Frequency-division multiple access
(also FDMA)
Frequency-division multiple access definition
Frequency-division multiple access is a telecommunications technique that allows multiple users or devices to divide a communication medium (such as a radio frequency band) between them. Frequency-division multiple access is rarely used today, but it still has a place in analog cellular networks and some satellite communications.
How frequency-division multiple access works
Frequency-division multiple access divides the available frequency spectrum into multiple non-overlapping frequency channels. This process is known as “channelization.” Each channel is assigned a specific range of frequencies and serves as an independent communication path.
Each user is then assigned one or more frequency channels within the spectrum. Guard bands (unused frequency ranges) are often used to prevent interference between adjacent channels, providing a buffer to minimize crosstalk or interference.
Prominent frequency division multiple access techniques
- Multiple channels per carrier or MCPC is a technique used in uplink (Earth to space) satellite communications to efficiently transmit multiple data channels or services over a single carrier frequency. In MCPC, different data channels are modulated separately and then multiplexed together onto the same frequency.
- Single channel per carrier or SCPC is used in downlink (space to Earth) satellite communications to transmit data channels or services over separate carrier frequencies. Each channel is modulated and transmitted independently of the others.