GPRS_AMA

General Packet Radio Service

(GPRS)

A new Dimension to Wireless Communication

all rights reserved A.M.A group Ahmed Mohamed Attia

Constraints with existing networkData 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


Comparison of GSM & GPRSTechnology GSM GPRSData Rates 9.6 Kbps 14.4 to

115.2 KbpsModulation Technique GMSK GMSK

Billing Duration of connection

Amount of data

transferred Type of

ConnectionCircuit – Switched

Technology

Packet - Switched

Technologyall rights reserved A.M.A group Ahmed Mohamed Attia

What is GPRS ?General Packet Radio Service (GPRS) is a packet based communication service for GSM that allows data to be sent and received across a mobile telephone network. GPRS is a step towards 3G and is often referred to as 2.5G.

Used to transfer user data packets in an efficient way between MS & external packet data network.


Benefits of GPRSNew Data ServicesHigh Speed (Data Rate 14.4 – 115 kbps)

Efficient use of radio bandwidth (Statistical Multiplexing)

Circuit switching & Packet Switching can be used in parallel

Constant connectivity (there is no need to dial up)


Statistical Multiplexing


•New and better applications(due to its high speed connection and always on connectivity GPRS enables full internet applications and services.

High Data RateGPRS uses radio channel i.e. 200 kHz wide.

Radio channel carries digital data stream of 271 kbps.

This rate is divided into 8 time slots each carrying

(271/8) = 34 kbps per time slot.Data rate 14.4 kbps per time slot achieved after corrections.

GPRS can combine up to 8 time slots giving data rate of (8*14.4)114 kbps.


GPRS ServicesBearer Services

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

• PTM - Point-To-Multipoint service(CONS Mode)

Supplementary Services• SMS Short Message Service


• CFU Call Forwarding Unconditional

• CFNRc Call Forwarding on mobile subscriber not reachable

Quality of Service• GPRS allows defining QoS profiles

- The ETSI (European Telecommunications Standard Institute) has defined 4 new coding schemes for Radio Interface.

- When the GPRS device talks to the base station they can use 1 of the 4 schemes.


- where CS – 1 is the same as standard GSM In simple terms CS – 1 is highly redundant

- CS-2 and CS-3 have less redundancy, whilst CS-4 has the least

-If radio quality is bad then coding scheme CS-1 is used, as the quality improves less error control is needed.

• Service precedence, reliability, delay, throughput


GPRS Handset ClassesClass AMS supports simultaneous operation of

GPRS and GSM servicesClass A terminals have 2 transceivers

which allow them to send / receive data and voice at the same time. This class of device takes full advantage of GPRS and GSM. You can be taking a call and receiving data all at the same time.


Class BMS can only use one of the two services at

a given time.Class B devices can send / receive data or

voice but not both at the same time. Generally if you are using GPRS and you receive a voice call you will get an option to answer the call or carry on.

Class CMS can attach for either GPRS or GSM

services


GPRS Network ElementsGPRS Architecture is same as GSM

except few hardware modifications : GPRS includes GSNs

SGSN : Serving GPRS Support Node

GGSN : Gateway GPRS Support Node

GPRS Register




Other GPRS PLMN

PDN

Other PLMN

or PSTN

IP Network



GPRS BACKBONE NETWORK

inter-PLMNsGPRS backbone

External Packet Data Network (PDN)

intra-PLMN2GPRS backbone

intra-PLMN1GPRS backbone

PLMN1

PLMN2

HostRouter

LAN

Functionally connected with BSC, physically can be at MSC or BSC site

One for few BSCs One SGSN can support BSCs of several

MSC sites

Main functions• Authenticates GPRS mobiles• Handles mobile’s registration in GPRS

network• Handles mobile’s mobility management • Collect charging information of air

interface usage

SGSN – Serving GPRS Support Node


• Delivers data packets to mobile stations & vice-versa .SGSN provides a similar role for the packet switched network as the

MSC/VLR provides to the circuit switched network• Detect and Register new GPRS MS in its serving area• Packet Routing, Transfer & Mobility Management• Authentication, Maintaining user profiles• Its location register stores location info.

& user profiles


Typically located at one of the MSC sitesOne (or few) per operatorMain functions:

• Interface to external data networks• Resembles to a data network router• Forwards end user data to right SGSN• Routes mobile originated packets to right

destination• Filters end user traffic• Collects charging information for data network

usage• Data packets are not sent to MS unless the user

has activated the PDP address

GGSN – Gateway GPRS Support Node


• Interfaces GPRS backbone network & external packet data networks. Converts the GPRS packets from SGSN to the PDP format

When packets arrive for the MS from an external network it is the GGSN which will receive them and route them to the correct SGSN for the final delivery to the MS

The GGSN does not need to know the location of the MS, only the address of the SGSN which is serving the MS

• Stores the current SGSN address and profile of the user in its location register. Performs authentication

Packets are routed across the GPRS IP-based packet network between the SGSN and GGSN using the GPRS tunneling protocol (GTP)


BG (Border Gateway)-Routes packets from SGSN/GGSN of one

operator to a SGSN/GGSN of an other operator-Provides protection against intruders from

external networksDNS (Domain Name Server) -Translates addresses from ggsn1.oper1.fi -

format to 123.45.67.89 format (i.e. as used in Internet)

Charging Gateway-Collects charging information from SGSNs and

GGSNs


GPRS RegisterGPRS Register is integrated with

GSM-HLR.Maintains the GPRS subscriber data and Routing information.

Stores current SGSN address


GPRS Backbone Network Enables communication between GPRS Support

Nodes Based on private IP networkTwo Backbones: *Intra-PLMN backbone

• Connects GPRS Support Nodes of one operator

• Operator decides the network architectureLAN, point-to-point links, ATM, ISDN, ...

*Inter-PLMN backbone• Connects GPRS operators via BGs• Provides international GPRS roaming• Operators decide the backbone in the

roaming agreementall rights reserved A.M.A group Ahmed Mohamed Attia

Subscription of GPRS service• Subscription storage: HLR• Each subscribed configuration contains

PDP type (e.g., IP, X.25)PDP address (static(by operator), e.g. 128.200.192.64)Subscribed QoS (level 1…4)Dynamic address allowed (by the

corresponding GGSN)VPLMN address allowedGGSN address


Subscription is copied from HLR to SGSN during GPRS Attach

Possible PDP address allocation alternatives•Static address allocated from

HPLMN•Dynamic address allocated from

HPLMN•Dynamic address allocated from

VPLMN


Date post:	21-Jul-2016
Category:	Documents
Upload:	mohamedsalah
View:	215 times
Download:	0 times

GPRS_AMA

Documents