52926489 LTE Technical Principles

8/2/2019 52926489 LTE Technical Principles

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LTE Technical Principles


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Agenda

1. LTE/LTE-A Requirements

2. E-UTRAN Architecture

3. LTE Physical Layer functionalities

4. LTE Higher Layer protocol stacks

5. LTE A Technologies


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3 | Titre de la prsentation | Mois 2008 Alcatel-Lucent 2008, d.r., XXXXX

LTE/LTE-A Requirements

1


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LTE Design Objective

Provide significantly improved power, bandwidth efficiencies, and

delay in e-UTRA User-plane latency: < 5 ms one way (UE to Core Network)

Control-plane latency: < 100ms (camped to active), < 50ms (dormant to active)

Facilitate the convergencewith other networks/technologies

Reduce transport network cost packet switching system

Downlink

100 Mbps peak data rate in 20 MHz

2x2 MIMO

User throughput

3-4x HSDPA (average)

2-3x HSDPA (5% CDF)

Spectral Efficiency

3-4x HSDPA

Uplink

50 Mbps peak data rate in 20 MHz

Assumes one Tx antenna

User throughput

2-3x E-DCH (average)

2-3x E-DCH (5% CDF)

Spectral Efficiency

2-3x E-DCH


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LTE/LTE-A Target Performance

Item LTE Requirement LTE Results LTE-A Requirement

Peak Data Rate

DL > 100Mbps

(5 bps/Hz)

326.4Mbps(4 layer)

172.8 Mbps(2 layer)

1 Gbps

(30 bps/Hz)

UL > 50Mbps

(2.5 bps/Hz)

86.4 Mbps (64QAM)

57.6 Mbps (16QAM)

500 Mbps

(15 bps/Hz)

Latency

C-plane Idle Active < 100msec 51.25 ms + 3 * S1

delay

< 50 ms

Dormant (DRX)

Active

< 50msec Much shorter than

51.25 ms

< 10 ms

U-plane < 5msec 4 ms < 5 msec (better

than LTE)


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Delay Budget to achieve 5 ms in UTRA

UEU-pla

ne latency components in LTE


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Items LTE Requirement Evaluation results LTE-A Requirements

Average

Spectrum

Efficiency

DL 3-4 UTRA (0.53

bps/Hz )

1.56 2.67 bps/Hz 3.5 bps/Hz

UL 3-4 UTRA (0.332

bps/Hz)

0.68 1.03 bps/Hz 1.7 bps/Hz

Cell Edge

Spectrum

Efficiency

DL 2-3 UTRA (0.02

bps/Hz)

0.04 0.08 bps/Hz 0.06-0.1 bps/Hz

UL 2-3 UTRA (0.009

bps/Hz)

0.01-0.052 bps/Hz 0.035-0.6 bps/Hz

VoIP 300 per 5 MHz

Average Throughput/Edge Throughput/VoIP Capacity



Coverage

LTE Target/Requirement Evaluation results LTE-A Requirments

User throughput and spectrum

efficiency should be met the

target in up to 5 km cell range

Same or somewhat lower

than that in ISD of 1732 m

Same as LTE

Support of very large cell Support for an adjustable random-access-burst length

for large cell

Same as LTE



EnhancedMBMSandNetworkSynchronization

Item LTE Requirement Evaluation results LTE-A Requirements

Enhanced MBMS 1 bps/Hz in an urban or

suburban environment

D1 3.13 bps/Hz (1619 ISD)

D2 3.02 bps/Hz (2310 ISD)

D3 0.99 bps/Hz (1619 ISD)

D4 3.18 bps/Hz (4375 ISD)

Better than LTE

Network

Synchronization

Inter-site time

synchronization should

be supported providedthese bring sufficient

benefits

The benefits of

synchronised system is

clarified

Same as R-8 LTE


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E-UTRAN Architecture

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E-UTRA Architecture

Objectives for the architecture evolution - Develop a System Tailored todeliver broadband and real time Packet Switched services

Reduced latency compared with the current UMTS system.

Fast state transition between dormant and connected mode

Reduce signalling and call set up time

Simplify system deployment and operation & maintenance plug & play

Competitive with other emerging technologies Flat-IP Architecture for e-UTRA

Scalability to support the high data rates required for LTE

No single point of failure and load sharing and redistribution capabilities

Reduced number of nodes for lower transport delay

Backhaul costs should be minimized

Simplicity in supporting system plug & play


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Outlook of E-UTRA Architecture Evolution

UMTS NodeB

GGSN

S1

GSN, MM, SM?

HSS interface,

UE temp ID

Security keys

Encryption

Headercompress

ion

RRC, Cell control,

Scheduling,

HARQ

aGW

LTE eNB

SGSN

MM, SM, HSS interface,

UE temp ID, Security keys

RNC

RRC, Encryption,

Header Compression,

Cell control

Scheduling,

HARQ

CN

RAN

Iu

LTE ArchitectureUMTS Architecture

Principal decisions:

- No geographical association of

upper nodes (removes single

point of failure)

- Security termination is in the

upper Node


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LTE Network architecture

IASA

S5b

Evolved Packet Core

Evolved RANS1 SGi

Op.

IPServ.(IMS,PSS,

etc)

Rx+

S2

GERAN

UTRAN

Gb

Iu

S3

MMEUPE

S4

non 3GPPIP Access

HSS

PCRF

S2

S7

S6

WLAN3GPP IP Access

* Color codi ng: red indicates new functional element / interface

3GPPAnchor

SGSN

SAEAnchor

GPRS Core

S5a


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Evolved Packet System (EPS) Architecture: Goals

The goal of the System Architecture Evolution (SAE) effort in 3GPP is to develop a

framework for the evolution and migration of current systems to a system whichsupports the following:

high data rates

low latency

packet-optimized (all IP network)

provides service continuity across heterogeneous access networks

Must allow co-existence with UMTS/HSPAand GSM/EDGE should be possible tomaintain a packet session in a way that isseamless to the user of a multi-modedevice

Allows operators to gradually roll out LTE in

the areas of highest demand first

Currently being extended to also support EV-

DO, and WiMAX

LTE coverage

UMTS/HSPA

coverage

GSM/EDGEcoverage


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Evolved Packet System Architecture Overview

EPS is based upon an end-to-end all-IP architecture

Every services are delivered over IP

Clearly delineated control plane & data plane

Simplified network architecture: from 2 to 1 core

MME

PCRF

SGW PDN GW

PDSN HA


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Evolution to EPS

A Unified IP-based Always-on, QoS-enabled Network

Legacy Infrastructure

RNCHA

Evolved Packet System

Radio MobilityIntelligence placed

in the eNB

BE to QoS/HAnon-blocking

1 2 4

BTS Internet

Multi-Media

Services

PDSN

Backhaul

(TDM/ATM)

RNC Bearer mobilitycollapse into

the SGW

3

Backhaultransition

To IP/Ethernet

Backhaul

(IP/Ethernet)

MCS voice and SGSNpacket mobility

collapse intothe SGW

RNC controldistributed into

the MME/eNB

SGSN controlcollapse into

the MME

CS Core

PS Core

5

CS and PSCollapse into a

Unified IPbackbone

Serviceaware and

mobile awareIP network

6

MME

SGW PDN GWeNB

PCRF


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Functional Implication of the New Mobile Core Architecture

3GPP Access Non-3GPP Access

PDSNRNCRNC SGSN/GGSN

MME

PCRF

SGW PDN GW

User Plane has Many Common Attributes with Fixed

Broadband

Broadband capacity

QoS for multi-service delivery

Per-user and per-application policies

Highly available network elements

Control Plane gained new Mobile-Specific

Attributes Mobility across networks & operators

Distributed mobility management

Massive increase in scalability

Dynamic policy management


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internet

eNB

RB Control

Connection Mobility Cont .

eNB Measurement

Configuration & Provision

Dynamic Resource

Allocation (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 Mobility

Handling

NAS Security

P-GW

UE IP address

allocation

Packet Filtering

EPS Architecture: Functional Description of Nodes

eNB- contains all radioaccess functions

Radio admission control

Scheduling of UL and DL data

Scheduling and transmission of

paging and system broadcast

IP header compression (PDCP)

Outer-ARQ (RLC)

Mobility Management Entity

Authentication

Tracking area list management

Idle mode UE reachability

S-GW/PDN-GW selection

Inter core network node signaling for

mobility between 2G/3G and LTE

Bearer management functions

Serving Gateway

Local mobility anchor for inter-eNB handovers

Mobility anchoring for inter-3GPP handovers

Idle mode DL packet buffering

Lawful interception

Packet routing and forwarding

PDN Gateway

IP anchor point for bearers

UE IP address allocation

Per-user based packet filtering

Connectivity to packet data network

Policy

PCRF

PolicyDecisions

Policy & Charging Rules Function

Network control of Service Data Flow

(SDF) detection, gating, QoS & flow

based charging

Dynamic policy decision on service

data flow treatment in the PCEF

(xGW)

Authorizes QoS resources


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S7c

Big Picture View of the EPS

SGi

GERAN

UTRAN

S11

S3

S5

eUTRAN

HSS

S4

S1-U

S1-MME

S6a

SGSN

IP Network

Gx

X2

AFPCRF

ServingGateway

S101

S12

PDNGateway

CDMA/EVDOeRNC

HSGW

S2a

Standards based interfacesfor inter-working with other

3GPP & non-3GPP networks

MME

MME, S-GW & PDN-GW arelogically defined functions !

New interface / directconnectivity now existsbetween eNBs

eNB

eNB


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LTE Physical Layer functionalities

3


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Fundamentals


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LTE Air Interface Technologies and System design

Air Interface physical and multiple access technologies:

DL: OFDMA UL: SC-FDMA

Frequency- and time-domain link adaptation frequency and timeselective scheduling

Hybrid ARQ: Incremental Redundancy (Chase combining as a special case)

Modulation schemes: QPSK, 16QAM. 64QAM for both DL and UL. Frequency reuse: universal reuse and interference mitigation scheme

Macro diversity for intra-NodeB DL transmission and e-MBMS in SFN

MIMO Technologies Single-user MIMO, Multi-user MIMO, SDMA,beamforming, and Transmit Diversity

Radio Resource Allocation distributed (DL only) and localized


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OFDMA/SC-FDMA Characteristics

OFDMA/SC-FDMA allows spectrum scalability of LTE system operation

Up to 20 MHz to enable very high data rates

UEs with Lower bandwidth (low cost) can be operated in the same system

OFDMA/SC-FDMA characteristic ISI removal with Cyclic Prefix

CP Useful OFDM symbol time

OFDM symbol


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Downlink


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LTE Downlink: Scalable OFDMA

The LTE downlink uses scalable OFDMA

Fixed subcarrier spacing of 15 kHz for unicast

symbol time fixed at T = 1/15kHz = 66.67 s

Different UEs are assigned different sets of subcarriers so that they remain orthogonal to eachother (except MU-MIMO)

Serial toParallel

IFFT

bitstreamuser 1

...

Parallelto Serial

addCP

Encoding +Interleaving

+ Modulation

20 MHz: 2048 pt IFFT

10 MHz: 1024 pt IFFT

5 MHz: 512 pt IFFT

Serial toParallel

bitstreamuser 2 Encoding +

Interleaving+ Modulation

No in-cell interference -different users use different

subcarriers


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Physical Channels to Support the LTE Downlink (Unicast)

eNode-BPhysicalDownlinkSha

redChannel

(PDSCH)

PhysicalDow

nlinkControl

Channel(PDCCH)

PhysicalUpli

nkControlCh

annel(PUCCH)

Carries DL traffic

DL scheduling grant

HARQ feedback for DL

CQI reporting

PhysicalBroa

dcastChanne

l(PBCH)

Carries basic systembroadcast information

Synchronizat

ionChannel

(SCH)

Allows mobile to get timing andfrequency sync with the cell

PhysicalCon

trolFormatI

ndicatorCha

nnel(PCFICH

)Time span of PDCCH

PhysicalHAR

QIndicatorC

hannel(PHIC

H)

HARQ feedbackfor UL

UE


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LTE Downlink: Mapping of Logical, Transport, Physical Channels

BCCHPCCH CCCH DCCH DTCH MCCH MTCH

BCHPCH DL-SCH MCH

DownlinkLogical channels

Downlink

Transport channels

Downlink

Physical ChannelsPDSCH PDCCHPBCH PHICHPCFICHSCHDL-RS PMCH

LTE makes heavy use of shared channels common control, paging, and part of

broadcast information carried on PDSCHPCCH: paging control channel

BCCH: broadcast control channel

CCCH: common control channel

DCCH: dedicated control channel

DTCH: dedicated traffic channel

PCH: paging channel

BCH: broadcast channel

DL-SCH: DL shared channel


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LTE Downlink: Channel Structure and Terminology

t

f

Physical Resource Block (PRB)

= 14 OFDM Symbols x 12

Subcarrier

This is the minimum unit of

allocation in LTE

first 1..3 OFDM symbols* reserved

for L1/L2 control signaling

(PCFICH, PDCCH, PHICH)

one

OFDM

symbol

Subcarrier

Resource Element is a

single subcarrier in an

OFDM symbol

Slot (0.5 ms)

Subframe (1 ms)

Slot (0.5 ms)

15 kHz

PRB

subframe

* 2..4 symbols for 1.4 MHz bandwidth only


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LTE Downlink: Maximum Number of Resource Blocks

frequency

1.4MHz

3MHz

5MHz

10MHz

20MHz

100 PRBs

50 PRBs

25 PRBs

15 PRBs

6 PRBs

15MHz

75 PRBs

All bandwidthoptions are

applicable toboth FDD and

TDD


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LTE Downlink Numerology (FDD)

FFT SizeSampling

Frequency

Number ofUsable

Subcarriers*Occupied BW

1.4 MHz 128 1.92 MHz 72 1.08 MHz

3 MHz 256 3.84 MHz 180 2.7 MHz

5 MHz 512 7.68 MHz 300 4.5 MHz

10 MHz 1024 15.36 MHz 600 9 MHz

15 MHz 1536 23.04 MHz 900 13.5 MHz

20 MHz 2048 30.72 MHz 1200 18 MHz

FFT sizes chosen

such that sampling

rates are a multiple of

the UMTS chip rate

(3.84 MHz)

Eases implementation

of dual mode

UMTS/LTE terminals

*DC subcarrier is not used in the LTE DL. Reason: direct conversion receivers (zero IF) inUE can introduce significant distortion on baseband signal components near 0 Hz


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LTE Downlink: Common Reference Signal (RS) Structure


f

Subframe (1 ms)

Reference Symbol

Reference signal is staggered inthe time-frequency plane;mobile interpolates to obtain a2-D picture of the channel


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LTE Downlink: Common RS Structure for 1, 2, and 4 Antenna Ports

R0

R0

R0

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

nn

aport

Physical Resource Block

f

Resource Element (k,l)

Reference Symbols

for this antenna port

not used for

transmission

Antenna Port 0 Antenna Port 1 Antenna Port 2 Antenna Port 3

OneAntenna

Port

TwoAntenna P

orts

FourAntenna

Po

rts

RS overhead

4.8% for 1 Tx

9.5% for 2 Tx 14.3% for 4 Tx

In the multi-antenna case, thereis a need for a RS power boost toovercome interference from

neighbor cell data transmission

Cell-specific frequency shift ofRS position to avoid RS overlap


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LTE Downlink: Dedicated Signal (RS) Structure in Support of Beamforming


f

Subframe (1 ms)

Common Reference

Symbol (Antenna Port 1)

UE can be configured to use adedicated RS for datademodulation

sent only within those PRBs inwhich data is scheduled forthe UE

beamforming weights appliedto dedicated RS

Dedicated Reference

Symbol

Common Reference

Symbol (Antenna Port 0)


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1 ms subframe

LTE Downlink: PBCH, SCH Location in Time & Frequency

10ms radio frame contains 10 subframes (20 slots)

P-SCHPBCH

0 1 2 3 4 5 6 7 8 9

innermost 6 PRBs (72

subcarriers = 1.08

MHz) same

structure used for all

system bandwidths

f

slot (0.5 ms)

subframe (1 ms)

slot (0.5 ms)

0 1 2 3 4 5 6 0 1 2 3 4 5 6

S-SCHPrimary sync channel (P-SCH) and secondary sync

channel (S-SCH) for cell search

1.4MHz

3MHz

5MHz

10MHz

20MHz

1.08 MHz


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LTE Downlink: Basics of Cell Search

1. Mobile searches for P-SCH location in time and frequency; givesOFDM symbol boundaries

5ms period in time, center 72 subcarriers of system bandwidth; 3

possible sequences

1. Once P-SCH is acquired, the S-SCH location is known, and S-SCHis scrambled based on P-SCH sequence; S-SCH indicates the10ms radio frame boundaries, and allows the mobile to obtainthe group ID (168 group IDs); P-SCH + S-SCH acquisition givesphysical layer cell ID

2. Knowledge of the transmission timing and physical layer cell IDallows the mobile to find the position of the downlink referencesymbols (6 possible frequency shifts) as well as the pseudo-random sequence used

3. Once the downlink reference signal is obtained, the mobile candecode the broadcast channel (PBCH)

5 ms

10 ms

10 ms

1.08 MHz

There are 504 unique physical layer cell IDs, organized in 168 groups of 3


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LTE Downlink: Broadcast of System Information

The Broadcast Control Channel (BCCH) is used to broadcast system information

needs to be heard over entire cell coverage area

The BCCH conveys RRC messages called SystemInformation (SI)

A particular SI carries a number ofSystem Information Blocks (SIBs) that have the same

scheduling period (i.e. RACH info, power control info, etc.)

SI-M is a special SI that carries a single SIB the Master Information Block (MIB)

The dimensioning of broadcast information is critical; hence in LTE, the BCCH issplit into a primary and dynamic component

Master Broadcast

carries SI-M; provides fast

access to the minimumrequired amount of

information for efficientdiscovery/mobility

procedures

Mapped to BCH PBCH

SI Broadcast

delivers SIs with semi-staticinformation valid for a longer time

period; access is not as timecritical

Mapped to DL-SCH PDSCH


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LTE Downlink: Downlink Shared Channel (DL-SCH)

DL-SCH transport channel carries scheduled packet data and is mapped

onto the physical downlink shared channel (PDSCH)

Transport block CRCattachment

Code block segmentation and

code block CRC attachment

Channel coding

Rate matching

Code blockconcatenation

Bit-level scrambling

24 bit CRC

Per-code-block CRC allows power savings indecoder with early termination, also allowsparallel processing of code words in a MIMOSIC receiver

Modulation

R=1/3 turbo code from UMTS but withimproved turbo interleaver (QPP) whichallows efficient parallelization to reducelatencySimplified circular buffer rate matching withsub-block interleaving; rate matching is percode block to allow parallel processing of

multiple code blocks

Per-user bit level scrambling introduced forinterference randomization

PDSCH supports QPSK, 16-QAM, and 64-QAM

Enhancementsintroduced to allowefficient processingfor very high data

rates


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LTE Downlink: Summary of Channels

Transport Channel Coding scheme Physical Channel Modulation

DL-SCH Turbo R=1/3 PDSCH QPSK, 16-QAM, 64-QAM

BCH Convolutional R=1/3 PBCH QPSK

PCH Turbo R=1/3 PDSCH QPSK

MCH Turbo R=1/3 PMCH QPSK, 16-QAM, 64-QAM

Control Information Coding Scheme Physical Channel Modulation

CFI Block code R=1/16 PCFICH QPSK

HI Repetition R=1/3 PHICH BPSK

DCIConvolutional R=1/3

with repetition/puncturingdepending on CCE aggregation

level

PDCCH QPSK


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Uplink


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Physical Channels to Support LTE Uplink

eNode-B

Random access for initial

access and UL timingalignment

PhysicalDow

nlinkControl

Channel(PD

CCH)

PhysicalRan

domAccessC

hannel(PRA

CH)

PhysicalUplinkSh

aredChanne

l(PUSCH)

PhysicalUpli

nkControlCh

annel(PUCC

H)

UL scheduling grant

Traffic and channelsounding reference

signal

UL scheduling request fortime synchronized UEs

PhysicalHARQIndicat

orChannel(

PHICH)

HARQ feedbackUE


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LTE Uplink: Mapping of Logical, Transport, Physical Channels

CCCH DCCH DTCH

RACH UL-SCH

UplinkLogical channels

Uplink

Transport channels

UplinkPhysical Channels

PUSCH PUCCHPRACH

CCCH: common control channel

DCCH: dedicated control channel

DTCH: dedicated traffic channel

RACH: random access channel

UL-SCH: UL shared channel

PUSCH: physical UL shared channel

PUCCH: physical UL control channel

PRACH: physical random access channel


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LTE Uplink: Multiple Access Scheme

To facilitate efficient power amplifier design in the UE, 3GPP chose singlecarrier frequency domain multiple access (SC-FDMA) in favor of OFDMA for

uplink multiple access

SC-FDMA improves the peak-to-average power ratio (PAPR) compared to OFDM

~4 dB improvement for QPSK, ~2 dB improvement for 16-QAM

Reduced power amplifier cost for mobile

Reduced power amplifier back-off

improved coverage

N o d e B

U E C

U E B

U E A

U E A T r a n s m i t T i m i n g

U E B T r a n s m i t T i m i n g

U E C T r a n s m i t T i m i

SC-FDMA is still an orthogonal multiple access

scheme

UEs are orthogonal in frequency

Synchronous in the time domain through the useof timing advance (TA) signaling

Only need to be synchronous within a fraction of theCP length

TA command sent as a MAC control element with 0.52 s timing resolution


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LTE Uplink: DFT-SOFDMA-1

DFT spreading of modulation symbols reduces PAPR, but also leads to the

possibility of inter-symbol interference (ISI) In OFDM, each modulation symbols sees a single 15 kHz subcarrier (flat channel)

In DFT-SOFDM, each modulation symbol sees a wider bandwidth (i.e. m x 180KHz) if channel is frequency selective within allocated bandwidth the we get ISI

Equalization is required in the SC-FDMA receiver

Simple one-tap frequency domain equalization facilitated by use of CP

f = 15 kHz

OFDMA

+1 -1 -1 +1 -1 -1 +1 -1 +1 +1 +1 -1

SC-FDMA

+1 -1 -1 +1 -1 -1 +1 -1 +1 +1 +1 -1

DFT spreading


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LTE Uplink: DFT-SOFDM Transmitter and Receiver Chain

SP...

IFFT

bitstream .

.. PS D/A

A/DSP..

.

FFT..

.

PS

add CP RFTx

RFRx

removeCP

Encoding +Interleaving

+ Modulation

Demod +de-

interleave+ decode

... DFT

IDFT..

.

Equalizer..

.

Subcarrier mapping

Subcarrier demapping


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LTE Uplink Numerology

Same numerology

between uplink anddownlink

FFT SizeSampling

Frequency

Number ofUsable

Subcarriers

Occupied

BW

1.4 MHz 128 1.92 MHz 72 1.08 MHz

3 MHz 256 3.84 MHz 180 2.7 MHz

5 MHz 512 7.68 MHz 300 4.5 MHz

10 MHz 1024 15.36 MHz 600 9 MHz

15 MHz 1536 23.04 MHz 900 13.5 MHz

20 MHz 2048 30.72 MHz 1200 18 MHz


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1. Data demodulation reference signal (DM-RS)

Sent with each packet transmission in order to demodulate data Occupies center SC-FDMA symbol of the slot

Possibility to signal different sequences (cyclic shift of base CAZAC sequence) foruse with MU-MIMO

1. Sounding reference signal (SRS)

Used to sound uplink channel to support frequency selective scheduling

Channel sensitive scheduling in both time and frequency

SRS parameters are UE specific and configured semi-statically

SC-FDMA symbol position (one symbol in subframe used for SRS)

Periodicity: {2, 5, 10, 20, 40, 80, 160, 320} ms

Bandwidth: narrowband or wideband (does not include PUCCH region) Frequency hopping

SRS is not sent when there is a scheduling request (SR) or CQI to be sent on PUCCH(to avoid multi-carrier transmission)

LTE Uplink: Reference Signals-1


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LTE Uplink: Reference Signals-2

DM-RS transmitted only over bandwidthallocated to UE

SRS can be transmitted over a widebandwidth to allow channel qualityestimation by the eNB uplink scheduler

Cyclic shift orthogonal sequences used to

separate out different UEs SRS (8 possible

shifts)

Repetition factor (RPF) = 2 creates twofrequency combs for increased multiplexing

capability

UE 1

UE 2

UE 3

Slot =0.5ms

Slot =0.5ms

SRS

DM-RSUE 1

DM-RSUE 2

DM-RSUE 3

Rules for SRS transmission

SRS only spans PUSCH bandwidth

SRS is not transmitted at the same time as

CQI or Scheduling Request (SR) on PUCCH

Shortened ACK/NACK format is used on

PUCCH to allow transmission of SRS while

maintaining single-carrier transmission


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LTE Uplink: Uplink Shared Channel (UL-SCH)

UL-SCH transport channel carries scheduled packet data and is mapped

onto the physical uplink shared channel(PUSCH)

Transport block CRCattachment

Code block segmentation andcode block CRC attachment

Channel coding

Rate matching

Code blockconcatenation

Bit-level scrambling

24 bit CRC

Per-code-block CRC allows power savings indecoder with early termination

Modulation

R=1/3 turbo code with improved turbointerleaver (QPP) which allows efficientparallelization to reduce latency

sub-block interleaving; rate matching is percode block to allow parallel processing ofmultiple code blocks

Per-user bit level scrambling introduced forinterference randomization

PUSCH supports QPSK and 16-QAM; 64-QAM isoptional

Enhancementsintroduced to allowefficient processingfor very high data

rates

control MUXACK/NACK

CQI/PMI Mux control when needed; data is rate matchedaround CQI/PMI, but ACK/NACK punctures outdata (kept indep. from RM to maintain turn-around)


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LTE Uplink: Physical Uplink Control Channel (PUCCH)

PUCCH carries ACK/NACKand CQI to support the downlink, as well as schedulingrequests (SR) for the uplink

PRBs targets on two extreme ends of the frequency band are configured by RRC

Number of PUCCH PRBs reserved semi-statically based on required amount of control

PUCCH is never transmitted simultaneously with PUSCH, in order to maintain single-carrier transmission

If ACK/NACK or CQI needs to be sent when there is PUSCH transmission, it must be multiplexed

together with PUSCH

resource 1

resource 0

0.5ms slot

resource 0

resource 1

0.5ms slot

System

BW

resource 2 resource 3

resource 2resource 3

PUCCHPUSCH


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LTE Uplink: PUCCH Format 1a/1b for ACK/NACK

1 bit for SIMO (format 1a: BPSK), 2 bits for MIMO (format 1b: QPSK)

ACK/NACK is repeated 8 times and spread with length 12 CAZAC sequence in frequency

CDM of ACK/NACK from different UEs by using different cyclic shifts of CAZAC sequence To further increase multiplexing capability, block-wise spreading via wi is added over each slot

Example: Use 6 cyclic shifts and 3 orthogonal RS covers gives 18 multiplexedUEs per resource

PUCCH resource index for ACK/NACK Tx lowest CCE for PDCCH in DL scheduling grant

If SRS is transmitted in the same subframe, a shortenedACK/NACK format is used where the

ACK/NACK symbol corresponding to the SRS location is punctured

CAZAC ACK/NACK

w1w0 w2 w3

IFFT IFFT IFFT IFFT

Reference symbols

Orthogonal cover

0.5ms slot

resource 1

resource 0

resource 0

resource 1

0.5ms slot



PUSCH

0.5ms slot

copy


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LTE Uplink: PUCCH Format 1 for Scheduling Request

On/Off keying based on ACK/NACK design

Two sequences: length 4 + length 3

Compatibility with ACK/NACK transmission from different UE

SR resource on PUCCH is configured via RRC (time multiplexing and sequence #)

SR and ACK/NACK from same user can be multiplexed

If SR needs to be sent, then ACK/NACK is transmitted using the assigned SR PUCCH resource

SR and CQI from same user cannot be multiplexed

SR and SRS is cannot be sent in the same subframe (SRS is dropped)

Sequence 1

Sequence 2

resource 1

resource 0

resource 0

resource 1

0.5ms slot



PUSCH

0.5ms slot

copy


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LTE Uplink: PUCCH Format 2 for CQI/PMI/RI

20 coded bits per subframe (10 symbols) with QPSK modulation CDM of UEs by spreading each symbol with a length 12 CAZAC sequence in frequency

CQI/PMI/RI PUCCH resources assigned via RRC ACK/NACK can be multiplexed with CQI (format 2a/2b); drop CQI when SR is transmitted

SRS not sent in same subframe as CQI (SRS dropped): higher layer config should try to avoid

resource 1

resource 0

resource 0

resource 1



PUSCH

CAZAC

IFFTIFFT IFFTIFFTIFFTIFFT IFFTIFFT IFFTIFFT

CQI

0.5ms slot

RS

IFFTIFFT IFFTIFFTIFFTIFFT IFFTIFFT IFFTIFFT

0.5ms slot


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LTE Uplink: Random Access Channel-1

The random access channel (RACH) is used during initial access, handoff, or when uplinksynchronization is lost

UE sends a RACH preamble on physical random access preamble (PRACH)

UE first obtains downlink timing from SCH, then sends RACH preamble (non-synchronized)

eNB detects timing preamble and sends a timing advance command to time synchronize UE

Gap time reflects the timing uncertainty due to

round trip propagation delay

CP is used to allow frequency domain processing,

and must cover the round trip propagation delay

as well as the delay spread

Formats #2 and #3 offer a 2 x 0.8ms preamble

repetition to improve detection performance in

poor channel conditions

fRA = 1/0.8ms = 1.25 kHz sensitivity to dopplershift from high speed UEs (greater than ~120 km/hr)

Root sequence length = 839; different signatures

are generated by first using different cyclic shifts

of a single root sequence (orthogonal), and then

using additional root sequences as needed (low

cross-correlation)

CP Zadoff-Chu (ZC) Sequence

Tcp Tseq Tgap

RA slot

Format RA slot Tcp Tseq Tgap Max cell size

#0 1 ms ~0.1 ms 0.8 ms ~0.1 ms ~15 km

#1 2 ms ~0.68 ms 0.8 ms ~0.5 ms ~75km

#2 2 ms ~0.2 ms 1.6 ms ~0.2 ms ~30 km

#3 3 ms ~0.68 ms 1.6 ms ~0.7 ms ~100 km

Max cell size (m) = 3E8 * Tgap/2


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LTE Uplink: Random Access Channel-2

PRACH sent in reserved time-frequency zone; configured semi-statically

PRACH resource = 6 PRBs (1.08 MHz); at most one PRACH resource per subframe

PRACH resource contains 64 preamble sequences (6 bits)

preambles can all be orthogonal for small cell sizes (different cyclic shifts of root ZC seq.)

not orthogonal for larger cell sizes (need to use different root ZC sequences)

PRACH access slots can occur every 1, 2, 5, 10, or 20ms

20ms option can only be used in synchronized networks

10ms max for non-synchronized networks so that UE does not need to obtain the SFN fromthe target cell BCH in handover scenario (radio frame timing provided by the SCH)

freqSched

uled

Data

1 ms

6 PRBs = 1.08 MHz

PRACHopportunities

PRACH cycle


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LTE Uplink: Contention Based Random Access Procedure

1. PRACH preamble: 6 bits (64 signatures) consistingof 5 bits random ID + 1 bit info

2. RA response generated by MAC on DL-SCH usingRA-RNTI on associated PDCCH

RA-RNTI tied to time/freq resource of PRACH

Semi-synchronous, no HARQ

Contains RA preamble identifier, timing alignment

info, initial uplink grant

1. First scheduled UL transmission on UL-SCH

Uses HARQ

For initial access, contains RRC connection request

carried on CCCH, NAS UE identifier but no NAS

message

1. Contention resolution on DL-SCH

Generated by RRC and carried on CCCH

UE eN

Random Access Preamble1

Random Access Response

Scheduled Transmission3

Contention Resolution


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LTE Uplink: Non-Contention Based Random Access Procedure

0. eNB assigns non-contention RA preamble toUE. Signaled by:

HO command generated by target eNB via

source eNB for handover

MAC signaling for DL data arrival

1. RA preamble transmission by UE on

assigned non-contention preamble

2. RA response on DL-SCH

Non-contention based random access

improves access time


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LTE Uplink: Power Control-1

Open-loop power control is the baseline uplink power

control method in LTE (compensation for path loss andfading)

Open-loop PC is needed to constrain the dynamic range

between signals received from different UEs

Unlike CDMA, there is no in-cell interference to combat;

rather,fading is exploited by rate control

In classic open-loop PC:

1. eNB broadcasts the total uplink interference level (Itot )

and the SINR target ( nominal ) together as Ponominal (dBm) =

nominal (dB) + Itot (dBm)

2. UE estimates path loss + shadowing (PL) on the downlink

by measuring downlink reference signal

3. UE sets its transmit PSD (power per PRB) in order to

achieve the broadcast SINR target. In dB scale:

TxPSD(dBm) = PL(dB) + Ponominal (dBm)

DLRe

feren

ceSig

nal

BCH:

Po_nom

inal

In classic open-loop PC, allUEs achieve the same target

SINR

UEs near interior of celltransmit at reduced PSD poor spectral efficiency


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Fractional power control is introduced to allow a more

flexible trade-off between spectral efficiency and celledge rates

TxPSD(dBm) = PL(dB) + Ponominal (dB)

Fractional compensation factor < 1 is introduced so

that only a fraction of the path loss is compensated

Target SINR is now a function of the UEs path loss targetSINR increases with decreasing path loss. In dB scale, we have

TargetSINR(dBm) = nominal (dB) + (1- )PL(dB)

With =1, we have classic open-loop PC

As we reduce , the range of target SINRs increases between

UEs, and we can achieve higher spectral efficiency at theexpense of cell edge rate

DLRe

feren

ceSignal

BCH:

Po_nom

inal,

TargetSINR


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Additional user-specific power offsets can be sent via

RRC signaling; can be used to correct open-loop errors(i.e. PA errors), or to allow proprietary methods tocreate a power profile

TxPSD(dBm) = PL(dB) + Ponominal (dB) +Pouser (dB)

DLRe

feren

ceSig

nal

BCH:

Po_nom

inal,

RRC:Po

_user

Aperiodic fast power control is made possible by additionally allowing a dynamicadjustment of the UE transmit PSD with 1 or 2 bit power control commands, caneither be accumulated adjustment or absolute. PC command sent via:

UL scheduling grant (DCI Format 0): 2 bit TPC command

Absolute: {-4, -1, +1, +4} dB

Accumulated: {-1, 0, +1, +3} dB

On separate power control channel (DCI Format 3/3A)

Format 3: 2 bits representing {-1, 0, +1, +3} dB

Format 3A: 1 bit representing {-1, +1} dB

TxPSD(dBm)

=

PL(dB)

+ Ponominal (dB)

+Po

user (dB)+ f(

)


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DLRe

feren

ceSig

nal

BCH:Po_

nomi

nal,

, _TF

RRC:Po

_user

The UE transmit PSD can optionally be made

dependent on the MCS level assigned, through useof TFwhich specifies power offsets as a function of

the MCS level assigned by the scheduler

TxPSD(dBm) = PL(dB) + Ponominal (dB)+Pouser (dB)

+ f( ) + TF

The UEs total power scales with the number ofassigned PRBs (M)

TxPower(dBm) = min( Pmax (dBm), TxPSD(dBm) + 10log10(M) )

SRS follows PUSCH power control with a configurable power offset

Separate power control parameters for PUSCH and PUCCH


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MIMO


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Multiple Antenna Techniques

Spatial Multiplexing (SM) SU-MIMO

Multiple data streams sent to the same user (max 2 codewords)

Significant throughput gains for UEs in high SINR conditions

Spatial Division Multiple Access (SDMA) or Beamforming

Different data streams sent to different users on same resource

Improves throughput even in low SINR conditions (cell-edge)

Works even for single antenna mobiles

User-specific RS (dedicated RS) supported to facilitatebeamforming; used for demodulation of PDSCH

Transmit Diversity

Improves reliability on a single data stream; space-frequencyblock coding (SFBC), cyclic delay diversity (CDD)

Fall back scheme if channel conditions do not allow SM; useful toimprove reliability on common control channels


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MIMO Support is Different in Downlink and Uplink

Downlink MIMO

Supports Spatial Multiplexing, MU-MIMO, and Transmit Diversity

Uplink MIMO

Initial release of LTE will only support MU-MIMO with a single PA at the

UE desire to avoid multiple PAs at UE

Cyclic-shift orthogonal pilots used in the uplink

to facilitate MU-MIMO operation


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DL Spatial Multiplexing Modes for Low and High Speeds

UE indicates best combo of CQI/PMI/RI for max throughput (i.e. high-rank/low-MCS vs. low-rank/high MCS)

Closed-loop SM is ideally suited for low speed scenarios when the CQI/PMI/RI feedback is accurate

Open-loop SM provides robustness in high speed scenarios when the feedback is not accurate

M Tx N Rx

VMIMO

HHH

RIHVUH =

UHSelect# codewords

Modulation+ coding

PMICQI

Modulation+ coding

Demod +decode

demod +decode

precoding

Layermapping

Closed-Loop SM Open-Loop SM

CQI separate CQI for each codeword fed back one value fed back applicable over all layers

PMI PMI feedback from UE based on instantaneous channel

state

no feedback from UE, fixed precoding at eNB with

large delay CDD to improve robustness

RI based on SINR and instantaneous channel matrix rankRI=1 corresponds to closed loop TxDiv (CLTD)

typically based only on SINR

RI=1 corresponds to open loop TxDiv (SFBC)


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Multi-codeword SM and Layer Mapping

LTE allows multi-codeword (MCW) SM in which the streams are encoded independentlyrather than jointly as in single codeword SM

Advantages: MCS can be adjusted on each stream independently to improve throughput, allows for SIC receiver

Disadvantages: Increased feedback as ACK/NACK as CQI are needed per codeword

A maximum of 2 codewords is supported, even when a rank-3 or rank-4 transmission isused in the case of 4x4 MIMO. Mapping of codewords to layers (e.g. streams) as below:

Precoding

(2x4)

CW#1

Precoding

(1x4)

CW#1

CW#2

Precoding

(4x4)

CW#1

CW#2

S/P

S/P

Precoding

(3x4)

CW#1

CW#2 S/P

Rank-1

Rank-3

Rank-2

Rank-4layers

Precoding

(2x4)CW#n S/P

Rank-2(useful for ReTx)

A single codeword can be

mapped to 2 layers only in the

case of 4 Tx antennas (for

efficient retransmission of a

codeword mapped to 2 layers in

the previous transmission)


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Codebook Based Precoding-1

Precoding vectors/matrices specified for 2 and 4 transmit antennas: 4 codebook entriesfor 2 Tx antennas, 16 codebook entries for 4 Tx antennas

Precoding vector for one codeword

Precoding matrix for two codewords

2 Tx antennas 4Tx antennasThis entry is only

used for open loopSM


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Codebook Based Precoding-2

Codebook entries support a variety of antenna spacings & configurations

Network can configure the UE to only consider a subset of the codebookentries

-100 -80 -60 -40 -20 0 20 40 60 80 1000

0.5

1

1.5

2

2.5

3

3.5

4

Angle (deg)

Gain

4 Antennas, /2 spacing

index 0

index 1

index 3index 4

index 5

index 6

index 7

Example: 4 antennas withhalf-wavelength spacing

Codebook entries

0,1,3,4,5,6,7 with 1 layer

form a set of fixed beams


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MBMS


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Inter-Cell Interference Mitigation

Principle - coordinate the transmission power and limit the inter-cellinterference

Interference Mitigation coordination-

Static inter-cell coordination strategy provision in advance

Semi-static S1/X2 signaling for inter-cell dynamic coordination

Inter-cell interference Mitigation schemes

Inter-cell interference-cancellation/suppression Spatial suppression by means of multiple antennas at the UE

Interference cancellation based on detection/subtraction of the inter-cellinterference

Inter-cell interference mitigation/coordination by means of

Intelligent scheduling based on priority allocation of sub-frame/sub-carrierallocation, frequency scheduling, power levels coupled to sub-band priorities,soft reuse: power levels coupled to groups of sub-bands etc.

Power control open loop


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Multicast/Broadcast in a Single Frequency Network (MBSFN)

Synchronized transmission from multiple cells on same set of subcarriers

Appears as extra multipath at the terminal, as long as signal components fromdifferent cells arrive within the CP length

Extended CP lengths used in broadcast to account for propagation delayfrom different cells

Signals from different cells combine coherently over the air

Macro-Diversity gains exploited in OFDMA system

Scheduler coordinates broadcast frames through RRM coordination

Data Synchronization


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Evolved Multimedia Broadcast Multicast Service (MBMS)

E-MBMS can be used in synchronous or asynchronous networks, and can either be on astand-alone E-MBMS carrier or multiplexed with unicast traffic

Subframes reserved for broadcast are reserved periodically in time

TDM of broadcast and unicast subframes (FDM is not allowed)

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icas

t

Un

icas

t

Un

icas

t

Broa

dcas

t

Un

icas

t

Un

icas

t

Un

icas

t

Un

icas

t

Un

icas

t

Broa

dc

as

t

Un

icas

t

Un

icas

ttime

1ms subframe

With E-MBMS, multiple users receive the same information using the same radioresources much more efficient approach for delivering common content

Examples: television broadcasts, news updates, sports scores, etc.

Broadcast: every user receives content

Multicast: only users with a subscriptions receive content

Un

icas

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icas

t

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icas

t

Un

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Un

icas

t


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Multicast Broadcast on a Single Frequency Network (MBSFN)

MBSFN refers to a mode of E-MBMS where synchronized transmission of the samecontent from multiple cells on same set of subcarriers takes place

Appears as extra multipath at the mobile, as long as signal components from different cells arrivewithin the CP length diversity gains exploited for free with over the air combining

An extended CP length is used for broadcast subframes to account for propagation delay from

different cells

CP length extended from 4.7 s to 16.6 s (increased CP overhead)

6 OFDM symbols per slot for broadcast (instead of 7 for unicast)


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MBSFN for Larger Cells (7.5 kHz Subcarrier Spacing)

To handle even larger cells with additional propagation delay, a second extended CP of

33 s is defined OFDM symbol time is doubled from 66.6 s to 133 s, so that the extended CP

overhead will not be excessive

Increased symbol time means subcarrier spacing reduces from 15 kHz to 7.5 kHz

Increased sensitivity to high doppler

The 7.5 kHz mode can only be used as a stand-alone E-MBMS carrier, cannot be

multiplexed with unicast traffic

16.6 s4.7 s 33.3 s

66.6 s 66.6 s 133.3 s

Unicastsubframe

(7% CP overhead)

Broadcastsubframe

(25% CP overhead)


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76 | Titre de la prsentation | Mois 2008 Alcatel-Lucent , d.r., XXXXX2008

LTE Higher Layer protocol stacks

4

LTE P t l M d l


77/99


LTE Protocol Model

Vertical Planes

User Plane

Control Plane

- RRC terminated in eNBBroadcast, Paging, RRC

connection management, RBcontrol, Mobility functions, UEmeasurement reporting andcontrol

- BMC layer is not needed in E-UTRAN,since MBMS is used to broadcast- RLC/MAC layer (terminated in eNB):

Scheduling, ARQ, HARQ

- PDCP layer (moved now to eNB):

Header Compression (ROHC),Ciphering, Integrity protection

eNB

PHY

UE

PHY

MAC

RLC

MAC

SAE Gate

PDCPPDCP

RLC

eNB

PHY

UE

PHY

MAC

RLC

MAC

MME

RLC

NAS NAS

RRC RRC

L 2 St t f DL i NB


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Layer 2 Structure for DL in eNB

Segm.ARQ

Multiplexing UE1

Segm.ARQ

...

HARQ

Multiplexing UEn

HARQ

BCCH PCCH

Scheduling / Priority Handling

Logical Channels

Transport Channels

MAC

RLC Segm.ARQ

Segm.ARQ

PDCP

ROHC ROHC ROHC ROHC

Radio Bearers

Security Security Security Security

...

LTE MAC


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LTE MAC

Mapping between logical and transport channels

BCCHPCCH CCCH DCCH DTCH MCCH MTCH

BCHPCH SCHRACH MCH

Logical

channels

Transport

channels

Main differences with UTRAN Rel6

mapping:

- Absence of CTCH ( no FACH)- Dedicated transport channels arenot supported- New shared channels: UL-SCH andDL-SCH

B

CH

BCCH

P

CH

PCCH

CCCH

DCCH

DTCH

CTCH

MBMSCH s

FA

CH

D

CH

CCCH

DCCH

DTCH

RA

CH

D

CH

HS-DSCH

E-DCH

Rel.6

MAC functionalities:- E-UTRAN MAC functions similar toUTRAN apart from the absence offunctions related to dedicatedtransport channels-Reduction of different MAC entities(e.g. MAC-d not needed due to the

absence of dedicated transportchannels)

RLC Services and Functions


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RLC Services and Functions

AM, UM and TM transfer modes

Error Correction through ARQ

Segmentation/concatenation of SDUs according to the size of the TB

When necessary, re-segmentation of PDUs that need to be retransmitted

The number of nested re-segmentations is not limited

In-sequence delivery of upper layer PDUs except at HO in the Uplink

Flow Control between eNB and UE (FFS)

Other

Duplicate Detection

Protocol error detection and recovery

SDU discard

Reset

RRC States


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RRC States

RRC_CONNECTED(UE has an E-UTRAN-RRC connection; UE has context in E-UTRAN; E-UTRAN

knows the cell which the UE belongs to; Network can transmit and/or receive data

to/from UE; Network controlled mobility (handover); Neighbour cell

measurements)

RRC_IDLE(UE specific DRX configured by NAS, Broadcast of system information, Paging,

Cell re-selection mobility, The UE shall have been allocated an id which uniquely

identifies the UE in a tracking area, No RRC context stored in the eNB)

No RRC states (Cell_DCH,Cell_FACH, Cell_PCH, URA_PCH)in Connected Mode and only twomacro RRC states


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PDCP Services and Functions

Header compression and decompression: ROHC only

Transfer of user data

In-sequence delivery of upper layer PDUs at HO in the uplink

Security

Ciphering termination is still under discussion in 3GPP

Integrity protection of control plane data (NAS signalling);

PDCP header is 1 or 2 bytes

1 byte header used to optimize VoIP

PDCPIntegrity

Protection

Ciphering Ciphering Ciphering

User Plane

NAS Data

Contro l Plane

NAS Signalling

ROHC ROHC

Ciphering

PDCP SDU (after compression)PDCP header

PDCP PDU

HARQ


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HARQ

N-process Stop-And-Wait HARQ is used

The HARQ is based on ACK/NACKs

In the downlink:

Asynchronous retransmissions with adaptive transmission parameters are

supported

In the uplink:

HARQ is based on synchronous retransmissions

The HARQ transmits and retransmits interval 8 ms

HARQ/ARQ i i


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HARQ/ARQinteractions

Multiplexing

...

HARQ

RACH

Scheduling/ Priority Handling

Transport Channels

Logical Channels

MA C

R LC

PDCP

Se gm.AR Q

Se gm.AR Q

Logical Channels

Radio Bearers

R OHC ROHC

SAE Bearers

C ip he rin g C ip he rin g

Possible because RLC and MAC are co-located (unlike in HSPA Rel6)

In HARQ assisted ARQ operation, ARQ uses knowledge obtained from the

HARQ about the transmission/reception status of a TB:

If maximum HARQ retransmission limit is

reached the ARQ is notified and

retransmission can be initiated

If the HARQ receiver is able to detect a

NACK to ACK error it is FFS if the

transmitting ARQ entities are notified

If the HARQ receiver is able to detect TBtransmission failure it is FFS if the receiving

ARQ entities are notified


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LTE A Technologies

5

LTE-A Technologies


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LTE-A Technologies

Support Wider BW Carrier Aggregation

UL Access Scheme SC-FDMA vs. OFDMA

MIMO extension DL up to 8x8 and UL up to 4x4

CoMP (Coordinated Multi-Point Tx/Rx)

Network MIMO

Coordinate MIMO

Macro Diversity Combining

Relay L1/L2/L3 Relay

MBMS enhancement non-SFN MBMS operation

Mobility enhancement soft handover

Support of Wider BW Carrier Aggregation


87/99


Support of Wider BW Carrier Aggregation

Support of contiguous and Non-contiguous carrier aggregation

Multiple component carriers with each component carrier up to 20 MHz BW

100 kHz channel raster as it is defined in R-8 & Asymmetrical UL/DL Alloc.

Reduced subcarriers between the component carriers

HARQ process one TB and one HARQ per component carrier

DL Control Signaling one per component or one for all

UL Control Signaling Associated with HARQ design

Guard band

= 2.6925 MHz

Frequency

18.015 MHz 18.015 MHz

18.3 MHz 18.3 MHz

18.015 MHz

19 sub-carriers

(285 kHz)

19 sub-carriers

(285 kHz)Total bandwidth

= 60 MHz

100-kHz channel raster

LTE-Advanced: MAC function per component carrier


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LTE Advanced: MAC function per component carrier

TB Mapping -MAC to physical layer mapping and control signaling for carrieraggregation

Single Transport Block per antenna per component carrier Minimizing control signaling overhead Ack/Nak

Backward compatible to possibly support Rel-8 UE at each component carrier

Channelcoding

Modulation

RB mapping

Component carrier 1 Component carrier 2

20MHz 20MHz

transport block

Channelcoding

Modulation

RB mapping

transport block

UL Transmission Scheme


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UL Transmission Scheme

OFDMA vs N x SC-FDMA

OFDMA has the performance advantage with diversity gain with the use of MLD decoding

N x SC-FDMA minimizing the Cubic matrix (PAPR) with comparable performance with

the use of interference cancellation

Agreed UL Transmission scheme

PUSCH transmission (MIMO and non-MIMO) uses DFT-precoding

On top of Rel-8 operation:

Control-data decoupling (simultaneous PUCCH and PUSCH transmission) supported in addition toTDM type multiplexing

Non-contiguous data transmission with single DFT per component carrier (CL-DFT-S-OFDM)

FFS: Resource allocation based on Rel-8 DL schemes (allocation type 0 and/or 1)

FFS: At most one new DCI format for non-MIMO

MIMO Configurations for MIMO extension and CoMP


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MIMO Configurations for MIMO extension and CoMP

MIMO

Single base Multiple bases(Network MIMO)

Co-locatedantennas

Distributedantennas

(RRH)

Non-coherent(Magnitude only)

Coherent(Magnitude/phase)

MacroscopicMIMO

SU-MIMO

MU-MIMO

Beamforming

CollaborativeMIMO

-SU MIMO

-MU MIMO

CoherentNetwork

MIMO

-SU MIMO

-MU MIMO

SU-MIMO,

MU-MIMO

Beamforming

MIMO Evolution for MIMO extension and CoMP


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Extended Precoding

Combinations of Beamforming and Diversity Transmission

Beamforming for Multi-User Transmission (SDMA), based on closely spaced antennaelements (0.5 lambda)

Optimized codebooks for CoMP and MIMO extension

Download codebooks reduce the number of stored codebook and entry expansion

Global codebook or Coordinate local codebooks for CoMP

Antenna Configuration - For up to 8 antenna elements in a 4x2 X-pol.

configuration ( compact housing)

MIMO channelBase-

station

data stream 1/2

data stream 3

MS 1

MS 2

Multiuser MIMO and scheduling for enhanced feedback mechanisms


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Multiuser MIMO and scheduling for enhanced feedback mechanisms

MU-MIMO enhancement

Principle of MU-MIMO beamforming to each user with minimizing cross-interference

DL Scheduler computation of pairing

UE feedback CQI/PMI + best companion PMI/CQI

A

C

B

D

Beam-

forming

Userdata

streams

User

selection

Channel state feedback

1 Users estimate channel and itscompanion with quantizedfeedback.

2 Base combine feedback fromusers and calculates beam weight

to maximize sum rate whileaddressing fairness.

3 Data is transmitted.

MU-MIMO 1

2

3

1

2

3

Collaborative/Network MIMO overview


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Collaborative/Network MIMO overview

Coordinate transmission and

reception of signals amongmultiple bases.

Reduces intercellinterference and improvescell-edge performance andoverall throughput.

Collaborative MIMO: shareuser data and long-termnoncoherent channelinformation.

Coherent network MIMO:share user data and short-term coherent channelinformation.

Key technologies in Multi-mode Adaptive MIMO


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Key technologies in Multi mode Adaptive MIMO

Cellular system

Collaborative/Network

MIMO MU-MIMO

SU-MIMO

SU-MIMOenhancement

Closed-loop MIMO

Iterative MIMO receiver

MU-MIMO optimization

MU precoding algorithm

Trade-off design of scheduler

between complexity and

performance

Collaborative/NetworkMIMO/Beam

Coordination

Implementation of multi-

BS collaboration with

channel information

Multi-dimension adaptationAdaptation strategyMulti-variable channelmeasurementLow-rate feedback mechanism

MulticastAnchor

Relay Technologies


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y g

Types of Relay

L1 Relay repeater or Amplify-and-forward

L2 Relay decode-and-forwardL3 Relay IP packet forwarding

Characteristic of Relay associated with eNode B

Transparent Relay same Physical cell ID as eNB

Non-transparent Relay separate Physical cell ID as eNB

Design Issues in L2/L3 Relays


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g y

L3 Relay Type 1 Relay agreed in LTE-A

TDM backhauling using MBSFN subframe to support Rel-8 UEs

Reducing the complexity

L2 Relay Design issues

Benefit of L2 Relay in system performance - Early termination gain

Timing of HARQ operation in DL and UL

Resource coordination

Scheduling coordination between eNB and Relay Node

PDCCH Tx between eNB and Relay Node for DL Coordinated Relay

Interference mitigation with Relay Node

Power allocation and interference management from neighboring cell and Relay

RS design and UE Channel Estimation

Channel vector from RS with/o Relay Tx at different subframe

L3 Relay Use Cases


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y

Characteristics of L3 Relay

Separate Physical Cell ID Backhauling through LTE-A air interface

Relay Node has complete eNode B functions cell search, RACH, broadcast, DL/UL control, RRC control signaling, mobility management

etc.

Inband Backhauling Assumption of static radio link for backhauling for performance gain Data transport/Control signaling of combination support of S1 & X2 interface.

Possible use of Macro eNode B to Home eNode B interface

Cost effective alternatives comparing to another eNB or RRH

Use Cases for L3 Relay with inband backhauling extended coverage

Remote rural area, isolation area (costly wireline backhaul)

Remote island with reachable distance (under sea backhaul)

Wireless PBX for corporate or small enterprise business (no leasing trunk)

Historical districts (no allowance of new wiring) Wireless home eNB (no wireline backhauling)

Moving objects - Train/Bus/Airplane (No cost effective alternatives)

Temporary coverage Olympics, special events, emergency events

L2 Relay Use Cases


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Characteristics of L2 Relay

Same Physical Cell ID with donor eNB -

Simplified RF/Baseband functions to enhance the cell edge throughput Transparent Backhauling Relay Node is considered an UE to the eNB with coordination of

Tx/Rx and control signaling.

Cost effective alternatives comparing to RRH

Use Cases

Enhancement of Cell edge coverage Remove the coverage hole

Extended coverage at indoor environment - overcome bad RF reception

Improving cell edge throughput Enhanced the penetration in high rise building

Hot spot area

Campus environments

Large Corporate

Bus/Train stops and Airports

Meeting/conference rooms

Tunnels/Bridge/stadium


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Date post:	05-Apr-2018
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52926489 LTE Technical Principles

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