1G – The first mobile phones were based on what is known as the First Generation, or 1G system. This was an analogue system and was circuit switched. This is a way of creating a connection between devices by setting up a specific communications circuit and keeping it open until the communication is terminated. This system had a number of problems. Often the voice contacts were of poor quality and handover (or handoff) tended to be unreliable so calls could be lost when moving between cells. (Handover is the process of transferring the call between base stations.) The capacity of the 1G networks were very limited. As voice communications were handled by analogue radio signals, listening in to other peoples calls was very easy and could be done with a simple radio receiver – in fact there was no such concept as 1G security.
2G – The somewhat clunky 1G network was replaced by the first digital mobile phone network implementation the 2G, or second generation. 2G networks protocols employed digital encoding. Implementations included GSM, D-AMPS (TDMA) and CDMA:
- GSM was the standard in Europe and is one of the most important ones in the world accounting for 70% of of total digital cellular communications. It uses a time division multiplex (TDM) system over four frequency bands. These are 800 MHz, 900 MHz, 1800 MHz and 1900 MHz.
- D-AMPS (TDMA) is a Time Division Multiple Access digital transmission system which allocates a different time slot on a specific frequency to each individual user. This system is used in the USA, Asia Pacific, Russia and new Zealand.
- CDMA stands for Code Division Multiple Access. This makes simultaneous use of multiple frequencies in a spread spectrum.
2.5G – The 2.5G system was based on the 2G system but with a few extra bolt-on goodies. In particular it introduced packet-switched connection (GPRS) along with HSCSD and EDGE technologies: - GPRS stands for General Packet Radio Service which allows packet switching to be which provides more efficient ISP connections. It also allowed for data volume rather than connect time charging so permanent network connection was possible. Data transmission rates of up to 30 Kbps became available.
- HSCSD is high speed circuit switched data which allows data transfer of up to 57.6 Kbps.
- EDGE is Enhanced Data Rates for GSM Evolution which provided data transfer rates of up to 384 Kbps. This makes 2G networks almost as fast as 3G ones.
Is your contract up for renewal? See which mobile phones are available on upgrade today at Phones4u, the best UK mobile phone shop. Click here and have a browse on the website.










