Asynchronous time-division multip lexing (ATD or ATDM) is a time-division multiplexed access strategy in which the connected data stations do not have fixed reserved transmission capacities with periodic time slots as in synchronoustime-division multiplexing ( STD).
In asynchronous time division multiplexing, the data streams to be transmitted are divided into information units of fixed or variable length and transmitted asynchronously. The information units are assigned via an identification number in the header with which each cell is provided.
The cells have a fixed length and consist of the header with the information for the controller and the payload, the user data. The payload data to be transmitted is buffered by an asynchronous multiplexer and divided into fixed data blocks before transmission and provided with the channel address. The transmission medium has time slots that can be freely assigned and in which the cells are transmitted. When transmitting cells with a fixed length, this is cell switching, and when transmitting data packets with a variable length, it is data packet switching.