statistical time division multiplexing
(STDM, StatMUX) A system developed to overcome some inefficiencies of standard time division multiplexing, where time slices are still allocated to channels, even if they have no information to transmit.
STDM uses a variable time slot length and by allowing channels to vie for any free slot space. It employs a buffer memory which temporarily stores the data during periods of peak traffic. This scheme allows STDM to waste no high-speed line time with inactive channels. STDM requires each transmission to carry identification information (i.e. a channel identifier). To reduce the cost of this overhead, a number of characters for each channel are grouped together for transmission.