Frequency-division duplex (FDD) allocates two distinct blocks of the radio spectrum for communication, one for the uplink and one for the downlink. This physical separation allows a device to transmit and receive simultaneously without the signals interfering with each other. It requires a guard band between the two frequencies to prevent crosstalk, making it highly reliable but less spectrum-efficient than time-based duplexing.
The new LTE deployment will use FDD on band 4, so make sure the duplexers are tuned correctly.
Also heard as
- frequency-division duplex
Do not mix it up with
- TDD: FDD separates uplink and downlink by frequency, whereas TDD separates them by time on the same frequency.
Related terms
TDD
A telecommunications device for the deaf is a terminal that allows text communication over a standard telephone line.
Guard band
An intentionally unused portion of the radio spectrum placed between active channels.
Uplink
The communication path originating from a remote device and traveling toward the core network.
Downlink
The transmission path from a satellite, cell tower, or network core to the end-user device.
Frequency band
A defined contiguous range of radio frequencies allocated for a specific purpose.