(1) (
Telecommunications
Device for the
Deaf) See
TDD/TTY.
(2) (
Time
Division
Duplexing) A transmission method that uses the same channel for the uplink and downlink (transmit and receive), but separates them by time slots. In 1/1 TDD, downlink slots are interleaved equally with the uplink; a 2/1 TDD gives the downlink twice as many slots as the uplink. However, in a wireless application, power is a critical factor. For example, mobile phone antennas transmit less power than the cell tower antennas, and even a 1/1 TDD yields a lower uplink speed to the tower than the downlink speed from the tower. Contrast with
FDD.