As of today (September 9, 2002), there are three main cellular technologies: the older analog FDMA (Frequency Division Multiple Access), the modern GSM TDMA (Time Division Multiple Access), and the newer CDMA (Code Division Multiple Access). While most people are familiar with the latter two, the first one has nearly vanished from the annals of cellular network technology.

I won’t delve too deeply into the technical intricacies of each network but will provide an overview of FDMA.

Analog transmission is regarded as an “older” cellular phone technology. In the early 1980s, it was the pioneering network technology to be successfully deployed. FDMA is used exclusively for analog cellular systems, although theoretically, it could be applied to digital networks as well.

Fundamentally, FDMA divides the allocated spectrum into numerous ‘channels,’ each approximately 30 kHz in bandwidth. During a data transfer, whether audio or video, an FDMA network assigns an entire channel to the phone. The data is then modulated into this channel’s frequency band and transmitted over the airwaves. At the receiver’s end, the information is retrieved using a simple band-pass filter. The phone uses a common control-channel function to acquire channels during handoffs (handoff refers to the process of switching broadcast sites).

FDMA analog transmission is the least efficient due to its limitation of accommodating only one user per channel. FDMA channels are not only larger, with no data compression, but there is also a waste of bandwidth during any silence in a conversation. Analog signals are particularly susceptible to noise, and this extra noise cannot be filtered out. Furthermore, analog cell phones must use higher power, ranging from one to three watts, to achieve acceptable call quality.

Therefore, it is understandable why FDMA networks failed to maintain their position. Digital technology offers significant advantages. Digital technology is much more efficient in utilizing bandwidth. Due to digital compression, more data can flow over a network efficiently. Digital signals are encrypted, difficult to decode, and more secure than analog. Digital technology easily integrates with personal communication systems such as handheld devices and palm pilots, and hopefully, in the future, with all things digital. Since digital is so efficient, it can also reduce average transmitter power as it works ‘less hard’ than analog transmissions. Digital systems enable smaller and less expensive individual receivers and transmitters.

All these factors combined have led to the phasing out of FDMA.