Keshav GPRS

8/8/2019 Keshav GPRS

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General Packet Radio ServiceGeneral Packet Radio Service

(GPRS)(GPRS)

A new Dimension to WirelessA new Dimension to Wireless

CommunicationCommunication


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Contents of PresentationContents of Presentation

GPRS and its Features GPRS Network Architecture

GPRS Protocol Architecture

GPRS Backbone Network

GPRS interworking with External Network Call routing in GPRS

Session Management in GPRS

Location Management in GPRS Mobility Management in GPRS

Logical Channels of GPRS

GPRS Applications


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Constraints with existingConstraints with existing

networknetwork

Data Rates too slow about 9.6 kbps

Connection setup time too long Inefficient resource utilization for bursty

traffic

Proves expensive for bursty traffic

utilization No efficient method for packet transfers


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Comparison of GSM &Comparison of GSM &

GPRSGPRSGSM GPRS

Data Rates 9.6 Kbps 14.4 to 115.2

Kbps

ModulationTechnique GMSK GMSK

Billing Duration of

connection

Amount of

data

transferredType of

Connection

Circuit Switched

Technology

Packet -

Switched

Technology


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GPRS in INDIAGPRS in INDIA

BPL Mobile

Bharti Cellular

Hutchison MaxHutchison Essar

Idea Cellular


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What is GPRS ?What is GPRS ?

General Packet Radio Service (GPRS) is a

new bearer service for GSM that greatly

improves and simplifies wireless access to

packet data networks

GPRS applies packet radio principal to

transfer user data packets in an efficient way

b/w MS & external packet data network


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Benefits of GPRSBenefits of GPRS New Data Services

High Speed (Data Rate 14.4 115 kbps)

Efficient use of radio bandwith (Statistical

Multiplexing)

Circuit switching & Packet Switching can be

used in parallel Constant connectivity


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Statistical MultiplexingStatistical Multiplexing


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Salient Features of GPRSSalient Features of GPRS

Important step on the path to 3G

Standardized by ETSI

GPRS is an overlay network over the GSM

Provides Data Packet delivery service Support for leading internet communication

protocols

Billing based on volume of data transferred

Utilizes existing GSM authentication andprivacy procedures.


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High Data RateHigh Data Rate

GPRS uses radio channel i.e. 200 kHz wide

Radio channel carries digital data stream of271 kbps

This rate is divided into 8 time slots eachcarrying 34 kbps per time slot

Data rate 14 kbps per time slot achieved after

corrections GPRS can combine upto 8 time slots giving

data rate of 114 kbps


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GPRS ServicesGPRS Services

Offers end-to-end packet switched data transfer

Bearer Services

PTP - Point-To-Point service (CLNS mode)

PTM - Point-To-Multipoint service(CONS Mode) PTM-M Multicast service

PTM-G Group call service

Supplementary Services

SMSShort Message Service

CFU Call Forwarding Unconditional


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GPRS Services (Contd.)GPRS Services (Contd.)

CFNRc Call Forwarding on mobile subscriber

not reachable

CUG Closed User Group

Tele action, access to data bases

Quality of Service

GPRS allows defining QoS profiles

Service precedence, reliability,delay,throughput


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GPRS TerminalsGPRS Terminals

Class A

MS supports simultaneous operation ofGPRS and GSM services

Class B

MS able to register with the n/w for bothGPRS & GSM services simultaneously.It can only use one of the two servicesat a given time.

Class C

- MS can attach for either GPRS or GSMservices


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GPRS Network ElementsGPRS Network Elements

GPRS Architecture is same as GSM except fewhardware modifications.

Two new nodes introduced for packet data Serving GPRS Support Node (SGSN)

handles all packet data for the appropriate geographicarea

monitors GPRS users

handles security and access control

may be regarded as the packet switched equivalent ofthe circuit-switched MSC

Gateway GPRS Support Node (GGSN) internetworking functionality

routes incoming data to correct SGSN

translates between different protocols and formats

Details of data services added to HLR


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Architecture of a GSMArchitecture of a GSM

NetworkNetwork

SD

Mo

ie Statio

BTS

MS /

VLR

SIMME

BS

Base Station

Subsystem

GMS

Network Subsystem

AUEIR HLR

Other Networks

Note: Inter es have been omitted forclarity purposes.

+

PSTN

PLMN

Internet


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Integrating GPRSIntegrating GPRS

SD

Mobie Station

BTS

MSC

BSC

Base Station

Subsystem

MSC

Network Subsystem

AUC

OtherNetworks

ote: Interfaces have been omitted for clarity purposes.

GGSNSGSN

SIM ME

+

PSTN

PLMN

Internet


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GPRS SYSTEM ARCHITECTURE

BSC

SGSN

MS

BTS

BTS

Other

GPRS

PLMN

GGSN

PDN

Gb

Gd

Gp

Gn

Gf

Gs

Gc

GGSN

EIRHLR+GPRS

Register

MSC LR

D

SMS-GMSCSMS-INMSC

Gi

Gr


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InterfacesInterfaces

Gb Connects BSC with SGSN

Gn SGSN SGSN/GGSN (in the samenetwork)

Gp SGSN GGSN (in different networks)

Gf For equipment querying at registeringtime

Gi Connects PLMN with external PacketData Networks (PDNs)

Gr To exchange User profile betweenHLR & SGSN

Gs To exchange Database betweenSGSN & MSC

Gd Interface between SMS & GPRS


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SGSNSGSN Serving GPRSServing GPRS

Support NodeSupport Node Delivers data packets to mobile stations &

vice-versa

Detect and Register new GPRS MS in its

serving area

Packet Routing, Transfer & MobilityManagement

Authentication, Maintaining user profiles

Its location register stores location info. &

user profiles


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GGSNGGSN Gateway GPRSGateway GPRS

Support NodeSupport Node Interfaces GPRS backbone network & externalpacket data networks

Converts the GPRS packets from SGSN to the

PDP format Converts PDP addresses change to GSM

addresses of the destination user

Stores the current SGSN address and profile of

the user in its location register

Performs authentication

Many-to- many relations among SGSNs & GGSNs


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GPRS RegisterGPRS Register

GPRS Register is integrated with GSM-HLR.

Maintains the GPRS subscriber data and

Routing information.

Stores current SGSN address


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GPRS Backbone NetworkGPRS Backbone Network

GSNs are connected through IP based backbone Two Backbones:

Intra PLMN backbone networks that connectsGSNs of the same PLMN & are private IPnetworks

Inter PLMN backbone networks that connectsGSNs of the different PLMN. Roaming agreementis necessary

GPRS Tunneling protocol (GTP)

PLMN- Inter PLMN interconnect are called Bordergateways (performs security functions to protectIntra- PLMN backbone against unauthorized usersand attacks).


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GPRS BACKBONE NETWORK

inter-PLMN

GPRS backbone

External Packet

Data Network (PDN)

intra-PLMN

GPRS backbone

intra-PLMN

GPRS backbone

PLMN1

PLMN2

SGSN

SGSNSGSN

GGSNGGSN

Border

gatewayBorder

gateway

Gp

Gn

Gi

Gn

Gn

BTS BTS

BSC

BSC

Host

Router LAN

MS

Gi

Gn

Gn

Gp


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Protocol StackProtocol Stack

GSM RF

SNDCP

IP / X.25

Application

Um GnGb

MAC

RLC

LLC

IP / X.25

GTP

L1

L2

LLC

GSM RF

Frame

RelayMAC

RLC BSSGP

L1bis

BSSGP

Frame

Relay

LLC

SNDCP GTP

L1bis L1

L2

IP

MS BSS (PCU) SGSN GGSN Gi

IP

UDP/

TCP

UDP/

TCP


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SNDCPSNDCP -- Sub Network DependentSub Network Dependent

Convergence ProtocolConvergence Protocol

Used to transfer data packets between SGSNand MS

Multiplexing of several connections ofnetwork layer onto one logical connection ofunderlying LLC layer

Compression and decompression of userdata and header information


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Data Link layerData Link layer Divided into two sub layers :

LLC layer (between MS-SGSN)

RLC/MAC (between MS-BSS)


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LLCLLC--Logical Link ControlLogical Link Control Establishes highly reliable logical link

between MS & its assigned SGSN

Works either in acknowledged or

unacknowledged modes

Data confidentiality is ensured by ciphering

functions


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RLC/MAC LayerRLC/MAC Layer Radio Link Control(RLC)

Establish a reliable link between MS & BSS Segmentation and reassembly of LLC frames

into RLC data blocks

Medium Access Control(MAC) Controls access attempts of an MS on radio

channels shared by several MSs

Employs algos. for contention resolution,multiuser multiplexing on PDTCH

Both ack and unack. Modes of operation aresupported in RLC/MAC layer


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Physical LayerPhysical Layer

Divided into two sub layers :

Physical Link Layer (PLL)

Physical RF Layer (RFL)

PLL Provides a physical channel betweenMS and BSS

Channel coding, interleaving, detection

of physical link congestion

RFL - Operates below PLL


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BSSGPBSSGP--(BSS GPRS(BSS GPRS

Application Protocol)Application Protocol)

Delivers routing & Quality of Servicerelated information between BSS and

SGSN


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GTPGTP GPRS TunnelingGPRS Tunneling

ProtocolProtocol GTP tunnels user data packets and related

signaling information between GSNs

Signaling is used to create, modify and deletetunnels

Defined both at Gn and Gp interface

Below GTP, TCP or UDP are employed totransport the GTP Packets within backbone

network


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Inter working with IPInter working with IP

networksnetworks GPRS n/w can be interconnected with an IP-

based packet data network

GPRS supports both IPv4 and IPv6 GPRS n/w looks like IP sub network and

GGSN looks like a IP router

DHCP, DNS servers are installed


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GPRSGPRS Internet ConnectionInternet Connection


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CALL ROUTINGCALL ROUTING

DATA CALL ORGINATING

DATA CALL TERMINATING


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DATA CALL ROUTING

inter-PLMN

GPRS backbone

External Packet

data network(PDN)

Intra-PLMN

GPRS backbone

intra-PLMN

GPRS backbone

PLMN1

PLMN2

SGSN

SGSNSGSN

GGSNGGSN

Border

gatewayBorder

gateway

Gp

Gn

Gi

Gn

Gn

BTS BTS

BSCBSC

Host

Router LAN

MS


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SESSION MANAGEMENT INSESSION MANAGEMENT INGPRSGPRS


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Attachment & DetachmentAttachment & Detachment

ProcedureProcedure

GPRS attach- User is registered in SGSN, after authentication

check from HLR

- SGSN assigns P-TMSI to MS

GPRS detach- Disconnection of MS from GPRS network is called

GPRS detach- It can be initiated by MS or by network(SGSN or

HLR)


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Session ManagementSession Management

Mobile Station applies for PDP address

For each session PDP context is created & itcontains

PDP type

PDP addressed assigned to MS

Address of GGSN that servers access pointto PDN

With active PDP context MS able to send or

receive data packetsAllocation of PDP address can be static or

dynamic


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PDP Context ActivationPDP Context Activation


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LOCATION MANAGEMENTLOCATION MANAGEMENT

IN GPRSIN GPRS


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State Model of GPRS MSState Model of GPRS MS


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Location ManagementLocation Management

Mobile station can be in 1 of the 3 statesdepending on traffic amount

Idle : MS is not using GPRS service

Ready : Performing GPRS Attach,

MS gets into READY State

Standby : When MS does not send anypackets for longer period of time,

Ready timer Expires


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Routing Area UpdateRouting Area Update

GSM Location Area(LA) is divided into

several Routing Areas(RA)

RA consists of several cells

SGSN is informed when MS moves to a newRA

MS sends a Routing Area Update Request

to its assigned SGSN


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Types of Routing AreaTypes of Routing Area

UpdateUpdate

Intra SGSN Routing Area Update

Inter SGSN Routing Area Update


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Routing Area UpdateRouting Area Update


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Mobility ManagementMobility ManagementConsists of two levels:

Micro mobility management :

- Tracks the current RA or cell of MS

- It is performed by SGSN

Macro mobility management :

- Keep tracks of MSs current SGSN

- Stores it in HLR, VLR, and GGSN


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Channels in GPRSChannels in GPRS

Logical ChannelTraffic Channels

Signaling Channels (Control Channels)

Physical Channels


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Logical ChannelsLogical Channels


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Packet Data Channel(PDCH)Packet Data Channel(PDCH)

Physical Channel for GPRS Traffic

PDCH are taken from all channels available

in the cell Depending on current traffic load and priority

of service, the physical channel are allocatedto either GPRS or GSM services.

Physical channels not currently used by GSMcan be allocated as PDCH to increase theQOS for GPRS

M ltif St t fM ltif St t f


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Multiframe Structure ofMultiframe Structure of

PDCHPDCH

Four consecutive TDMA frame formsone block - B0 B11TwoTDMA frames for transmissionof PTCCH - T

Two Idle frames - X


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BillingBilling

GGSN

MSC

PSTN

BSC

SGSNGPRS

Network

Charging Gateway

Mediation

MSC

Billing


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Applications of GPRSApplications of GPRS

Web browsing

Corporate & Internet Email

Vehicle Positioning

Remote LAN Access

Home Automation

Document Sharing/Collaborative

working


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THANKTHANK YOUYOU

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Keshav GPRS