Chap 26 General Packet Radio Service

8/14/2019 Chap 26 General Packet Radio Service

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By:- Gaurav Kumar

ZEPHYR SYSTEM PVT. LTD

We hink and operate globally


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By:- Gaurav Kumar

General Packet Radio Service


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By:- Gaurav Kumar

Topics to be covered in this session :-

Need Of GPRSGPRS Architecture

GPRS Terminals

GPRS Protocol

Session Objective


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By:- Gaurav Kumar

GPRS

GPRS is a new bearer service for GSM

Packet Data Network (PDN) to the Internet.

Short comings of existing cellular data services :Data rates are too slow

Connection setup takes too long and complicatedService is too expensive for most users.


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By:- Gaurav Kumar

GPRS Benefit

GPRS improves the utilization of the radio resources

Offers volume-based billing

Higher data transfer rates (Data Rate 14.4 115 kbps)

Shorter access times

Simplifies the access to packet data networks

New Data Services

High Speed Efficient use of radio bandwidth

Circuit switching & Packet Switching can beused in parallel

Constant connectivity


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GSM vs GPRS

GSM GPRS

Data Rate 9.6 Kbps 14.4 to 115.2 Kbps

Modulation Techniques GMSK GMSK

Billing Duration ofconnection

Amount of data

transferred

Type of Connection CS technology PS

technology


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Need Of GPRS

GPRS Architecture

GPRS Terminals

GPRS Protocol



GPRSPLMN

GSM PLMN

HLR

MSC/VLR

MSC

SGSN

SGSN

GGSN

BSS

Same Radio

for Packet

and Circuit

TrafficCircuit

Packets

SS7

GGSN

X.25

IP

IntraPLMN IP

Backbone

BSC

GPRS System Architecture



GPRS Network Elements

GPRS includes GSNs

SGSN : Serving GPRS Support Node

GGSN : Gateway GPRS Support Node

GPRS Registers




SGSN Node serving multiple MS and BSS

Establishes mobility management context

Interfaces with HLR to perform security functions and

access control

GPRS PLMNBSS

BSS

SGSNBSS GGSN

HLR




GGSN Gateway to the IP Packet Data Network

Stores SGSN routing info for each GPRS user

Stores specific information on IP addresses

One PLMN may contain multiple GGSNs

GPRS PLMN

IP

PDN

BSS

BSS

SGSN

SGSN

GGSN



GPRS Terminals

Class A

MS supports simultaneous operation of GPRS and

GSM services

Class B

MS able to register with the n/w for both GPRS &

GSM services simultaneously. It can only use one

of the two services at a given time.

Class C

- MS can attach for either GPRS or GSM services



GPRS Speed & Profiles

Ex : 1) Class 10 is also known as 4+2, means 4 slots to download

and 2 slots to upload, but no more than 5 slots used at a time.

For applications where data is sent back-and-forth in roughly

equal amount, such as instant messaging.

2) Class 8 is also known as 4+1, means 4 slots to download

and 1 slot to upload

For applications where data is mostly downloaded,

such as web browsing.



Routing 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 new RA

MS sends a Routing Area Update Request to its assigned SGSN

Types of Routing Area Update

Intra SGSN Routing Area UpdateInter SGSN Routing Area Update




Need Of GPRS

GPRS Architecture

GPRS Terminals

GPRS Protocol Architecture



Protocol Architecture




Controls access attempts of an MS on radio channels shared by

several MSs

Employs algos. for contention resolution, multiusermultiplexing on PDTCH

Both ack and unack. Modes of operation are supported in

RLC/MAC layer

Medium Access 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

Establish a reliable link between MS & BSS

Segmentation and reassembly of LLC frames into RLC data blocks

Logical Link Control

Radio Link Control




Used to transfer data packets between SGSN and MS

Multiplexing of several connections of network layer onto one logical

connection of underlying LLC layer Compression and decompression of user data and header information

Data Link layer

Divided into two sub layers :

LLC layer (between MS-SGSN) RLC/MAC (between MS-BSS)

Sub Network Dependent Convergence Protocol




Delivers routing & Quality of Service related information between BSS

and SGSN

GPRS Tunneling Protocol

GTP tunnels user data packets and related signaling

information between GSNs

Signaling is used to create, modify and delete tunnels

Defined both at Gn and Gp interface Below GTP, TCP or UDP are employed to transport the GTP

Packets within backbone network

BSS GPRS-Tunneling Protocol



REVIEW

In this session we discussed about the:-

Need Of GPRS

GPRS Architecture

GPRS Terminals

GPRS Protocols


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Chap 26 General Packet Radio Service

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