lte system interfaces
TRANSCRIPT
-
7/31/2019 LTE System Interfaces
1/66
www.huawei.com
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.
Security Level: Internal Use
LTE System Interfaces
2010-09
-
7/31/2019 LTE System Interfaces
2/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page2
On completion of this course, you should be able to:
Know the overall architecture of E-UTRAN, function split
between CN and RAN
Know the radio interface protocol stack and the function of
each layer
Know the physical layer functions and basic procedures
Know S1/X2 interface protocol stack and the functions of the
interfaces.
Objectives
-
7/31/2019 LTE System Interfaces
3/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page3
References
3GPP TS36.211
3GPP TS36.300
3GPP TS36.410
3GPP TS36.420
-
7/31/2019 LTE System Interfaces
4/66Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page4
1. Overview
2. Radio interface
3. S1 interface
4. X2 interface
Contents
-
7/31/2019 LTE System Interfaces
5/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page5
LTE/SAE Architecture
SGSN
GPRS
UMTS
E-UTRAN
cdma2000
MME
HSS PCRF
Serving GW PDN GW
BTS BSC/PCU
NodeB RNC
eNodeB
S2b
S1-U
S6a
Gx
S5/8
Gb
Iu
S1-MMES12
S3
S4S11
SGi
S9S10
User plane
Control plane
BTS
Internet
Corporate
Internet
Operator Service
Network
EPS (Evolved Packet System)
S6d
PDSNBSC
A10/A11
MME: Mobility management entity
PCRF: Policy and Charging Rules Function
-
7/31/2019 LTE System Interfaces
6/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page6
Functional Split between E-UTRAN and EPC
internet
eNB
RB Control
Connection Mobility Cont.
eNB Measurement
Configuration & Provision
Dynamic ResourceAllocation (Scheduler)
PDCP
PHY
MME
S-GW
S1
MAC
Inter Cell RRM
Radio Admission Control
RLC
E-UTRAN EPC
RRC
Mobility
Anchoring
EPS Bearer Control
Idle State MobilityHandling
NAS Security
P-GW
UE IP address
allocation
Packet Filtering
eNB
MME / S-GW MME / S-GW
eNB
eNB
S1
S1
S1
S1
X2
X2X2
E-UTRAN
-
7/31/2019 LTE System Interfaces
7/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page7
General protocol model for E-UTRAN interfaces
General principle for S1/X2 is that the layers and planes are logically
independent of each other. Therefore, as and when required, the
standardization body can easily alter protocol stacks and planes to fit
future requirements.
ApplicationProtocol
TransportNetwork
Layer
Physical Layer
SignallingBearer(s)
TransportUser NetworkPlane
Control Plane User Plane
TransportUser NetworkPlane
RadioNetwork
Layer
DataBearer(s)
-
7/31/2019 LTE System Interfaces
8/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page8
Control plane protocol stacks
SCTP
L2
L1
IP
L2
L1
IPSCTP
S1-MMEeNodeB MME
S1-APS1-AP
NAS
MAC
L1
RLC
PDCP
UE
RRC
MAC
L1
RLC
PDCP
RRC
LTE-Uu
NASRelay
-
7/31/2019 LTE System Interfaces
9/66
-
7/31/2019 LTE System Interfaces
10/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page10
1. Overview
2. Radio interface
3. S1 interface
4. X2 interface
Contents
-
7/31/2019 LTE System Interfaces
11/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page11
Radio interface protocol stack
LTE does not have BMC entity
All types of RB need PDCP processing
NAS
relay
S1 UuUuS1
-
7/31/2019 LTE System Interfaces
12/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page12
RRC services and functions
-
7/31/2019 LTE System Interfaces
13/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page13
RRC services and functions
Broadcast of System Information related to NAS and AS
Mobility functions including:
UE measurement reporting and control of the reporting for mobility;
UE cell selection and reselection and control of cell selection and reselection;
Context transfer at handover.
Establishment, maintenance and release of an RRC connection between the
UE and E-UTRAN including:
Allocation of temporary identifiers between UE and E-UTRAN;
Configuration of signaling radio bearer(s) for RRC connection:
Security functions including key management;
Establishment, configuration, maintenance and release of point to point
Radio Bearers;
-
7/31/2019 LTE System Interfaces
14/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page14
RRC protocol states & state transitions
LTE supports 2 RRC states: RRC_IDLE and RRC_CONNECTED
RRC_IDLE:
PLMN selection;
Broadcast of system information;
Paging;
Cell re-selection mobility;
No RRC context stored in the eNB
RRC_CONNECTED
UE has an E-UTRAN-RRC connection;
E-UTRAN knows the cell which the UE
belongs to;
Network can transmit and/or receive
data to/from UE;
Neighbor cell measurements;
-
7/31/2019 LTE System Interfaces
15/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page15
Relation between RRC state and NAS states
EPS Mobility Management (EMM) state includes:
EMM-DEREGISTERED
EMMREGISTERED
EPS Connection Management (ECM) state includes:
ECM-IDLE ECM-CONNECTED
-
7/31/2019 LTE System Interfaces
16/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page16
E-UTRAN identities
E-UTRAN Cell Global Identifier (ECGI): used to identify cells globally.
The ECGI is constructed from the MCC (Mobile Country Code), MNC (Mobile
Network Code) and the ECI (E-UTRAN Cell Identifier).
ECI: used to identify cells within a PLMN.
ECI has a length of 28 bits and contains the eNB Identifier.
Global eNB Identifier: used to identify eNBs globally.
The Global eNB Identifier is constructed from the MCC (Mobile Country Code),
MNC (Mobile Network Code) and the eNB-Id (eNB Identifier).
eNB Identifier: used to identify eNBs within a PLMN.
The eNB Id is contained within the E-UTRAN Cell Identifier
-
7/31/2019 LTE System Interfaces
17/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page17
Segm.
ARQ etc
Multiplexing UE1
Segm.
ARQ etc...
HARQ
Multiplexing UEn
HARQ
BCCH PCCH
Scheduling / Priority Handling
Logical Channels
Transport Channels
MAC
RLCSegm.
ARQ etc
Segm.
ARQ etc
PDCP
ROHC ROHC ROHC ROHC
Radio Bearers
Security Security Security Security
...
Layer 2 in overall
Layer 2 is split into the following sublayers:
Medium Access Control (MAC), Radio Link Control (RLC) and
Packet Data Convergence Protocol (PDCP)
-
7/31/2019 LTE System Interfaces
18/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page18
PDCP Sublayer
The main services and functions of the PDCP sublayer
Header compression and decompression for user plane data.
Security functions:
ciphering and deciphering;
integrity protection and verification
eNB
RLC
MAC
PHY
PDCP
RRC
NAS Signaling
Control Plane
Encryption
Integrity Checking
User Plane
IP Header Compression
Encryption
Sequencing and Duplicate Detection
-
7/31/2019 LTE System Interfaces
19/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page19
RLC Sublayer
The main services and functions of the RLC sublayer include:
Transfer of upper layer PDUs supporting AM, UM and TM
Error Correction through ARQ (CRC check provided by the physical layer)
Concatenation of SDUs for the same radio bearer;
Duplicate Detection;
Segmentation;
SDU discard;;
eNB
RLC
MAC
PHY
PDCP
RRC
NAS Signaling
TM (Transparent Mode)UM (Unacknowledged Mode)
AM (Acknowledged Mode)Segmentation and Re-Assembly
ConcatenationError Correction
-
7/31/2019 LTE System Interfaces
20/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page20
MAC Sublayer
The main services and functions of the MAC sublayer include:
Mapping between logical channels and transport channels;
Multiplexing/demultiplexing of RLC PDUs belonging to one or different radio
bearers into/from transport blocks (TB) delivered to/from the physical layer;
Priority handling between logical channels of one UE;
Priority handling between UEs;
Error correction through HARQ;
Padding;
Transport format selection;
eNB
RLCMAC
PHY
PDCP
RRC
NAS Signaling
Channel Mapping and MultiplexingError Correction - HARQ
QoS Based Scheduling
-
7/31/2019 LTE System Interfaces
21/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page21
Physical Layer
eNB
RLC
MAC
PHY
PDCP
RRC
NAS SignalingError Detection
FEC Encoding/DecodingRate Matching
Mapping of Physical ChannelsPower Weighting
Modulation and DemodulationFrequency and Time Synchronization
Radio MeasurementsMIMO ProcessingTransmit Diversity
Beamforming
RF Processing
-
7/31/2019 LTE System Interfaces
22/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page22
LTE channel mapping-downlink
DL-SCH
Physical Layer
MAC Layer
RLC Layer
PDCP Layer
RRC Layer
PhysicalChannels
TransportChannels
LogicalChannels
PDSCH
PDCCH
PHICHPCFIC
HPBCH
BCH PCH
BCCH PCCH CCCH DCCH DTCH
TM TM TM UM/AM UM/AM
Ciphering
Integrity
Ciphering
ROHC
RRC
ESM EMM IPNAS Layer
-
7/31/2019 LTE System Interfaces
23/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page23
LTE channel mapping-uplink
Physical Layer
MAC Layer
RLC Layer
PDCP Layer
RRC Layer
PhysicalChannels
TransportChannels
LogicalChannels
PUSCH
PUCCH
PRACH
RACH
CCCH
TM UM/AM UM/AM
Ciphering
Integrity
Ciphering
ROHC
RRC
ESM EMM IPNAS Layer
UL-SCH
DCCH DTCH
-
7/31/2019 LTE System Interfaces
24/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page24
Transport channels
Downlink:
Broadcast Channel (BCH)
fixed, pre-defined transport format;
Downlink Shared Channel (DL-SCH)
support for HARQ
support for dynamic link adaptation by varying the modulation, coding and
transmit power;
possibility to use beam forming;
support for both dynamic and semi-static resource allocation;
support for UE DRX to enable UE power saving;
support for MBMS transmission
-
7/31/2019 LTE System Interfaces
25/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page25
Transport channels
Downlink: Paging Channel (PCH)
support for UE DRX to enable UE power saving
mapped to physical resources which can be used dynamically also for
traffic/other control channels
Multicast Channel (MCH)
support for MBSFN combining of MBMS transmission on multiple cells
-
7/31/2019 LTE System Interfaces
26/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page26
Transport channels
Uplink:
Uplink Shared Channel (UL-SCH)
possibility to use beam forming
support for dynamic link adaptation by varying the transmit power and
potentially modulation and coding;
support for HARQ;
support for both dynamic and semi-static resource allocation.
Random Access Channel(s) (RACH)
limited control information;
collision risk;
-
7/31/2019 LTE System Interfaces
27/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page27
Physical layer frame structure -FDD
Type 1, applicable to FDD
The downlink OFDM sub-carrier spacing is f= 15 kHz, a reduced sub-carrier
spacing f= 7.5 kHz is only for MBMS-dedicated cell
Slot (0.5ms)
Radio Frame Tf = 307200 x Ts = 10ms
Subframe (1ms)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Ts = 1/(15000x2048) =
32.552083ns
Tslot = 15360 x Ts
Ph i l l f TDD
-
7/31/2019 LTE System Interfaces
28/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page28
Physical layer frame structure -TDD
Type 2 Radio Frame Tf = 307200 x Ts = 10ms
0
Special
Subfram
e
2 3 4 5 7 8 9
DwPTS
(Downlink Pilot
Time Slot)
GP (Guard
Period)
UpPTS (Uplink
Pilot Time Slot)
Page 28
Type 2, applicable to TDD
-
7/31/2019 LTE System Interfaces
29/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page29
Type 2 Radio Frame Switching Points
Configuration SwitchingPoint
Periodicity
Subframe Number
0 1 2 3 4 5 6 7 8 9
0 5ms D S U U U D S U U U
1 5ms D S U U D D S U U D
2 5ms D S U D D D S U D D
3 10ms D S U U U D D D D D
4 10ms D S U U D D D D D D
5 10ms D S U D D D D D D D
6 5ms D S U U U D S U U D
Page 29
Physical layer frame structure FDD(1/2)
-
7/31/2019 LTE System Interfaces
30/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page30
Physical layer frame structure-FDD(1/2)
In the case of 15 kHz sub-carrier spacing there are two cyclic-prefix lengths,
corresponding to seven and six OFDM symbols per slot respectively
Normal cyclic prefix:
TCP = 160
Ts (OFDM symbol #0) , TCP = 144
Ts (OFDM symbol #1 to #6) Extended cyclic prefix: TCP-e = 512Ts (OFDM symbol #0 to OFDM symbol #5)
In case of 7.5 kHz sub-carrier spacing, there is only a single cyclic prefix length
TCP-low = 1024Ts, corresponding to 3 OFDM symbols per slot.
Radio Frame = 10ms
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
7 OFDMSymbols (Normal
Cyclic Prefix)
6 OFDM Symbols
(Extended CyclicPrefix)
0 1 2 3 4 5 6
0 1 2 3 4 5
CP (Cyclic
Prefix)
Ts
Ts
Ph i l l f t t FDD(2/2)
-
7/31/2019 LTE System Interfaces
31/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page31
Physical layer frame structure-FDD(2/2)
h l d f
-
7/31/2019 LTE System Interfaces
32/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page32
LTE physical resource definition
Basic definitions
Resource element
Resource block
RB
scN
ULsymbNConfiguration
Normal cyclic prefix 12 7
Extended cyclic prefix 12 6
h i l l i
-
7/31/2019 LTE System Interfaces
33/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page33
Physical layer processing
Bit level processing:
Transport block from MAC layer
24 bit CRC is the baseline
Channel coding: Turbo coding Channel coding
Rate matching
Code blockconcatenation
110 ,...,, Aaaa
110 ,...,, Bbbb
110 ,...,, rKrrr ccc
)(
1
)(1
)(0 ,...,,
iDr
ir
ir r
ddd
110 ,...,, rErrr eee
110 ,...,, Gfff
Transport blockCRC attachment
Code block segmentationCode block CRC attachment
Ph i l l i
-
7/31/2019 LTE System Interfaces
34/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page34
Physical layer processing
Symbol level processing:
The scrambling stage is applied to all downlink physical channels, and serves the
purpose of interference rejection
Modulation: QPSK, 16QAM, and 64QAM (64 QAM optional in UE)
ScramblingModulation
Mapper
Layer
MapperPrecoding
Resource
Element
Mapper
OFDM
Signal
Generation
Resource
Element
Mapper
OFDM
Signal
Generation
ScramblingModulation
Mapper
Codewords LayersAntenna
Ports
Synchronization signals
-
7/31/2019 LTE System Interfaces
35/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page35
Synchronization signals
The primary and secondary synchronization signals are used in the cell search
procedure. The particular sequences which are transmitted for the PSS andSSS in a given cell are used to indicate the physical layer cell identity to the UE
The synchronization signals are always transmitted on the 62 centre sub
carriers and specified symbols.
d i f
-
7/31/2019 LTE System Interfaces
36/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page36Page36
PSS and SSS Location for FDD
0 1 2 3 4 5 6
Bandwidth
0 1 2 3 4 5
Bandwidth
Normal CP
Extended CP
Radio Frame
Slots 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Repeated in
slots 0 and 10
72Subcarriers
PSS (PrimarySynchronizationSequence)
SSS(SecondarySynchronizationSequence)
62Subcarri
ers
Synchronization signals
-
7/31/2019 LTE System Interfaces
37/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page37
Synchronization signals
There are 504 unique physical layer cell identities in LTE, grouped into 168
groups of three identities.
The three identities in a group would usually be assigned to cells under the
control of the same eNodeB. Three PSS sequences are used to indicate the
cell identity within the group.
168 SSS sequences are used to indicate the identity of the group.
cell (1) (2)
(1)
(2)
DownlinkSyn
chronizationS
ignals
eNB
UE
Where:
NID = 3NID + NID
NID = 0,..167NID = 0, 1, or 2
Ph i l C ll Id titi
-
7/31/2019 LTE System Interfaces
38/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page38Page38
Physical Cell Identities
eNB
eNB
eNB
PSS - One of 3 Identities
SSS - One of 168
Group Identities
504 Unique Cell
Identities
l
-
7/31/2019 LTE System Interfaces
39/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page39Page39
PSS Correlation
Subframe
Correlation
PSS0
PSS1
PSS2
SSS C l i
-
7/31/2019 LTE System Interfaces
40/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page40Page40
SSS Correlation
Subframe
SSS
SSS
Cyclic Shift based
on Cell ID and
Subframe (0 or 5)
Device can identify
Cell ID and frame
timing
E l f SSS I di
-
7/31/2019 LTE System Interfaces
41/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page41Page41
Example of SSS Indices
N 1ID m0 m1 N
1ID m0 m1 N
1ID m0 m1 N
1ID m0 m1 N
1ID m0 m1
0 0 1 34 4 6 68 9 12 102 15 19 136 22 27
1 1 2 35 5 7 69 10 13 103 16 20 137 23 28
2 2 3 36 6 8 70 11 14 104 17 21 138 24 29
3 3 4 37 7 9 71 12 15 105 18 22 139 25 30
. . . . .
. . . . 167 2 9
33 3 5 67 8 11 101 14 18 135 21 26
Cell search procedure
-
7/31/2019 LTE System Interfaces
42/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page42
Cell search procedure The first step of cell search is to do matched filtering between the received
signal and the sequences specified for the primary synchronization signal,
When the output of the matched filter reaches its maximum, the terminal is
likely to have found timing on a 5 ms basis, and the identity within the cell-
identity group.
The second step is to detects the cell-identity group, by observing pairs ofslots where the secondary synchronization signal is transmitted, since each
combination (s1, s2) in subframe zero and five represents one of the cell
identity groups uniquely
In the case of the initial synchronization, in addition to the detection of
synchronization signals, the UE proceeds to decode the Physical Broadcast
CHannel (PBCH), from which critical system information is obtained.
Cell Search
-
7/31/2019 LTE System Interfaces
43/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page43Page43
Cell Search
0 1 2 3 4 5 6 7 8 9
Frame - 10ms
5MHz (25ResourceBlocks)
PSS
SSS
PBCH
Downlink Reference signals
-
7/31/2019 LTE System Interfaces
44/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page44
Downlink Reference signals
Cell-specific downlink reference signals
The reference signal is used to make channel estimation and carry out downlinkcoherent detection and demodulation
The RS sequence also carries unambiguously one of the 504 different cell identities
Cell-specific reference symbol arrangement in the case of normal CP length for one
antenna port:
R
R
R
R
R
R
R
R
Physical Cell ID = 0
R
R
R
R
R
R
R
R
Physical Cell ID = 8
RS position is basedon Physical Cell ID
(Physical Cell ID mod
6)
eNB eNB
Downlink Reference signals
-
7/31/2019 LTE System Interfaces
45/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page45
Downlink Reference signals
Cell-specific downlink reference signals in case of 2 and 4 antenna port
Downlink Physical channels
-
7/31/2019 LTE System Interfaces
46/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page46
Downlink Physical channels
Physical broadcast channel (PBCH)
P-BCH transmitted only in the centred frequency, BW is 72 subcarriers
P-BCH use QPSK
P-BCH occupy symbol 7,8,9,10 of the centred 6RB
P-BCH is used to carry BCH for system information broadcast
Only MIB (Master Information Block) which consists of a limited number of the most
frequently transmitted parameters essential for initial access to the cell is carried on
PBCH
Other System Information Blocks (SIBs) which, at the physical layer, are multiplexed
together with uncast data are transmitted on the Downlink Shared Channel
PBCH-physical broadcast channel
-
7/31/2019 LTE System Interfaces
47/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page47
MIB
System
Bandwidth
CRC
Channel Coding
Rate Matching
Scrambling
ModulationLayer Mapping
Precoding
Mapping to REs
10ms Frame
PBCH
PBCH physical broadcast channel
Downlink Physical channels
-
7/31/2019 LTE System Interfaces
48/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page48
Downlink Physical channels
Physical downlink shared channel (PDSCH)
PDSCH is used to carry DL-SCH, PCH and BCH
User data, broadcast system information which is not carried on the
PBCH, and paging messages may be transmitted on PDSCH
Physical multicast channel (PMCH)
PMCH is used to carry MCH for MBMS service
Downlink Physical channels
-
7/31/2019 LTE System Interfaces
49/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page49
Downlink Physical channels
Physical control format indicator channel (PCFICH)
Carries information about the number of OFDM symbols used for
transmission of PDCCHs in a subframe.
Three different CFI values are used in the first version of LTE.
In order to make the CFI sufficiently robust each codeword is 32 bits in
length. These 32 bits are mapped to 16 resource elements using QPSK
modulation
In order to achieve frequency diversity, the 16 resource elements carrying
the PCFICH are distributed across the frequency domain. This is done
according to a predefined pattern in the first OFDM symbol in each
downlink subframe.
Downlink Physical channels
-
7/31/2019 LTE System Interfaces
50/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page50
Downlink Physical channels
Physical downlink control channel (PDCCH)
Informs the UE about the resource allocation of PCH and DL-SCH, and
Hybrid ARQ information related to DL-SCH
Carries the uplink scheduling grant
Multiple PDCCHs can be transmitted in a subframe
The set of OFDM symbols possible to use for PDCCH in a subframe is the
first n OFDM symbols where n 3
Physical Hybrid ARQ Indicator Channel (PHICH)
Carries Hybrid ARQ ACK/NAKs in response to uplink transmissions.
Downlink resource allocation sample
-
7/31/2019 LTE System Interfaces
51/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page51
p
72 center RE
Control channelCFI/PHI/PDCCH
Sync channel PBCH
User 1 PDSCH User 2 PDSCH
-
7/31/2019 LTE System Interfaces
52/66
Uplink Reference signals
-
7/31/2019 LTE System Interfaces
53/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page53
p g
Demodulation reference signal (DM RS)
The DM RSs associated with uplink PUSCH data or PUCCH control transmissions
are primarily provided for channel estimation for coherent demodulation, and
are present in every transmitted uplink slot.
The DM RSs of a given UE occupy the same bandwidth as its PUSCH/PUCCH
data transmission (same RBs)
The position of uplink reference signals in a slot:
Uplink Reference signals
-
7/31/2019 LTE System Interfaces
54/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page54
p g
Sounding reference signal (SRS)
The subframes in which SRS are transmitted by any UE within the cell are
indicated by cell-specific broadcast signalling (srsSubframeConfiguration)
The SRS transmissions are always in the last SC-FDMA symbol in the configured
subframes
The eNodeB in LTE may either request an individual SRS transmission from a UE
or configure a UE to transmit SRS periodically until terminated
The specific SRS bandwidth to be used by a given UE is configured through RRCsignalling
Uplink Physical channels
-
7/31/2019 LTE System Interfaces
55/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page55
p y
Physical uplink shared channel (PUSCH)
carries data from the Uplink Shared Channel (UL-SCH) transport channel
Physical uplink control channel (PUCCH)
Carries Hybrid ARQ ACK/NAKs in response to downlink transmission;
Carries Scheduling Request (SR);
Carries CQI reports.
Uplink Physical channels
-
7/31/2019 LTE System Interfaces
56/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page56
p y Physical random access channel (PRACH)
Carries the random access preamble
One or several subframes is reserved for preamble transmission in a frame, and
In the frequency domain, the random-access preamble has a bandwidth
corresponding to six resource blocks
The physical layer random access burst consists of a cyclic prefix, a preamble,
and a guard time to avoid interference
A fixed number (64) of preamble signatures is available
Initial Procedures
-
7/31/2019 LTE System Interfaces
57/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page57
PLMN/Cell
Selection
Downlink Synchronization
Complete
Power On Cell SearchRACH
Process
Uplink SynchronizationComplete
Send
Preamble
Identify RACHPreambles
Identify
PRACH
Format
Receive
Response
No
Decode
Response
Yes
Send RRC
Connection
Request
MAC
Connection
Resolution
SRB
Established
Uplink Physical channels
-
7/31/2019 LTE System Interfaces
58/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page58
Contention-based random access procedure
On request of higher layers which should provides:Random access channel parameters, a single preamble istransmitted using an random selected preamble sequence
network transmitting a timing advancecommand and assigns uplink resources to
the terminal to be used in the third step
transmission of the mobile-terminal identity to the network, C-RNTI(LTE-CONNECTED) or a CN terminal identifier(IDLE)
contention-resolution message is transmitted on the DL-SCH, If theterminal has not yet been assigned a C-RNTI, the temporary identityfrom the second step is promoted to the C-RNTI, Terminals which donot find a match between the identity are considered failed
LTE channel mapping
-
7/31/2019 LTE System Interfaces
59/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page59
pp g
Contents
-
7/31/2019 LTE System Interfaces
60/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page60
1. Overview
2. Radio interface
3. S1 interface
4. X2 interface
S1 Interface architectureS1 f ti
-
7/31/2019 LTE System Interfaces
61/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page61
EPCEUTRAN
eNode
B
S1-U
S1-MME
S-GTW
MME
eNode
B
S-GTW
MME
S1 functions:
S1 UE context management function:
Establishment/release SAE bearer context, security context, UE S1 signalingconnection ID(s), etc.
SAE bearer management functions
GTP-U tunnels management function
S1 Signalling link management function
Intra-LTE handover
Inter-3GPP RAT handover
Paging function
Network sharing function
NAS node selection function
Security function
S1 Interface
-
7/31/2019 LTE System Interfaces
62/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page62
eNB
IP
Layer 2
Layer 1
SCTP
S1AP
Control Plane
S1-MME
MME
IP
Layer 2
Layer 1
UDP
GTP-U
User Plane
eNB
S1-U
S-GW
Contents
-
7/31/2019 LTE System Interfaces
63/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page63
1. Overview
2. Radio interface
3. S1 interface
4. X2 interface
X2 Interface architecture
-
7/31/2019 LTE System Interfaces
64/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Page64
X2 functions:
Intra LTE-Access-System Mobility Support for UE in LTE_ACTIVE: Context transfer from source eNB to target eNB;
Control of user plane tunnels between source eNB and target eNB;
Handover cancellation.
Load Management
Inter-cell Interference Coordination
Uplink Interference Load Management;
General X2 management and error handling functions:
Error indication.
Trace functions
X2 Interface
-
7/31/2019 LTE System Interfaces
65/66
Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved.Copyright 2010 Huawei Technologies Co., Ltd. All rights reserved. Page65
eNB eNB
X2
IP
Layer 2
Layer 1
SCTP
X2AP
Control Plane
IP
Layer 2
Layer 1
UDP
GTP-U
User Plane
-
7/31/2019 LTE System Interfaces
66/66
Thank you
www.huawei.com