Friday, March 4, 2011

General Packet Radio Service (GPRS) .........Boon to the world .

GPRS-  General packet radio services .


It is a packet oriented mobile data service on the 2G and the 3G cellular communications .
Standardized by European Telecommunication Standard Institute (ET SI) and now maintained by 3GPP Third Generation Partnership Project.
It is a best effort service where quality of service (Qos) is not guaranteed during the connection.In 2G system data rates are 56kbits/sec -114 kbits/sec.It uses Time division multiple access technique (TDMA) where same frequency is used by different users at different time slots .


Services Offered by GPRS

1.Internet access
2.Multimedia messaging (MMS)
3.Push to Talk (PTT/POC)
4.Instant Messaging
5.Internet applications through the Wireless access protocols (WAP)
6.Point to point inter networking with the Internet


Protocols supported by GPRS


Internet protocols - IPV4, IPV6
Point to point  protocol is used to tunnel the IP  to the phone 
X.25 connections 


Hardware devices supporting the GPRS are divide into three classes  


Class A- These devices support the GSM and GPRS at the same time and both services can be used simultaneously.


Class B-These devices support the GSM and GPRS at the same time but we can use one service at a time .


Class C-These devices either support GSM or GPRS and are switched manually between each other.


 Addressing in  GPRS


A GPRS service is established by reference to its Access point name (APN).Access point name defines the GPRS services.


GPRS tunneling protocol defines the IP protocol of the GPRS core network.Allows the end users of a GSM or WCDMA network to move from one place to the other with continuing to the Internet.It does this process by carrying the subscribers data from the Serving gprs support network node  (SGSN) to the Gateway gprs support network node ( GGSN)


Three types of GPRS tunneling protocols are used by the GPRS.


1.GTP-U transfers the users data .
2.GTP-C is used for the control reasons . 
3.GTP' is used for transfer of the changing  data from the GNSs to the charging function.


Coding schemes used in the GPRS .


Convolution coding scheme is used in the GPRS technology .In the convolution coding scheme each  m bit information  is  converted into  the n bit symbol.


m/n is the code rate 
n should be greater than equal to m
and the transformation is the function of the last k information symbol.




The network nodes SGSN and GGSN we will discuss in the upcoming blogs .


Refrence-Wireless Communications by Wiley.
                  http://www.ericsson.com/

Thank you .









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