Once the second-generation systems became established it soon became apparent that the limited data capabilities of some of the 2G systems were a significant disadvantage. Many applications for data transfer with the increased use of the Internet and laptop computers were seen. Even though the third generation systems were on the horizon, developments were needed to provide a service before they entered the market. One of the first was the General Packet Radio Service (GPRS) development for the GSM system. Its approach centred on the use of packet data. Up until this time all circuits had been dedicated to a given user in an approach known as circuit switched, i.e. where a complete circuit is switched for a given user. This was inefficient when a channel was only carrying data for a small percentage of the time. The new packet switched approach routed individual packets of data from the transmitter to the receiver allowing the same circuit to be used by different users. This enabled circuits to be used more efficiently and charges to be metered according to the data transferred.
Further data rate improvements were made using a system known as EDGE (Enhanced data Rates for GSM Evolution). This basically took the GPRS system and added a new modulation scheme, 8PSK, to enable a much higher data rate to be achieved. Whilst the symbol rate remained the same at 270.833 samples per second, each symbol carried three bits instead of one.
Whilst GPRS and EDGE were applied to GSM networks, enhancements were also applied to the CDMA system that originated in the USA. Here an evolutionary path from 2G through 2.5G to 3G was created.
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