(1)

t

Symbolsd(0)

t

Tx 2d(1)

t

t

t

d(0) * -d(1)*

LayerMapper Precoding

Resourceelementmapper

d(0)

d(1)

d(0) *

-d(1)*

t

f

t

f

Resourceelementmapper

1 code word

Space Frequency Coding (SFC)


MIMO Precoding in LTE (DL)Tx diversity (4 antennas)

d(0)d(1)d(2)d(3)

t

Symbols

d(0)

t

d(1)

t

d(2)

t

d(3)

t

d(0)d(1)00

t

00d(2)d(3)

t

00

t

00

t

-d(1)*d(0)*

d(2)* -d(3)*

Tx 1

d(0)

d(1)

t

f

0

0

Tx 2

t

f

0

0

Tx 3

t

f

0

0

Tx 4

t

f

0

0

d(2)

d(3)

-d(1)*

d(0)*

d(2)*

-d(3)*

1 code word

Not all antennas transmit at the same time and frequency !


MIMO Precoding in LTE (DL)Spatial multiplexing – Code book for precoding

Codebook

index

Number of layers υ

1 2

0

0

1

10

01

2

1

1

1

0

−11

11

2

1

2

1

1

2

1

− jj

11

2

1

3

−1

1

2

1 -

4

j

1

2

1 -

5

− j

1

2

1 -

Code book for 2 Tx:

Additional multiplication of the layer

symbols with codebook entry


MIMO Precoding in LTE (DL)Spatial multiplexing – Code book for precoding

2 examples for 2 layers and 2 Tx antennas

10

01

2

1

−11

11

2

1

d(0)d(1)

t

Layer 1

b(0)b(1)

t

Layer 2

d(0)d(1)

t

Layer 1

b(0)b(1)

t

Layer 2

Tx 1

Tx 2

d(0)

d(1)

b(1)

b(0)

t

f

t

f

2

1

2

1

Tx 1

Tx 2

t

f

t

f


But there is more to LTE layer 1 than just MIMO…

� LTE physical layer procedures

� Cell search

� Link Adaptation

� Power control

� Uplink synchronisation and Uplink timing control

� Random access related procedures

� Support of HARQ related procedures


Some technical details of LTE / EUTRA


UMTS Long Term Evolution (LTE) All new again, here‘s what is most important:

l New radio transmission schemes

l OFDMA in downlink:

Orthogonal Frequency Division Multiple

Access

l SC-FDMA in uplink:

Single Carrier Frequency Division Multiple

Access

l MIMO Multiple antenna technology

l New radio protocol architecture

l Complexity reduction

l Focus on shared channel operation, no

dedicated channels any more

l New network architecture

l New functional split between radio network nodes

l More functionality in the base station (eNodeB)

l Focus on packet switched domain

l System architecture evolution (SAE)

l MBMS

l Support of Multimedia Broadcast, Multicast Service


LTE Physical Layer


LTE Downlink: Physical layer tasks

� Error detection on the transport channel and indication to higher layers

� FEC encoding/decoding of the transport channel

� Hybrid ARQ soft-combining

� Rate matching of the coded transport channel to physical channels

� Mapping of the coded transport channel onto physical channels

� Power weighting of physical channels

� Modulation and demodulation of physical channels

� Frequency and time synchronisation

� Radio characteristics measurements and indication to higher layers

� Multiple Input Multiple Output (MIMO) antenna processing

� Transmit Diversity (TX diversity)

� Beamforming

� RF processing(Note: RF processing aspects are specified in the TS 36.100 series)


LTE: new physical channels for data and control

Physical Downlink Control Channel PDCCH:Downlink and uplink scheduling decisions

Physical Downlink Shared Channel PDSCH: Downlink data

Physical Control Format Indicator Channel PCFICH:Indicates Format of PDCCH

Physical Hybrid ARQ Indicator Channel PHICH:ACK/NACK for uplink packets

Physical Uplink Control Channel PUCCH:ACK/NACK for downlink packets, scheduling requests, channel quality info

Physical Uplink Shared Channel PUSCH: Uplink data


LTE Downlink: Downlink Physical Channels

- Physical Downlink Shared Channel, PDSCH: � Used for data transfer, shared principle, variable modulation

� Mapping between DL-SCH and PCH

� MBMS information can be mapped

- Physical Downlink Control Channel, PDCCH� specific control information, shared principle, fixed modulation QPSK

� Carries scheduling decision from eNodeB

� Informs UE about resource allocation fo PCH and DL-SCH

� HARQ information related to DL-SCH

� UL scheduling grant

� Mapped to 2-4 symbols in case of less than 10 RB

� Mapped to 1-3 symbols in case of bigger than 10 RB

- Common Control Physical Channel, CCPCH� General control information, broadcast principle, fixed modulation QPSK

- Physical Multicast Channel, PMCH� Like PDSCH, but no transmit multiplexing


LTE Downlink: Downlink Physical Channels

- Physical control format indicator channel, PCFICH : � The physical control format indicator channel carries information about the number of

OFDM symbols (1-3 or 2-4) used for transmission of PDCCHs in a subframe. Only

QPSK.

� Transferred in every sub-frame

- Physical HARQ Indicator Channel, PHICH� The PHICH carries the hybrid-ARQ ACK/NAK, fixed modulation QPSK

- Physical Broadcast Channel PBCH� General control information, broadcast principle, fixed modulation QP나� MIB (Master Information Block) Transmission

� 4 subframes within a 40ms interval

� 40 ms timing is blindly detected


LTE Uplink: Uplink Physical Channels

- Physical Uplink Shared Channel, PUSCH• For user data, shared scheduling principle, variable modulation scheme: QPSK, 16-

QAM, 64-QAM. Timing similar to downlink

- Physical Uplink Control Channel, PUCCH• For uplink control information, never transmit simultaneous to PUSCH. Frequency

and time multiplexed, fixed modulation scheme: QPSK.


LTE Physical Layer:OFDMA in downlink


LTE Downlink:How does the OFDMA signal look like?

…

Sub-carriersFFT

Time

Symbols

5 MHz Bandwidth

Guard I ntervals

…

Frequency

� Each sub-carrier (frequency channel) carries a separate low-rate stream of data

� Frequencies are chosen so that the modulated data streams are orthogonal to each other

� Each sub-carrier is independently modulated

� A guard time is added to each symbol (cyclic prefix in LTE)

� Symbol duration is relatively long compared to channel delay spread -> less intersymbol interference


LTE Downlink:OFDMA Time/Frequency Representation

OFDM symbols (time domain)

Sub carriers (frequency domain)

0

0

1 LTE slot of 0.5 ms =

6 / 7 OFDM symbols dep. on cyclic prefix length

(3 symbols for 7.5 kHz spacing / MBMS scenarios)

• Sub-carrier spacing in LTE = 15 kHz

(7.5 kHz for MBMS scenarios)

• Data is allocated in multiples of resource blocks

• 1 resource block spans 12 sub-carriers in the

frequency domain and 1 slot in the time domain

• Resource block size is identical for all bandwidths

1 LTE Resource Block =

12 sub-carriers

Normal scenario: carrier

spacing of 15 kHz

Big cell scenario: 7,5 kHz +

extended guard time


time

frequency

1 resource block =

180 kHz = 12 subcarriers

1 slot = 0.5 ms =

7 OFDM symbols**

1 subframe =

1 ms= 1 TTI*=

1 resource block pair

LTE DownlinkOFDMA time-frequency multiplexing

*TTI = transmission time interval

** For normal cyclic prefix duration

Subcarrier spacing = 15 kHz

QPSK, 16QAM or 64QAM modulationQPSK, 16QAM or 64QAM modulation

UE1UE1

UE4UE4

UE3UE3UE2UE2

UE5UE5 UE6UE6


LTE – spectrum flexibility

l LTE physical layer supports any bandwidth from 1.4 MHz

to 20 MHz in steps of 180 kHz (resource block)

l Current LTE specification supports only a subset of 8

different system bandwidths

l All UEs must support the maximum bandwidth of 20 MHz

Transmission

Bandwidth [RB]

Transmission Bandwidth Configuration [RB]

Channel Bandwidth [MHz]

Resource block

Channel e

dge

Channel edge

DC carrier (downlink only)Active Resource Blocks

100755025[16][TBD][7][TBD]TDD mode

100755025n/a15 n/a6FDD mode

20151053.23 1.61.4

Channel

bandwidth

BWChannel

[MHz]

number of resource blocks


LTE Downlink:Downlink slot and (sub)frame structure

Ts = 32.522 ns

#0 #0 #1 #1 #2 #2 #3 #3 #19 #19

One slot, T slot = 15360 × T s = 0.5 ms

One radio frame, T f = 307200 × T s = 10 ms

#18 #18

One subframe

We talk about 1 slot, but the minimum resource is 1 subframe = 2 slots !!!!!

( )2048150001s ×=T

Symbol time, or number of symbols per time slot is not fixed


LTE Downlink:baseband signal generation

OFDM

Mapper

OFDM signal

generationLayer

Mapper

Scrambling

Precoding

Modulation

Mapper

Modulation

Mapper

OFDM

Mapper

OFDM signal

generationScrambling

code words layers antenna ports

Avoid

constant

sequences

QPSK

16 QAM

64 QAM

For MIMO

Split into

Several

streams if

needed

Weighting

data streams

for MIMO

1 OFDM

symbol per

stream

1 stream =

several

subcarriers,

based on

Physical

ressource

blocks


LTE Downlink: Bandwidth agnostic L1

Will be defined by RAN4

One downlink slot, Tslot

One resource block,

NRBsubcarriers

subcarriers

NBW

DL

subcarriers

NBW

DL

NBW

DL

Resource element

OFDM symbolsDLsymbN OFDM symbolsDLsymbN

RBBW

DLBW

RBBW 1106 NNN ×≤≤×

DLBWN

4324

86

Extended cyclic

prefi x

97

12

Normal cyclic prefi x

Frame structure t ype 2Frame structure t ype 1

Configuration

DLsymbNDL

symbN

kHz 15=∆f

kHz 15=∆f

kHz 5.7=∆f

Effective bandwidth is a multiple of

physical ressource block, i.e. 12 * 15kHz or 24 * 7,5 kHz

RB

BWN


LTE Downlink: Resource-element Groups(REG)

� Basic unit for mapping of PDCCH, PHICH,

PCFICH

� Resource-element groups are used for defining

the mapping of control channels to resource

element

� Mapping of a symbol-quadruplet <z(i),

z(i+1),z(i+2),z(i+3)> onto a REG is defined such

that elements z(i) are mapped to resource

elements (k,l) of the REG not used for cell-specific

reference signals in creasing order of i and k


Modulation

QPSK, 16QAM, 64QAMPDSCH

QPSK, 16QAM, 64QAMPMCH

Modulation schemesPhysical channel

QPSKPBCH


QPSKPCFICH


QPSKPDCCH


BPSKPHICH



LTE Downlink: Mapping

Transmit DiversityNumber of layers Number of code words Codeword-to-layer mapping

1 1 )()(

)0()0(idix = 1,...,1,0 symb −= Mi

2 1

)12()(

)2()(

)0()1(

)0()0(

+=

=

idix

idix

2)1(,...,1,0 symb −= Mi

4 1

Spatial Multiplexing

2 code words are

sent = higher data

rate

1 code word is

sent on separate

pathes = better SNR

Transmission rank Number of code words Codeword-to-layer mapping

1 1 )()()0()0(idix =

2 2 )()(

)0()0(idix =

)()()1()1(idix =

3 2 )()0(id is mapped to layer 0

)()1(id is mapped to layer 1 and 2

4 2 )(

)0(id is mapped to layer 0 and 1

)()1(id is mapped to layer 2 and 3


LTE Downlink: Precoding

Number of antenna ports

Transmission rank

Codebook

P ρ

1 1 [ ]1 - - - - -

1

0

1

1

0

1

1

2

1

−1

1

2

1

j

1

2

1

− j

1

2

1

2

2

10

01

2

1

−11

11

2

1

− jj

11

2

1 - - -

1 2

3 4

4

Precoding base on cyclic delay diversity, UE proposes which

Codebook entry shall be selected by transmitter


LTE Downlink: Downlink Reference Signals

� Downlink reference signal(s) can be used for

� Downlink-channel-quality measurements

� Downlink channel estimation for coherent demodulation/detection at the UE

� Cell search and initial acquisition (carries cell ID)

Of course, there will be reference signals

� Cell-specific reference signals, associated with non-MBSFN transmission

� MBSFN reference signals, associated with MBSFN transmission

� UE-specific reference signals (supported in frame structure type 2 only)


LTE Downlink: Cell-specific Ref. Signals■ Normal and extended CP

� 504 unique Cell ID

• 168(N1) Cell ID group, 3(N2) Cell ID within each group

• Cell ID = 3xN1+N2 = 0~503 index

� 504 pseudo-random sequences

� One to one mapping between the Cell ID and Pseudo-random sequences

� Transmit on antenna port {0,1,2,3}

� Cell-specific Frequency Shift (N1 mod 6) (effective with RS boosting)

• 1 RE shift from current RS position in case of next Cell ID index

■ Pseudo-random sequence generation

� ns is the slot number within a radio frame

� l is the OFDM symbol number within the slot

� The pseudo-random sequence c(i) is a length-31 Gold sequence

( ) ( ) 11210 ,)12(212

1)2(21

2

1)( PDSCH

RB, −=+⋅−+⋅−= N,...,,mmcjmcmrsnl

( )( ) ( ) CPcellID

cellIDs NNNlnc +⋅++⋅⋅+++⋅⋅= 212117210init

(2)ID

(1)ID

cellID 3 NNN +=


LTE Downlink, Common Control physical channel:Downlink Reference Signals - mapping

R0

R0

R0

R0

R0

R0

R0

R0

0=l 6=l 0=l 6=l

R0

R0

R0

R0

R0

R0

R0

R0

0=l 6=l 0=l 6=l

R1

R1

R1

R1

R1

R1

R1

R1

0=l 6=l 0=l 6=l

even-numbered slots odd-numbered slots

R3

R3

R3

R3

0=l 6=l 0=l 6=l

R0

R0

R0

R0


R0

R0

R0

R0

0=l 6=l 0=l 6=l

R1

R1

R1

R1


R1

R1

R1

R1

0=l 6=l 0=l 6=l

even-numbered slots odd-numbered s lots

R2

R2

R2

R2

0=l 6=l 0=l 6=l

One antenna port

Two antenna ports

Four antenna ports

Antenna port 0 Antenna port 1 Antenna port 2 Antenna port 3

Not used for transmission on this antenna port

Reference symbols on th is antenna por t

( )lk,element Resource

1 antenna configuration



Pilots are place

that each antenna

can be recognised


LTE Downlink: Hopping/Boosting for DL RS

■ Cell-specific frequency hopping or shifting (FH/FS) is supported �� No hopping

� The mode of operation in a cell is static

� FH/FS sequence acquired from cell group ID (FH/FS per sub-frame)

• There is one-to-one mapping between the RS hopping sequence and the two-dimensional PRBS

� Blind detection of hopping mode and non-hopping mode by UE

■ RS power Boosting

�Motivation : provisioning of enough RS power to the cell edge UEs

� Boosting of all of the unicast RS

� By the NodeB configuration, puncturing can be applied (UE is informed by system

information) to data subcarriers in the same OFDM symbol


Initial synchronizationBCH and SCH always located at the center

Primary synchronisation channel:

Secondary synchronisation channel:

•Created from Zadoff-Chu sequence (zero Autocorrelation codes)

•The primary synchronization signal is transmitted on 72 active subcarriers, centred around the DC subcarrier.

•Created from Zadoff-Chu sequence (zero Autocorrelation codes)

•The primary synchronization signal is transmitted on 72 active subcarriers, centred around the DC subcarrier.

•secondary synchronization signal is transmitted in and only in slots where the primary •synchronization signal is transmitted.

2DLsymb −= Nl

1DLsymb −= Nl( ) 61,...,0

231 ,

RB

sc

DL

RB, =+−== n

NNnknda lk

( ) 61,...,0 2

31 ,

RB

sc

DL

RB

, =+−== nNN

nknda lk


Initial synchronization : PSS

■ The sequence for the PSS is generated from a freq.-domain Zadoff-Chu sequence (Length-62)

=

== ++−

+−

61,...,32,31

30,...,1,0)(

63

)2)(1(

63

)1(

ne

nend

nnuj

nunj

u π

π

■ Background of Zadoff-Chu Sequence

� Appeared in IEEE Trans. I in 1972

� Poly-phase sequence

� Cyclic autocorrelations are zero for all non-zero lags Non-zero cross-correlations

� PAPR이낮아 (신호의 Amplitude 일정) 전력소모적측면에서유리

� CAZAC (Constant Amplitude Zero Auto Correlation) Sequence의일종

{ }2,1,0)2(ID ∈N

)(21)(~ ixic −= 300 ≤≤ i

( ) 250 ,2mod)()3()5( ≤≤++=+ iixixix

)31mod)3((~)(

)31mod)((~)(

)2(

ID1

)2(

ID0

++=

+=

Nncnc

Nncnc

<TS 36.211 / Table 6.11.1.1-1>


Initial synchronization : SSS

■ The sequence for the PSS is an interleaved concatenation of two m-sequence (length 31)

■ The concatenated sequence is scrambled with a scrambling sequence given by PSS

■ 2 m-sequences are differ between subframe 0 and subframe 5

( )( )( ) ( )( ) ( )

=+

=

5 subframein )(

0 subframein )()12(

5 subframein )(

0 subframein )()2(

)(11

)(0

)(11

)(1

0)(

1

0)(

0

10

01

1

0

nzncns

nzncnsnd

ncns

ncnsnd

mm

mm

m

m

)31mod)3((~

)(

)31mod)((~

)(

)2(ID1

)2(ID0

++=

+=

Nncnc

Nncnc ( )( )31mod)(~

)(

31mod)(~

)(

1)(

1

0)(

0

1

0

mnsns

mnsns

m

m

+=

+=

)31mod))8mod(((~)( 0)(

10 mnznz

m +=

)31mod))8mod(((~)( 1)(

11 mnznzm +=

<TS 36.211 / Table 6.11.2.1-1>


LTE Downlink: BCH■ Primary BCH

�Master information block of system information is transmitted on Primary BCH

• L1 parameters (e.g. DL system BW[4bits], etc…

• System frame Number (SFN)

• PHICH duration (1bit)

• PHICH resource (2bits)

• Etc…

■ Dynamic BCH

� After successful reception of PBCH, UE can read D-BCH in PDSCH (including PCFICH and PDCCH) which carries system information not included in PBCH

• Uplink information (uplink bandwidth, uplink RS configuration and TX power

• PRACH information (time/freq-domain configuration, preamble format, root sequence index, zerocorrelation zone length, high-speed flag, power setting, RA-RNTI)

• Sounding reference signal information (subframes with SRS transmission)

• PUCCH, PUSCH information (base sequence group, hopping pattern, …)

• One or more PLMN identities and related information

• Tracking Area Code

• Cell Identity

• Number of transmit antennas

• RS transmit power

• Etc…


LTE Downlink: BCH

■ The coded BCH transport block is mapped to four subframes (slot#1 in subframe #0)

■ BCH mapped to 4 OFDM symbols within a subframe

■ Each subframe is assumed to be self-decodable, i.e. the BCH can be decoded from a signal

reception, assuming sufficiently good channel conditions

■Single (fixed-size) transport block per TTI (40ms)

� No HARQ

� Cell-specific scrambling, BPSK with ½ tail-biting Conv. Code, TX diversity(1,2,4)

� 6RBs = 72 subcarries (excluding DC)

■ PBCH is mapped into RE assuming RS from 4 antennas are used at eNB, irrespective of the actual

number of TX antenna

■ Different transmit diversity schemes per # of antennas

� # of ant=2 : SFBC

� # of ant=4 : SFBC + FSTC (Frequency Switching Transmit Diversity)

■ No explicit bits in the PBCH to signal the number of TX antennas at eNB

� PBCH encoding chain includes CRC masking dependent on the number of configured TX antennas at eNB

� Blind detection of the number of TX antenna using CRC masking by UE


LTE DownlinkConfiguration of synchronization signals

10 ms radio frame

1 2 3 4 5 6 7 1 2 3 4 5 6 7

0.5 ms slot

1 ms subframe

Primary synchronization signal

Secondary synchronization signal

Screenshot of R&S SMU200A signal generator


LTE DownlinkConfiguration of physical broadcast channel

10 ms radio frame

1 2 3 4 5 6 7 1 2 3 4 5 6 7

0.5 ms slot

1 ms subframe

Primary synchronization signal

Secondary synchronization signalPhysical Broadcast Channel (PBCH)

PBCH has 40 ms transmission time interval


LTE downlinkSynchronization and reference signals, PBCH

50 resource

blocks in 10 MHz

10 subframes = 140 OFDM symbols

Screenshot of R&S

SMU200A signal generator


LTE downlinkHierarchical cell search scheme

0 1 ………….. 167

Physical layer identity 0 1 20 1 20 1 2

Physical layer cell identity group

identified by:

Physical layer

cell identity

(1 out of 504)


LTE DownlinkCell search procedure

1. Primary synchronization signal:

3 possible sequences to identify the cell’s physical layer identity (0, 1, 2)

Transmitted every 5 ms to identify 5 ms timing

2. Secondary synchronization signal:

168 different sequences to identify physical layer cell identity group

Transmitted every 5 ms to identify radio frame timingDownlink

reference signal

3. Physical broadcast channel (PBCH):

Carrying broadcast channel with predefined information:

system bandwidth, number of transmit antennas, reference

signal transmit power, system frame number,…

Physical layer

cell identity

(1 out of 504)


Initial synchronizationBCH and SCH always located at the center

20MHz bandwidth

SCH

10 MHz bandwidth

1.25 MHz bandwidth

BCH


CAZAC sequence – constellation diagramConstant Amplitude Zero Auto Correlation


Constellation Display (DL FDD, 10 MHz) I

QPSK-modulated user data


Constellation Display (DL FDD, 10 MHz) II

Reference signals in 1st and 5th OFDM symbol (Symbol #0 and #4)


Constellation Display (DL FDD, 10 MHz) III

Secondary Synchronization

Signal in 6th OFDM symbol(= symbol #5, RBPSK modulation)

Primary Synchronization

Signal in 7th OFDM symbol(= symbol #6, Zadoff-Chu-Sequence)


LTE Downlink: PCFICH

■ The number of OFDM symbols used for control channel is variable

■ TTI마다바뀔수 있음

■ CFI (Control Format Indication)

■ Information about the number of OFDM symbols (1~4) used for transmission of PDCCHs in a subframe

■ PCFICH carries CFI

■ Cell-specific scrambling prior to modulation

■ 2 info bits � Coding rate of 1/16 � Number ofo bits = 32bits

■Modulation : QPSK

■Mapping to resource elements : 4REG (16 RE excluding RS) in the 1st OFDM symbol

■ Spread over the whole system bandwidth

■ Same mapping for 1,2 and 4 antennas

3GPP TS 36.212 / Table 5.3.4-1: CFI codewords

<0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0>4 (Reserved)

<1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1>3

<1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0>2

<0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1,1,0,1>1

CFI codeword < b0, b1, …, b31 >CFI

<10 RB : 2~4 OFDMA symbols

>10RB : 1~3 OFDMA symbols


LTE Downlink: PDCCH

■ First n OFDM symbols

■ <10 RB : 2~4 OFDMA symbols

■ >10RB : 1~3 OFDMA symbols

■ Scheduling assignment

■ Transport format, resource allocation, HARQ info related to DL-SCH, PCH

■ Transport format, resource allocation, HARQ info related to UL-SCH

■ DPCCH format based on # of CCE (Control Channel Element = 9 REGs) used

3GPP TS 36.211 / Table 6.8.1-1: Supported PDCCH formats

576

288

144

72

Number of PDCCH bits

7283

3642

1821

910

Number of REGsNumber of CCEsPDCCH format

■ Cell-specific scrambling, QPSK with tail-biting Conv. Code

■ TX diversity, the same antenna ports as PBCH

■ Mapped to REG no assigned to PCFICH or PHICH


LTE Downlink: PDCCH

■ DCI transports downlink or uplink scheduling information, or uplink power control commands

For the transmission of TPC commands for PUCCH and PUSCH with single bit power

adjustment3A

For the transmission of TPC commands for PUCCH and PUSCH with 2-bit power

adjustment3

For scheduling PDSCH to use configured in open-loop SM2A

For scheduling PDSCH to use configured in closed-loop SM2

For the compact scheduling of one PDSCH codeword with precoding and power offset

information1D

For very compact scheduling of one PDSCH codeword (paging, RACH response and

dynamic BCCH scheduling)1C

For the compact scheduling of one PDSCH codeword with precoding information

(closed-loop single-rank)1B

For the compact scheduling of one PDSCH codeword (SIMO, TxD)1A

For the scheduling of one PDSCH codeword (SIMO, TxD)1

For the scheduling of PUSCH0

DescriptionDCI Formats


PDCCH layer 1/2 control channel contentsUplink scheduling grant (DCI format 0)

� Hopping flag – 1 bit

� Resource block assignment and hopping resource allocation

� Modulation and coding scheme, redundancy version – 5 bits

� New data indicator – 1 bit

� TPC command for scheduled PUSCH – 2 bits

� Cyclic shift for demodulation reference signal – 3 bits

� Uplink index for TDD - 2 bits

� CQI request – 1 bit


PDCCH layer 1/2 control channel contentsDownlink scheduling assignment (DCI format 2)

� Resource allocation header (allocation type 0 or 1) – 1 bit

� Resource block assignment

� TPC command for PUCCH and persistent PUSCH – 2 bits

� Downlink assignment index for TDD – 2 bits

� Number of layers – 2 bits

� HARQ process number – 3 bits (FDD), 4 bits (TDD)

� Transport block to code word swap flag – 1 bit

� Precoding information and confirmation

For the first codeword:

� Modulation and coding scheme – 5 bits

� New data indicator – 1 bit

� Redundancy version – 2 bits

For the second codeword:

�Modulation and coding scheme – 5 bits

�New data indicator – 1 bit

�Redundancy version – 2 bits


LTE Downlink: PHICH

■ HARQ ACK/NACK in response to UL transmission

■ PHICH group

■ Multiple PHICHs mapped to the same set of REs (CDM & I/Q)

■ HI codewords with length of 12 Res = 4 (spreading) X 3 (repetition)

■ Orthogonal sequence : Walsh

■ BPSK Modulation with I/Q multiplexing

■ SF4 X I/Q = 8 PHICHs in normal CP

■ SF4 X I/Q = 4 PHICHs in extended CP

■ Cell-specific scrambling

■ TX diversity, the same antenna ports as PBCH

■ 3 groups of 4 contiguous REs (not used for RS and PCFICH)

3GPP TS36.811 / Table 6.9.1-2: Orthogonal sequences for PHICH

3GPP TS36.812 / Table 5.3.5-1: HI codewords

< 1,1,1 >1

< 0,0,0 >0

HI codeword

< b0, b1, b2 >HI


LTE DownlinkConfiguration of physical broadcast channel


Physical Downlink SharedChannel (PDSCH)

I would like to receive data on

PDSCH but I don‘t know which

resource blocks are allocated for meand how they look like

?

Physical Downlink ControlChannel (PDCCH)

Check PDCCH for your UE ID. As soon as you are addressed, you will

find all the information you need there.

LTE downlinkScheduling of downlink data


I would like to read the PDCCH butwhere is it?

?

Physical Control Format

Indicator Channel (PCFICH)

Check PCFICH. It will tell you how manysymbols (1, 2, or 3)in the beginning of the

subframe are allocated for PDCCH.

Physical Control Format Indicator Channel (PCFICH) Indicating PDCCH format

Physical Downlink Control

Channel (PDCCH)


Physical Hybrid ARQ Indicator Channel (PHICH) Acknowledging uplink data packets

Physical Uplink Shared Channel

(PUSCH)

I have sent data packets on PUSCHbut I don‘t know whether they have

been received correctly.

?

Physical Hybrid ARQ

Indicator Channel (PHICH)

Read the PHICH. It carries ACK orNACK for each single packet.


LTE Physical Layer:SC-FDMA in uplink


LTE Uplink:How to generate an SC-FDMA signal in theory?

� LTE provides QPSK,16QAM, and 64QAM as uplink modulation schemes

� Each subcarrier carries a portion of superposed DFT spread data symbols

� CAZAC (Constant Amplitude Zero Autocorrelation) sequence 사용

� Ref. signal 및제어정보채널전송시각단말들의신호를구분하기위해CDM을수행하는경우,

CAZAC sequence를주로사용

� CAZAC sequence는 time/freq. domain에서일정한 amplitude를유지하는특성을가지므로단말의 PAPR을낮추어커버리지를증가시키기에적합함

� MU-MIMO 지원

DFT Sub-carrier Mapping

CP insertion

Size-NTX Size-NFFT

Coded symbol rate= R

NTX symbols

IFFT


LTE Uplink:How does the SC-FDMA signal look like?

� In principle similar to OFDMA, BUT:

� In OFDMA, each sub-carrier only carries information related to one specific symbol

� In SC-FDMA, each sub-carrier contains information of ALL transmitted symbols


LTE uplinkSC-FDMA time-frequency multiplexing


LTE Uplink: SC-FDMA parametrization for PUSCH and PUCCH, slot format

One uplink slot, T slot

2 1 0

Modulation symbol

2 UL symb − N 1 UL

symb − N

2 , UL symb − N u a


LTE Uplink: Physical Channels in uplink� Physical Uplink Shared Channel, PUSCH

� Uplink data with localized transmission (with/without hopping)

� Frequency hopping is available on both slot basis and subframe basis

� Physical Uplink Control Channel, PUCCH� Carries HARQ ACK/NACK in response to DL transmission

� Carries Scheduling Request (SR), CQI, PMI and RI

� PUCCH transmission

� Physical Random Access Channel, PRACH

� Carries the random access preamble

� UCI transmission with PUSCH

� CQI/PMI is multiplexed with PUSCH and mapped into PUSCH bands

� ACK/NAK is multiplexed with PUSCH by punchuring the data

� RS would be transmitted through RRC Signalling (RAN2)

� UL Signal� An uplink physical signal is used by the physical layer but does not carry information originating from

higher layers

� UL RS (Uplink Reference Signal) for PUSCH, PUCCH

� UL Sounding RS not associated with PUSCH, PUCCH transmission

※ Can’t send PUSCH/PUSCCH at same time


LTE Uplink: Reference Signals

� DM RS

� Uplink channel estimation for uplink coherent demodulation/detection

� CAZAC sequence로생성

� Normal CP = 4th symbol / Extended CP = 3rd symbol

� Inter-cell Interference를완화하기위해 Group hopping/Sequence Hopping 적용

� Group hopping :

� Base seq. group index값이 slot단위로변화

� 17개의 hopping pattern마다 30개의Group hopping Index (shift pattern)

� Seq. hopping :

� DM RS의길이가 5RB보다큰경우, 한한한한 sub-frame내에서내에서내에서내에서 slot단위로단위로단위로단위로 Base seq. index간간간간hopping이이이이 이루어짐이루어짐이루어짐이루어짐

� Sounding RS

� uplink channel-quality estimation for better scheduling decisions

� PUxCH와 무관

� SRS 전송주기/서브프레임/대역폭은 각단말마다 고유하게할당 (최소 4RB)

� SRS는 subframe의 마지막 SC-FDMA symbol로전송

� Not used yet


LTE Uplink : Physical Uplink Control Channel (PUCCH)

frequency

1 ms subframe

resource i

resource i

resource j

resource j

� PUCCH is never transmitted simultaneously with PUSCH from the same UE

� Only needed when there is no PUSCH available

� Carries Uplink Control Information (UCI) in PUCCH or PUSCH

� Carries ACK/NACK, CQI, PMI, RI and SR (Scheduling Request)

� Symbol mapping of BPSK or QPSK

� 2 consecutive PUCCH slots in Time-Frequency Hopping at the slot boundary


LTE UplinkPhysical Uplink Control Channel (PUCCH)


LTE Uplink : PUSCH Frequency Hopping

� PUSCH Transmission

� 1 bit indication in UL grant whether frequency hopping or not (in DCI format=0 / hopping bit=1)

� Localized transmission w/o frequency hopping

Frequency Selective Scheduling Gain

� Localized transmission with frequency hopping

Frequency Diversity Gain, Inter-cell Interference Randomization

Hopping based on the hopping information in UL grant (type 1 – according to hopping bits)

Hopping according to a predefined hopping pattern (type 2 - according to hopping pattern)

� Transmission and hopping modes are given from UL scheduling grant

� Inter subframe / Intra subframe PUSCH hopping (related to UE mobility)

� Set of PRBs (for PUSCH) to be used for transmission are given by scheduling grant

If hopping with predefined hopping pattern is enabled, a predefined pattern is used together

� When grant is absent, e.g., in cases of persistent scheduling and HARQ retransmission, UE follows the

indication for hopping mode in the initial grant (with RACH)

� A single bit signalled by higher layer indicates whether PUSCH frequency hopping is inter-subframe

only or both intra and inter-subframe


50 resource

blocks in 10 MHz

Demodulation pilot signal

Screenshot of R&S SMU200A

signal generator

LTE UplinkPhysical Uplink Shared Channel (PUSCH)


LTE Uplink: Resource allocation


LTE Uplink: Random Access Procedure

Higher layers indicate position of random access in frequency/time domain


LTE Uplink : Random access preamble

CPT SEQT

9Even15

0, 1, 2, 3, 4, 5, 6, 7, 8, 9Any14

1, 3, 5, 7, 9Any13

0, 2, 4, 6, 8Any12

3, 6, 9Any11

2, 5, 8Any10

1, 4, 7Any9

3, 8Any8

2 ,7Any7

1, 6Any6

7Any5

4Any4

1Any3

7Even2

4Even1

1Even0

Subframe numberSystem frame numberPRACH configuration

� PRACH 는 RA 과정에서단말이기지국으로전송하는 Preamble

� 6RB를차지하며 subcarrier는 1.25KHz (Format #4는 7.5KHz)

� Sequence 부분은길이 839의 ZC sequence로구성 (Format#4는길이 139)

� 5 types of preamble formats (Higher layers control the preamble format/configuration)


LTE Protocol ArchitectureBasic


Packet Date Convergence Protocol

•compression of redundant protocol control

information(TCP/IP, RTP/UDP/IP headers)

•Transfer of user data(PDCP SDU from NAS) to

RLC

•support of losless relocation of SRNS

Broadcast/Multicast Control Protocol

•Storage of Cell Broadcast Messages.

•Traffic volume monitoring and radio

resource request for CBS.

•Scheduling of BMC messages.

•Transmission of BMC messages to UE.

•Delivery of Cell Broadcast messages to

upper layer (NAS)

Summary of layers


WCDMA/HSPA

UE UENode-B Node-B RNCRNC

HSDPA HSUPA


User plane

PDCP = Packet Data Convergence Protocol

RLC = Radio Link Control

MAC = Medium Access ControlPHY = Physical Layer

SDU = Service Data Unit

(H)ARQ = (Hybrid) Automatic Repeat Request

Header compression (ROHC)

In-sequence delivery at handoverDuplicate detection

Ciphering for user/control plane

Integrity protection for control plane

Timer based SDU discard in Uplink…

AM, UM, TM

ARQ

(Re-)segmentation

ConcatenationIn-sequence delivery

Duplicate detection

SDU discard

Reset…

Mapping between logical and

transport channels(De)-Multiplexing

Traffic volume measurements

HARQ

Priority handlingTransport format selection…


Control plane

EPS = Evolved packet system

RRC = Radio Resource ControlNAS = Non Access Stratum

ECM = EPS Connection Management

Broadcast

Paging

RRC connection setupRadio Bearer Control

Mobility functions

UE measurement control…

EPS bearer management

Authentication

ECM_IDLE mobility handling

Paging origination in ECM_IDLESecurity control…


LTE Protocol ArchitectureUser and Control Plane


E-UTRA Logical Channel – Transport Channel

Uplink

Downlink

LTE

BCHBCCH

PCH

PCCH

CCCH

DCCH

DTCH

CTCH

MBMS CHs

FACH

DCH

CCCH

DCCH

DTCH

RACH

DCH

BCHBCCH

PCH

PCCH

CCCH

DCCH

DTCH

MBMS-CHs

DL-SCH

MCH

CCCH

DCCH

DTCH

RACH

UL-SCH

HS-DSCH

E-DCH

Rel. 6


LTE – channels

PRACH PUCCH PUSCH

UL-SCHRACH

DTCHCCCH DCCH

UL logical channels

UL transport channels

UL physical channels


l Reduced number of transport channels

l Shared channels instead of dedicated channels

l Reduction of Medium Access Control (MAC) entities

l Streamlined concepts for broadcast / multicast (MBMS)

l No inter eNodeB soft handover in downlink/uplink

l No compressed mode

l Reduction of RRC states

LTE Protocol ArchitectureReduced complexity


Initial access procedure

UE eNB

Random Access Preamble1

Random Access Response 2

Scheduled Transmission3

Contention Resolution 4

Random ID

Sent on DL-SCH;

assignment of Temporary

C-RNTI and initial uplink

grantSent on UL-SCH; includes

NAS UE identifier and RRC CONNECTION REQUEST

Sent on DL-SCH; addressed

to Temporary C-RNTI (early

contention resolution)


RRC Connection Establishment

RRC CONNECTION SETUP

RRC CONNECTION REQUEST

UE EUTRAN

RRC CONNECTION SETUP COMPLETE


Initial context establishment


LTE measurements


LTE RF Testing AspectsUE requirements according to 3GPP 36.521/523

�Transmitter Characteristics:� Maximum output power

� Frequency error

� Output power dynamics (power control, transmit on/off power,…)

� Output RF spectrum emissions (occupied bandwidth, out of band emissions, spectrum emisssionmaks, ACLR,…)

� Transmit intermodulation

� Modulation quality, EVM� …

TR 36.803: User Equipment (UE) radio

transmission and reception

�Receiver characteristics:� Reference sensitivity level

� Maximum input level

� Adjacent channel selectivity� Blocking characteristics

� Spurious response

� Intermodulation characteristics

� Spurious emissions� …

�Performance


There will be enough topics

for future trainings ☺

Thank you for your attention!

Comments and questions welcome!

umts long term evolution (lte) overview.pdf · 2010-12-14 · -lte 전환시시시시, ... cost...

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