The large number of different mobile phone or cellphone systems that are talked about today can be very confusing. Whilst not all are in use today, some of the older systems have been superseded and some of the newer systems have not all been rolled out yet, nevertheless many different names and technologies are talked about. The table below gives a summary of the main systems that have been used, are being used or are due for introduction.

Generation 1G

1. AMPS, (Advanced Mobile Phone System) this analogue system first developed and used in the USA.
Channel Spacing 30 khz , Access Method FDMA

2.NAMPS, Narrow band version of AMPS chiefly used in the USA and Israel based on a 10 kHz channel spacing.
Channel Spacing 10 khz , Access Method FDMA

3.TACS, Analogue system originally in the UK. Based around 900 MHz, this system spread world wide. After the system was first introduced, further channels were allocated to reduce congestion, in a standard known as Extended TACS or ETACS
Channel Spacing 25 khz , Access Method FDMA

4.NMT, (Nordic Mobile Telephone) This analogue system was the first system to be widely used commercially being launched in 1979. It was used initially on 450 MHz and later at 900 MHz. It was used chiefly in Scandinavia but it was adopted by up to 30 other countries including Oman.
Channel Spacing 12,5 khz , Access Method FDMA

5.NTT, (Nippon Telegraph and Telephone) The system used in Japan, using a 900 MHz frequency band, and 55 MHz transmit receive spacing. (A high capacity version is known as HICAP).
Channel Spacing 25 khz , Access Method FDMA

6.C450, The system adopted in West Germany (East Germany was separate at this time). It used a band in the region of 450 MHz along with a 10 MHz receive / transmit spacing.
Channel Spacing 20 khz , Access Method FDMA


Generation 2G

1.GSM , Originally called Groupe Speciale Mobile, the initials later stood for Global System for Mobile communications. It was developed in Europe and first introduced in 1991. The service is normally based around 900 MHz although some 850 MHz allocations exist in the US
Channel Spacing 200 khz , Access Method TDMA

2.DCS 1800, 1800 MHz derivation of GSM and is also known as GSM 1800.
Channel Spacing 200 khz , Access Method TDMA

3.PCS 1900, 1900 MHz derivation of GSM, and is also known as GSM 1900.
Channel Spacing 200 khz , Access Method TDMA

4.TDMA, Although it was originally known as US Digital Cellular (USDC) and was introduced in 1991. It is sometimes called North America Digital Cellular and also known by its standard number IS-54 that was later updated to standard IS136. It is a 2G digital system that was designed to operate alongside the AMPS system.
Channel Spacing 30 khz , Access Method TDMA

5.PDC, (Pacific or Personal Digital Cellular) The system found only in Japan where it has gained very widespread use. It has many similarities with IS-54 although it uses a different speech coder and a 25 kHz bandwidth.
Channel Spacing 25 khz , Access Method TDMA

6.CDMAone, This is the brand name for the system with the standard reference IS95. It was the first CDMA system to gain widespread use. The initial specification for the system was IS95A, but its performance was later upgraded under IS95B which the cdmaOne specification actually uses. Apart from voice it also carries data at rates up to 14.4 kbps for IS95A and under IS95B data rates of up to 115 kbps are supported
Channel Spacing 1,25 Mhz , Access Method CDMA


Generation 2,5G

1.GPRS, (General Packet Radio Service) A data service that can be layered onto GSM. It uses packet switching instead of circuit switching to provide the required performance. Data rates of up to 115 kbps attainable.
Channel Spacing 200 khz , Access Method TDMA

2.CDMA2000 1x, This system supports both voice and data capabilities within a standard 1.25 MHz CDMA channel. CDMA2000 builds on cdmaOne to provide an evolution path to 3G. The system doubles the voice capacity of cdmaOne systems and also supports high-speed data services. Peak data rates of 153 kbps are currently achievable with figures of 307 kbps quoted for the future, and 614 kbps when two channels are used
Channel Spacing 1,25 Mhz , Access Method CDMA

3.EDGE, (Enhanced Data rates for GSM Evolution). The system uses a different form of modulation (8PSK) and packet switching which is overlayed on top of GSM to provide the enhanced performance. Systems using the EDGE system may also be known as EGPRS systems.
Channel Spacing 200 khz , Access Method TDMA


Generation 3G

1.CDMA2000 1xEV-DO, The EV-DO stands for Evolution Data Only. This is an evolution of CDMA 2000 that is designed for data only use and its specification is IS 856. It provides peak data rate capability of over 2.45 Mbps on the forward or downlink , i.e. from the base station to the user. The aim of the system is to deliver a low cost per megabyte capability along with an always on connection costed on the data downloaded rather than connection time
Channel Spacing 1,25 Mhz , Access Method CDMA

2. CDMA2000 1xEV-DV, This stands for Evolution Data and Voice. It is an evolution of CDMA2000 that can simultaneously transmit voice and data. The peak data rate is 3.1 Mbps on the forward link. The reverse link is very similar to CDMA2000 and is limited to 384 kbps.
Channel Spacing 1,25 Mhz , Access Method CDMA

3.UMTS, (Universal Mobile Telecommunications System). Uses Wideband CDMA (W-CDMA) with one 5 MHz wide channel for both voice and data, providing data speeds up to 2 Mbps.
Channel Spacing 5 Mhz , Access Method CDMA/TDMA

4. TD-SCDMA, Time Division Synchronous CDMA. A system developed in China to establish their position on the cellular telecommunications arena. It uses the same bands for transmit and receive, allowing different time slots for base stations and mobiles to communicate. Unlike other 3G systems it uses only a time division duplex (TDD) system
Channel Spacing 1,6 Mhz , Access Method CDMA