What is GPRS

GPRS (General Packet Radio Service)

It is a non-voice service added to existing TDMA networks, It is an enhancement to GSM or TDMA (IS-95) network. It uses existing cellular network infrastructure with software upgrade at base stations and the addition of a GPRS Gateway that connects the GPRS network to the Internet.
TDMA is the underlying transport mechanism used by GSM networks.
GPRS provides the transmission of IP packets over existing cellular networks.

GPRS Architecture -

Components :-

1. SGSN (Serving GPRS Support Node) - It monitors the state of the mobile station and tracks its movements within a given geographical area. It is also responsible for establishing and managing the data connections between the mobile user and the destination network.
2. GGSN (Gateway GPRS Support node) - It provides the point of attachment between the GPRS domain and external data networks such as the internet and Corporate Intranets. Each external network is given a unique Access Point Name (APN) which is used by the mobile user to establish the connection to the required destination network.
3. WAP Servers - Its used for General Information Services like Train Timetables, etc.
4. RADIUS Server - Remote Access Dial-in User Server. 

GPRS Mobile devices

The key use for GPRS is to send and receive data to a computer application such as Email, web browsing or even telemetry (telemetry refers to devices not being controlled by humans such as cash point machines or traffic monitoring cameras etc.). To use GPRS the service is 'dialed' in a similar manner to a standard data call (though there is no phone no.) at which point the user is 'attached' and an IP address is allocated. From then on data can flow to and from the Internet until either the network unattaches you (maybe because of a time-out, fault or congestion) or you manually unattach.

Some of the key issues are:

• Using GPRS will not stop you making or receiving voice calls.Current phones will usually suspend the data session while a voice call takes place.
• Battery life will be reduced when using GPRS.
• Do not keep it near your ear for long periods while data transfers are taking place.

As a business GPRS user you will have a choice of methods to connect to the GPRS network - by far the most common method will be via the Internet. For larger users you may connect your company LAN to the GPRS networks using leased lines or Frame Relay virtual circuits.

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