GPRS stands for General Packet Radio Service. It is a packet based data bearer service for wireless communication services that is delivered as a network overlay for GSM, CDMA and TDMA networks. GPRS applies a packet radio principle to transfer user data packets in an efficient way between GSM mobile stations and external packet data networks. Packet switching is where data is split into packets that are transmitted separately and then reassembled at the receiving end. GPRS enables any existing IP or X.25 application to operate over a GSM cellular connection. Cellular networks with GPRS capabilities are wireless extensions of the internet and X.25 networks.

These networks can be, for example, the internet or corporate intranets. The GSM-BSS provides the radio interface and the GPRS core network handles mobility and access to external packet networks and services. This is shown in figure

 GPRS access to packet switching networks

The key benefits of GPRS are speed, always on connectivity, new and better applications, GSM operator costs etc. Figure shows the architecture of a GPRS network. This system brings some new network elements to an existing GSM network. These elements are:

• Packet Control Unit (PCU)
• Serving GPRS Support Node (SGSN)
• Gateway GPRS Support Node (GGSN)
• Boarder Gateway (BG)
• Intra-PLMN backbone: an IP based network inter connecting all the GPRS elements
• Charging Gateway (CG)
• Legal Interception Gateway (LIG)
• Domain Name System (DNS)
• Firewalls: used whenever a connection to an external network is required.

Not all of the network elements are compulsory for every GPRS network.

  Architecture of GPRS network.