TDD

(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.