FDMA-TDMA-CDMA: An Introduction By Dr. Ernest Simo
2.0 FREQUENCY DIVISION MULTIPLE ACCESS
In FDMA systems a channel is defined by a center frequency (Fi) and its associated bandpass filter (slice of total bandwidth B). Here a channel may be regarded as a Frequency Gate.
Since the total band width B is subdivided into N frequency slices or channels, only N users may be supported simultaneously.