EVERYTHING YOU EVER WANTED TO KNOW ABOUT LTE

(1)

EVERYTHING YOU EVER

WANTED TO KNOW ABOUT

LTE

(BUT WERE AFRAID TO ASK)

SEMINAR –

PART 2/2

Jonathan Buschmann

Ericsson Italy

(2)

Objectives of the seminar

Answer these questions

›

How have mobile networks evolved over the years?

›

What are the main performance targets for LTE/SAE?

›

What is the new core architecture?

›

How does mobility work in LTE?

›

How are some key services supported?

›

What is LTE physical layer like?

(3)

Everything You Ever Wanted to Know About LTE | Public | © Ericsson AB 2011 | 2011-03-15 | Page 3 (23)

›

1G FDMA (NMT, AMPS, TACS)

80’s

- Voice (analog traffic, digital signaling)

›

2G TDMA (GSM, D-AMPS, PDC) and CDMA (IS-95)

90’s

-

Voice, SMS, CS data transfer ~ 9.6 kbit/s (50 kbit/s HSCSD)

›

2.5G TDMA (GPRS)

00’s

- PS data transfer ~ 50 kbit/s

2.75G TDMA (GPRS+EDGE)

00’s

- PS data ~ 150kbit/s

›

3-3.5G WCDMA (UMTS) and CDMA 2000

00’s

- PS & CS data transfer ~ 14-42 Mbit/s (HSPA/HSPA+), Voice, SMS

›

3.9G OFDMA (LTE/SAE)

10’s

- PS Data and Voice (VoIP) ~ 100Mbit/s

›

4G IMT Advanced

History of Mobile

Communications

(4)

• Peak Data Rate

WCDMA comparison

(Release 6)

• Peak Spectral Efficiency

DL ≥5 bps/Hz UL ≥

2.5 bps/Hz

DL = 2.9 bps/Hz

UL = 1.2 bps/Hz

1.4; 3; 5; 10 ;15; 20 MHz

5 MHz (single layer)

• Spectrum Flexibility

• User Plane Latency

UL

≥

50 Mbps (@ 20 MHz)

UL = 5.8 Mbps (5 MHz)

DL

≥

100 Mbps (@ 20 MHz)

DL = 14.4 Mbps (5 MHz)

< 10 ms

(two way latency)

_{50 ms}

• Mobility

Speeds up to 350 km/h

• Coverage

Cell radius up to 30 km

• Interworking

with existing 2G/3G radio access networks

LTE/SAE Main Targets

• Packet Network

>60 VoIP

calls / MHz

CS & PS layers

(5)

CN

SAE CN (EPC)

RNC

NodeB

e-NodeB

WCDMA

LTE/SAE

Moving RNC functions

to e-NodeB

UE

A flat architecture

for optimized

performance and

cost efficiency

SGSN

GGSN

P/S-GW

Architecture Evolution

(6)

eNB

_eNB

eNB

MME/S-GW

_MME/S-GW

S1

X2

SAE

(System Architecture Evolution)

LTE

(Long Term Evolution)

EPC

(Evolved Packet Core)

E-UTRAN

EPS

(Evolved Packet System)

UE

EPS Architecture

(7)

LTE/SAE USER & CONTROL PLANES

PHY

MAC

RLC

PDCP

RRC

UE

PHY

MAC

RLC

PDCP

eNB

RRC

NAS

CONTROL Plane

MME

Uu

SCTP

S1-AP

IP

L2

L1

SCTP

S1-AP

IP

L2

L1

SCTP

S1-AP

IP

SCTP

S1-AP

L2

IP

SCTP

S1-AP

L1

L2

IP

SCTP

S1-AP

S1-CP

S5/S8

PHY

MAC

RLC

PDCP

IP

UE

PHY

MAC

RLC

PDCP

eNB

APPLICATION

USER Plane

PDN GW

Uu

GTP-U

UDP/IP

L2

L1

SCTP

S1-AP

IP

L2

L1

SCTP

S1-AP

IP

SCTP

S1-AP

L2

IP

SCTP

S1-AP

L1

L2

UDP/IP

GTP-U

IP

S1-UP

Serving GW

GTP-U

UDP/IP

L2

L1

GTP-U

UDP/IP

L2

L1

Peer Entity

S1-AP

L2

L1

S1-AP

L2

S1-AP

L1

L2

IP

APPLICATION

IP PACKET

(8)

S1-UP

Internet

eNodeB

Gi

S-GW

P-GW

S5/S8

EPC & E-UTRAN Detailed Architecture

S11

MME

S1-CP

eNodeB

• Radio Resource Management

• Radio Physical layer

• Encryption of UP & CP

• Measurement ctrl & reporting

• Mobility Control

Serving Gateway

• Packet routing & forwarding

• Mobility anchor

• Collecting information for charging

• Buffering U-plane packets while paging

PDN Gateway

• UE IP Address Allocation

• QoS Enforcement

• Packet filtering (QoS)

• Lawful Interception

• Charging (Service)

• Non-3GPP Mobilty Anchor

• Not seen by terminal

Mobility Management Entity

• Idle mode mobility management

• EPS Bearer Management (QoS)

• Security –

AAA (both data and signalling)

• UE attach/detach

eNodeB

E-UTRAN

LTE

MME

S10

Evolved Packet Core

SAE

X2-UP

X2-CP

(9)

S1-UP

eNodeB

Gi

S-GW

P-GW

S5/S8

S4/S11

SGSN/

MME

S1-CP

eNodeB

LTE

SAE

X2-UP

X2-CP

UE

Implementation of SAE/LTE

Integration with 2G/3G

Iub

UTRAN

Node B

Iu-CP

BTS

Gb

Abis

BSC

S4

-UP

Iu-

UP

RNC

GRAN

3G

Internet

(10)

User Equipment States

DETACHED

• No UE-MME connection

• UE not known by MME

REGISTERED

(UE attached)

DEREGISTERED

(UE not attached)

ATTACH !

CONNECTED

• UE-MME connection

• Data transfer possible

UE OFF

IDLE

• UE-MME connection released

• No data transfer

• UE stands by for paging

Signalling Connection release

Signalling Connection re-activation

TA update

DETACH !

eNodeB

MME

UE position known on Cell level in eNB

Handover

eNB

MME

_{Tracking Area (TA)}

UE ON

(active)

UE ON

(idle)

UE ON

(active)

UE OFF

DETACH !

(11)

S1

X2

Intra-LTE Handover with no MME

relocation

Source e-NB

VII

Target e-NB

Gi

MME/

S-GW

I

III

II

HANDOVER REQUEST

I

HANDOVER REQUEST ACK

II

HANDOVER COMMAND

III

VI

HANDOVER CONFIRM

V

PACKET FORWARDING

IV

PATH SWITCH REQUEST

VI

PATH SWITCH ACK

VII

RELEASE RESOURCE

VIII

IV

Internet

P-GW

(12)

IP/Ethernet

transport

IP/Ethernet

transport

Gi

S5

Gi

1

2 IP PoP

S-GW(

2 )

S-GW(

1 )

S-GW

_S-GW

S-GW

P-GW

S10

MME

_MME

Internet

Handower

in LTE (Inter-pool

(13)

EPS services

IP Multimedia Subsystem

›

I

P

M

ultimedia

S

ubsystem (IMS)

›

IMS is an all-IP network for multimedia

services

›

3GPP standard

›

SIP – main protocol from IETF

›

IMS is access independent

›

The only 3GPP standardized means to

support voice

›

3GPP

One-Voice

profile promotes IMS

(14)

›

Application: Mobile TV

›

Broadcast/Multicast Services

⇒

Point-To-Multipoint transmission in downlink

- saves network resources

›

New entities

–

Broadcast Multicast Service Center (BM-SC) in the IP network

–

MBMS Gateway in the EPC Network

–

MCE (Multicell Coordination Entity) in the E-UTRAN (may be integrated in the E-NB)

BM-SC

Content

Provider

EPS services

Multimedia Broadcast Multicast Service

MCE

E-UTRAN

eNB

MBMS

_Gateway

(15)

LTE PHYSICAL LAYER

Multiple Access TECHNIQUES

F

requency

D

ivision

M

ultiple

A

ccess

Each User has a unique

frequency (

1 voice channel per

user).

All users transmit at the same time

Each User has a unique

s

crambling code

Many users share the same

frequency

and

time

C

ode

D

ivision

M

ultiple

A

ccess

Each User has a unique

time slot

Several users share the same

frequency.

T

ime

D

ivision

M

ultiple

A

ccess

time

frequency

time

frequency

O

rthogonal

F

requency

D

ivision

M

ultiple

A

ccess

Each User and has a unique

Time and Frequency Resource

Many users are separated in

frequency and/or time

1G (i.e.TACS)

2G (i.e. GSM)

_{3G (i.e. WCDMA)}

_{4G (i.e. LTE)}

FDMA

_OFDMA

_TDMA

_CDMA

(16)

›

Flexible

bandwidth

›

Uplink: SC-FDMA with dynamic

bandwidth

–

Low PAPR

¨

Higher power efficiency

–

Reduced uplink interference

›

Downlink:

Adaptive OFDM

–

Channel-dependent scheduling and

link adaptation

›

Multi-Antennas, both RBS and

terminal

–

Interference rejection

–

High bit rates

–

Coverage

TX

RX

time

frequency

time

frequency

›

FDD, TDD & Half

Duplex TDD

10

15 20 MHz

3 f

_DL

f

_UL

FDD

-

only

f

_DL

f

_UL

Half

-

duplex FDD

f

_DL/UL

TDD

-

only

∆

f=15kHz

1 m

_s

180 kHz

1.4

5 LTE PHYSICAL LAYER

(17)

Advanced Antenna Communications

–

Tx & Rx Diversity

–

Multi-Layer Transmission (Spatial Multiplexing)

–

Beam-Forming

TX

MIMO 2x2

⇒

channel capacity x ~ 2

MIMO 4x4

⇒

channel capacity x ~ 4

LTE PHYSICAL LAYER

(18)

e-NB

Example of Spatial Multiplexing

La

yer

₁

Layer 2

UE

LTE PHYSICAL LAYER

(19)

›

Bandwidth flexibility LTE physical-layer specification supports any bandwidth

in the range 6 RBs to 100 RBs in steps of one RB

6 RB (

≈

1.1 MHz)

100 RB (

≈

20 MHz)

›

Radio requirements only specified for a limited set of bandwidths

›

Relatively straighforward to extend to additional bandwidths

›

All UEs must support the maximum bandwidth of each supported band

LTE PHYSICAL LAYER

RF Spectrum flexibility

10

15 20 MHz

3

1.4

5

(20)

1

2

3

4

5 DL peak rate

₁₀

₅₀

₁₀₀

₁₅₀

₃₀₀

UL peak rate

₅

₂₅

₅₀

₇₅

Max DL mod

_64QAM

Max UL mod

_16QAM

_64QAM

Layers for

spatial mux.

1

2

4 ›

All UEs support 4 Tx antennas at eNodeB

›

Soft buffer sizes under discussion

›

MBMS is a separate capability

›

FDD, HD-FDD and TDD are independent capabilities

(21)

Simple deployment & Management

Automated Neighbor Relations (ANR)

Cell A

Ncell list;

- CGI 17

- CGI 22

Cell B

PCI = 5

CGI =19

X2

UE

OSS-RC

(22)

Simple deployment & Management

Node selection

›

DNS used for node

selection

›

EPS uses S-NAPTR

(RFC 3958) to map

services and protocols

(i.e. interfaces) to

(23)

What frequencies for LTE?

›

First deployments in Europe in 2.6 GHz band (Sweden and

Norway)

›

Most “appetizing” band is the Digital Dividend – 800 MHz

(24)

What frequencies for LTE?

In italy

›

Re-farming for 900 MHz already agreed:

–

TI, VFE, WIND: 10 MHz

–

Extra 5 MHz destined to H3G

›

AGCOM just announced preliminary rules and public

consultation for auction for 800, 1800, 2000 and 2600

–

Single auction for all spectrum

–

1800 spectrum liberated by DoD and GSM (25 MHz FDD)

–

2000 (UMTS TDD band left from IPSE)

–

2600 (70 MHz)

(25)

Metro

Access

Core

RNC

Mobile Broad Band

State of the Art & Evolution

Fibre/MW

Copper

I

_ub

ATM

xDSL

Microwave

WCDMA

I

ub

ATM

PDH

RNC

MSC

CS core

PS core

SGSN

GGSN

MGW

Node B

e-Node B

OFDMA/SC-FDMA

up to nx100 Mbps

w MIMO (n=2, 3)

S

₁

/X

₂

IP

ETH

Node B

LTE

Long Term Evolution

P/S-GW

SGSN/MME

SAE

System Architecture Evolution

EPC

WCDMA

HSPA/HSPA+

up to 14/42 Mbps

I

_ub

ATM

PDH

I

_ub

IP

ETH

IP Network

ETH

SDH

ATM

SDH

IP TRANSFORMATION

HSPA EVOLUTION

(26)

references

›

SAE and the Evolved Packet Core (Academic Press)

–

Magnus Olsson, Shabnam Sultana, Stefan Rommer, Lars Frid,

Catherine Mulligan

›

3G Evolution: HSPA and LTE for Mobile Broadband

(Academic Press)

–

Erik Dahlman, Stefan Parkvall, Johan Skold, Per Beming

›

4G LTE/LTE-Advanced for Mobile Broadband

(Academic Press)

(27)

(28)

ATM

Asynchronous Transfer Mode

CS Core

Circuit Switched Core

e-Node B

Evolved Node B (refers to LTE Access Network)

DNS

Domain Name System

EPC

Evolved Packet Core

EPS

Evolved Packet System

E-UTRAN

Evolved UMTS Radio Access Network

HSPA

High Speed Packet Access (UMTS Broadband Technology)

IMS

IP Multimedia Systems

LTE

Long Term Evolution (refers to radio interface and network functionalities evolution in

RAN)

OFDM

Orthogonal Frequency Division Multiplexing

OFDMA

Orthogonal Frequency Division Multiple Access

MBMS

Multimedia Broadcast Multicast Service

MIMO

Multiple Input Multiple Output (multiple port antenna systems both at Node B and User