As of today (September 9, 2002) there are three main cellular technologies: Older analog FDMA (Frequency Division Multiple Access), modern GSM TDMA (Time Division Multiple Access) and Newer CDMA (Code Division Multiple Access.) People mostly know of the latter two and the first one is almost wiped off from the history of Cellular Network technology.
I am not going too deep into the technical aspect of all the networks and am just giving an outline of FDMA.
Analog transmission is considered an “older” cellular phone technology. Back in the early 198o’s, it was the first network technology to be deployed successfully. FDMA is used exclusively for analog cellular systems, even though in theory FDMA can also be used with digital networks.
Essentially, FDMA splits the allocated spectrum into many ‘channels,’ each of approx 30 kHz bandwidth. During a data transfer, in form of audio or video, an FDMA networks allocates the entire channel to the phone and the data is modulated into this channel’s frequency band and sent over airwaves. At the receiver’s end, the information is recovered using a simple band-pass filter. The phone then uses common control-channel function to acquire channels during Handoffs.