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Prepared by:

Agilent Technologies600 Atlantis RoadMelbourne, FL 32904 USAPhone: (321) 952-8300Fax: (321) 725-5062www.agilent.com

Copyright2001 by Agilent TechnologiesAll rights reserved. No part of this book shall bereproduced, stored in a retrieval system, or transmittedby any means, electronic, mechanical, photocopying,recording, or otherwise, without written permissionfrom Agilent Technologies

RF Engineering

Continuing Education & Training

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Page 2Agilent RestrictedGPRS Slides (Rev A).ppt

Class Agenda

Overview of GSM

What is GPRS?

Network Architecture

Protocol Stack

Air Interface Mobility Management

Quality of Service

Optimization and RF Planning

Traffic Planning HSCSD, EDGE and 3G Growth Path

Conclusions

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Class Agenda

Overview of GSM


Air Interface

Additional Features

What is GPRS? Network Architecture

Protocol Stack

Air Interface

Mobility Management Quality of Service


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Overview of GSM


F1

F2

F3

F4

F1

F2

F3

F4

F2

F1

F2

N=4 Frequency Reuse Concept

Second GenerationTechnology

Groupe Speciale Mobile

Developed by ETSI

International wireless standard

Based on the cellular concept

Frequency reuseimplementation

Over 480 million subscribers

GSM900, DCS1800,PCS1900, R-GSM

100 200 300 400 5000

GSM

IS-95

IS-136

PDC (Japan)

Analog

Millions of subscribers (Feb 2001)source: EMC

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Series Specification Area

01 General

02 Service Aspects

03 Network Aspects

04 MS-BS Interface and Protocol

05 Physical Layer and the Radio Path

06 Speech Coding Specification

07 Terminal Adapter for MS

08 BS-MSC Interface

09 Network Interworking

10 Service Internetworking

11 Equipment and Type Approval Specs12 Operation and Maintenance

Overview of GSM

All GSM documents arestandardized by ETSI

Standards are grouped into 12series

Allows for easy integration ofnetwork elements from differentequipment vendors

Significantly reduces the cost ofthe overall network deployment

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Introduction to GPR

Overview of GSM - Network Architecture

GSM network can be divided into three main subsystems:

Base Station Subsystem - BSS

Mobile Station Subsystem - MSS

Network Switching Subsystem - NSS

GSM Network Layout

MSC

Area

HLR

MSCArea

VLR

MSCTRAUBSC

BTS

BTS

BSS

MSC Area

BSS

BSSBTS

PSTN

PLMN - Public Land Mobile Network

GatewayMSC

NSS

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Overview of GSM - Mobile Station

Introduction to GPR

Keyboard

Control

Display

Transmit AudioSignal

Processing

Receive Audio

SignalProcessing

ChannelDecoding

Deinterleaving

MessageRegenerator

ChannelEncoding

Interleaving

MessageGenerator

Ciphering

Ciphering

RF

Processing

RFProcessing

SIM

Duplexer

Antenna

ANTENNA

ASSEMBLY

TRANSMITTER

RECEIVER

TRANSCEIVER UNITCONTROLSECTION

Offered as a phone forvoice services

Data services will bringnew devices to the market

Two functional parts: HW/SW radio

interface

SIM

Two types of SIM

Smart Card

Plug-in

GSM Mobile Architectural Diagram

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Overview of GSM - Base TransceiverStation

BTS is a set of transceivers (TX/RX).

GSM BTS can host up to 16 TX/RX.

In GSM one TX/RX is shared by 8 users.

The main role of TX/RX is to provideconversion between traffic data on the networkside and RF communication on the MS side.

Depending on the application, it can be

configured as macrocell, microcell, omni,sectored, etc. BTS

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Overview of GSM - Base Station Controller

Provides a small digitalexchange with somemobility tasks

Connects to one or severalBTS on the Abis Interface

Connects to the MSC onthe A Interface

Designed to offload most ofthe radio link related

processes from the MSC Provides clock distribution

to BTS

Communicates with theOMC

Introduction to GPR

Central Module

SwitchMatrix

Database

OMC

OMC - Operation and Maintenance

AInterfaceTowards

MSC

AbisInterfaceTowards

BTS

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Overview of GSM - TRAU

TRAU is responsible fortranscoding the user data from16Kb/sec to standard ISDNrates of 64Kb/sec.

It can physically reside on

either BSC side or MSC side.

If it resides on the MSC side, itprovides substantial changes inthe backhaul 4 users over asingle T-1/E-1 TDMA channel.

TRAU, BSC and BTSs form

Base Station Subsystem (BSS)

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Overview of GSM - MSC

Responsible for connecting themobile to the landline side

GSM MSC is commonlydesigned as a regular ISDNswitch with some added

functionality for mobility support GSM Network can have more

than one MSC

One of the MSC has an addedfunctionality for communicationwith public network GatewayMSC (GMSC)

All calls from the outside

networks are routed throughGMSC

GSM MSC and Gateway MSC

BTS

BSC MSC GMSC

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Overview of GSM - HLR/AuC

Database for permanent or semi-permanent data associated with theuser

Logically, there is only one HLR per network

Typical information stored in HLR: International Mobile Service

Identification Number (IMSI), service subscription information,supplementary services, current location of the subscriber, etc.

HLR is usually implemented as an integral part of MSC

AUC is an integral part of HLR responsible for ciphering andencryption.

GSM specifies elaborate encryption schemes.

There are three levels of the encryption:

A5/1 Used by countries in Europe and USA

A5/2 Used by countries and the so called COCOM list

No encryption used by all other countries

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Overview of GSM - VLR and EIR

Temporary database that keeps the information about the users within theservice area of the MSC

Usually there is one VLR per MSC

The main task of the VLR is to reduce the number of queries to HLR. Whenthe mobile, registers on the system its information is copied from HLR to VLR

VLR is usually integrated with the switch

Separation of SIM and mobile opens possibility for market of stolen andfraudulent equipment.

GSM Systems are equipped with Equipment Identity Register (EIR)responsible for tracking the equipment eligibility for service.

EIR maintains three lists of mobile terminals:

White list: is the list of approved mobile types.

Black list: list of the International Mobile Equipment Identity (IMEI) numbersthat are barred from service.

Gray List: The list of mobiles that are tracked within the GSM system.

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Overview of GSM - Interfaces

GSM defines differentinterfaces betweentwo systemcomponents

Allows for multi-vendorimplementation

Promotes morecompetition

Lower costs

Air interface islimiting in terms ofcapacity

Air interface is alsocalled Um interface

GSM Interfaces

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Overview of GSM - Air Interface

GSM is a FDMA/TDMA basedtechnology

Transmissions arediscontinuous

Each user is assigned a timeslot Each frequency is divided into

eight timeslots

Each channel has a 200 kHzbandwidth

Overhead signaling is requiredfor coordination and control

Information is sent in bursts

Several types of bursts

GSM as a FDMA/TDMA Interface

BTS

USER 1 USER 2 .... USER 8

US ER 6 US ER 7 US ER 8 US ER 1

USER 1,ARFCN1

USER 2,ARFCN1

USER 8,ARFCN1

USER 9,ARFCN

2

USER 10,ARFCN2

USER 16,

ARFCN2

ARFCN1

ARFCN2

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Overview of GSM - Burst Types

Tail Traffic/Signaling Flag Training Sequence Flag Traffic/Signaling Tail

3 57 1 26 1 57 3

Tail Synchronization Training Sequence Synchronization Tail

3 33939 64

Used to carry information on both control and traffic channels

Mixture of data and overhead

GSM defines 8 training sequences assigned in color code mode Both on the forward and reverse link

Facilitates the synchronization of the MS to the network at the baseband

Commonly referred to as S-burst

Only on the forward link

The same sync sequence is used in all GSM networks

Synchronization Burst

Normal Burst

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Used when the MS is accessing thesystem

Shorter in length burst collision

avoidance

Extended synchronization sequence

Used only on the reverse link

Supports MAHO

Used to ensure constant power level of the broadcast control channel


Dummy Burst

Access Burst

Tail Predefined Bit Sequence Tail

3 3142

Tail Synchronization Access Bits Tail

8 41 36 3

GSM mobiles use slottedALOHA to access thesystem

In the case of collisiona hashing algorithm isprovided

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Sometimes referred to as theF-burst

Provides mobile with precisereference to the frequency ofthe broadcast control channel

Inserting the F-bursts on thecontrol channel producesspectral peak 67.7 KHz abovethe central frequency of thecarrier


Spectral characteristics of thecontrol channel.

The peak in the spectrumallows for easier MS networkacquisition

Tail Fixed Bit Sequence (All zeros) Tail

3 3142

fc

fc+67.7 KHz frequency

Power Spectrum Density

BW = 200KHz

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Overview of GSM - Physical Channels

Group Name Function Fwd.

Link

Rev.

Link

BCCH Broadcast control Yes No

FCCH Frequency correction Yes No

BCH

SCH Synchronization Yes No

PCH Paging Yes No

AGCH Access Grant Yes No

CCCH

RACH Random Access No Yes

SDCCH Standalone dedicated control Yes Yes

SAACH Slow-associated control Yes Yes

DCCH

FACCH Fast-associated control Yes Yes

TCH TCH Traffic data and voice Yes Yes

A GSM physical channel can carry several different types of logicalchannels

Can be divided into two categories: traffic and signaling

Signaling channels can be further categorized as:

Broadcast Common Control

Dedicated Control

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Overview of GSM - Additional Features

GSM supports additional features that enable a better spectrumutilization and increased capacity:

Timing Advance - TA

Discontinuous Transmission - DTX

Mobile Assisted Handover - MAHO

Dynamic Power Control - DPC

Hierarchical Cell Structure - HCS

Frequency Hopping - FH

Intracell handovers

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Overview of GSM - Quiz!

Name some of the components of the GSM architecture and brieflyexplain their function

What are the different types of bursts?

_______________

_______________ _______________

_______________

_______________

What are the different types of logical channels ?

_______________, _______________, _______________

_______________, _______________, _______________

_______________, _______________, _______________

_______________

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Class Agenda

Overview of GSM

What is GPRS?


Protocol Stack

Air Interface

Mobility Management

Quality of Service


Traffic Planning

HSCSD, EDGE, and 3G Growth Path

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I t d ti t GPR

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What is GPRS?

9.619.2

56

128

GSM IS-95 CDMA Analog Modem ISDN

9.6

57.6

160

384

GSM HSCSD GPRS EDGE

2G technologies were designed formobile telephony

Landline services have higher datarates than wireless counterparts

Next step: mobile wireless dataservices

GPRS: General Packet RadioService

GSM has distinctive approachtowards 3G

Intermediate step refers to as 2.5 G

Allows for smooth transition fromvoice to data services

Maintain upgrade costs to aminimum

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What is GPRS?

Source: Ericssons Web Site Oct-00

Subscribe

rs(M)

0

900

300

600

96 98 00 02 03

In voice networks, RF is the main limiting factor. In datanetworks, RF and many other factors will affect the performancefor individual users

Fixed network infrastructure performance

Types of applications and service provision

Number of users active in an area

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What is GPRS? - Circuit vs Packet Switch

2G technologies are circuitswitched

Dial-up type connections

A single user occupies a

channel for the entiretransmission

Requires time-oriented billing

GSM transmissions are bursty

Bursty nature favors dataservices

GPRS is packet switchedtechnology

More appropriate for dataservices

Continuous flow is not required

Access is based on demandonly

Several users can bemultiplexed

Billing based on negotiatedoS and usa e

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What is GPRS? - Types of Data Services

9.6

128

1500

SMS WWW Audio Video

128

Most popular Internet dataapplications include:

E-mail

Web browsing

File transfers

Real time audio

Streaming video

Different services have differentthroughput requirements

GSM evolution is expected toprovide services at throughputssimilar to their landlinecounterparts

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What is GPRS? - A 2.5 G Solution

GPRS is a 2.5 G solution implemented over existing GSM network

Theoretical data rates are up to 160 kbps

GPRS makes a more efficient use of the air interface

Supports point-to-point and point-to-multipoint transmissions

GPRS will take over short message service (SMS) from GSMsignaling channels

New QoS parameters:

Precedence

Reliability

Delay

Throughput

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What is GPRS? - Important Challenges

There are several hardware and softwarelimitations that will decrease the expected datarates significantly

Mobile data will impose a demand for more IPaddresses. The existing version of IP isalready reaching saturation

The idea that the market will accept mobiledata service with eagerness is still somewhatquestionable

The 3G standards are already finalized andimplementation will follow shortly after 2.5 G

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Class Agenda

Overview of GSM

What is GPRS?


SGSN, GGSN

GR, PCU

Mobile Station

Protocol Stack

Air Interface

Mobility Management Quality of Service


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GPRS Network Architecture

GPRS introduces new entities to support data packet

transmissions

New entities are PCU, GSN, Border Gateway, and GPRSregister

GPRS Network Architecture

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GPRS Network Architecture - SGSN

SGSNPCU

BSS

BSS

BSS

SGSNPCU

SGSNPCU

GGSN

Serving GPRS support node

Delivers data packets to the mobilestations

Each SGSN is assigned to a specificservice area

Allows for very little change in theBTS and BSC

All mobile stations communicate to the SGSN in the area

Provides authentication and ciphering

Handles mobility management

Introduction of the routing area - RA

Also responsible for billing over the air interface

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GPRS Network Architecture - GGSN

GGSN

GGSN GGSN

PDN

PDN

PLMN

PDN

Gateway GPRS support node

Allows the GPRS network tocommunicate with external PDNs

Routes all packet data units through

the corresponding SGSN Whereas the SGSNs can change

during cell reselections, the GGSNremains the same during an ongoingpacket transaction

Supports PTP and PTMtransmissions

Responsible for billing related toconnections with external PDNs

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GPRS Network Architecture - GR and PCU

GPRS Register Database containing information about GPRS subscribers

Packet Control Unit

Manages and controls radio-related operations

Converts frames coming from the SGSN into TRAU frames Compresses and decompresses frames

PCU allows very few modifications to the BSS

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GPRS Network Architecture - PCULocations Possibilities for location are similar to the TRAU

From the resource utilization perspective, the best location for thePCU is at the SGSN

Conceptually, PCU still remains a part of the BSC

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GPRS Network Architecture - BorderGateway

ForeignPLMN

BGBGGGSN GGSN

HomePLMN

Risk from hackers in external PLMNs

Protect subscribers from security break-ins

Border Gateway is implemented to provide a maximum level ofsecurity

Acts as a firewall to the GPRS network

No guidelines for protection at the Gi interface

Gi security is left open to equipment manufacturers

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GPRS

ClassType GSM and GPRSSimultaneously GSM or GPRSSequentially GSM OnlyGPRS Only

Class A Yes Yes Yes

Class B No Yes Yes

Class C No No Yes

GPRS standard defines three mobile station classes

Class A supports simultaneous circuit and packet switchedcommunications

Class B supports packet and circuit switched sequentially

Currently only Class B mobiles being developed

Class C does not support parallel operation

Operates in either packet or circuit mode only

Low cost unit available for mass market deployment

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GPRS Network Architecture - GSM andGPRS

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GPRS Network Architecture - Quiz!

Name some of the components of the GPRS architecture and brieflyexplain their function

What are two types of GSNs?

_______________

_______________ What are the different types of mobile classes ?

_______________

_______________

_______________

Which component allows for few changes at the BSS?

_______________

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Class Agenda

What is GPRS?


Protocol Stack

OSI/ISO Model

GPRS Protocol Stack

GTP

SNDCP and BSSGP

RLC/MAC and LLC

Air Interface

Mobility Management

Quality of Service


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GPRS Protocol Stack - ISO/OSI Model

Session Layer

Transport Layer

Network Layer

Data Link Layer

Presentation

Layer

Physical Layer

Application

Layer

1

2

3

4

5

6

7

Session Layer

Transport Layer

Network Layer

Data Link Layer

Presentation

Layer

Physical Layer

Application

Layer

1

2

3

4

5

6

7

Network Layer

Data Link Layer

Physical Layer

Node A Node B Node C

peer-to-peer protocol

International Telecommunications Union (ITU) and InternationalStandardization Organization (ISO) developed Open SystemsInterconnect (OSI)

Allows for compatibility between different equipment manufacturers

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GPRS Protocol Stack - GTP

GPRS Tunneling protocol

Allows communication between the GGSN and SGSN

Data transfer is done via encapsulation and tunneling

GTP header includes such as PDU type, QoS parameters, andtunnel identifier (TID)

TID differentiates PTP from PTM transactions

GTP PDU

N PDUTCP/IPHeader

User Data

Network Layer

GTP Layer

GTPHeader

TID User Data

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GPRS Protocol Stack - SNDCP & BSSGP

Subnetwork Dependent Convergence Protocol

Makes GPRS network transparent to the common subscriber regardless ofwhat application is running

Responsible for converting network packet data units into GPRS suitableformat

Multiplexing of SN packet data units over the LLC layer

Segmentation and Desegmentation of SN packets into LLC packets Compression of the IP header information

Base Station Subsystem GPRSProtocol

Routing between SGSN and PCU

Provide radio related info for

RLC/MAC

Routing goes via Network Relay

Transparent transfer of LLC frames

Convey QoS information

TCP/IP

HeaderUser Data

Network Layer

SNDCP Layer

SN-PDU

HeaderC ompressed Information Tail

SN-PDU

HeaderCompressed Infor mation Tail

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GPRS Protocol Stack - LLC

Logical Link Control

Provides a logical reliable link between MS and SGSN

Designed as independent as possible from the radio interface layers

Encapsulation of SNDCP packet data units

Ciphering procedures between MS and SGSN

Detection and recovery of lost LLC packet data units

Responsible for acknowledged/unacknowledged operation

FrameHeader

Radio Blocks

SNDCP Layer

SN-PDUHeader

Compressed Information TailSN-PDUHeader

Compressed Information Tail

FCS

LLC Layer

FrameHeader

Radio Blocks FCSFrameHeader

Radio Blocks FCS

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GPRS Protocol Stack - RLC / MAC

RLC sublayer

Transmission of data blocks across the air interface

Retransmission of error data blocks using ARQ

MAC sublayer

Provides access to a given transmission medium Controls access signaling, medium sharing by multiple users

Release operations over the radio channel

Access is based on slotted ALOHA

Performs mapping of RLC blocks onto the GSM physical channels

PC PCT TRLC

HeaderRLC/MAC Signaling

InformationUSF BCS USF BCS

RLC/MACLayer

RLC Data

RLC Data Block RLC/MAC Signaling Block

FrameHeader

Radio Blocks FCS

LLC Layer

FrameHeader


Radio Blocks FCS

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GPRS Coding Schemes

GPRS defines four codingschemes

Only CS-1 is mandatory for theBTS

All coding schemes aremandatory for the MS

The higher the coding scheme,the higher the throughput

The higher the throughput, the

lower protection against errors

RLCHeader

RLC Data

160 Data Bits (depends on size RLC header)

RLCHeader

RLC Data


RLC

Header

RLC Data


RLCHeader

RLC Data


CS-1

CS-2

CS-3

CS-4

1 TS 2 TS 3 TS 4 TS 8 TSCS-1 9.05 kbps 18.1 kbps 27.15 kbps 36.2 kbps 72.4 kbps

CS-2 13.4 kbps 26.8 kbps 40.2 kbps 53.6 kbps 107.2 kbps



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GPRS Radio Block Structure

A packet transmissionis referred to as atemporary block flow(TBF)

Each TBF is assigned atemporary flow identity(TFI)

The TFI is locatedinside the LLC headerinformation

The TFI allows formultiplexing severalusers over the sametimeslot

The TFI also allows to

assign priority classes

PC PC

NormalBurst

NormalBurst

NormalBurst

NormalBurst

NormalBurst

NormalBurst

NormalBurst

NormalBurst

T TRLC

HeaderRLC/MAC Signaling

InformationUSF BCS USF BCS

Network Layer

SNDCP Layer

LLC Layer

RLC/MACLayer

RF Layer

RLC Data

approx 1.6 KB

1.5 KB or less

20 - 50 bytes

4 x 114 bits

RLC Data Block RLC/MAC Signaling Block

FrameHeader



Radio Blocks FCS

SN-PDUHeader

Compressed Information TailSN-PDUHeader

Compressed Information Tail

TCP/IPHeader

User Data

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Protocol Stack - Quiz!

Mention the seven different layers of the ISO/OSI reference model: _______________, _______________, _______________

_______________, _______________, _______________

_______________

The GPRS protocol stack consists of the following protocols _______________, _______________, _______________

_______________, _______________

The maximum throughput achieved using CS-2 and two timeslots is:

_______________ Different packet transactions from different users can be identified via

the

_______________

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Class Agenda


Protocol Stack

Air Interface

GPRS Logical Channels

The Master Slave Concept

The 52-Multiframe

Timing Advance

Power Control

Mobility Management

Quality of Service Optimization and RF Planning


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GPRS Air Interface

Air interface continues to belimiting factor in terms of capacity

GPRS shares the same interfacewith GSM

Recall GSM has 200 kHz and eightTS

GPRS utilizes multiplexing anddynamic channel allocation to usethe air interface more efficiently

Some channels can be configuredfor data traffic and others for voicetraffic

Channels are reconfiguredaccordingly based on demand

GPRS Air Interface

PhysicalLayer

MAC

RLC

RFL

MAC

RLC

MS BSS

RLC - Radio Link ControlMAC - Medium Access Control

RFL - Radio Frequency Link

MS - Mobile StationBSS - Base Station Subsystem

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GPRS Logical Channels

Signaling and traffic channels are also required for GPRS A new family of packet data channels PDCHs has been defined

Some of the existing GSM signaling channels can still be used forGPRS

The GPRS mobile still requires to listen to the GSM broadcastchannel for GPRS channel information

Group Channel Direction Function

PBCH PBCCH FL Broadcast

PPCH FL Paging

PRACH RL Random Access

PAGCH FL Access Grant

PCCCH

PNCH FL Group Notification

PDTCH FL / RL Traffic

PACCH FL / RL Associated Control

PTCH

PTCCH FL / RL Timing Advance

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GPRS 52-Multiframe

Each radio block is transmitted over 4 TDMA frames Resource allocation is done in terms of blocks for both uplink and

downlink

A 52-Multiframe consists of:

twelve blocks for PDCHs signaling and traffic two timing advance frames

two idle frames (for neighbor list and power control)

12 x 4 +2 + 2 = 52 frames

0

Block 0 Block 1 Block 2TA

1 2 3 4 5 6 7 8 9 10 11 12 13

Block 3 Block 4 Block 5 I

14 15 16 17 18 19 20 21 22 23 24 25 26

Block 6 Block 7 Block 8TA

27 28 29 30 31 32 33 34 35 36 37 38 39

Block 9 Block 10 Block 11 I

40 41 42 43 44 45 46 47 48 49 50 51

TA - Timing Alignment FrameI - Idle Frame

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GPRS Timing Advance - Uplink

0 1

2 3

4 5

6 7

8 9

10 11

12 13

14 15

8 x 52-multiframe = 416 framesTAI = 0 - 15

The PTCCH/U is divided into 16subchannels with eight 52-multiframes

The 16 subchannels can beassigned to 16 different active

mobile stations Every PTCCH/U has a cycle of 1.92

s

Active mobile stations will transmitone access burst with TA=0 to theBTS once per eight 52-multiframeswithin their subchannel

Based on the PTCCH/U message,the BTS can recalculate the timingadvance value

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GPRS Timing Advance - Downlink

One TA message in 4 normal burstsfor up to 16 MS

0 1

3 4

Each mobile is assigned a timing advance index (TAI) value via thePTCCH/D

The TA message sent on the downlink can convey timing advanceinformation for up to 16 mobile stations

The timing advance message contains the TAI values associated witheach mobile station

Since the message requires 4 frames, it is carried within fourconsecutive TA frames

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GPRS Timing Advance - Example

Example: An uplink temporary block flow (TBF) isinitiated between a mobile station and a serving basestation. The total file size is 80 kilobits and is transmittedusing CS-1. The base station assigns the mobile stationa timing advance index (TAI = 3). Assuming a constant

data rate and no block retransmissions, how many timingadvance messages are required from the mobile duringthis transmission.

1 frame =

1 block = A 52-multiframe =

Time between identical TAIs =

Total transmission time =

Number of timing advances =

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GPRS Power Control - MS Power Classes

Class Max Power

(dBm)

Min Power

(dBm)

Power

Increments

2 39 5 18

3 37 5 17

4 33 5 15

5 29 5 13

Class Max Power

(dBm)

Min Power

(dBm)

Power

Increments

1 30 0 16

2 24 0 13

3 36 0 19

Power control is used to minimize the transmit power and stillmaintain a reliable link

GSM power control is done by the BTS based on RXLEV andRXQUAL

GPRS power control is performed by the mobile based on severalparameters including:

Maximum allowed Tx power

Received Signal Level - RSL

Mobile station power class

Several mobile station powerclasses have been defined forGSM 900 and DCS 1800respectively

Mobile Station Power Class GSM 900

Mobile Station Power Class DCS 1800

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GPRS Power Control - Power ControlCalculation

The formula for power control calculation as defined by ETSI (GSM03.64 version 8.50)

)),48(min( max0

PCPch CH

0= 39 dBm for GSM 900 and 36 dBm for DCS 1800

CH= mobile and channel specific power control parameter. It is sent to the mobile in anyresource assignment message. The values range from 0 to 62 dB in 2 dB incrementsbased on interference measurements of the BTS. At any time during a packet transfer,the network can send new CH values to the mobile on the downlink PACCH

[0,1] = is a system parameter. Its default value is broadcast on the PBCCH.Furthermore, the mobile and channel specific values can be sent to the mobile togetherwith CH

C= received signal level at the mobile

Pmax= maximum allowed transmit power in the cell

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GPRS Power Control - Example

A GSM-1800 Class 3 mobile station is engaged in powercontrol. The network parameters are =0.5, and CH= 4.The mobile reported C is85dBm. What is the transmitpower Pch ?

)),48(min( max0

PCPch CH

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Air Interface - Quiz!

What are the different types of GPRS logical channels ? _______________

_______________, _______________, _______________

_______________, _______________, _______________

GPRS packet data channels are mapped onto a new structure called________________

The Uplink PTCCH is divided into _____ subchannels

One timing advance message on the downlink is transmitted over_____ normal bursts and contains a timing advance index for up to

_____ users

In GSM, power control is done at the ____________. In GPRS,power control is done at the _____________.

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Class Agenda


Protocol Stack

Air Interface

Mobility Management

Mobility Management States

GPRS Attach

Mobile Originated Transfer

Mobile Terminated Transfer

Cell Selection/Reselection

Quality of Service Optimization and RF Planning


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GPRS Mobility Management States

Mobility management statesapply for both the mobile andthe SGSN

Idle: Mobile is powered on butnot attached to GPRS

Standby: Mobile is powered onand attached to GPRS. Nopacket transfer is in progress.Routing area updates are sentas needed.

Ready: The mobile is currentlyengaged in packet transfer orrecently terminated a packettransfer. The Ready state isdetermined by a timer. No

need to page a mobile inRead state

GPRS Mobility Management States for MS

Idle

Ready

Standby

Ready-TimerExpiry

PDUTransfer

GPRSDetach

GPRSAttach

PDUTransfer

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GPRS Attach Process

Process of registration of the mobile into the GPRS network Occurs when mobile is first powered on and can occur afterwards

based on network settings

Mobile registers directly with the SGSN

Information Exchanged

IMSI or P-TMSI

TLLI

RA, LA

Power class mark Type of

registration(GSM, GPRS)

Authentication

Ciphering

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GPRS PDP Context Activation

The mobile need to activate a packet data protocol context before itcan transmit or receive information

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GPRS Mobile Originated Transfer

A mobile initiates a transfer onthe random access channelRACH or PRACH

One phase access: Networkprovides immediate packet

channel assignment messagewith reserved PDTCHs foruplink

Two phase access: Networkprovides immediate packet

channel assignment messagewith only one single radio blockreservation. Mobile sends amore detailed packet resourcerequest. Network responds withmessage that contains reserved

resources

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GPRS Acknowledged/UnacknowledgedMode

RLC layer can be set to mode ofoperation

Unacknowledged mode offers nomeans for error detection

Acknowledged mode uses ARQ for

error detection

Message type ACK/NACK containsa bitmap of received blocks(UL/DL)

Recipient sends ACK/NACKmessage after receiving a packettransfer

Correct blocks are 1, incorrectblocks are 0

Erroneous blocks are retransmitted

GPRS Mobility Management States

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GPRS Mobile Terminated Transfer/CellReselection Mobile terminated transfer

The Countdown Value is used on the uplink to determine the end ofa TBF

The Final Block Indicator is used in the downlink to indicate the endof a TBF

Cell reselection

There are no handovers in GPRS, mobile performs cell reselection

In GSM, cell reselections are performed when mobile is in idlemode

GSM uses C1 and C2 algorithms for cell reselection

GPRS Cell reselections can be network or mobile controlled GPRS uses C31 and C32 algorithms for cell reselection

C31 is based on selecting the best GPRS server in the area

C32 allows for cell ranking when HCS is implemented

C31 and C32 allow for a more efficient cell planning of GPRS

networks

Q

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Mobility Management - Quiz!

What are the different mobility management states ? _______________, _______________, _______________

In order to register to the GPRS network, the mobile station mustperform a ________________

In order to engage in a packet transfer, the mobile station mustperform a ________________

The two options for mobile originated transfer are:

__________________

__________________

For downlink multiplexing, the ________ is used

For uplink multiplexing, the ________ is used

Errors in transmitted blocks are notified to the transmitting party viathe _____

Cl A d

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Class Agenda


Protocol Stack

Air Interface

Mobility Management

Quality of Service

Precedence Class

Throughput

Delay Class

Reliability Class


Traffic Planning

Q li f S i P d Cl

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Quality of Service - Precedence Class

PrecedencePrecedence

NameInterpretation

1 High PriorityService commitments shall be maintained ahead of

precedence classes 2 and 3

2 Normal Priority Service commitments shall be maintained ahead ofprecedence class 3

3 Low PriorityService commitments shall be maintained after

precedence classes 1 and 2

Under normal network conditions, all users have equal access. During network congestion, users with a higher priority level shall be

served before users with a lower priority

A user with lower priority will suffer higher delay times and packetlosses

Three precedence class are defined

Q lit f S i P k Th h t

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Quality of Service - Peak Throughput

Peak throughput refers to themaximum data rate forpackets to be transferredacross the network

There is no guarantee that this

maximum data rate can beachieved or sustained for anytime period

Peak throughput is measuredin octets per second

Values are shown in bits persecond for easier clarification

Network may limit thesubscriber to the negotiatedpeak throughput regardless of

additional capacity

Peak Throughput

Class

Peak Throughput

(octets per second)

1 Up to 1,000 (8 kbps)

2 Up to 2,000 (16 kbps)

3 Up to 4,000 (32 kbps)4 Up to 8,000 (64 kbps)

5 Up to 16,000 (128 kbps)

6 Up to 32,000 (256 kbps)

7 Up to 64,000 (512 kbps)

8 Up to 128,000 (1024 kbps)

9 Up to 256,000 (2048 kbps)

Q lit f S i M Th h t

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Quality of Service - Mean Throughput

Mean Throughput

Class

Mean Throughput

(octets per hour)

1 Best effort

2 100 (~0.22 bps)

3 200 (~0.44 bps)

4 500 (~1.11 bps)

5 1,000 (~2.2 bps)

6 2,000 (~4.4 bps)

7 5,000 (~11.1 bps)8 10,000 (~22 bps)

9 20,000 (~44 bps)

10 50,000 (~111 bps)

11 100,000 (~0.22 kbps)

12 200,000 (~0.44 kbps)

13 500,000 (~1.11 kbps)

14 1,000,000 (~2.2 kbps)

15 2,000,000 (~4.4 kbps)

16 5,000,000 (~11.1 kbps)17 10,000,000 (~22 kbps)

18 20,000,000 (~44 kbps)

19 50,000,000 (111 kbps)

Average rate at which datais expected to betransferred across theGPRS network

Measured in octets per

hour Displayed in bits per

second for easierclarification

GPRS network may limit

the subscriber to the meanthroughput regardless ofadditional capacity

A best effort throughputcan be negotiated based

on need and availability

Q lit f S i D l

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Quality of Service - Delay

Delay (maximum values)

SDU size: 128 octets SDU size: 1024 octets

Delay Class Mean Transfer

Delay

(sec)

95 percentile

Delay

(sec)

Mean Transfer

Delay

(sec)

95 percentile

Delay

(sec)1.(Predictive) < 0.5 < 1.5 < 2 < 7

2.(Predictive) < 5 < 25 < 15 < 75

3.(Predictive) < 50 < 250 < 75 < 375

4.(Best Effort) Unspecified

ETSI has defined the maximum values for mean delay and 95percentile delay that a packet may encounter while transferred overthe GPRS network

Delay class does not include delays caused by networks outside thePLMN

Delay is defined based on the transfer of a service data unit (SDU)

Two SDU sizes are specified: 128 octets and 1024 octets

Q lit f S i R li bilit

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Quality of Service - Reliability

Reliability

ClassGTP Mode

LLC Frame

Mode

LLC Data

Protection

RLC Block

ModeTraffic Type

1 Acknowledged Acknowledged Protected Acknowledged

Non real-timetraffic, error

sensitiveapplication that

cannot cope with

data loss

2 Unacknowledged Acknowledged Protected Acknowledged

Non real-time

traffic, error-

sensitive that can

cope with

infrequent data

loss

3 Unacknowledged Unacknowledged Protected Acknowledged

Non real-time

traffic, error

sensitive

application that

can cope with

data loss,

GMM/SM, and

SMS

4 Unacknowledged Unacknowledged Protected Unacknowledged

Real-time traffic,

error-sensitiveapplication that

can cope with

data loss

5 Unacknowledged Unacknowledged Unprotected Unacknowledged

Real-time traffic,

error non-

sensitive

application that

can cope with

data loss

Q lit f S i R li bilit

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Quality of Service - Reliability

Reliability

Class

Probability

of Lost

Packets

Probability

of Duplicate

Packets

Probability

of Out of

Sequence

Packets

Probability

of Corrupt

Packets

Example of Application

Characteristics

1 10e 9 10e 9 10e 9 10e 9Error sensitive, no errorcorrection capability, limited

error tolerance capacity

2 10e 4 10e 5 10e 5 10e 6Error sensitive, limited error

correction capability, good

error tolerance capacity

3 10e 2 10e 5 10e 5 10e 2Not error sensitive, error

correction capability and/or

very good error tolerance

Reliability class defines the probability of: Loss packets

Out of sequence packets

Duplicate packets

Corrupted packets

Cl A d

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Class Agenda

Air Interface

Mobility Management

Quality of Service


GSM Metrics

GPRS Metrics

Measurement Model

RF Performance, Signal Quality, Data Performance

Traffic Planning

HSCSD, EDGE, and 3G Growth Path Conclusions

Net ork Optimi ation Process

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Network Optimization Process

Identify RF and fixed network parameters that impact networkperformance

RxLev

RxQual

BCH Pwr

BLERC/I

Throughput

Packet Delay

Re-Connects

DNS Lookup

Packet Failure

Drive

Test

Data

Problem

Problem

ID

RF

Problem

Ev

aluat

ion

Action

s

GSM Metrics RXLEV and RXQUAL

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GSM Metrics - RXLEV and RXQUAL

Reported as a quantized value RXLEV: RXLEV = RSL[dBm] + 110

Minimum RXLEV: -110, MAX RXLEV = -47

Downlink measurements for both serving cell and up to 32 neighbors

Up to 6 strongest neighbors are reported back to BTS throughSACHH

Only on the serving channel Reported as a quantized value

RXQUAL

For a good quality call RXQUAL

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