GPRS: General Packet Radio Service

The introduction of second generation cellular mobile systems witnessed an impressive growth in the number of mobile subscribers. The most popular second generation systems are GSM and IS-95. The GSM system is based on FDMA-TDMA technology and is widely used in Europe, many parts of Asia and Africa. The IS-95 system is based on CDMA technology and is used in North America. With the increasing popularity of these systems there was an increasing demand for the data services over the wireless. These systems were designed for supporting circuit switched voice data and supported packet data on limited basis, but could not meet of today's traffic requirements. In future it is expected that the wireless systems would be able to provide various kind of services like Internet access over wireless, streaming audio and video, text and multimedia messaging services.

Existing cellular systems do not fulfill the current data needs. The data rates are slow, the connection setup time is long and the services are too expensive. The reason for this is that these systems are designed primarily to handle circuit switched voice data and a channel is dedicated to a single user for the entire duration of the call. This leads to inefficient channel utilization for the packet switched data since it is bursty in nature and many calls could utilize same channel. If packet switched bearer service is provided, the channels can be allocated to the users when needed, leading to sharing of the physical channel (Statistical multiplexing) and thus efficient channel utilization.

The General Packet Radio Service (GPRS) has been developed to address the above inefficiencies and to simplify the wireless access to packet data network. It applies packet radio principles to efficiently transfer data between GSM mobile stations and external packet data network. GPRS supports both X.25 and IP (IPv4 as well as IPv6) networks. GPRS offers session establishment time below one second and data rates up to several tens kbit/s. It also provides for user friendly billing since the billing is based on the amount of transmitted data as against GSM where user is billed based on the duration of the call. This is suitable for applications with bursty traffic (e.g. web browsing) where user can be ``online'' for longer period of time but will be billed based on transmitted data volume.