A time unit (TU) is a unit of time equal to 1024 microseconds.[1] It was originally introduced in IEEE 802.11-1999 standard[2] and continues to be used in newer issues of the IEEE 802.11 standard.[1]
In the 802.11 standards, periods of time are generally described as integral numbers of time units. The unit allows for maintaining intervals that are easy to implement in hardware that has a 1 MHz clock (by dividing the clock signal in half ten times, rather than operating a phase-locked loop or digital divider to divide such a clock signal by 1000).
One time unit is equal to one millionth of a kibisecond (1 TU = 10−6 Kis).