evolved packet system wisense seminar may 19 2011

8/6/2019 Evolved Packet System WiSense Seminar May 19 2011

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Evolved Packet System:The Next Generation

Mobile Network for 4Gsystems

Presented by: Dr. Khaled Ali
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Outline

Introduction

Evolved Packet System Architecture

LTE Radio Network Evolved Packet Core (EPC) Network

QoS Control in the EPS

Conclusion

05/27/11 EPS Systems 2


3/20

Introduction

Different access and core networks

Different QoS control mechanisms

Different mobility managementmechanism

High deployment and maintenancecost

High cost per bit

GERAN

UTRAN

CN

CDMA200 HRPD

WiMAX

WLAN

CN

CN

LegacyCS

services

IPnetwork

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4/20

Introduction Unified core network architecture for

heterogeneous access networks

New radio access network

Maintaining a competitive wirelesssystem from 2010-2020

3GPP system architecture evolution(SAE) Objectives:

Evolved- (UMTS) Terrestrial RadioAccess Network; Long Term Evolution(LTE)

OFDMA downlink radio technology

SC-FDMA uplink radio technology

Increased data rates

Lower latency

Reduced connection setup time

Low cost per bit

Evolved Packet Core (EPC) network

All IP Supporting 3GPP and non-3GPP radio access

technologies

Seamless service continuity for multi-modeterminals

GERAN

E-UTRAN

CDMA200 HRPD

WiMAX WLAN

EPC

LegacyCS

services

IPnetwork

UTRAN

Evolved

PacketSystem(EPS)



5/20

EPS Network Architecture

E-UTRAN (LTE)

enhanced Node B (eNB)

User Equipment (UE)

EPC

Serving Gateway (S-GW)

Packet Data Network Gateway (P-GW)

Mobility Management Entity (MME)



6/20

LTE Radio Network: Features Simplified flat radio network architecture

Flexible and expandable spectrum bandwidth

High data throughput (Macro eNB& Home eNB)

Support for multi-antenna scheme (up to 4x4 MIMO )

Time-frequency scheduling on shared-channel

Cost-reduction per bit

Reduced latency

Seamless inter radio access technology (inter-RAT)mobility



7/20

LTE Radio ProtocolStructure

RLC and MAC sublayers: Data packet segmentation

Scheduling mobile users anddata flows

Retransmission andmultiplexing of data flows

PHY sublayer: QPSK, 16-QAM, 64-QAM

OFDMA modulation

Antenna assignment

Resource allocation

Segmentation,ARQ

Segmentation,ARQ

Segmentation,ARQ

Segmentation,ARQ

Multiplexing

HARQ

DFTAntennamapping

OFDMmodulation

Coding, ratematching

Modulation

PayloadSelection

Priorityhandling,PayloadSelectionRetransmission Control

Code rate

ModulationScheme

Antenna andresourceallocation

UplinkOnly

RLC

MAC

PHY



8/20

LTE Bandwidth Flexibility

1.4MHz

20 MHz

fDL

fUL

fDL/UL

Unpaired spectrumPaired spectrum

Operates in different frequency

bands Can be deployed with different

bandwidths in order to operate inspectrum of different sizes

Efficient migration of other radiotechnologies to LTE

Enabling asymmetric spectrumutilization



9/20

LTE: OFDM Large degree of freedom

Channel coding is mandatoryfor combating fading

Multi-path propagationcontrolled by cyclic prefix

OFDM receivers design has

less complexity than Rakereceivers

Flexible spectrum expansion

High peak-to-average ratio

Doppler effect Frequency

Tim

e

1ms

1 resource block = 180 kHz = 12 or 14 sub carriers

f1 f2 fn



10/20

LTE Frame Structure FDD and TDD schemes

Single radio interface

Virtually, identical PHYlayer processing

Low cost implementation

FDD: Two carrier frequencies,

fUL and fDL

10 subframes for each ULand DL

Simultaneous transmission

TDD: Single carrier frequency

Seven different uplink-downlink configurations

DwPTS, Guard periods

UpPTS Sounding signals and random

access

FDD

fUL

fDL

One subframe, Tsubframe =

1ms

One radio frame, Tframe =

10ms

TDD

UL

fUL/

fD

L

Subframe #0 #1 #2 #3 #4 #5 #6#7 #8 #9

(Specialsubframe)

(Specialsubframe)

DwPTS GPUpPTS

DL

UL

DL



11/20

LTE Scheduling Uplink and downlink transmission are scheduled by the eNB MAC

scheduler UE requests uplink transmission resources from eNB through

Scheduling Request (SR) mechanism Dedicated SR (D-SR)

Random Access SR (RA-SR)

Buffer Status Report (BSR) after SR mechanism is required

Distribute available radio resources in the frequency domain

Dynamical change of the allocated resources every 1ms

In addition to the resource block, the scheduler defines themodulation and coding schemes, MIMO or beamformaing

Providing the desired QoS on a shared channel

QoS class, Queuing delay of the available data, instantaneouschannel conditions



12/20

LTE Scheduling: Channel QualityIndicator (CQI) Varying radio-channel

quality in space, time andfrequency

Channel-dependentscheduling in time andfrequency domain can beexploited

Efficient radio resourcesutilization

Fast channel variationtracking ,utilized by thescheduler

Certain mobile users arescheduled for transmissionfor each 1 ms subframe

Uplink sounding referencesignal



13/20

LTE Retransmission Handling

Occasional Tx errors No bit error propagation to upper

layers, drop or reTX

Physical layer attaches 24-bit CRCchecksum to the data unit

HARQ at the MAC layer

retransmits the corruptedtransport blocks

Multiple stop-and-wait HARQprocess

Single-bit HARQ feedback

ACK/NACK with a fixed timingrelation to the corresponding Tx

Simple, low latency, lowoverhead, reliable

Complemented by ARQ at the RLClayer

ULARQTX

ULARQRX

DLHARQ

Rx

ULHARQ

Tx

ULHARQ

Rx

DLHARQ

Tx

Uplink L1

Downlink L1

RLC STATUS RLC STATUS as

DL HARQ data

RLC PDULocal

NAK

HARQ ACK/

NACKTransport block



14/20

EPC Network All IP core network

Evolution of GPRS Integration with non-

3GPP systems

Supports PMIPv6mobility

Mobility Management

Entity (MME) node

Serving Gateway (S-GW)

Packet Data Gateway(P-GW)

Evolved Packet DataGateway (ePDG)

Policy and ChargingRule Function (PCRF)from (IMS)

GERAN

E-UTRAN

CDMA200 HRPD

WiMAX

WLAN

LegacyCS

services

IPnetwork

UTRAN

MSC MSC

GGSN

SGSN

S-GW

P-GW

MME

HSS/AAA

PCRF

ePDG

Non-3GPP

EPS-3GPP

ControlInterfaces Data Interfaces

3GPP



15/20

QoS Control in EPS networks Operators are moving from Single to

multi-service offering

Number of broadband subscribers andtheir traffic volume are rapidlyincreasing

EPS QoS concept standardized in 3GPPRel. 8

Enable service and subscriberdifferentiation

Bearer; the central element of EPSQoS concept

The Bearers and their assigned QoSparameters are managed through aset of network initiated signalingprocedures

EPS QoS concept is a class-based

Network initiated QoS concept + classbased approach gives operators fullcontrol over the QoS provided for theoffered services

Subscriber

differentiation

Business Vs. Standard

Post- VS. Pre-paidFlat rate abusers

etc.

Service

differentiation

Public Internet

VPNP2P file sharing

Video streaming

IMS voice

CS

Mobile-TV

etc.



16/20

QoS Control in EPS networks: EPS Bearer Identifies packet flows that

receives a common treatment

Packet flows are defined by afive-tuple based packet filters

One bearer exist per acombination of QoS class andIP address of a terminal

A terminal can have multipleIP address; one for eachAccess Point Name (APN)

Tunnel Header

DSCP

GBR vs. non-GBR Bearers Default vs. Dedicate Bearers



17/20

QoS Class Identifier (QCI) specifies the user-plane treatment for a packet on a specified bearer

Allocation and Retention Priority (ARP) Specifies the control plane treatment a bearer receives

Maximum Bit Rate (MBR)

Guaranteed Bit Rate (GBR)

Aggregate Maximum Bit Rate (AMBR) defined by group of non-GBR bearers for differentiated subscription

QoS Control in EPS networks: QoSParameters

QoS Control in EPS networks: QoSMechanism

Control-Plane Signaling PCRF issues Policy and Charging Control (PCC) rules to the gateway

User-Plane Functions (3GPP and O&M configuration throughsignaling Procedures) Classified into

Packet-Flow Level Functions

Bearer-Level Functions

DSCP-Level Functions



18/20

Network-Initiated QoS Control

Network initiates the signal forestablishing a dedicated bearerwith a specific QoS

Triggered by AP or DPI

Client is access QoS unaware

Needs a policy controller

Terminal-Initiated QoS Control Terminal initiates the signaling for

establishing the dedicated bearer

The networks initiates the signalingto the RAN

The client must be aware of theQoS model of the access networks

No need for a policy controller

QoS Control in EPS networks: DedicatedBearer Set up

Client

(accessQoS

unaware)

Service layer signaling(SIP)

AF/DPI

Network

Terminal

Initiate dedicated bearer (ULpacket filters)

Initiate dedicated bearer(QoS info)

RAN

Network-Initiated

Client(access

QoSaware)

Service layer signaling(SIP)

AF/DPI

Network

Terminal

Initiate dedicated bearer(QoS info)

RAN

Terminal-Initiated

Initiate dedicated bearer (QoS info + DLpacket filters)



19/20

VoIP call setup with the EPS QoS concept



20/20

Conclusion

Unified Core Network

New Radio Access Network for 4Gsystems

Enhanced scheduling andretransmission mechanism

Bearer-based QoS control paradigm


evolved packet system wisense seminar may 19 2011

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