LTE Systems & Architecture presentation

LTE Systems &

Architecture

OBJECTIVES

o Introduction

Wireless Technology Evolution Mobile Evolution Data Forecast 4th Generation Mobile System

o Network Architecture

4G Mobile System E-UTRAN Architecture UE eNodeB E-UTRAN Interfaces and Protocols

o LTE Air Interface Principle

Principles of OFDM LTE Channel Structure LTE Frame Structure

o Evolved Packet Core Architecture (SAE)

Mobility Management Entity Serving Gateway Packet Data Network Gateway IMS

OBJECTIVES

INTRODUCTION

Wireless Technology Evolution

Mobile Evolution

World Data Forecast

4th Generation Mobile System

Key IMT Advance Features

A high degree of common functionality worldwide while retaining the flexibility to support a

wide range of services and applications in a cost efficient manner

Compatibity of services within IMT and fixed networks

Capability of interworking with other radio access systems

High quality mobile services

User equipment suitable for worldwide use

User-friendly applications, services and equipment

Worldwide roaming

Enhanced peak data rates to support advanced services and applications (100Mbits/s for

high and 1Gbits/s for low mobility were identified as targets)

3GPP RELEASE

4th Generation Mobile System

GSM

9.6kbps

Phase 1

EDGE

473.6kbps

R99

HSDPA

14.4Mbps

R5

HSPA+

28.8Mbps

R7/8

Phase 2+(R97)GPRS

171.2kbps

R99UMTS

2Mbps

R6HSUPA

5.76Mbps

R8LTE

+300Mbps

R9/10LTE Advanced

E-UTRAN ARCHITECTURE

E-UTRAN ARCHITECTURE UE eNODEB

E-UTRAN ARCHITECTURE

eNB eNB

E-UTRAN EPC

MME

S-GW PDN-GWUE

IMS

Video ASCSCFHSS

USER EQUIPMENT

FUNCTIONAL ELEMENTS UE CATEGORIES UE IDENTITIES

USER EQUIPMENT (UE)

USIM Mobile Equipment (ME)

RADIO RESOURCE EMM(EPS Mobility Management) ESM(EPS Session Management)

FUNCTIONAL ELEMENTS:

LTE SIM

UE FUNCTIONAL ELEMENTS

EPS Mobility & EPS

Session

Management

IP Adaptation

Function

RADIO

RESOURCE

UEControl

Plane

User

Plane

EPS Session Management

Bearer Activation

Bearer Modification

Bearer Deactivation

EPS Mobility Management

Registration

Tracking Area Update

Handover

Radio Resource

RRC, PDCP, RLC, MAC & Phy

Layer Protocols

UE FUNCTIONAL ELEMENTS

UE

Category

Maximum

Downlink

Data Rate

Number of

Downlink

Data

Streams

Maximum

Uplink Data

Rate

Support

for Uplink

64QAM

1 10.3Mbits/s 1 5.2Mbits/s No




5 302.8Mbits/s 4 75.4Mbits/s Yes

USER EQUIPMENT (UE)

IDENTITIES

MME Identity + MME Codes

MME Global Identity

Globally Unique MME Identity + MME-TMSI

Globally Unique Temporary Identification

GUTI

GUMMEI

MCC MNC MMEGI

MMEI MMEC

M-TMSI

eNODEB

FUNCTIONAL ELEMENTS eNODEB CATEGORIES

GSM / UMTS Network

Architecture

LTE Network Architecture

EPC

MME

S-GW

eNB

eNB

E-UTRAN

UE

eNODEB Functional Elements

Radio Resource

ManagementUL/DL Resources Allocation

Access Control

Mobility Control

Data Compression

Data ProtectionRoutingS1-C (MME)

S1-U (S-GW)

Packet Classification and

QoS Policy Enforcement

eNB

eNODEB Identities

TAI (Tracking Area Identities) ~ RAI

ECGI (Evolved Cell Data Identity) MCC+MNC+ECI

E-UTRAN INTERFACE AND

PROTOCOLS

Uu Interfaces

eNODEB Identities

EPC

MME

S-GW

eNB

eNB

E-UTRAN

X2

S1-MME

S1-MMES1-U

S1-U

Uu

UE

UU INTERFACE

eNODEB Identities

EPC

MME

S-GW

eNB

eNB

E-UTRAN

X2

S1-MME

S1-MMES1-U

S1-U

Uu

UE

LTE AIR INTERFACE

Radio Interface Techniques

4G and future wireless systems optimize a

combination of frequency, time and coding

e.g. OFDMA & SC-FDMA

FDMA: frequency domain multiple access

TDMA: time domain multiple access

CDMA: code domain multiple access

What is OFDM

Subcarriers used.

The subcarriers are orthogonal to

each other and can be overlapped.

Suitable for multipath fading

channels and high data rates`

OFDM Orthogonal Frequency Division Multiplexing

o Many closely-spaced sub-carriers, chosen to be

orthogonal, thus eliminating inter-carrier interference

o Varies bits per sub-carrier based on instantaneous

received power

LTE OFDM

Statistical Multiplexing ( in

OFDMA)

Dynamically allocates user data to sub-carriers based oninstantaneous data rates and varying sub-carrier capacities

Highly efficient use of spectrum

Robust against fading, e.g. for mobile operation

Orthogonal Frequency Division

Multiple Access ( OFDMA )

Orthogonal Frequency Division Multiple Access

Supercedes CDMA used in all 3G variants

OFDMA = Orthogonal Frequency Division Multiplexing(OFDM) plus statistical multiplexing

Optimization of time, frequency & code multiplexing

OFDMA already deployed in 802.11a & 802.11g

Took Wi-Fi from 11 Mbps to 54 Mbps & beyond

FDMA vs. OFDMA

OFDMA more frequency efficient

OFDMA Dynamically maps traffic to frequencies based on their

instantaneous throughput

FDMA

ChannelGuard

band

OFDMA

OFDMA

Each user allocated a

different resource which

can vary in time and

frequency

Frequency

Power

LTE Air Interface

Orthogonal Frequency Division Multiple

Access

Single Carrier-Frequency Division

Multiple Access

eNB

UE

OFDMA and SC-FDMA

OFDMA and SC-FDMA

ADVANTAGE:

High spectrum utilization efficiency due to orthogonal subcarriers need no protection bandwidth

(SC-FDMA) can release the (LTE)UE PA limitation caused by high PAPR(Peak to Average Power)

OFDMA Orthogonal FDMA

Orthogonal Frequency Division Multiple Access

Supercedes CDMA used in all 3G variants

OFDMA = Orthogonal Frequency Division Multiplexing(OFDM) plus statistical multiplexing

Optimization of time, frequency & code multiplexing

OFDMA already deployed in 802.11a & 802.11g

Took Wi-Fi from 11 Mbps to 54 Mbps & beyond

OFDMA Subcarrier

OFDM:

Spectral efficiency is achieved by reducing the spacing between FDM subcarrier

Subcarrier overlap due to their orthogonally with other subcarrier thus reduce adjacent channel interference

Frequency

Channel

Bandwidth

Orthogonal

Subcarrier

Center Subcarrier

Not Orthogonal

Fast Fourier Transform

SERIAL

TO

PARALLEL

IFFT RFCoded

Bits

Subcarrier

ModulationInverse Fast

Fourier

Transform

Complex

Waveform

LTE FFT Sizes

Channel

BandwidthFFT Size

Subcarrier

BandwidthSampling Rate

1.4Mhz 128 1.92Mhz

3Mhz 256 3.84Mhz

5Mhz 512 7.68Mhz

10Mhz 1024 15.36Mhz

15Mhz 1536 23.04Mhz

20Mhz 2048 30.72Mhz

15Khz

EXAMPLE:

For BW=10Mhz

15.36Mhz/15Khz=1024

OFDMA Symbol Mapping

Frequency

AmplitudeTime

Modulated

OFDM

Symbol

OFDM

Symbol

Cyclic

Prefix

CALCULATIONS:

1 OFDM Symbol = 12 Subcarriers

1 Subcarrier = 15Khz (BW)

12 SC x 15Khz = 180Khz (OFDM Symbol BW)

For a 10Mhz LTE Carrier:

10Mhz/180Khz ~ 55 (Rows of 12 OFDM

Symbols)

OFDMA Structure

PRB consist of 12

Subcarrier for 0.5ms

Time

Frequency

Channel

BandwidthOFDMA

Device is allocated one

or more PRB (Physical

Resource Blocks)

Channel

Bandwidth

(Mhz)

PRB

1.4 6

3 15

5 25

10 50

15 75

20 100

Physical Resource Block and

Resource Element

Slot 8 Slot 9

0 1 2 3 4 5 6 7 8 9

Radio Frame=10ms

Subframe

Resource Element

(RE)

1 2 3 4 5 6 7

2

3

4

5

6

7

8

9

10

11

12

Physical Resource

Block (PRB)

Symbols

Su

bca

rrie

r

Ph

ys

ica

l R

es

ou

rce

Blo

ck

(P

RB

)

CALCULATIONS:

12x7=84 RE

LTE Physical Signals

PCI, Physical Channel Id

= 0~503

= PSS+SSS

Where:

PSS= 0,1,2

SSS= 0~167

Synchronization Sequence

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

0 1 2 3 4 5

0 1 2 3 4 5 6

Repeated in

slots 0 and 10

PSS(Primary

Synchronization

Sequence)

SSS(Secondary

Synchronization

Sequence)

Bandwidth

Bandwidth

Extended CP

Normal CP72 Subcarriers62

SCFDMA Single Carrier FDMA

Single carrier multiple access

Used for LTE uplinks

Being considered for 802.16m uplink

Similar structure and performance to OFDMA

Single carrier modulation with DFT-spreadorthogonal frequency multiplexing and FD

equalization

Lower Peak to Average Power Ratio (PAPR)

Improves cell-edge performance

Transmit efficiency conserves handset battery life

SCFDMA Signal Generation

DFT Subcarrier

MappingIDFT

CP

InsertionSymbols

.

Time Domain Time DomainFrequency Domain

http://www.youtube.com/watch?v=

dr4YQAfifKA

Multiple Input Multiple Output (MIMO)

o Multiple Input Multiple Output smart antenna

technology

o Multiple paths improve link reliability and

increase spectral efficiency (bps per Hz),

range and directionality

Multiple Input Multiple Output (MIMO)

LTE supports MIMO as the base option, with multipletransmitter and receiver antennas in a same eNode-B.

Up to four antennas can be used by a single LTE cell(gain: spatial multiplexing)

MIMO is considered to be the core technology toincrease spectral efficiency.

Rake receiver are use to efficiently received transmitted RF signal from eNODEB to UE ( User Equipment )

MIMO Category

Increase capacity

since a single user

benefits from multiple

data streams.

eNB

SU-MIMO

eNB

MU-MIMO

Increase sector

capacity by allowing

users to share

streams.

Spatial Multiplexing

eNB

MIMO

TB Port 0

Port 1TB

TB

TB

2X2 Spatial Multiplexing

Space Time Coding

eNB

MIMO

Port 0

Port 1

TB

Increase Robustness

1 2 3 4 5 6

TB

1 2 3 4 5 6

3 6 5 2 1 4

TB still recoverable

Interference

Adaptive MIMO Switch

eNB

High SNRLow SNR

Eff

icie

ncy

AMS Point

Spatial

Multiplexing

Space Time

Coding

TRANSMISSION MODES

LTE Types

o LTE FDD (Type 1)

Long Term Evolution Frequency Division Duplex Evolved from 3G HSPA

o LTE TDD (Type 2)

Long Term Evolution Time Division Duplex Evolved from WiMAX

FDD vs. TDD

o Differences between TDD and FDD These two standards are based on LTE network

technology and are similar in nature. The main

difference is in the actual physical layer.

FDD LTE is able to be linked to a subframe from an uplink.

the amount of uplink and downlink subframes differs which means that such associative links cannot be

made in TDD LTE TDD LTE performance is less efficient because of guard

periods.

FDD vs. TDD

o Advantage of TDD Channel estimations that are used for beam-forming

or similar antenna techniques have to apply for the

downlink and uplink

o Advantage of FDD The benefits of FDD only become apparent in cases

where both the downlink and uplink transmissions of

data are symmetrical in nature which makes

communication much more streamlined

Type 1 (LTE FDD)Uplink Downlink

(MHz) (MHz)

1 1920 - 1980 2110 - 2170 60

2 1850 - 1910 1930 - 1990 60

3 1710 - 1785 1805 -1880 75

4 1710 - 1755 2110 - 2155 45

5 824 - 849 869 - 894 25

6 830 - 840 875 - 885 10

7 2500 - 2570 2620 - 2690 70

8 880 - 915 925 - 960 35

9 1749.9 - 1784.9 1844.9 - 1879.9 35

10 1710 - 1770 2110 - 2170 60

11 1427.9 - 1452.9 1475.9 - 1500.9 20

12 698 - 716 728 - 746 18

13 777 - 787 746 - 756 10

14 788 - 798 758 - 768 10

15 1900 - 1920 2600 - 2620 20

16 2010 - 2025 2585 - 2600 15

17 704 - 716 734 - 746 12

18 815 - 830 860 - 875 15

19 830 - 845 875 - 890 15

20 832 - 862 791 - 821 30

21 1447.9 - 1462.9 1495.5 - 1510.9 15

22 3410 - 3500 3510 - 3600 90

23 2000 - 2020 2180 - 2200 20

24 1625.5 - 1660.5 1525 - 1559 34

25 1850 - 1915 1930 - 1995 65

Width of Band

(MHz)LTE Band

Type 1 (LTE FDD)

Uplink

Channel

Bandwidth

Downlink

Channel

Bandwidth

Duplex Spacing

Frequency

Type 1 (LTE TDD)

33 1900 - 1920 20

34 2010 - 2025 15

35 1850 - 1910 60

36 1930 - 1990 60

37 1910 - 1930 20

38 2570 - 2620 50

39 1880 - 1920 40

40 2300 - 2400 100

41 2496 - 2690 194

42 3400 - 3600 200

43 3600 - 3800 200

Allocation

(MHz)

Width of Band

(MHz)LTE Band

TDD

Frequency

Downlink

and Uplink

TimeDownlink Uplink

Asymmetric

Allocation

TDD Frame

LTE CHANNEL STRUCTURE

Logical Transport Physical Radio

Control Logical Channels

System Information

Messages

Paging Devices

Low Priority

NAS Signaling

DCCH

DCCH

CCCH

BCCH

PCCH

CCCH

SRB 0

SRB 0

SRB 1

SRB 2

Traffic Logical Channel

DTCH

Carries AM or UM

RLC Traffic

DRB

Transport Channel

RACH

UL-SCH

BCH

PCH

DL-SCH

Evolved Packet Core

Simplified LTE Architecture

eNB eNB

E-UTRAN EPC

MME

S-GW PDN-GWUE

IMS

Video ASCSCFHSS

SAE

MME Mobility Management Entity

MME

NAS Signaling

and Security

S-GW and

PDN-GW

Selection

Tracking Area List

Management and

Paging

Authentication

Inter MME

Mobility

Serving - Gateway

Mobility Anchor

Downlink

Packet

Buffering

Packet Routing and

Forwarding

GTP/PMIP

Support

Lawful

Interception

S-GW

PDN - Gateway

Packet Filtering

Lawful

Interception

IP Address

Allocation

Accounting

Transport Level

Packet Marking

PDN-GW

IMS IP Multimedia Subsystem

IMS

Video ASCSCFHSS

o IP Multimedia Subsystem

The IP Multimedia Subsystem (IMS) is a concept for an integrated network of telecommunications carriers

that would facilitate the use of IP (Internet Protocol)

for packet communications

Additional Network Elements

and Interface

EPC

MME

S-GW PDN-GW

MME

HSS

EIR

SGSN

PCRF

RNCePDG

CDMA

2000Untrusted

Non 3GPP

IP Access

CDMA

2000

Trusted

Non 3GPP

IP Access

S10

S5/S8

S11

S6a

S13

S3

S4

S12

S103 S2b

S2a

S101

Gx

Wn

Additional Network Elements

and Interface7

5

SGSN GGSNRNC

IP

BACKBONE

IP

BACKBON

E

Node B

eNode B

MME

S-GW/P-GW

DataIP

BACKBONE

LTE Network Diagram

3G Network Diagram

LTE Network Elements

EPC

S1 C S1 - MME

S1 U

THANK YOU!!!

Documents

LTE Systems & Architecture presentation