GSM was a circuit switched technology which gave a maximum data rate of 9.6 Kbps. GSM version 2 gave a maximum data rate of 14.4 Kbps. The increase from the speed of 9.6 Kbps to 14.4 Kbps was due to a nominal reduction in the error-correction overhead of the GSM radio link protocol (RLP), allowing the use of a higher data rate. Although 2G GSM could provide some data capability it was far too slow to be used for any real time applications. To provide better data rates, some new switching techniques were proposed which gave rise to new technologies. These technologies promised high data rates and thus Mobile Communication evolved from mere SMS transmission to email, web browsing to eventually high speed multimedia access. The GSM evolution path to 3G is summarized in Figure 1.

Deployment of GSM was in the era of 1990-1992. In the year 1998, a few service providers adopted a new technology called as High Speed Circuit Switching for Data (HSCSD) technology. This was a circuit switched technology which promised a maximum data rate of 56 Kbps. This technology was not so widely accepted as just one year later, a packet switching technology was proposed. In 1999, most of the service providers implemented General Packet for Radio Service (GPRS) along with GSM to provide data access. Application downloading, email, GPS integration for location messages became possible with this. GPRS gave a data rate of 115.2 kbps which was far more as compared to GSM’s 9.6 Kbps. Hence GPRS was categorized as 2.5 G technology.

Year 2000 saw an exponential increase in the demand of data rate by the users. Hence, by modifying modulation techniques and channel coding techniques, a new technology was implemented. This was Enhanced Data Rates for Global Evolution (EDGE). This technology gave a data rate of 384 kbps and was considered to be a 2.75 G. Streaming audio/video became possible with this technique.