lte n future trends

7/27/2019 LTE n Future Trends

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1

An Introduction of

Long Term Evolution

(LTE)



2

What is LTE ?

In Nov. 2004, 3GPP began a project to

define the long-term evolution (LTE) of

Universal Mobile Telecommunications

System (UMTS) cellular technology

Higher performance

Backwards compatible

Wide application



1G

2G

GSM + VAS

GSM+GPRS

GSM + EDGE

3G

4G

Future

Evolution of Mobile Networks



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 01’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 future

Wireless Generations



5

Evolution of Radio Access

Technologies

LTE (3.9G) :

3GPP release8~9

LTE-Advanced :

3GPP release

802.16d/e

802.16m



3GPP Releases

The 3GPP produces a complete set of globally applicableTechnical Specifications and Reports for the UMTS standard.

These are published in releases…

R4MSS,

IP Core

R6HSDPA P2,

EUL P1,…

R5HSDPA P1,

IMS…

R991st 3G

networks

R7MIMO,

ALL - IP

R8A-bis

Over IP

R10LTE

Adavanced

DL – 0.4 Mbps

UL - 0.4 Mbps

DL – 14 Mbps

UL - 0.4 Mbps

DL – 14 Mbps

UL - 5.7 Mbps

DL – 84 Mbps

UL - 22 Mbps

DL – 168 Mbps

UL - 50 Mbps

DL – 1000 Mbps

UL - 500 Mbps

DL – 0.4 Mbps

UL - 0.4 Mbps



3GPP Releases

• 3GPP started working on System Architecture Evolution(SAE) in the end of 2004

• Feasibility of technical options was studied in 2005-2006

• Actual standardisation started after the feasibility studyin the beginning of 2007

• Nowadays, the system is called Evolved Packet System(EPS) instead of SAE

– The PS core part is called Evolved Packet Core(EPC)

• LTE have been developed by the same standardizationorganization – 3GPP. The target has been simple

multimode implementation and backwards compatibility.



Operators - Cost per bit with high traffic growth

Source: Light Reading (Adapted)

Voice dominated Data dominated

Traffic volume

Revenue

Time

Network cost(LTE)

Network cost(existing technologies)

Profitability

LTE reduces thecost/Mb

Mobile network

traffic and costs



9

LTE Basic Concepts

LTE employs Orthogonal Frequency

Division Multiple Access (OFDMA) for

downlink data transmission and Single

Carrier FDMA (SC-FDMA) for uplinktransmission



AccessFlat Overall Architecture

• 2-node architecture

• IP routable transport architecture

Improved Radio Principles• peak data rates [Mbps ] 173 DL , 58 UL

• Scalable BW: 1.4, 3, 5, 10, 15, 20 MHz

• Short latency: 10 – 20 ms

New Core Architecture• Simplified Protocol Stack

• Simple, more efficient QoS

• UMTS backward compatible security

LTE / SAE introduces the mechanism to fulfill the

requirements of a next generation mobile network

Access Core Control

LTE BTS

(eNodeB)

MME

SAE-GW

IMS HLR/HSS

RF Modulation:• OFDMA in DL

• SC-FDMA in UL

LTE : Basic Concepts / Architecture

MME

S-GW and P-GW



TDMA FDMA CDMA OFDMA

f f

f

t

f

t

f

f

t

f

t

f

• Time Division • Frequency Division • Code Division • Frequency Division

• Orthogonal subcarriers

Multiple Access Methods

User 1 User 2 User 3 User ..



Results of Multipath Fading

Reflections and multipath-fading

result in large variationsof frequency response



13

FDM vs. OFDM



Downlink - OFDMSubchannels / Tones (each 15 kHz)

1 TTI

= 1ms

1 PRB (Physical Resource Block) = 12 Subcarriers = 180 kHz

1 PRB = 2 Slots = 2 * 0.5 ms

1.4 MHz = 72 Tones 20 MHz = 1200 TonesUser 1

User 2

User 3

User ..



15

LTE-Downlink (OFDM)

Improved spectral

efficiency

Reduce ISI effect

by multipath

Against frequency

selective fading



16

LTE Uplink (SC-FDMA)

SC-FDMA is a new single carrier multipleaccess technique which has similar structureand performance to OFDMA

A salient

advantage of SC-

FDMA over

OFDM is low to

Peak to AveragePower Ratio

(PAPR) :

Increasing

battery life



The Beauties of LTE

Channel only changes amplitude and phase of subcarriers

Fast Link

Adaptation

due to

channel

behaviour

Short TTI = 1 ms

Transmission

time interval

Advanced Scheduling

Time & Freq. (Frequency

Selective Scheduling)

TX RX

Tx Rx

MIMO

Channel

DL: OFDMA

UL: SC-FDMA

scalable

HARQ: Hybrid

Automatic Repeat Request

64QAM

Modulation

1

2

21

NACK ACK

Rx Buffer

Combineddecoding



LTE Radio Principles

• Power efficient uplink increasing battery lifetime

• Improved cell edge performance by low peak to average ratio

• Reduced Terminal complexity

Uplink:

SC-FDMA

• Enabling peak cell data rates of 173 Mbps DL and 58 Mbps in UL *

• Scalable bandwidth: 1.4 / 3 / 5 / 10 /15 / 20 MHz also allows deployment

in lower frequency bands (rural coverage, refarming)

• Short latency: 10 – 20 ms **

• Improved spectral efficiency

• Reduced interference

• Very well suited for MIMO

* At 20 MHz bandwidth, FDD, 2 Tx, 2 Rx, DL MIMO, PHY layer gross bit rate ** roundtrip ping delay (server near RAN)

Downlink:

OFDMA

Subchannels / Tones (each 15 kHz)

t i m e

1 TTI

= 1ms

1 PRB (Physical Resource Block)

= 12 Subcarriers = 180 kHz

1 PRB = 2 Slots

= 2 * 0.5 ms

User 1

User 2

User 3

User ..

Subchannels / Tones (each 15 kHz)

t i m e

1 TTI

= 1ms

1 PRB (Physical Resource Block)

= 12 Subcarriers = 180 kHz

1 PRB = 2 Slots

= 2 * 0.5 ms

User 1

User 2

User 3

User ..



Access Aggregation

LTE Network Elements All protocols over IP

Inter-BTSconnectivity

X2-u/c

O&M

S1-u

S1-c(S1_MME)

BTS

BTS

S-GW

MME

Ethernet will be the predominant equipment interface technology.

Inter-BTS connectivity (X2) for handover comes along with

Ethernet Transport architecture.

Transportnetwork

C f S S



Comparison of UMTS and EPS

Evolved Packet Core

eUTRAN

UMTS Core Network

UTRAN

NB

NB

MSC

Iu-CS

Iur

NB

RNC

Iu-PS

eNB evolved NodeB

MME Mobility Management

Entity

SGW Serving Gateway PGW PDN Gateway

MSC Mobile Switching Center

NB NodeB

RNC Radio Network Controller

SGSN Serving GPRS Support Node

GGSN Gateway GPRS Support Node

IubeNB

S1-U

X2

S1-MME

eNB

eNB

MMESGSN

GGSN

SGW

PGW



21

Operator ServicesInternet

CorporateServices

Overall Evolved Packet System architecture

Evolved Packet Core

PCRF

ePDG

Gb

Iu S4

S1-MME

S1-U

S11

S2c

S2a

S2b

Gx

Rx+

SGi

HSS

S6b

S5

User planeControl plane

S3

S6a

SGSN

BSC

RNC

S10

AAA

RAN

NodeB

eNodeB

PGW

S12

Gxc

SGW

MMELTE

3G

2G

Non3GPP

Untrusted Non-3GPP

IP Access

Trusted Non-3GPP IP

Access

Gr/S6d

S16

SWx



22

LTE Network Nodes and Interfaces

From IP point of view the LTE network can be split in three parts:

• Access Network and Transport Network

• Evolved Packet Core

• Applications



23

• It is the only network element defined as part of EUTRAN.

• It replaces the old Node B / RNC combination from 3G.

• It terminates the complete radio interface including physical

layer.

• It provides all radio management functions

• An eNB can handle several cells

• To enable efficient inter-cell radio management for cells not

attached to the same eNB,

• there is a inter-eNB interface X2 specified.

Evolved Node B



24

•It is a pure signaling entity inside the EPC; P-GW & S-GWselection•SAE uses tracking areas to track the position of idle UEs. Thebasic principle is identical to location or routing areas from2G/3G.•MME handles attaches and detaches to the SAE system, aswell as tracking area updates•NAS signaling & security - The Non-Access Stratum (NAS)signaling terminates at the MME and it is also responsible for

generation and allocation of temporary identities to UEs•Interface towards the HSS which stores the subscriptionrelevant information and the currently assigned MME in itspermanent data base.

Mobility Management Entity



25

• Manages the user data path (SAE bearers) within EPC

• It connects via the S1-U interface towards eNB and receives

uplink packet data from here and transmits downlink packet

data on it.

• The serving gateway has packet data anchoring functionwithin EPC.

• It relays the packet data within EPC via the S5/S8 interface to

or from the PDN gateway.

• A serving gateway is controlled by one or more MMEs via S11interface.

Serving Gateway



26

• The PDN gateway provides the connection between EPC anda number of external data networks.

• PDN Gateway is comparable to GGSN in 2G/3G networks.• Mobility anchor for mobility between 3GPP access systems

and non-3GPP access systems.• Policy Enforcement (PCEF)• Per User based Packet Filtering (i.e. deep packet inspection)• Charging & Lawful Interception support• IP Address Allocation for UE•

Packet screening (firewall functionality)

Packet Data Network Gateway



27

Policy and Charging Rule Function

• The PCRF major functionality is the Quality of Service (QoS)

coordination

Home Subcriber Server

• Permanent and central subscriber database• Stores mobility and service data for every subscriber

• Contains the Authentication Center (AuC) functionality.

PCRF & HSS



28

Evolution towards a flat architecture

Iu over IP

Separation of CP and UP:

Direct Tunnel Implementation

NodeB becomes intelligent,

with RNC functionality



29



Wireless Network Trends

Unified Flat

Converged All IP

Time

Network

Architecture

Radio

Access

Terminal

IMS

IP UTRAN

Enhanced IMSE2E IP

RNC LTE

Soft-switch

IP CN

Ultra-high speed

Ubiquitous coverage

Higher Spectrum efficiency

Various access technology

Low Cost

Indoor coverage

UMA

WiMAX

OFDM

MIMO

HSDPA

HSUPA

WIFI

Multi Band

Multi Mode

Multi Media

Software

Defined Radio

Online

Reconfigurable

Dual Band

Dual Mode

Converged

Intelligent

Integration

The wireless networks converge in the core network and the terminal.

Wireless access adds value to services, and users will choose best value connection.

Usage goes indoor! More than 70% traffic has moved from highway to hallway

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