JPL's Wireless Communication Reference Website

Chapter: Cellular Telephone Networks
Section: Multiple Access

Frequency Division Multiple Access (FDMA)

In an FDMA system, each user has its own frequency channel. This implies that relatively narrow filters are needed in each receiver and transmitter. Most duplex FDMA systems must transmit and receive simultaneously. (Frequency Division Duplex, FDD) This requires expensive and bulky duplex filters to avoid strong transmit signals leaking into the receiver.


Figure: Time and bandwidth occupancy of three user signals with FDMA

Examples of systems using FDMA


Figure: equipment for private mobile radio system often uses FDMA.

Early cellular telephony mostly used FDMA analogue transmission. Walkie talkies and mobile networks for closed user groups often use FDMA. More advanced systems time-share frequencies among different user groups. This concept is called "trunking".

Another example of FDMA is AM or FM radio broadcasting, where each station has its own channel.



JPL's Wireless Communication Reference Website © 1993, 1995.