GPRS for Eng

7/28/2019 GPRS for Eng

http://slidepdf.com/reader/full/gprs-for-eng 1/296

General Packet RadioGeneral Packet RadioServiceService

(GPRS)(GPRS)For EngineersFor Engineers



Day 1D

ay 1

1. Concepts1. Concepts

2. Mobile Data Evolution2. Mobile Data Evolution

3. GPRS Overview3. GPRS Overview

4. GPRS Architecture & Interfaces4. GPRS Architecture & Interfaces

5. GPRS Air Interface5. GPRS Air Interface

6. Protocols Overview6. Protocols Overview

7. GPRS Protocols7. GPRS Protocols

Course OutlineCourse Outline

Day 2D

ay 2

8. Mobility Management8. Mobility Management

9. Radio Resource Management9. Radio Resource Management

10. Packet Routing and Transfer 10. Packet Routing and Transfer

11. GPRS Operational Issues11. GPRS Operational Issues

12. Interaction with GSM Services12. Interaction with GSM Services

13. GPRS Internetworking13. GPRS Internetworking



Course ProgressCourse Progress

Day 1D

ay 1








Day 2D

ay 2









Section 1 - ConceptsSection 1 - Concepts

1.2 Circuit Switching and Packet Switching 1.2 Circuit Switching and Packet Switching

1.4 Virtual Circuits (VCs)1.4 Virtual Circuits (VCs)

1.3 Packet Switching Technologies1.3 Packet Switching Technologies

1.5 Forward and Backward Error Correction1.5 Forward and Backward Error Correction

1.1 Introduction1.1 Introduction



Circuit SwitchingCircuit Switching

CIRCUITCIRCUIT

SWITCHSWITCH

CIRCUITCIRCUIT

SWITCHSWITCH

CIRCUITCIRCUIT

SWITCHSWITCH

CIRCUITCIRCUIT

SWITCHSWITCH

CIRCUITCIRCUIT

SWITCHSWITCH



12345

Packet SwitchingPacket Switching

PACKETPACKET

ASSEMBLER/ASSEMBLER/DISASSEMBLERDISASSEMBLER

PACKET SWITCHPACKET SWITCH

12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

123

123



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

1

2

12

3

3



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

1

2

12 3

3



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH 2

1 3

1

3

2



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

132

132



12345


PACKETPACKET



12

3

5

4

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

132

132123

123

1

2

12

3

3

1

2

12 3

3

2

1 3

1

3

2



Advantages of Packet SwitchingAdvantages of Packet Switching

• More efficient use of existing bearers

• More suited to bursty-type traffic such as Internetaccess.

• Compatibility with existing packet-switchednetworks (PSNs) such as the Internet



Advantages of Circuit SwitchingAdvantages of Circuit Switching

• More suited to time-sensitive applications

• No contention for network resources

• Less data overheads for routing requirements

• Compatibility with existing circuit-switched networks(eg PSTN/ISDN)





Packet Data DeliveryPacket Data Delivery

• Acknowledged Mode:• Guarantees error-free delivery

• Supports flow control

• Requires additional overheads

• Lower data throughput

• Unacknowledged Mode• Packets are delivered to the network and forgotten

• No indication of delivery or error correction

• Generally relies on higher layer protocols for error detectionand correction

• More efficient in reliable networks



Packet Switching TechnologiesPacket Switching Technologies

• X.25X.25

• Frame RelayFrame Relay

• ATMATM

X.25 Fr Relay ATM

Transmission Speed <256kbps <2Mbps >45Mbps

Data Block Size Var Var 53 octets

Block Header+Trailer 6 octets 7 octets 5 octets

Payload Size Var Var 48 octetsSwitching Type CNLS CNLS CONS



The Virtual Circuit (VC) ConceptThe Virtual Circuit (VC) Concept

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKETSWITCH

132

132123

123

1

2

12

3

3

1

2

12 3

3

2

1 3

1

3

2

Virtual CircuitVirtual Circuit

Virtual CircuitVirtual Circuit



Virtual Circuit ConnectionsVirtual Circuit Connections

• Permanent Virtual Circuit (PVC):

• Established by NMC

• Dedicated resource for specific user

• Connectionless

• Switched Virtual Circuit (SVC):

• Setup on request

• Temporary allocation of resources

• Cleared on completion of session





Summary – Section 1Summary – Section 1

• Circuit and Packet Switching

• CONS, CNLS, Ack/Unack Modes

• Packet Switching Technologies

• X.25, Frame Relay, ATM

• Virtual Circuits• PVCs, SVCs

• Forward and Backward Error Correction

• Block Error Detection, ARQ, Convolution Coding

PACKET

SWITCH

PACKETSWITCH

PACKET

SWITCH

PACKET

SWITCH

PACKET

SWITCH




Day 1Day 1








Day 2Day 2









Section 2 - Mobile Data EvolutionSection 2 - Mobile Data Evolution

2.2 The Requirement for Mobile Data2.2 The Requirement for Mobile Data

2.4 HSCSD2.4 HSCSD

2.5 EDGE (ECSD/EGPRS)2.5 EDGE (ECSD/EGPRS)

2.3 Current and Emerging Mobile Technologies2.3 Current and Emerging Mobile Technologies




The Requirement for Mobile DataThe Requirement for Mobile Data

• Projected increase in demand for data traffic

• Requirement to develop additional revenue-generatingstreams

• Exponential growth in Internet Access

• Demand for Internet access on the move.

• Evolution towards 3G services







Emerging Mobile Data TechnologiesEmerging Mobile Data Technologies

22ndnd GenerationGeneration

33rdrd GenerationGeneration

2 . 5 G

e n e r a t i o n

2 . 5 G

e n e r a t i o n

CSD

GPRS

HSCSD

ECSD

UMTS

14.4 kb/s

21.4 kb/s

69.2 kb/s

384 kb/s

2 Mb/s

EGPRSEDGEEDGE

SMS

CSD9.6 kb/s

Circuit Switched

Packet Switched

38.8 kb/s





HSCSD Mobile EquipmentHSCSD Mobile Equipment

• HSCSD handsets are typically limited to 4HSCSD handsets are typically limited to 4timeslots, allowing:timeslots, allowing:

• 2 up / 2 down (28.8 kb/s in both directions)2 up / 2 down (28.8 kb/s in both directions)

• 3 down and 1 up (43.2 kb/s down 14.4 kb/s up)3 down and 1 up (43.2 kb/s down 14.4 kb/s up)

• This limitation arises because the handsetThis limitation arises because the handsetoperates in half duplex and needs time to changeoperates in half duplex and needs time to changebetween transmit and receive modesbetween transmit and receive modes

• Nokia cardphone (PCMCIA card for laptops) usesNokia cardphone (PCMCIA card for laptops) usesHSCSD (Orange network)HSCSD (Orange network)

- quotes data downloads at 28.8 kb/s- quotes data downloads at 28.8 kb/s






• Requirement for Mobile Data

• CONS, CNLS, Ack/Unack Modes

• Current Mobile Data Technologies

• CSD(9k6), CSD(14k4), USSD, SMS

• Emerging Mobile Data Technologies

• HSCSD, EDGE

GPRS

HSCSD

ECSD

UMTS

EGPRSEDGEEDGE

SMS

CSD




Day 1Day 1








Day 2Day 2











Wh t i GPRS?



What is GPRS?What is GPRS?

• Packet-switching technology• Transparent end-to-end data transport of data packets

over a modified GSM network

• Shares Radio Resources with GSM

• New GPRS core network distinct from GSM









Key GPRS User EnhancementsKey GPRS User Enhancements



• Speed

• Immediacy

• Simultaneity

• New and Improved

Applications

• Affordability (?)

Key GPRS User EnhancementsKey GPRS User Enhancements



Limitations of GPRSLimitations of GPRS



• Slower data rates thananticipated.

• Cell capacity.

• Sub-optimal modulationtechnique.

• Transit delays.

•No store and forward.

Limitations of GPRSLimitations of GPRS



Most Popular GPRS ServicesMost Popular GPRS Services



1. Corporate Email

2. Internet Email

3. Information Services

4. Job Despatch

5. Remote LAN Access

6. File Transfer7. Web Browsing

8. Still Images

9. Moving Images

Most Popular GPRS ServicesMost Popular GPRS Services

Source: GSM WorldSource: GSM World

GPRS-Associated Bodies/PortalsGPRS-Associated Bodies/Portals



GPRS-Associated Bodies/PortalsGPRS-Associated Bodies/Portals





• Review of GSM Architecture

• Overview of GSM Network Elements• GPRS Features

• Phase 1/Phase 2 Introduction

• GPRS Network Architecture Overview

• Overview of new GPRS network entities

• User and Network Enhancements provided by GPRS

• Limitations of GPRS

• Current GPRS Global Deployment

• Useful Internet GPRS Resources

BTSBTS BSCBSC

HLRHLR

SGSNSGSN

VLVL

RR

EIREIR

InternetInternet

TRXTRX

BSSBSS

MSMS

MSMS

MSMS

GGSNGGSN

MSCMSC

SMSSMS

GMSGMS

CC

PLMNPLMN

PCUPCU





Day 1Day 1








Day 2Day 2







Section 4 - GPRS Architecture and InterfacesSection 4 - GPRS Architecture and Interfaces



Section 4 GPRS Architecture and InterfacesSection 4 GPRS Architecture and Interfaces

4.3 Mobile Station GPRS Modifications4.3 Mobile Station GPRS Modifications

4.4 BSS GPRS Modifications4.4 BSS GPRS Modifications

4.5 GPRS Core Network Modifications4.5 GPRS Core Network Modifications

4.6 GPRS-Associated Interfaces4.6 GPRS-Associated Interfaces

4.2 Elements of the GPRS Network 4.2 Elements of the GPRS Network


Elements of the GPRS NetworkElements of the GPRS Network



Elements of the GPRS NetworkElements of the GPRS Network

BTSBTS BSCBSC

SGSN

Inter-PLMN

Network

GPRSGPRSBackboneBackbone

BG

CG

GGSN

GGSN

Internet

Intranet

NMS

Billing

Centre

LIG

DNSRouter

Server

Corporate LAN

PCU

Core NetworkCore Network

GSM/GPRS Mobile Terminal (MT)GSM/GPRS Mobile Terminal (MT)



GSM/GPRS Mobile Terminal (MT)GS /G S ( )

TETE MSMS

Mobile Terminal (MT)Mobile Terminal (MT)

TE - Terminal Equipment

TA - Terminal Adaptor MS - Mobile Station

ME - Mobile Equipment

SIM - Subscriber Identity Module

Base StationBase Station

SubsystemSubsystem

SS UUmm

GPRS CoreGPRS Core

NetworkNetwork

MEMESIMSIM

TA

Reference PointsReference Points

RR GGbb

GPRS Mobile Terminal ClassesGPRS Mobile Terminal Classes



• Three GPRS Terminal Classes:• A - Simultaneous support for GPRS and other

GSM services.

• B - Can monitor GPRS and GSM services but

can support only one at any one time.

• C - Supports GPRS or GSM services. Theother service is not available.

GPRS Mobile Terminal ClassesGPRS Mobile Terminal Classes

GPRS Mobile Station (MS) ModificationsGPRS Mobile Station (MS) Modifications



• New Mobile Stations will berequired

• Backward compatibility with GSM

•SIM Card updates to include GPRSfunctionality

GPRS Mobile Station (MS) Modifications( )

MotorolaMotorola

GPRS-enabledGPRS-enabled

Timeport t250Timeport t250



GPRS Terminal Form FactorsGPRS Terminal Form Factors



• Many GPRS form factorslikely:

• Mobile Handset

• PCMCIA Card

• PDA

Base Station Subsytem (BSS) ModificationsBase Station Subsytem (BSS) Modifications



• BTS Requires software upgrade

• Inclusion of a CCU in the BTS

• BSC requires software upgrade and

addition of PCUSN• PCUSN can contain multiple PCUs

y ( )y ( )

Siemens BSCSiemens BSC

Packet Control Unit Support Node (PCUSN)Packet Control Unit Support Node (PCUSN)



pp ( )( )

BTSBTS

CCU

CCU

BSCBSC

PCUSNPCUSN

AABISBIS

AAGPRSGPRS

MSC/VLRMSC/VLR

GGBB

AA

SGSNSGSN

Physical ConnectivityPhysical Connectivity

Packet Control Unit (PCU) FunctionsPacket Control Unit (PCU) Functions



•Provides physical and logical data interface

out of the BSS for packet data traffic

• LLC layer PDU segmentation/reassembly of

RLC blocks

• Packet data transfer scheduling

• ARQ functions

• Radio channel management function

( )



PCU ConfigurationsPCU ConfigurationsUU



BTSBTS

CCU

CCU

BSC SiteBSC Site SGSN SiteSGSN Site

PCU

BTSBTS

CCU

CCU


PCU

BTSBTS

CCU

CCU


PCU

AA

BB

CC

AAbisbis

UUmm

GGbb

GGbb

Circuit Switch (16/64kbps)Circuit Switch (16/64kbps) Packet SwitchPacket Switch

Channel Codec Unit (CCU) FunctionsChannel Codec Unit (CCU) Functions



• Data coding / decoding (CS1-4)

• CS 1-2 require software upgrade only

• CS 3-4 require hardware upgrade

• Forward error correction (convolution coding)

• Air interface interleaving

• Radio channel measurements (RxQual)

• Radio management



Databases – VLR/HLRDatabases – VLR/HLR



• GPRS can share GSM database resources

• Database software upgrades required toaccommodate new GPRS functionality andparameters when interacting with GSM

• SGSN acts as VLR for GPRS-specific VLR functions

• EIR/AuC will also require software upgrades forGPRS-specific authentication/authorisation

VLR

HLR

Serving GPRS Support Node (SGSN)Serving GPRS Support Node (SGSN)



• Packet routing

• MS Session management

• Authentication and Ciphering

• Mobility management

• Billing information collection

Nokia SGSN

Gateway GPRS Support Node (GGSN)Gateway GPRS Support Node (GGSN)



• Interface between GPRS backbone andexternal PDNs.

• PDP Conversion and contextmanagement

• IP address assignment management

• Packet routing to/from SGSNs

• Billing information collection

NetSpira GGSN

Additional Elements of the GPRS NetworkAdditional Elements of the GPRS Network



BTSBTS BSCBSC

SGSN

Inter-PLMN

Network

GPRSGPRS

BackboneBackbone

BG

CG

GGSN

GGSN

Internet

Intranet

Billing

Centre

LIG

DNS

Router

Server

Corporate LANCore NetworkCore Network

DHCP

PCU

GPRS-Associated InterfacesGPRS-Associated Interfaces



Gf Gf Gr Gr GcGc

GsGs

GdGd

BTBT

SSBSCBSC

HLRHLR

SGSNSGSN

VLRVLR

EIREIR

InternetInternet

TRTR

XX

BSSBSS

GGSGGS

NN

MSCMSC

SMSSMS

GMSCGMSC

GbGb GnGn

PLMNPLMN

GpGp

Gi - reference pointGi - reference point

UmUm

Gb = compulsory interfaceGb = compulsory interface

= optional interface= optional interface

PCUPCU

GPRS CORE NETWORKGPRS CORE NETWORK

MSMS

MSMS

MSMS

Gf Gf




• Mobile Station Modifications

• Terminal Description and Functions,• Terminal Types (A,B,C) and Multislot Classes (1-29)

• Terminal Form Factors

• Base Station Subsystem (BSS) Modifications

•Packet Control Unit (PCU) Functionality

• Channel Coding Unit (CCU) Functionality

• Core Network Modifications

• SGSN, GGSN , HLR/VLR

• GPRS-Associated Interfaces BTS BSCPCU

MSC/VLR

SGSN

Gateway

MSC

GGSN

HLR

Circuit Switched

Packet Switched

PSTNPSTN

PDNPDN

A

Gb

TRAU




Day 1Day 1








Day 2Day 2







Section 5 - GPRS Air InterfaceSection 5 - GPRS Air Interface



5.2 GSM/GPRS Physical Channels5.2 GSM/GPRS Physical Channels

5.3 GPRS Logical Channels5.3 GPRS Logical Channels

5.4 GPRS Multiframe Structure5.4 GPRS Multiframe Structure

5.5 GPRS Coding Schemes5.5 GPRS Coding Schemes


GPRS UGPRS Umm Air InterfaceAir Interface



• New Packet logical channels defined• New multiframe structure defined

• Ability for multiple users to share single or multiple timeslots

• Dynamic Resource Allocation

• Four new channel coding schemes

P-GSM Physical ChannelsP-GSM Physical Channels



Uplink Downlink

890 915 935 960 MHz

Duplex spacing = 45 MHz

Guard Band

100 kHz wide Channel Numbers (n) (ARFCN)

200 kHz spacing

Range of ARFCN:

1 - 1241 n

Guard Band

100 kHz wide

Fu(n)

2 3 4

0 1 2 3 4 5 6 7

4.615 ms

timeslot = 0.577 ms

1 frame period

Raw data rate =

33.75kbps per traffic channel

270kbps per carrier channel

E-GSM Physical ChannelsE-GSM Physical Channels



Guard Band


200 kHz spacing

Range of ARFCN:

1 – 124

975 – 10231 n

Guard Band

100 kHz wide

Fu(n)

2 3 4

0 1 2 3 4 5 6 7

4.615 ms

timeslot = 0.577 ms

1 frame period

Raw data rate =



Uplink Downlink

880 915 925 960 MHz


DCS-1800 Physical ChannelsDCS-1800 Physical Channels



Guard Band


200 kHz spacing

1 n

Guard Band

100 kHz wide

Fu(n)

2 3 4

0 1 2 3 4 5 6 7

4.615 ms

timeslot = 0.577 ms

1 frame period

Raw data rate =



Uplink Downlink

1710 1785 1805 1880 MHz


Range of ARFCN:

512 - 885

GPRS Multiframe StructureGPRS Multiframe Structure



B0 to B11 = Radio Blocks

T = PTCCH (Timing Advance)

X = Signalling/BSIC Measurements

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11T TX X

52-frame GPRS Traffic Channel Multiframe

T TT T T T T T T T T T T T T T T T IT T T T TTS

26-frame GSM Traffic Channel Multiframe

• Each radio block comprises 4 x 114-bit bursts

• Radio bursts are assigned in the sequence:B0, B6, B3, B9, B1, B7, B4, B10, B2, B8, B5, B11

0 5126

GPRS Control Channel MappingGPRS Control Channel Mapping



• GPRS may operate without GPRS control channels (GPRS Phase I),utilising the GSM equivalent logical channels

• GPRS does not utilise a dedicated physical signalling channel (TS0)

• Where GPRS control channels are implemented:

• One GPRS PDCH is designated as the ‘master’ channel

• Up to 4 blocks may be allocated to PBCCH on the master PDCH

• PBCCHs blocks are assigned in same sequence as PDTCHs

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11T X

0 5126

GPRS Logical ChannelsGPRS Logical Channels



• GPRS shares GSM for many logicalcommon

control channel functions (e.g. FCCH, SCH)

• New GPRS logical dedicated control channelsare used (e.g. PDTCH, PACCH and PTCCH)

• Packet control channels are optional

• GSM control channels may be substituted

GPRS Logical Channel StructureGPRS Logical Channel Structure



• Two types of logical channel are defined; common and dedicated

• Each is further sub-divided as shown:

PDTCHPDTCHPCCCHPCCCHPBCCHPBCCH PDCCHPDCCH

PPCHPPCH

PRACHPRACH

PAGCHPAGCH

PNCHPNCH

PACCHPACCH

PTCCHPTCCH

Common ChannelsCommon Channels Dedicated ChannelsDedicated Channels

PBCCH/PCCCH Logical ChannelsPBCCH/PCCCH Logical ChannelsChannels U / D Purpose Notes



p

PBCCH

PBCCH PacketBroadcastControl Channel

D Used to broadcastpacket data specificsystem information.

If PBCCH is not allocated,this information can bebroadcast on BCCH.

PCCCH

PRACH Packet Random Access Channel

U Used by MS to initiatethe uplink transfer of data or signallinginformation.

Uses Packet Access burstand Extended Packet Access burst. Access burstis used to obtain TA.

PPCH Packet PagingChannel

D Page MS prior todownlink packet transfer.

Paging groups allow DRX.Can be used for CS and PSdata services

PAGCH Packet AccessGrant Channel

D Sends resourceassignment messages toMS prior to packettransfer.

Additional resourceassignment messages canbe sent on a PACCH if theMS is currently involved inpacket transfer.

PNCH PacketNotificationChannel

D Sends a Point ToMultipoint – Multicast(PTM-M) notification to agroup of MSs prior to aPTM-M packet transfer. Assigns resources for packet transfer.

PTM-M is not specified inGPRS Phase 1DRX mode is provided for monitoring PNCH.Optionally a “PTM-M newmessage” indicator may besent on PPCH to each MS

show when they need tolisten to PNCH.

PDTCH/PDCCH Logical ChannelsPDTCH/PDCCH Logical Channels

Channels U / D Purpose Notes



Channels U / D Purpose Notes

PDTCH

PDTCH Packet DataTraffic Channel

U/D Allocated for datatransfer. Temporarily

dedicated to one MS or a group of MSs for PTM-M.

In multislot operation, oneMS may use several

PDTCHs in parallel for individual packet transfer. A PDTCH is uni-directional:uplink (PDTCH/U) for amobile originated packettransfer ;downlink (PDTCH/D) for amobile terminated packettransfer.

PDCCH

PACCH Packet

AssociatedControl Channel

U/D Signalling information for

a specific MS, e.g.:acknowledgements,power control,resource assignmentand reassignmentmessages,

PACCH shares resources

with PDTCHs that arecurrently assigned to oneMS.

An MS transferring packetdata can be paged for CSservices on PACCH.

PTCCH Packet Timing Advance ControlChannel

U/D Uplink transmits randomaccess burst for TAestimation.Downlink transmits TA

updates.

The downlink TAtransmission is sent toseveral MSs.One downlink PTCCH

(PTCCH/D) is paired withseveral uplink PTCCHs(PTCCH/U).

Packet Channel TerminologyPacket Channel Terminology



• PDTCH - User-generated information

• PTCH – Traffic multiframe comprising PDTCH and

Dedicated Control Channels (PDCCHs)

• PDCH - Packet Channel comprising possible

combination of PTCH and Packet Control Channel

(PCCCH/PBCCH)

• MPDCH – The PDCH carrying the PBCCH.

PDCH

PDCCH

PDTCH

PTCH

PBCCH/PCCCH

Packet Data Channels (PDCHs)Packet Data Channels (PDCHs)



• Physical channel allocated to packet traffic

• Can comprise combinations of control and user

data

• May be permanently allocated to a physical

channel

• May be dynamically assigned to a physical

channel on a contention basis

• Unlike GSM, GPRS PDCHs are not duplex

PDCH ConfigurationsPDCH Configurations



• PBCCH + PCCCH

• PCCCH + PDTCH

• PBCCH + PCCCH + PDTCH

• PDTCH only

123

31 2

PBCCH

PCCCH

PDTCH

Logical Packet Channels 1 PDCH

2





GPRS Data EncodingGPRS Data Encoding

CS-2



BlockBlockCheckCheckCodingCoding

USFUSF

pre-codingpre-codingaddadd

tail bitstail bits

convolutionconvolution

codingcoding puncturingpuncturing

data indata in

Data outData out

290 bits290 bits

294 bits294 bits

588 bits588 bits 456 bits456 bits

287 bits287 bits

CS 2

+16 bits+16 bits

+3 bits+3 bits

+4 bits+4 bits

x2x2

-132 bits-132 bits

Add USFAdd USF268 bit268 bit

blockblock

+3 bits+3 bits

274 bits274 bits

GPRS Coding Scheme 1 (CS-1)GPRS Coding Scheme 1 (CS-1)

3 181 40



6

USF Segmented LLC Frame Data BCS

3 181 40

224 bits

USF RLC Block

4 tail bits added

rate ½ convolutional

coding

(224+4) x 2 = 456 bits

Data Rate = 181 payload bits per 20mS sample = 9.05kbps

MAC Frame


6 268 16




USF Segmented LLC Frame Data BCS 290 bits

RLC Block

4 tail bits added

½ rate convolutional

coding

12

456 bits

Puncturing (132 bits)

12

(290+4) x 2 = 588 bitsUSF

USF

MAC Frame






12

USF Segmented LLC Frame Data BCS

12 428 16

456 bits

USF RLC Block

No Coding

456 bits


MAC Frame

Coding Scheme PerformanceCoding Scheme Performance

Average Data Throughput per TS vs Average Connection C/I



C / I

CS-2

CS-3

CS-4

CS-1

g g p p g

D a

t a t h r o u g h p u t

(Data Source: Nokia Network Testing Results)




PDTCHPDTCH

PCCCHPCCCH

PBCCHPBCCH

PDCCHPDCCH

PPCHPPCH

PRACHPRACH

PAGCHPAGCH

PNCHPNCH

PACCHPACCH

PTCCHPTCCH

Common ChannelsCommon Channels

Dedicated ChannelsDedicated Channels

• GSM/GPRS Physical Channel Structure

• FDMA, TDMA, P-GSM900, E-GSM900, DCS1800

• GPRS Logical Channels

• Logical Control Channels, Logical Data channels

• GPRS Multiframes

• GPRS Coding Schemes


Day 1D

ay 1 Day 2D

ay 2



Day 1Day 1








Day 2Day 2







Section 6Section 6Protocols OverviewProtocols Overview



6.2 Protocols and the ISO 7-Layer OSI Model

6.3 Protocol Stacks and Inter-Layer Communications

6.4 Data Encapsulation

6.5 Data Tunneling

6.6 GPRS Protocol Stacks

6.1 Protocols and the ISO 7-Layer OSI Model

ProtocolsProtocols

• A protocol is a set of rules, agreed by both sides, to allowi f l i ti t t k l



meaningful communication to take place

• Protocols are needed whenever systems need to passinformation from one to another

?

ISO 7-Layer OSI ModelISO 7-Layer OSI Model



APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL

End-to-end message transfer End-to-end message transfer

Network routing, addressing, call managementNetwork routing, addressing, call management

Data link control (framing, error control)Data link control (framing, error control)

Mechanical and electrical interfacingMechanical and electrical interfacing

Application entity dialogue and synchronisationApplication entity dialogue and synchronisation

Syntax and data representation managementSyntax and data representation management

File transfer, access managementFile transfer, access management

44

33

22

11

55

66

77

Horizontal (Peer-to-Peer) CommunicationHorizontal (Peer-to-Peer) Communication



APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL

APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL

NETWORK

DATA LINK

PHYSICAL

NETWORK

DATA LINK

PHYSICAL

NETWORK (Transmission Channel)NETWORK (Transmission Channel)

HOST AHOST A HOST BHOST B

Node ANode A Node BNode B

Virtual LinkVirtual Link




Vertical (Entity-to Entity) CommunicationVertical (Entity-to Entity) Communication



APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL

APPLICATION

PRESENTATION

SESSION

TRANSPORT

NETWORK

DATA LINK

PHYSICAL

NETWORK

DATA LINK

PHYSICAL

NETWORK

DATA LINK

PHYSICAL

HOST AHOST A

HOST BHOST B

Node ANode A Node BNode B


Vertical (Entity-to-Entity) CommunicationVertical (Entity-to-Entity) Communication

• Each layer requests a service from the layer below



Each layer requests a service from the layer below

• The layer below responds by providing a service tothe layer above

• Each layer can provide one or more services tothe layer above

• Each service provided is known as a service

‘Entity’• Each Entity is accessed via a Service Access

Point (SAP) or a ‘gate’.

• Each SAP has a unique SAP Identifier (SAPI) R e q u e s t

S e r v i c e

Entity

Entity

SAP



Protocol EncapsulationProtocol Encapsulation



APPLICATIONAPPLICATION

PRESENTATIONPRESENTATION

SESSIONSESSION

TRANSPORTTRANSPORT

NETWORKNETWORK

LINKLINK

PHYSICALPHYSICAL

HOST AHOST A HOST BHOST B

NETWORK (Transmission Channel)NETWORK (Transmission Channel)

User Data

APPLICATIONAPPLICATION

PRESENTATIONPRESENTATION

SESSIONSESSION

TRANSPORTTRANSPORT

NETWORKNETWORK

LINKLINK

PHYSICALPHYSICAL



Data TunnellingData Tunnelling

“A technology that enables one network to send its data via



another network's connections.

Tunneling works by encapsulating a network protocol withinpackets carried by the second network”

(Webopedia definition)

A tunnel is a point-to-point (PTP) virtual connection betweentwo end points across a network through which data packetscan be transported, transparent to the bearer network

Data TunnellingData Tunnelling

Tunneling is used by many technologies:



Tunneling is used by many technologies:

GPRS (GTP)

Mobile IP

Internet (PPTP)

MPLS

VPNs

The GPRS Protocol StackThe GPRS Protocol Stack

GPRS CoreGPRS CoreBSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25

ApplicationApplication

RelayRelay

RelayRelay

MSMS BSC/PCUSNBSC/PCUSN SGSNSGSN GGSNGGSN

UDP/TCPUDP/TCP

GTPGTP

L1L1

L2L2

IPIP

L2L2

IP/X.25IP/X.25

L1L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bisL1bis

NetworkNetworkServiceService

BSSGPBSSGP

LLCLLC

SNDCPSNDCP

UDP/TCPUDP/TCP

L1L1

L2L2

IPIP


BSSGPBSSGP

GTPGTP

L1bisL1bis

GPRS CoreGPRS Core

NetworkNetwork

PSDNPSDNGGSN

BSC/PCU

SGSN

UUmm GGbb GGnn GGii

• T f PDP PDU f i t t t

Relay FunctionRelay Function



• Transfers PDP PDUs from input port to

appropriate output port

• Packet sequence numbering

• Packet re-sequencing

• Buffering

• Employs maximum holding time

The Network Access Signalling ProtocolsThe Network Access Signalling Protocols

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLCRelayRelay

MSMS BSC/PCUSNBSC/PCUSN

L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bisL1bis


BSSGPBSSGP

BSC/PCU

SGSN

UUmm GGbb

L1bisL1bis

MACMAC

RLCRLC

LLCLLC

SGSNSGSN

S N D C P

S N D C P

S M S

S M S

G M M / S M

G M M / S M

S N D C P

S N D C P

S M S

S M S

G

M M / S M

G

M M / S M

GPRS Core Network Signalling ProtocolsGPRS Core Network Signalling Protocols

NetworkNetwork NetworkNetwork



MAP

TCAP

SCCP

MTP-3

MTP-2

L1

MAP

TCAP

SCCP

MTP-3

MTP-2

L1

Networket o

NODE ANODE ANetworkNetwork

NODE BNODE B

MAP – Mobile Application Part

TCAP – Transaction Capabilities Application PartSCCP – Signalling Connection Control Part

MTP – Message Transfer Part


• Introduction to Protocols

• Definition ISO 7 Layer Model



• Definition, ISO 7-Layer Model

• Protocol Stacks• Horizontal (Peer-Peer) Communication

• Vertical (Entity-Entity) Communications

• SAPs

• Protocol Encapsulation• Data Tunneling

• GPRS Protocol Stacks

• Transmission Protocol Stack

• Network Access Signalling Protocol Stack

• Core Network Signalling Protocol Stack

?


Day 1D

ay 1 Day 2D

ay 2
















14. GPRS Network Planning14. GPRS Network Planning

ConsiderationsConsiderations

Section 7Section 7The GPRS Transmission ProtocolsThe GPRS Transmission Protocols




7.2 Um (Air) Interface Transmission Protocols7.2 Um (Air) Interface Transmission Protocols

7.3 Gb (BSS-SGSN) Interface Transmission Protocols7.3 Gb (BSS-SGSN) Interface Transmission Protocols

7.4 Gn (SGSN-GGSN) Interface Transmission Protocols7.4 Gn (SGSN-GGSN) Interface Transmission Protocols

GPRS Transmission ProtocolsGPRS Transmission Protocols

GGbb



IP-based CoreIP-based Core

NetworkNetwork

InternetInternet

GGSN

UUmm

bb

GGnn GGii

Frame RelayFrame RelayNetworkNetwork

BTS PCU

BSSBSS

AAGPRSGPRS

SGSN

GSM RFGSM RF

TDMA/GMSKTDMA/GMSK

ISDN/E1ISDN/E1

PSPDNPSPDN

UUmm (Air) Interface Protocols(Air) Interface Protocols

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

UUmm Interface – Higher Layer ProtocolsInterface – Higher Layer Protocols

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

• Application Layer:

Higher Layer ProtocolsHigher Layer Protocols



• Generated by TE connected to MT• Application generated data

• Transparent to GPRS Network

• IP/X.25 Layer:• Generates packet data.

• Adds routing information to application data

• Interrogated by GGSN for correct routing



SAPI DefinitionsSAPI Definitions



SAPI Description0001 1 GMM

0011 3 User Data QoS1


0111 7 SMS1001 9 User Data QoS3




SNDCP Layer FunctionsSNDCP Layer Functions

• An Interface between higher level network protocols and theGPRS LLC layer.



y

• Translation of higher level packets into SNDCP packets(SN-PDUs) through segmentation and re-assembly

• Applies an NSAPI packet encapsulation to identify context

• Data Compression

• Buffering of N-PDUs

• Supports acknowledged and unacknowledged data transfer modes

• Provides NSAPI-specific buffering for Ack and Nack modes

N-PDU to SN-PDU SegmentationN-PDU to SN-PDU Segmentation



LLC Layer

Header Payload Network Layer Header Payload

SNDCP Layer

Network PDUs

(N-PDUs)

SNDCP

PDUsSN-PDUSH SN-PDUSH SN-PDUSH SN-PDUSH SN-PDUSH

Higher Level (IP/X.25) Data Packet

SH – SNCDP PDU Header

CompressionCompression

He..

SNDCP SN-PDU FormatSNDCP SN-PDU Format

• The SNDCP Header comprises 2 (SN-Data PDU) or 5 (SN-The SNDCP Header comprises 2 (SN-Data PDU) or 5 (SN-Unitdata PDU) octets:Unitdata PDU) octets:



Unitdata PDU) octets:U tdata U) octets

8 7 6 5 4 3 2 1

1 X F T M

2

……

n

8 7 6 5 4 3 2 1

1 X F T M

2

3

4 E

5

……n

NSAPI

DCOMP PCOMP

NSAPI

Data Segment

N-PDU# (continued)

N-PDU (extended)

Data Segment

PCOMP

SEGMENT # N-PDU#

UUmm Interface – LLC ProtocolInterface – LLC Protocol

BSC/PCU

SGSNSGSN



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLCLLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

LLC Layer FunctionsLLC Layer Functions

• Secure and reliable logical link between MS and SGSN



• Independent of lower layers

• Conveys Signalling (GMM/SM), SMS and SNDCP data in

variable length information packets

• Supports Acknowledged and Unacknowledged data transfer modes

• Supports precedence QoS classes

• Based on HDLC format (less flag fields)

Logical Link IdentifiersLogical Link Identifiers

• Data Link Connection Identifier (DLCI)



• Uniquely identifies a Logical Link connection between a specific MS and theSGSN

• Assigned by SGSN on completing a ‘GPRS Attach’ Procedure

• Comprises a SAPI and Temporary Logical Link Identifier (TLLI)

• SAPI

• Identifies the service required by each peer entity (MS and SGSN)

• TLLI

• Uniquely identifies the MS.

• Derived from the MS’s assigned P-TMSI

LLC Frame StructureLLC Frame Structure

From Layer 3



SAPI

to RLC/MAC Layer

AddressField

Frame

Check

Sequence

y

Control

Field

Transfer ModeFrame Type

LLC Frame No

Variable Length Information (payload) Field

Header

LLC Frame FormatLLC Frame Format

8 7 6 5 4 3 2 1

1 PD C/R X X SAPI Address Field



3

n

n+1

n+m

n+m+1n+m+2

n+m+3

Information Field (Variable Length)

Control Fie ld (max 36 octets)

FCS Field (3 octets)

PD = Protocol Discriminator bit

C/R = Command/Response bit

X = not defined

SAPI = Service Access Point Identifier FCS = Frame Check Sequence

LLC Frame CreationLLC Frame Creation

Header Payload Network Layer Header PayloadNetwork PDUs

(N-PDUs)



SNDCP Layer SNDCP

segmentsSNDCP

segmentPH SNDCP

segmentPH SNDCP

segmentPH SNDCP

segmentPH SNDCP

segmentPH

FH SNDCP Segment FCSLLC Frame LLC Layer

to RLC/MAC Layer

PH

LLC Acknowledged/Unacknowledged ModesLLC Acknowledged/Unacknowledged Modes

• Unacknowledged Mode:

• Known as Asynchronous Disconnected Mode (ADM)



• LLC Transmissions may be initiated without prior establishment of a logical connection

• LLC does not guarantee ordered delivery

• LLC can detect but not correct errors

• Depending on protected or unprotected mode, erroneous packets may be forwarded or

discarded as appropriate

• Acknowledged Mode:

• Known as Asynchronous Balanced Mode (ABM)

• Each terminating entity is responsible for flow control and error recovery

• Provides mechanisms for a reliable, ordered packet delivery service

• Each terminating entity acts as a data source and data sink allowing bi-directional flows

UUmm Interface – RLC Layer Interface – RLC Layer

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

RLC Layer FunctionsRLC Layer Functions

• Provides reliable radio link.



• Transfer of LLC-PDUs between LLC and MAClayers.

• Segmentation and reassembly of LLC-PDUs intoRLC data blocks.

• Segmentation and reassembly of RLC/MAC controlmessages into RLC/MAC blocks

• Provision of ARQ backward error correction

Uplink RLC Data BlockUplink RLC Data Block

8 7 6 5 4 3 2 1

PR TFI FBI Octet 1

BSN E Octet 2



Length Indicator M E Octet 3 (optional)

Length Indicator M E Octet M(optional)

LLC PDU(s)

Octet M+1

Octet N2-1

Octet N2

Spare (if present)

PR = Power Reduction E = Extension bit

TFI = Temporary Flow Indicator M = More bit

FBI = Final Block Indicator

BSN = Block Sequence Number

Radio Link Control Block GenerationRadio Link Control Block Generation

FH Information field FCSLLC PDUsLLC PDUs LLC Layer LLC Layer



B

HBCS

B

H

Information

fieldBCS

B

HBCS

segment

RLC BlocksRLC Blocks

Information

fieldInformation

field

segment segment

MACMAC

BSSBSS

RLCRLC

MSMS

RLCRLC

LinkLink

MACMAC

LinkLink

UUmm Interface – MAC Layer Interface – MAC Layer

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

MAC Layer FunctionsMAC Layer Functions

• Multiplexing



• Channel allocation

• Access control

• Uplink contention arbitration

• Downlink packet queuing and scheduling

• QoS prioritising

MAC Access ModesMAC Access Modes



• Dynamic Allocation

• Extended Dynamic Allocation

• Fixed Allocation

• Exclusive Allocation

Downlink MAC Header Downlink MAC Header



8 7 6 5 4 3 2 1

Payload Type RRBP S/P USF

RLC Block

Payload Type = Control/data block

RRBP = Relative Reserved Block Period

S/P = Supplementary Polling bit

USF = Uplink State Flag

UUmm Interface MAC Frames GenerationInterface MAC Frames Generation

FH Information field FCSLLC PDUsLLC PDUs LLC Layer LLC Layer



B

HBCS

B

H

Information

fieldBCS

B

HBCS

segment

RLC BlocksRLC Blocks

Information

fieldInformation

field

segment segment

MACMAC

BSSBSS

RLCRLC

MSMS

RLCRLC

LinkLink

MACMAC

LinkLink

MAC FrameMAC Frame

MAC

HEADERRLC Block

UUmm Interface – GSM RF Layer Interface – GSM RF Layer

BSC/PCU

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii

Link Layer Link Layer

The Link Layer is divided into two parts:

R di F (RF) t



• Radio Frequency (RF) part:• carrier frequency

• modulation schemes

• TRX characteristics

• channel structures

• Physical Link part:• communications between MS and network

• FEC

• burst interleaving





UUmm (Air) Interface BSC Protocols(Air) Interface BSC Protocols

BSC/PCU

BSC/PCU



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCP

L1

L2

IP

NetworkService

BSSGP

GTP

L1bis

BSC/PCU

UUmm GGbb GGnn GGii



GGbb Interface BSSGP ProtocolInterface BSSGP Protocol

BSC/PCU

BSC/PCU

SGSN



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bisL1bis


BSSGPBSSGP

LLCLLC

SNDCPSNDCP

UDP/TCP

L1

L2

IP


BSSGPBSSGP

GTP

L1bisL1bis

UUmm GGbb GGnn GGii

BSSGP Layer FunctionsBSSGP Layer Functions

• Transports payload data and signalling between SGSNand BSS



• One BVC is established for each SGSN-BSS connection,identified by unique BVCI

• Provides SGSN-BSS flow control

• Separates LLC frames into user data, signalling, GMMand Network management information

• Provides QoS and routing information for SGSN-BSSdata transfer

BSSGP – Virtual CircuitsBSSGP – Virtual Circuits

BVCI 1BVCI 1

BV CI 1BV CI 1

GGbb InterfaceFrame RelayFrame Relay

E1 LinkE1 Link



SGSNSGSN

BVCI 1BVCI 1

BSCBSC

BVCI 2BVCI 2

BVCI 4BVCI 4

BVCI 3BVCI 3 B V C I

2 B V C I 2

B V C I

3 B V

C I 3

B V C I 4

B V C I 4

BVCI 5BVCI 5

SGSN-BSS SignallingSGSN-BSS Signalling

GGbb Interface Network Service Layer ProtocolInterface Network Service Layer Protocol

BSC/PCU

BSC/PCU

SGSN



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bisL1bis


BSSGPBSSGP

LLCLLC

SNDCPSNDCP

UDP/TCP

L1

L2

IP


BSSGPBSSGP

GTP

L1bisL1bis

UUmm GGbb GGnn GGii

Network Services Layer FunctionsNetwork Services Layer Functions

• Based on Frame Relay (FR) technology

• Utilises FR PVCs known as NS-VCs to transport dataacross the FR ‘cloud’



• Utilises FR PVCs, known as NS-VCs to transport dataacross the FR cloud

• One or more NS-VCs established between an SGSNand each supported BSC

•FR N-PDUs transport BSSGP PDUs

• Each DLC can contain one or more BVCs

• Offers detection of but not recovery from errors

• Provides congestion control



GGbb NS Layer Virtual Links/ConnectionsNS Layer Virtual Links/Connections

GGbb InterfaceInterface

NS-VCNS-VC



SGSNSGSN

Frame Relay NetworkFrame Relay Network

BSCBSC

SGSNSGSNBSCBSC

PTP 64kbps ISDNPTP 64kbps ISDN

NS-VLNS-VL NS-VLNS-VL

S C

NS-VCNS-VC

Network Services Layer DLCsNetwork Services Layer DLCs

BSS 1BSS 1 FRFR

SwitchSwitch 1111

3838

NS-VC1NS-VC1



SGSNSGSNFRFR

SwitchSwitch

BSS 3BSS 3

FRFR

SwitchSwitch

FRFR

SwitchSwitch

BSS 2BSS 2

FRFR

SwitchSwitch

1919

2323

3232

77

6767

4444

22

8585

4444 = Data Link Circuit Identifier (DLCI)= Data Link Circuit Identifier (DLCI)

(Frame Relay Circuits)(Frame Relay Circuits)

7777

NS-VC2NS-VC2

NS-VC3NS-VC3

GGbb L1bis Interface ProtocolsL1bis Interface Protocols

BSC/PCU

BSC/PCU

SGSN

UU GG GG GG



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCP

GTP

L1

L2

IP

L2

IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bisL1bis


BSSGPBSSGP

LLCLLC

SNDCPSNDCP

UDP/TCP

L1

L2

IP


BSSGPBSSGP

GTP

L1bisL1bis

UUmm GGbb GGnn GGii

GGbb L1bis Interface ProtocolsL1bis Interface Protocols

• One or more physical links between SGSN and

each BSS



each BSS

• Based on E1/T1 links

• Supports G703/704 Protocols

• Each Physical link can support multiple NS-VCs

The GThe Gnn InterfaceInterface

GPRS CoreGPRS Core

NetworkNetworkGGSNSGSN

UU GG GG GG



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCPUDP/TCP

GTPGTP

L1L1

L2L2

IPIP

L2

IP/X.25IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCPUDP/TCP

L1L1

L2L2

IPIP

NetworkService

BSSGP

GTPGTP

L1bis

UUmm GGbb GGnn GGii

The GPRS Tunnelling Protocol (GTP)The GPRS Tunnelling Protocol (GTP)

GPRS CoreGPRS Core


UU GG GG GG



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCPUDP/TCP

GTPGTP

L1L1

L2L2

IPIP

L2

IP/X.25IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCPUDP/TCP

L1L1

L2L2

IPIP

NetworkService

BSSGP

GTPGTP

L1bis

UUmm GGbb GGnn GGii

GPRS Tunnelling Protocol (GTP)GPRS Tunnelling Protocol (GTP)

• Enables reliable transportation of multi-protocolpackets between SGSNs and GGSNs.



• Defined for both the Gn (SGSN-GGSN) and Gp(GGSN-GGSN) interfaces.

• Two modes of operation:

• Unacknowledged (UDP/IP)

• Acknowledged (TCP/IP)

GPRS Tunnelling ConceptGPRS Tunnelling Concept

GPRS COREGPRS CORE

Gp

BGBG

SGSNSGSN



BSCBSCBTS

INTERNETINTERNET

GTP Protocol

Gn

GPRS COREGPRS COREGn

SGSNSGSN

BGBG

GGSNGGSN

SGSNSGSN

BSCBSC

BTS

GTP Header FormatGTP Header Format

• The GTP Header comprises 20 octets:The GTP Header comprises 20 octets:

8 7 6 5 4 3 2 1

1 PT SNN2

Version Spare '1 1 1'Message Type



20 Octets20 Octets

8 Octets8 Octets

2

3

4

5

6

7

89

10

11

12

13-20

Spare

Spare

Spare

TID (IMSI+NSAPI)

Message Type

Length

Sequence Number

Flow LabelSNDCP NPDU Number



GGnn Interface - TCP/UPD ProtocolsInterface - TCP/UPD Protocols

GPRS CoreGPRS Core


UUmm GGbb GGnn GGii



GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

RelayRelay

RelayRelay


UDP/TCPUDP/TCP

GTPGTP

L1L1

L2L2

IPIP

L2

IP/X.25IP/X.25

L1

RelayRelay L3L3

L1L1

L2L2

GSM RF

MAC

RLC

L1bis

NetworkService

BSSGP

LLC

SNDCP

UDP/TCPUDP/TCP

L1L1

L2L2

IPIP

NetworkService

BSSGP

GTPGTP

L1bis

mm bb nn ii

UDP EncapsulationUDP Encapsulation

User Data (e.g IP datagram)

User Data PayloadGTP

HeaderSNDCPSNDCP GTPGTP GTPGTP

IP/X.25IP/X.25

GGSNGGSN

SGSNSGSN



L1L1

Header


Header

UDP

Header

L1bisL1bis

L2L2NetworkNetworkServiceService

LLCLLC UDP/TCPUDP/TCP

IPIPBSSGPBSSGP

L1L1

L2L2

UDP/TCPUDP/TCP

IPIP



Backbone IP EncapsulationBackbone IP Encapsulation

User Data (e.g IP datagram)


Header SNDCPSNDCP GTPGTP GTPGTP

IP/X.25IP/X.25

GGSNGGSN

SGSNSGSN



L1L1


Header

UDP

Header


Header

UDP

Header

GPRSBackbone IP

header

L1bisL1bis

L2L2NetworkNetworkServiceService

LLCLLC UDP/TCPUDP/TCP

IPIPBSSGPBSSGP

L1L1

L2L2

UDP/TCPUDP/TCP

IPIP

GPRS Transport ChannelsGPRS Transport Channels

SGSNSGSN

MSMS

GGSGGS

NNBSSBSS

GGbb GGnnUUmm



Virtual TunnelVirtual Tunnel

BSSGP VCBSSGP VC BVCIBVCI

TIDTID

CONNECTION TYPECONNECTION TYPE

CONNECTIONCONNECTION

IDENTIFIERIDENTIFIER

TDMA TCHTDMA TCHTCH nTCH n

GPRS Physical Connection ProtocolsGPRS Physical Connection Protocols

SGSNSGSN

MSMS

GGSGGS

NN

BSC/BSC/

PCUPCU

GGbb GGnnUUmm

BTSBTS

AAGPRSGPRS



ProprietaryProprietary

TDMATDMA

E1E1

G703G703

GMSKGMSK

ISDN/E1ISDN/E1

Frame RelayFrame Relay


SGSNSGSN

MSMS

GGSGGS

NNBSSBSS

GGbb GGnnUUmm



TCP/UDPTCP/UDP

IPIP

BSSGPBSSGP

RLCPRLCP

SNDCPSNDCP

MACPMACP

LLCPLLCP

GTPGTP

Layer 3 Services to the LLC Layer Layer 3 Services to the LLC Layer

BSC/PCU

BSC/PCU

SGSN

UUmm GGbb



GSM RFGSM RF

MACMAC

RLCRLC

LLCLLCRelayRelay

MSMS BSC/PCUSNBSC/PCUSN

L3L3

L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bisL1bis


BSSGPBSSGP

L1bisL1bis

MACMAC

RLCRLC

LLCLLC

SGSNSGSN

S N D C P

S N D C P

S M S

S M S

G M M / S M

G M M / S M

S N D C P

S N D C P

S M S

S M S

G M M / S M

G M M / S M

Using SAPIs and NSAPIsUsing SAPIs and NSAPIs

AOLAOL

IPv4IPv4AOLAOL

IPv6IPv6FreeserveFreeserve

IPv4IPv4X.25X.25

ServiceService

PDP Contexts defined inGPRS user’s subscription

profile



N-PDU

NSAPIs

SAPIs

profile

SN-PDU

GMMGMM

SignallingSignalling SMSSMS

7135911LLC

SNDCP

Other Layer 3 Services

4321


• MS-BSS UmInterface Protocols

• SNDCP, LLC, RLC, MAC, Link Layer

• BSS SGSN G Interface Protocols



• BSS-SGSN GbInterface Protocols

• BSSGP, Network Services (FR Relay) L1bis physicallayer

• SGSN-GGSN GnInterface Protocols

• GTP, TCP/UDP, IPIP-based CoreIP-based Core

NetworkNetwork

InternetInternet

GGSN

UUmm

GGbb

GGnnGGii

Frame RelayFrame RelayNetworkNetwork

BTS PCU

BSSBSS

AAGPRSGPRS

SGSN

GSM RFGSM RF

TDMA/GMSKTDMA/GMSK

ISDN/E1ISDN/E1

PSPDPSPD


Day 1D

ay 1

1. Concepts1. Concepts2. Mobile Data Evolution2. Mobile Data Evolution

Day 2D

ay 2

8. Mobility Management8. Mobility Management9. Radio Resource Management9. Radio Resource Management



ob e ata o ut o






9. Radio Resource Managementg







8.2 Mobility Management (MM) States8.2 Mobility Management (MM) States

Section 8 - Mobility ManagementSection 8 - Mobility Management




8.3 GPRS Attach/Detach Procedures8.3 GPRS Attach/Detach Procedures

8.4 Routing Areas8.4 Routing Areas

8.5 Location Management8.5 Location Management

8.6 Paging8.6 Paging

8.7 Cell Reselection8.7 Cell Reselection



GMM State ModelsGMM State Models

READY STANDBYIDLE

No Data

Data

Send

GPRS

Detach

GPRS

Attach

MS MM State Model:



SGSN

Time-out

READY STANDBYIDLE

No Data

Transfer

Receive

GPRS

Detach

GPRS

Attach

SGSN MM State Model:

• Idle to Ready:• GPRS attach

• Ready to Standby:

• Ready timer expired• Forced to Standby

MM State Change ConditionsMM State Change Conditions



y

• Abnormal RLC conditions (SGSN context)

• Standby to Ready:• Packet transmission/reception required

• Ready to Idle:• GPRS detach

• Location cancelled (SGSN context)

• Standby to Idle:• Implicit detach (SGSN context)

• Location cancelled (SGSN context)

• Set in both MS and SGSN

• Reset on LLC PDU transfer

Ready State Timer Ready State Timer



• Forces MS to Standby on expiry

• Configurable only by SGSN:

• All 0’s - immediately forces MS to Standby state

• All 1’s - timer disabled (MS remains in Ready

state)

The GPRS Attach ProcedureThe GPRS Attach Procedure

1 3



BSCBSC2

4 HLRHLRMSC/MSC/

VLRVLR

1

2

4

3

3

3

2

SGSNSGSN

BTSBTS

Basic GPRS Attach ProcedureBasic GPRS Attach Procedure

HLRHLREIREIRSGSNSGSNBSSBSSMSMS

Attach RequestAttach Request

Identity RequestIdentity Request

Identity ResponseIdentity Response

MSC/VLRMSC/VLR



Update LocationUpdate Location

Attach AcceptAttach Accept

AuthenticationAuthentication

IMEI CheckIMEI Check

Insert Subscriber DataInsert Subscriber Data

Insert Subscriber Data AckInsert Subscriber Data Ack

Update Location AckUpdate Location Ack

Attach CompleteAttach Complete

IMSI AttachIMSI Attach

The GPRS Detach CircumstancesThe GPRS Detach Circumstances

• A GPRS MS may detach from the network when:

• The MS is turned off or the user manually

disconnects from the GPRS network



disconnects from the GPRS network.

• The MS ‘Reachable Timer’ expires.

• The SGSN forces a GPRS Detach due to radio

link problems

GPRS Detach Types and ModesGPRS Detach Types and Modes

• GPRS Detach Types:

• IMSI Detach• GPRS Detach



GPRS Detach

• Combined IMSI/GPRS Detach

• GPRS Detach Modes:

• Explicit – MS initiated

• Implicit – Network initiated

MS-Initiated GPRS Detach ProcedureMS-Initiated GPRS Detach Procedure

GGSNGGSNSGSNSGSNBSSBSSMSMS

Detach RequestDetach Request

Delete PDP Context RequestDelete PDP Context Request



Delete PDP Context ResponseDelete PDP Context Response

Detach AcceptDetach Accept

SGSN-Initiated GPRS Detach ProcedureSGSN-Initiated GPRS Detach Procedure

GGSNGGSNSGSNSGSNBSSBSSMSMS







• Mobile Reachable Timer:

• Stops when MS enters READY state

MS Reachable Timer MS Reachable Timer



• Reset and restarted when MS entersSTANDBY state

• Forces IDLE state on expiry (no paging)

Routing ZonesRouting Zones

SGSN-1SGSN-1

BSC-1BSC-1BSC-3BSC-3

SGSN-2SGSN-2

BSC-2BSC-2



RA-1RA-1

RA-2RA-2 RA-3RA-3

LA-1LA-1

LALA

CELL

CELL

CELLCELL

CELL

CELL

CELL

CELL

- Routing AreaRARA

- Location Area

LA-2LA-2

Routing AreasRouting Areas

• Served by only one SGSN

• Subset of a Location Area



• Cannot Span more than one Location Area

• Contains one or more GPRS Cells

Area IdentitiesArea Identities

• Location Area Identity (LAI) comprises:

• Mobile Country Code (MCC)

• Mobile Network Code (MNC)

• Location Area Code (LAC) Location Area

R ti A Id tit (RAI) i



Cells within RAs

• Routing Area Identity (RAI) comprises:

• Location Area Identity (LAI)

• Routing Area Code (RAC)

• Cell Global Identity (CGI) comprises:

• Cell Identity (CI)

• LAI (or RAI)

Routing Areas within LA

• The Periodic RA Update Timer:

• Monitors RA Update procedure in the MS

Routing Area (RA) Update TimersRouting Area (RA) Update Timers



• Unique for each RA

• Initiates periodic RA Update procedure onexpiry

• Reset after periodic RA update completed

Location Management RequirementLocation Management Requirement

• Why the need for location management?

• Network must know when and where a GPRS MS attachesto the network.

• Network must know where to route packets.



• Network must know when a ‘Ready’ State MS changes celland/or RA.

• Network must know when a ‘Standby’ State MS changes RA.

• Network must know when an MS changes MM state.

Location Information StorageLocation Information Storage

• Location information stored is dependantupon MM state of MS:

• IDLE - no current location information held



• STANDBY - only Routing Area information held

• READY - Routing Area and cell information held

Location Management FunctionsLocation Management Functions

• Functions provided:

• Mechanisms for cell and PLMN selection

• A mechanism to know the RA for MSs in a STANDBYstate



• A mechanism to know the Cell ID for MSs in a READYstate

• The Network provides the MS with information to beable to:

• Detect entering a new cell or RA

• Determine when to perform a RA update

Location Update CircumstancesLocation Update Circumstances

• Location updates take place when:

• An MS attaches to the network

• A Ready-state MS changes cell



A Ready state MS changes cell

• A Ready or Standby-state MS changes RA

• A Ready or Standby-state MS changes SA

• An MS periodic RA update timer expires

Location Update ScenariosLocation Update Scenarios

• When a GPRS terminal camps on to a newcell, one of 3 possible scenarios is indicated:

• A cell update is required



• A Routing Area update is required

• A combined Routing Area and Location Areaupdate is required

Changing CellsChanging Cells

• Notification only required if MS in ‘Ready’ state

• MS detects change by comparing stored Cell ID with

received Cell ID

• Change indicates requirement for one of three



g qprocedures:

• Cell ID update

• RAI Update (inter or intra-SGSN update)

• Combined LAI / RAI update

Changing GPRS Routing Area(RA)Changing GPRS Routing Area(RA)

• Notification only required if MS in ‘Ready’ or ‘Standby’state

• Update required when:

• New RAI detected by MS



• Periodic RA update timer expires

• MS detects change by comparing stored RAI withreceived RAI

• Cell ID update implicit in RA update

Changing SGSN Service Area (SA)Changing SGSN Service Area (SA)

• When a MS changing RA, one of two states occur:

• MS has moved to new RA in same SGSN SA as old RA

• MS has moved to new RA in new SGSN SA

• If new SA is entered, an ‘Inter-SGSN’ RA update is



, pinitiated by SGSN

• If new RA is in same SA, ‘Intra-SGSN’ RA update isinitiated by MS

• Periodic RA updates are always of ‘Intra-SGSN’ type

Routing Area Update RequestRouting Area Update Request

MSMS SGSNSGSNBSSBSS

Intra-SGSN Location UpdatingIntra-SGSN Location Updating



Routing Area Update AcceptRouting Area Update Accept

Routing Area Update ConfirmRouting Area Update Confirm

Security Functions

Inter-SGSN Location UpdatingInter-SGSN Location UpdatingMSC/VLRMSC/VLRHLRHLRGGSNGGSNOld SGSNOld SGSNNew SGSNNew SGSNBSSBSSMSMS

Routing Area Update RequestRouting Area Update RequestSGSN Context RequestSGSN Context Request

SGSN Context ResponseSGSN Context Response

SECURITY FUNCTIONS

SGSN Context AckSGSN Context Ack

Forward PacketsForward Packets

Update PDP Context RequestUpdate PDP Context Request



Routing Area Update CompleteRouting Area Update Complete

Update PDP Context ResponseUpdate PDP Context Response


Cancel LocationCancel Location

Cancel Location AckCancel Location Ack




Location Update RequestLocation Update Request

Location Update AcceptLocation Update Accept

Routing Area Update AcceptRouting Area Update Accept

MSMS SGSNSGSNBSSBSS

Paging RequestPaging Request

GPRS Paging ProcedureGPRS Paging Procedure

PDP PDUPDP PDU

G SGPRS P i



GPRS PagingGPRS Paging

RequestRequest

Any LLC FrameAny LLC Frame

Any LLC FrameAny LLC Frame

Cell Reselection ProceduresCell Reselection Procedures• In standby or Ready states, handover procedures used

• In Idle state, C31 and C32 cell reselection criteria used:

• C31 Parameter - Signal strength criterion to prioritise cell selection

• C32 Parameter - Improvement over C31 by applying:

• individual offset and hysteresis value to each pair of cells



• uses temporary offsets like C2

• additional values that require routing area updates

• C31, C32 are only used if PBCCH is implemented. Otherwisethe C2 criteria is used





Using Spare GSM Air Interface CapacityUsing Spare GSM Air Interface Capacity

Circuit Switched Demand

Available

for GPRS

Available

for GPRS

Maximum Capacity

T i m

e s l o

t U

s a g

e

Time (hours)



T

i

m e s

l

o t s

Time

Time

0 24

Time (hours)

GPRS traffic assigned to dedicated channel

GPRS traffic dynamically assigned

T r a f f i c L e v e l

The Packet Data Traffic Channel (PDCH)The Packet Data Traffic Channel (PDCH)

• Channel allocated for packet data transfer

• Temporary or permanent allocation for one or multiple

GPRS terminals• Unidirectional in either:

• Uplink (PDTCH/U)



• Uplink (PDTCH/U)

• Downlink (PDTCH/D)

• When used for single timeslot operation can be:• Half rate (PDTCH/H)

• Full Rate (PDTCH/F)

• Must be full rate in multislot operation

System Timeslot Resource AllocationSystem Timeslot Resource Allocation

• GPRS timeslot allocation to terminals:

• Up to 8 timeslots on the same carrier can be allocated to a

single GPRS terminal• Up to 8 GPRS terminals can share a single timeslot



• GPRS timeslot allocation for traffic:

• Timeslots specifically allocated for GPRS traffic• Allocation of spare CS timeslot capacity on a statistical basis

Operator Timeslot Resource AllocationOperator Timeslot Resource Allocation

• Operators can specify the following:

• GPRS capacity cell-by-cell or TRX-by-TRX

• Dedicated GPRS timeslots



• GPRS-capable channels that can be allocated for CS traffic

• CS channels dynamically configured to carry GPRS traffic

• BCCH or non-BCCH TRX preferences for GPRS

Uplink Timeslot AllocationUplink Timeslot Allocation

Dynamic resource allocation - using theUSF

• Fixed resource allocation



• Exclusive resource allocation (optional)

Temporary Block Flow (TBF)Temporary Block Flow (TBF)

• Supports uni-directional transfers of LLC PDUs onphysical channels between the MS and BSC.

• Allocated Radio resources on one or more PDCHs

• Consists of one or more MAC/RLC blocks carrying one or more LLC PDUs



more LLC PDUs

• Exists only for the duration of a specific call

• Each TBF is allocated a Temporary Flow Identifier (TFI)

• One MS can be assigned multiple TBFs

Temporary Flow Identifier Temporary Flow Identifier

• Identifies recipient MS at RLC/MAC Layer

• Assigned by network

• Contained within each RLC/MAC radio block• Only unique for one PDCH in one direction



UUmm

BTS PCU

BSSBSSAAGPRSGPRS

GSM RFGSM RF

TFI1

TFI1



Packet Paging RequestPacket Paging Request

Packet Channel RequestPacket Channel Request

PPCH or PCHPPCH or PCH

PRACH or RACHPRACH or RACH

MobileMobile BSSBSS

Network-Initiated TBF EstablishmentNetwork-Initiated TBF Establishment



Packet Downlink AssignmentPacket Downlink Assignment

Packet Paging ResponsePacket Paging Response

PAGCH or AGCHPAGCH or AGCH

PACCHPACCH



One and Two-Phase TBF AccessOne and Two-Phase TBF Access

• 1-Phase Access:

• When PCCCH is available in Cell

• When in Acknowledged mode

• Total data to be transmitted does not exceed 8 RLC/MACblocks



• When layer 3 signalling is requested

• 2-Phase Access• When PCCCH is not available in Cell

• When in Unacknowledged mode

• Total data to be transmitted does exceeds 8 RLC/MAC blocks





Radio Resource Operating ModesRadio Resource Operating Modes

• Packet Idle Mode• No TBF

• Listens for paging request

• Class A terminals can establish CS connections

• Packet Transfer Mode



• TBF established

• TBF suspended on handover

• Dual Transfer Mode• Simultaneous CS and PS connection




Day 1D

ay 1




4 GPRS Architecture & Interfaces4 GPRS Architecture & Interfaces

Day 2D

ay 2




11 GPRS Operational Issues11 GPRS Operational Issues












10.2 Packet Data Protocol (PDP) States10.2 Packet Data Protocol (PDP) States

10.4 PDP Contexts and Addresses10.4 PDP Contexts and Addresses

10.3 Effect of MM States on Packet Transfer 10.3 Effect of MM States on Packet Transfer

Section 10 - Packet Routing and Transfer Section 10 - Packet Routing and Transfer




10.5 Access Point Names10.5 Access Point Names

10.6 PDP Context Activation/Deactivation10.6 PDP Context Activation/Deactivation

10.7 Packet Transfer Functions10.7 Packet Transfer Functions



The Packet Data Protocol (PDP) ContextThe Packet Data Protocol (PDP) Context

• A contract set up with the GPRS network toallow connection to external PDNs

• Requires allocation of IP Address:

• Static allocation

• Dynamic allocation

• This contract (context) specifies:



• Protocol Type (IPv4 or IPv6)

• IP Address assigned to the MS• QoS level requested

• GGSN access point identity



Access Point Names (APNs)Access Point Names (APNs)

• Identifies external PDN access point at the GGSN

• 3 APN selection modes:

• Requested by MS at PDP activation (APN(R))

• Supplied by SGSN at PDP activation (default APN(SGSN))

• Extracted from subscriber profile at HLR (APN(S))



Extracted from subscriber profile at HLR (APN(S))

• Invalid APN will reject PDP activation at the GGSN• APN format in two parts:

• {network identifier}.{operator identifier}





Network Requested PDP Context ActivationNetwork Requested PDP Context Activation

ProcessProcess

SGSNSGSN

MSMS

GGSGGS

NN

GPRS CoreGPRS CoreNetworkNetworkBSSBSS

PDP Notification RequestPDP Notification Request

PDP PDUPDP PDU



Request PDP Context ActivationRequest PDP Context Activation

PDP Context Activation ProcedurePDP Context Activation Procedure

PDP Notification ResponsePDP Notification Response

PDP Context Modification ProcessPDP Context Modification Process

SGSNSGSN

MSMS

GGSGGS

NN


Update PDP Context RequestUpdate PDP Context Request



Modify PDP Context RequestModify PDP Context Request

Update PDP Context ResponseUpdate PDP Context Response

Modify PDP Context AcceptModify PDP Context Accept

• Connection at TE-MT (R reference point)

broken

• Radio connection lost

Valid PDP Context Deactivation CasesValid PDP Context Deactivation Cases



• TE deactivates last remaining PDP context

• MS initiates a deactivation procedure

SGSNSGSN

MSMS

GGSGGS

NN

GPRS CoreGPRS CoreNetworkNetwork

Deactivate PDP Context RequestDeactivate PDP Context Request

BSSBSS

MS PDP Context Deactivation ProcessMS PDP Context Deactivation Process



GTP Delete PDP Context RequestGTP Delete PDP Context Request

GTP Delete PDP Context ResponseGTP Delete PDP Context Response

Deactivate PDP Context AcceptDeactivate PDP Context Accept

SGSNSGSN

MSMS

GGSGGS

NN




SGSN PDP Context Deactivation ProcessSGSN PDP Context Deactivation Process




pp


SGSNSGSN

MSMS

GGSGGS

NN

GPRS CoreGPRS CoreNetworkNetwork


BSSBSS


GGSN PDP Context Deactivation ProcessGGSN PDP Context Deactivation Process






• Downlink:• Ready - packet download possible

• Standby - Paging required• Idle - no data transfer possible

• Uplink:

Effect of MM States on Packet Transfer Effect of MM States on Packet Transfer



Uplink:• Ready - packet upload possible

• Standby - PDP context must be established

• Idle - GPRS Attach required








SGSNSGSN

MSMS

GGSGGS

NN

BSSBSS

GGbb GGnnUUmm

TCP/UDPTCP/UDP

IPIP



BSSGPBSSGP

RLCPRLCP

SNDCPSNDCP

MACPMACP

Frame RelayFrame Relay



Packet Transfer Over the Gb InterfacePacket Transfer Over the Gb Interface

BSSBSS

SGSNSGSNFRFRSwitchSwitch

FRFR

SwitchSwitch

FRFR

SwitchSwitch

BSSBSS

1919

2323

1111

3232

77

3838

22

7777



BSSBSS

FRFR

SwitchSwitch

FRFR

SwitchSwitch

77

6767

4444

8585

4444 = Data Link Circuit Identifier (DLCI)= Data Link Circuit Identifier (DLCI)






• PDP Contexts

• Context States

• Addressing

• Activation / Deactivation

• Effects of MM States on Packet Transfer

• Access Point Names (APNs)

• Packet Transfer Functions



• Packet Transfer Functions

BSSBSS

SGSG

SNSNFR SwitchFR Switch

BSSBSS

FR SwitchFR Switch

FR SwitchFR Switch

FR SwitchFR Switch

BSSBSS

FR SwitchFR Switch

1919

2323

1111

3232

77

6767

4444

3838

22

8585

7777


Day 1D

ay 1





5 GPRS Ai I t f5 GPRS Ai I t f

Day 2D

ay 2





12 I t ti ith GSM S i12 I t ti ith GSM S i










Section 11 - GPRS Operational IssuesSection 11 - GPRS Operational Issues

11.2 Bearer Services11.2 Bearer Services

11.3 Quality of Service (QoS)11.3 Quality of Service (QoS)

11 4 GPRS Security11 4 GPRS Security




11.4 GPRS Security 11.4 GPRS Security

11.5 Billing 11.5 Billing



GPRS Quality of Service (QoS)GPRS Quality of Service (QoS)

• Why the need for QoS?

• Address customer requirements

• Dynamic resource allocation



• Customer confidence

GPRS Quality of Service (QoS)GPRS Quality of Service (QoS)

• Service Precedence (priority)

• Reliability

•

3 classes (GSM 02.60)• 5 classes (GSM 03.60)

• Delay

• 4 delay classes



•

Throughput• max and mean bit rates





QoS - ReliabilityQoS - Reliability

ReliabilityClass

GTP Mode LLC Frame Mode LLC Data RLC Block Mode Traffic Type

1 Acknowledged Acknowledged Protected Acknowledged

Non real-time traffic,error-sensitiveapplication that cannotcope with data loss.

2 Unacknowledged Acknowledged Protected Acknowledged

Non real-time traffic,error-sensitiveapplication that cancope with infrequentdata loss.

3 Unacknowledged Unacknowledged Protected Acknowledged

Non real-time traffic,error-sensitiveapplication that can

ith d t l



cope with data loss,GMM/SM, and SMS.

4 Unacknowledged Unacknowledged Protected Unacknowledged


5 Unacknowledged Unacknowledged Unprotected Unacknowledged




QoS - DelayQoS - Delay

Delay (maximum values)

SDU size : 128 octets SDU size : 1024 octets

Delay Class

MeanTransfer

Delay (sec)

95 percentileDelay (sec)

Mean Transfer Delay (sec)

95 percentileDelay (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



QoS – Peak ThroughputQoS – Peak Throughput

Peak Throughput Classes Peak Throughput (octets/sec)

1 Up to 1000 (8kbps)

2 Up to 2000 (16kbps)

3 Up to 4000 (32kbps)

4 Up to 8000 (64kbps)

5 Up to 16000 (128kbps)

6 Up to 32000 (256kbps)



7 Up to 64000 (512kbps)

8 Up to 128000 (1024kbps)

9 Up to 256000 (2048kbps)



Purposes of GSM Security include:

• Protecting of user identity confidentiality

• Use of temporary identities (TMSI)

• Protection against unauthorised access

• Authentication & service request validation

• Pro ision of data confidentialit

Purposes of GPRS SecurityPurposes of GPRS Security



• Provision of data confidentiality

• Encryption (Ciphering)

• Provision of network signalling confidentiality

Protecting User ID ConfidentialityProtecting User ID Confidentiality

• Benefits of user ID confidentiality include:

• Ensures IMSI is not disclosed without authorisation

• Prevents location tracking using air interface data

• Prevents user ID from being extracted from signallinginformation



• Implemented using replacement Temporary MobileSubscriber Identity (P-TMSI)

AuthenticationAuthentication

• Benefits of authentication include:

• Prevents unauthorised network access

• Prevents illegal impersonation of legitimate subscribers

• Implemented by using an authentication procedure.

• Procedure triggered by:

A h i b ib fil d t t th SGSN



• A change in subscriber profile data at the SGSN

• Accessing a service

• First network access after SGSN restart

• Cipher key sequence number mismatch

BSSBSS

The GPRS Authentication ProcessThe GPRS Authentication Process

[IMSI][IMSI]

Authentication & ciphering RequestAuthentication & ciphering Request

Send Authentication infoSend Authentication info

MSMS SGSNSGSN AuCAuC

Send Authentication info AckSend Authentication info Ack

IMSI, Triplets (RAND,SRES,Ki)IMSI, Triplets (RAND,SRES,Ki)

A th ti ti & i h i RA th ti ti & i h i R

[RAND][RAND]A3 A3

KiKi KiKiRANDRAND

SRESSRES SRESSRES

MSMS SGSNSGSN



Authentication & ciphering ResponseAuthentication & ciphering Response

[SRES][SRES]==

User Data EncryptionUser Data Encryption

• Benefits of user data encryption include:

• Provides confidentiality for user data across air interface

•Selection from seven encryption algorithms

• Capability is mandatory for MS and network

• Implementation is optional

• Does not provide for end-to-end encryption



Does not provide for end-to-end encryption

The GPRS Encryption ProcessThe GPRS Encryption Process

A8 A8

KiKi KiKiRANDRAND

KcKc KcKc

MSMS SGSNSGSN

DataDataDataData



A5 A5

Kc + DataKc + Data

Signalling Data EncryptionSignalling Data Encryption

• Signalling data encryption provides confidentiality for user identities across air interface

• Applied to selected fields of signalling messages

including:• International Mobile Equipment Identity (IMEI)

• International Mobile Subscriber Identity (IMSI)

• Calling subscriber directory number (mobile terminating calls)

• Called subscriber directory number (mobile originated calls)



Called subscriber directory number (mobile originated calls)

• These fields are not protected on initial connection

• Does not provide for end-to-end encryption

Charging for GPRS ServicesCharging for GPRS Services

• GSNs collects GPRS-related billing datasuch as:

• destination and source address

• usage of radio interface

• usage of external PDNs

• usage of PDP addresses

• usage of general GPRS resources

Internet

£

£



• location of mobile station• volume of packet traffic

££

£

Charging for GPRS ServicesCharging for GPRS Services

• GPRS allows the user to be ‘always connected’

• Some possible methods of charging are:

• By volume of data transferred

•Flat rate for Internet access

• Time spent on-line

• By Transaction

• For content - operator may provide ownpages (value added services)

• These charging methods can be modified by:

Internet

£

£



g g y

• Enhanced quality of service

• Enhanced security

££

£

UK GPRS Service Provider TariffsUK GPRS Service Provider Tariffs

• Vodafone UK:• GPRS: No monthly access charge. 2p for every 1KB sent or received.

• GPRS 1: £7.49 monthly access charge including 1MB of information.

0.5p for every additional 1KB sent or received.

• BT Cellnet:

• Pay As You Use: £3.99 monthly access charge. 2p for every 1KB sentor received.



• Value Bundle: £7.99 monthly access charge including 1MB of information. 0.39p for every additional 1KB sent or received.


• Subscriber Services

• PTP, PTM

• Quality of Service

• Precedence, Reliability, Delay, Throughput,

• Security

• Authentication, Encryption, User ID Confidentiality

• BillingKiKi KiKiRANDRAND

MSMS SGSNSGSN



• Parameters, Methods, Existing Tariffs.A8 A8

KiKi KiKiRANDRAND

KcKc KcKc

A5 A5

DataDataDataData

Kc + DataKc + Data


Day 1D

ay 1


2. Mobile Data Evolution2. Mobile Data Evolution3. GPRS Overview3. GPRS Overview



Day 2D

ay 2


9. Radio Resource Management9. Radio Resource Management10. Packet Routing and Transfer 10. Packet Routing and Transfer










12.2 Interactions Between SGSN and MSC/VLR 12.2 Interactions Between SGSN and MSC/VLR

12.4 Combined IMSI/GPRS Attach/Detach12.4 Combined IMSI/GPRS Attach/Detach

12.3 Network Operating Systems12.3 Network Operating Systems

Section 12 - Interaction With GSM ServicesSection 12 - Interaction With GSM Services




12.5 Combined Location Updating 12.5 Combined Location Updating

12.6 Paging Coordination12.6 Paging Coordination

SGSN-MSC/VLR Supported FunctionsSGSN-MSC/VLR Supported Functions

•Combined IMSI/GPRS attach

•Coordinated / combined RA / LA updating

•Coordinated paging for CS/GPRS connections

• Alert procedures for non-GPRS services.



•Identification procedure

•MM Information procedure

Network Operating Mode INetwork Operating Mode I

BSS

MSC/

VLR

SGSN

Gs

• Combined LA/RA Update

• Combined paging

• Longer MS sleep periods

• Smaller Paging Load (MSonly paged in RA)

A

Gb





Network Operating Modes II & IIINetwork Operating Modes II & III

BSC

MSC/

VLR

SGSN

• Separate LA and RA updates

• Two types of paging channels to bemonitored

• MS paged in LA

• Mode II - PPCH not available in cell

• Mode III - PPCH available in cell

Gb

A



Combined IMSI/GPRS Attach ProcedureCombined IMSI/GPRS Attach Procedure

oldoldMSC/VLRMSC/VLR

HLRHLROld SGSNOld SGSNNew SGSNNew SGSNMSMS

Attach RequestAttach Request

Identification RequestIdentification Request

Identification ResponseIdentification Response








ID RequestID Request

newnewMSC/VLRMSC/VLR

ID ResponseID Response

Update LocationUpdate LocationCancel LocationCancel Location

SECURITY FUNCTIONS




Insert Sub’ DataInsert Sub’ Data

Insert Sub Data AckInsert Sub Data Ack

Update Location AckUpdate Location AckLocation Update AcceptLocation Update Accept

Attach AcceptAttach Accept

Attach CompleteAttach Complete

TMSI Reallocation CompleteTMSI Reallocation Complete

MSC/VLRMSC/VLRGGSNGGSNSGSNSGSNBSSBSSMSMS




IMSI Detach IndicationIMSI Detach Indication

GPRS Detach IndicationGPRS Detach Indication

Combined IMSI/GPRS Detach ProcedureCombined IMSI/GPRS Detach Procedure




Combined Intra-SGSN RA/LA UpdateCombined Intra-SGSN RA/LA Update

oldold

MSC/VLRMSC/VLRHLRHLRSGSNSGSNMSMS

RA Update RequestRA Update Request

newnew

MSC/VLRMSC/VLR




Insert Sub’ DataInsert Sub’ Data

Insert Sub’ Data AckInsert Sub’ Data Ack


Location Update AcceptLocation Update Accept

SECURITY FUNCTIONS




RA Update AcceptRA Update Accept

RA Update CompleteRA Update Complete

TMSI Reallocation CompleteTMSI Reallocation Complete



Network Modes - Paging CoordinationNetwork Modes - Paging Coordination

• Operating Mode I:

• CS paging takes place on GPRS paging or traffic channel(PCCCH or PPCH)

• MS only monitors one paging channel

• Operating Mode II:• GPRS and CS paging takes place on CS paging channel (CCCH)

• MS only monitors one paging channel

• Operating Mode III:

• CS paging uses the CS paging channel (CCCH)

GPRS ith CCCH PCCCH



• GPRS uses either CCCH or PCCCH• MS must monitor both paging channels

Network Modes - Paging CoordinationNetwork Modes - Paging Coordination

Mode GSM Paging Channel GPRS Paging Channel Paging Coord?

I Packet Paging Channel Packet Paging Channel

CS Paging Channel CS Paging Channel Yes

Packet Data Channel not applicable

I I CS Paging Channel CS Paging Channel No

I I I CS Paging Channel Packet Paging Channel No

CS P i Ch l CS P i Ch l



CS Paging Channel CS Paging Channel


• Interactions Between SGSN and MSC/VLR

• The Gs Interface

• Network Operating Modes

• Combined IMSI/GPRS Attach / Detach Procedures

• Combined GSM/GPRS Location Updating

• GSM/GPRS Paging CoordinationMSC/

VLRA



BSS

VLR

SGSN

Gs

A

Gb


Day 1D

ay 1






6 Protocols Overview6 Protocols Overview

Day 2D

ay 2






13 GPRS Internetworking13 GPRS Internetworking








Section 13 - GPRS InternetworkingSection 13 - GPRS Internetworking

13.2 The Interworking Interfaces13.2 The Interworking Interfaces

13.3 The Gi Interface IP Connection13.3 The Gi Interface IP Connection

13.4 The Gi Interface X.25 Connection13.4 The Gi Interface X.25 Connection




13.5 The Inter-PLMN Gp Interface13.5 The Inter-PLMN Gp Interface

GPRS Interworking InterfacesGPRS Interworking Interfaces

PUBLIC PACKET DATA NETWORKPUBLIC PACKET DATA NETWORK

INTER-PLMN BACKBONEINTER-PLMN BACKBONE

GGSN BG BG GGSN

Gp Interface

Gi InterfaceGi Interface



SGSN SGSN

GPRS Core

Network

SGSN SGSN

GPRS Core

Network

InternetInternet

X.25X.25

GPRS-PDN (GGPRS-PDN (Gii) Interface) Interface

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25


RelayRelay

RelayRelay

UDP/TCPUDP/TCP

GTPGTP

L2L2

IP/X.25IP/X.25

RelayRelay L3L3

L2L2

LLCLLC

SNDCPSNDCP

UDP/TCPUDP/TCP

GTPGTP

GPRS CoreGPRS Core

NetworkNetworkGGSN

BSC/PCU

BSC/PCU

SGSN

UUmm GGbb GGnn GGii



GSM RFGSM RF

MACMAC

RLCRLCRelayRelay


L1L1

L2L2

IPIPL2L2

L1L1 L1L1

L2L2

GSM RFGSM RF

MACMAC

RLCRLC

L1bisL1bis


BSSGPBSSGP

L1L1

L2L2

IPIP


BSSGPBSSGP

L1bisL1bis

GGii Interface IP ConnectionInterface IP Connection

GPRS

NETWORK

GGii

IP

NETWORK(S)TE

PLMN

TE

IPv4 or IPv6IPv4 or IPv6

AddressingAddressing



IPv4 or IPv6IPv4 or IPv6

AddressingAddressing

GGSNGGSN


SGSNSGSN

DNSDNS

MobileMobileOperator Operator

IPIPNetworkNetwork

GPRSGPRS

BackboneBackbone

DHCPDHCP

FirewallFirewallLANLAN

GGnn GGnn

GGii



InternetInternet

HostHost


GGSNGGSN

L2L2

L1L1

GGii

GPRSGPRS

Bearer Bearer

Router Router

IP NetworkIP Network

Router Router

L2L2

L1L1

IPIP IPIP IPIP IPIP



GGii Interface X.25 ConnectionInterface X.25 Connection

GPRS

NETWORK

GGii

PSPDN

DCE

TEDTE

PLMN TE

X.121 AddressingX.121 Addressing

X.121 AddressingX.121 Addressing



GGii Interface X.25 ConnectionInterface X.25 Connection

GGSNGGSN

LAPBLAPB

L1L1

GGii

GPRSGPRS

Bearer Bearer

X.25X.25

RelayRelay

LAPBLAPB

L1L1

X.25X.25 X.75X.75

PSDNPSDN

RelayRelay



Inter-PLMN Working Over the GInter-PLMN Working Over the Gpp InterfaceInterface

SGSN

PUBLIC/PRIVATE DATAPUBLIC/PRIVATE DATA

CONNECTIONCONNECTION

GGSN BG

GPRS Core

Network 1

SGSN SGSN

BG GGSN

GPRS Core

Network 2

Gp Interface

SGSN



SGSN SGSN SGSNSGSN

Inter-PLMN Roaming IssuesInter-PLMN Roaming Issues

Addressing

Inter-PLMN Link Establishment

QoS Implementation

Security

Routing Protocol Agreement

Charging Agreements



Charging Agreements




Day 1D

ay 1







Day 2D

ay 2









7. GPRS Protocols7. GPRS Protocolsgg



14.2 Coverage14.2 Coverage

14.3 Capacity 14.3 Capacity

14.4 C/I Interference14.4 C/I Interference

14 5 Effect on QoS14 5 Effect on QoS

Section 14

GPRS Network Planning Considerations




14.5 Effect on QoS 14.5 Effect on QoS

• Coverage

• Capacity

• C/I Interference

• QoS Implementation

Some GPRS Radio Planning IssuesSome GPRS Radio Planning Issues



CoverageCoverage

• Current GSM networks designed primarily for voice/CSdata.

• GPRS coverage may differ from that of GSM

• Coding scheme used is radio path quality dependant

GSMCS1

CS2

CS3CS4



GSM only cell Enabling

GPRS

GSM

coverage

CapacityCapacity

• Most existing GSM900 networks are capacityrestricted now

• Difficult to add new services due to restricted capacity

• GSM1800 networks have most to offer

• Smaller cell sizes

• Typically higher capacity availability



C/I InterferenceC/I Interference

• GPRS data throughput is coding scheme dependant

• Coding scheme used relates to C/I levels

• Lower C/I

• Packet loss, retransmissions

• Higher C/I

• Increase of throughput

• C/I improvements can be achieved by:

• Minimising cell overlap by optimising the network



• Cell splitting

Impact of GPRS on GSM Network QualityImpact of GPRS on GSM Network Quality

• Increase in Blocked Call Rate

• Increase in Dropped Call Rate

• Avoiding impact on speech channels:

• No dedicated GPRS resources

• GPRS upgrade only if there are enough idle speechchannels (2-3 TS)

• GPRS downgrade if the load on speech channels increases(number of idle speech channels kept at the level of 1-2 TS)




• GPRS deployment requires reconsideration of the cell planningand frequency planning strategies

• The analysis of the network should include both circuit switched& packet switched traffic

• Throughput relates to C/I

• Lower C/I = Packet loss, retransmissions, delays

• Higher C/I = Increased throughput

• C/I improvements can be achieved by

• Minimising cell overlap by optimising the network



• Cell splitting

GSM only cell Enabling

GPRSGSM

coverage

CS

CS2

CS3CS4

Day 1D

ay 1






6. Protocols Overview6. Protocols Overview7 GPRS Protocols7 GPRS Protocols

Course SummaryCourse Summary

Day 2D

ay 2






13. GPRS Internetworking13. GPRS Internetworking14 GPRS Network Planning14 GPRS Network Planning



7. GPRS Protocols7. GPRS Protocols 14. GPRS Network Planning14. GPRS Network Planning


Date post:	03-Apr-2018
Category:	Documents
Upload:	nguyen-ngoc-dang-khai
View:	218 times
Download:	0 times

GPRS for Eng

Documents