tdma fdma
As I understand, both of the technologies is used in Cellular Communications Systems.
For FDMA, it's used in first generation cellular com. systems. (e.g. NMT, ETACS, AMPS, etc...)
(Frequency Division Multiple Access) The technology used in the analog cellular telephone network that divides the spectrum into 30 kHz channels.
For TDMA, it's a second generation mobile. (e.g. GSM, PCS, etc...)
(Time Division Multiple Access) A satellite and cellular phone technology that interleaves multiple digital signals onto a single high-speed channel. For cellular, TDMA triples the capacity of the original analog method (FDMA). It divides each channel into three subchannels providing service to three users instead of one. The GSM cellular system is also based on TDMA, but GSM defines the entire network, not just the air interface.
Cellular Generation
1G - Analog
Introduced in the late 1970s and early 1980s, the first cellular systems were analog. They were used for data just like land-based telephone lines are used for dial-up with analog modems. A handful of cellphone models could be adapted to laptop modems and transfer data at less than 15 Kbps while traveling. (e.g. AMPS, TACS and NMT.)
2G - 2.5G - Digital
The second generation refers to digital voice cellphone systems deployed in the 1990s, which were based on GSM, TDMA or CDMA. Several so-called 2.5G (or 2G+) technologies added data services for Internet access and e-mail with typical downstream speeds ranging from 64 to 200 Kbps for the user. These include GPRS, EDGE and IS-95B. (e.g. GPRS, EDGE and IS-95.)
3G - High Speed
Launched after the turn of the century, the third generation offers faster access to the Internet and other data services with typical downstream speeds ranging from 400 Kbps up to 1 Mbps for the user. Defined by the ITU under the IMT-2000 framework, 3G is implemented regionally in Europe (UMTS), North America (CDMA2000) and Japan (NTT DoCoMo). EV-DO, WCDMA and HSDPA are examples of 3G data services. 3G also embraces worldwide roaming for global travelers. (e.g. GAN, EV-DO, WCDMA, HSDPA, CDMA2000, UMTS and 3GPP.)
4G - Higher Speed for Movies and TV
In the 2008-2010 time frame, 4G cellphones are expected to support TV in realtime as well as video downloads at high speed. It is also expected to embrace automatic roaming to non-cellular systems such as Wi-Fi, satellite and other wireless networks, whichever is most appropriate. NTT DoCoMo's 4G service is based on WCDMA; however, carriers in the U.S. and Europe are expected to deploy other air interfaces. (e.g. NTT DoCoMo and WCDMA.)