Frequency Division Multiple Access shares spectrum by giving each user a different frequency band. It is like a radio dial with many stations. Each station has its own frequency. Users talk at the same time but on different channels. FDMA was used in first-generation analog cellular networks.

FDMA is simple. It divides the available spectrum into channels. Each call gets one channel. The channel is dedicated for the duration of the call. No other user can use it. This wastes capacity when the user is silent. But it is easy to implement and works reliably.

FDMA characteristics

• Each user gets a separate frequency
• Continuous transmission during call
• Simple to implement
• Wasteful of spectrum
• Used in 1G cellular and some satellite systems

FDMA was replaced by TDMA and CDMA, which use spectrum more efficiently. But the concept remains. OFDMA, used in 4G and 5G, is a form of FDMA with many subcarriers. It assigns different subcarriers to different users. The idea of dividing spectrum by frequency is still fundamental.