(technology brief to students of lund university) · enhanced uplink (hsupa) mimo cpc lte rel 4 rel...

© 2

012 T

ieto

Corp

ora

tio

n

LTE (Technology brief to Students of Lund

University)

Prasad Pechetty

System Architect

Tieto,

[email protected]

© 2012 Tieto Corporation

Table of contents

• Motivation

• LTE Network Architecture

• Channels

• Frame Structure

• LTE PHY Key aspects

2012-02-06 2


3GPP releases

• R99: WCDMA Evolved

• R5: HSDPA – High Speed Downlink Packet Access

• R6: HSUPA – Enhanced Uplink

• LTE – Long-Term Evolution

• LTE Advanced.

Enhanced Uplink

(HSUPA) MIMO

CPC

Rel 4 Rel 5 Rel 6

HSDPA WCDMA

R99 Rel 7 Rel 8

HSPA Evolution

LTE

= Third Generation Partnership Project

1999 2002 2004 2007 2008 2011 2012

3

HSUPA

LTE Advanced

© 2

012 T

ieto

Corp

ora

tio

n

Motivation for

LTE

© 2012 Tieto Corporation 5

• Higher User throughput of 3-4 times that of HSDPA (Rel.6) in downlink and 3-4 times that of enhanced Uplink (Rel.6)

• Mobility optimized for low mobile speed from 0 to 15 km/h, also supports higher mobile speeds

• Optimal cell size of 5 km, 30 km sizes with reasonable performance, and up to 100 km cell sizes supported with acceptable performance

• Supports a large number of users per cell of at least 200 users/cell (5Mhz)

• Spectrum flexibility & Co-existence with legacy standards

Motivation


3G Evolution • Radio side ( LTE – Long Term Evaluation)

• Spectral flexibility, Spectral efficiency, User throughput & Latency

• Simplification of the Radio Network

• Efficient support og packet based services ( MBMS, IMS etc)

• Network side ( SAE – System Architecture Evaluation) • Improvement in latency, capacity & throughout

• Simplification of the core network

• Optimization for IP traffic and services

• Simplified support and handover to non-3GPP access Technologies

6


LTE Race for throughputs

© 2

012 T

ieto

Corp

ora

tio

n

LTE Network

Architecture


LTE is Packet Only • 2G/3G and CDMA

• LTE

Packet

domain

Circuit

domain

2G /3G

Access

Packet

domain

LTE

Access

CS Bearer

PS Bearer

PS Bearers

Voice

Internet

Access

Voice or

TV

Internet

Access

9


LTE Network Architecture • The LTE architecture comprises of

radio access network and core network • The evolved radio access network is

referred to as E-UTRAN (Evolved-UTRAN)

• The evolved core network is referred to as EPC

(Evolved Packet Core network)

• This is collectively referred to as Evolved packet system

eNB

MME / S-GW MME / S-GW

eNB

eNB

S1

S1

S1

S1

X2

X2X

2

E-UTRAN

Ref:3GPP TS 36.300 V8.7.0


Functions of eNodeB :

• Functions for Radio Resource Management, i.e Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink

• IP header compression and encryption of user data stream;

• Selection of an MME at UE attachment when no routing to an MME can be determined from the information provided by the UE

• Routing of User Plane data towards Serving Gateway

• Scheduling and transmission of paging messages (originated from the MME);

• Scheduling and transmission of broadcast information

eNB


eNB

eNB

S1

S1

S1

S1

X2

X2

X2

E-UTRAN


• MME

• Inter CN node signalling for mobility between 3GPP access networks

• Idle mode UE Reachability

• Tracking Area list management (for UE in idle and active mode)

• PDN GW and Serving GW selection

• MME selection for handovers with MME change

• SGSN selection for handovers to 2G or 3G 3GPP access networks

• Roaming

• Authentication

• S-GW

• The local Mobility Anchor point for inter-eNB handover

• Lawful Interception

• Packet routing and forwarding

Functions of MME & S-GW

eNB


eNB

eNB

S1

S1

S1

S1

X2

X2

X2

E-UTRAN


IP Transport Network

LTE Network

• Cost efficient two node architecture

• Fully meshed approach with tunneling mechanism over IP network

• Access gateway (AGW)

• Enhanced Node B (eNB)

IP Service Network

S1

X2 X2

X2 X2

S1 S1 S1

AGW AGW

eNB

eNB

eNB

eNB

eNB

13


LTE with other RANs


NAS

RRC

PDCP

RLC

MAC

PHY

UE

RRC

PDCP

RLC

MAC

PHY

eNB

NAS

MME

Handovers

Ciphering

Segmentation

HARQ

Modulation,

coding

NAS

RRC

PDCP

RLC

MAC

PHY

UE

RRC

PDCP

RLC

MAC

PHY

eNB

Control Plane User Plane

Radio bearers

Logical channels

Transport channels

Physical channels

15

Protocol overview

© 2

012 T

ieto

Corp

ora

tio

n

Channels


LTE Transport Channels

• Broadcast Channel (BCH)

• Paging Channel (PCH)

• Downlink Shared Channel (DL-SCH)

• Multicast Channel (MCH)

• Uplink Shared Channel (UL-SCH)

• Random Access Channel (RACH)


LTE Physical Channels • DL

• Physical Broadcast Channel (PBCH)

• Physical Control Format Indicator Channel (PCFICH)

• Physical Downlink Control Channel (PDCCH)

• Physical Hybrid ARQ Indicator Channel (PHICH)

• Physical Downlink Shared Channel (PDSCH)

• Physical Multicast Channel (PMCH)

• UL • Physical Uplink Control Channel (PUCCH)

• Physical Uplink Shared Channel (PUSCH)

• Physical Random Access Channel (PRACH)


BCH PCH DL-SCHMCH

Downlink

Physical channels

Downlink

Transport channels

PBCH PDSCHPMCH PDCCH

Uplink

Physical channels

Uplink

Transport channels

UL-SCH

PUSCH

RACH

PUCCHPRACH

Mapping between Transport and

Physical Channels

© 2

012 T

ieto

Corp

ora

tio

n

Frame Structure &

Physical resources

20 2012-02-06


LTE Frame Structure

• Frame Type 1: FDD

#0 #1 #2 #3 #19#18

One radio frame, Tf = 307200Ts = 10 ms

One slot, Tslot = 15360Ts = 0.5 ms

One subframe

• Frame Type 2: TDD

One slot,

Tslot=15360Ts

GP UpPTSDwPTS

One radio frame, Tf = 307200Ts = 10 ms

One half-frame, 153600Ts = 5 ms

30720Ts

One subframe,

30720Ts

GP UpPTSDwPTS

Subframe #2 Subframe #3 Subframe #4Subframe #0 Subframe #5 Subframe #7 Subframe #8 Subframe #9


DL& UL Configurations in TDD

Uplink-

downlink

configura

tion

Downlink-

to-Uplink

Switch-

point

periodicit

y

Subframe number

0 1 2 3 4 5 6 7 8 9

0 5 ms D S U U U D S U U U

1 5 ms D S U U D D S U U D

2 5 ms D S U D D D S U D D

3 10 ms D S U U U D D D D D

4 10 ms D S U U D D D D D D

5 10 ms D S U D D D D D D D

6 5 ms D S U U U D S U U D


One downlink slot, Tslot

sub

carr

iers

NB

WDL

Resource element

OFDM symbolsDLsymbN OFDM symbolsDLsymbN

NB

Wsu

bca

rrie

rsR

B

Resource block

RBBW

DLsymb NN resource elements

RBBW

DLsymb NN resource elements

Resource Grid

23


DL Reference Signals • To carry out downlink coherent demodulation

• Transmitted during the first and third last OFDM symbols of each slot with a frequency-domain spacing of six subcarriers

• Four symbols per Slot

• Is the product of a pseudo-random sequence and an orthogonal sequence.


Sampling Frequency and BW

25

Bandwidth 1.4

MHz

3

MHz

5

MHz

10

MHz

15

MHz

20

MHz

Sampling

Frequency

1.92

MHz

3.84

MHz

7.68

MHz

15.36

MHz

23.04

MHz

30.72

MHz

FFT Size 128 256 512 1024 1536 2048

RBs 6 15 25 50 75 100


• MIMO

Multiple Input Multiple Output

• OFDM Orthogonal Frequency Division Multiplexing

NTx Transmit

Antennas

NRx Receive

Antennas

27


• Sub-carriers are orthogonal

• All the sub-carriers allocated to a given user are transmitted in parallel.

• The carrier spacing is 15kHz

OFDM

28


OFDMA vs SC-FDMA

29


MIMO Basics • Minimum antenna requirement: 2 at eNodeB 2 Rx at UE

• Transmission of several independent data streams in parallel => increased data rate

• The radio channel consists of NTx x NRx paths

• Theoretical maximum rate increase factor = Min(NTx x NRx)

30


• An example of how samples are mapped:

• Maps onto resources on each of the antenna ports

• The values of the precoding matrix are selected from the codebook configured in the eNodeB and the UE.

)(

)(

)(

)(

)(

)1(

)0(

)1(

)0(

ix

ix

iW

iy

iy

P

)(iW

MIMO


Transport

Channel Processing

32


Requirement comparison Requirement HSPA (Rel 6) LTE

Peak data rate 14 Mbps DL

5.76 Mbps UL

300 Mbps DL

150 Mbps UL

5% packet call throughput 64 Kbps DL

5 Kbps UL

3-4x DL / 2-3x UL

improvement

Averaged user throughput 900 Kbps DL

150 Kbps UL

3-4x DL / 2-3x UL

improvement

Control plane capacity > 200 users per cell (for

5MHz spectrum)

User plane latency 50 ms 5 ms

Call setup time 2 sec 50 ms

Broadcast data rate 384 Kbps 6-8x improvement

Mobility Up to 250 km/h Up to 350 km/h (500 km/h

for wider bandwidths)

Bandwidth 5 MHz 1.4, 3, 5, 10, 15, 20 MHz

33


Feature comparison

Feature HSPA (Rel 6) LTE

minimum TTI size 2 ms 1 ms

Modulation DL: QPSK, 16 QAM

UL: QPSK

DL: QPSK, 16 QAM, 64

QAM

UL: 16 QAM

HARQ Async DL,

Sync UL

Async DL,

Sync UL

Fast scheduling TDS (time domain) TDS and FDS (frequency

domain)

34


Conclusion • Scalable bandwidth

• Downlink and uplink peak data rates are 300 and 150 Mbps respectively for 20 MHz band width.

• MIMO

• OFDM

• At least 200 mobile terminals in the active state for 5MHz bandwidth. If bandwidth is more than 5MHz, at least 400 terminals should be supported.

• PHY key technologies enable higher spectral efficiency, peak rate and lower latency

35


Questions?

(technology brief to students of lund university) · enhanced uplink (hsupa) mimo cpc lte rel 4 rel...

Documents