Editing Time-division multiplexing (section)

==Statistical version==
{{main|Statistical time-division multiplexing}}
Statistical time-division multiplexing (STDM) is an advanced version of TDM in which both the address of the terminal and the data itself are transmitted together for better routing. Using STDM allows bandwidth to be split over one line. Many college and corporate campuses use this type of TDM to distribute bandwidth.

On a 10-Mbit line entering a network, STDM can be used to provide 178 terminals with a dedicated 56k connection (178 * 56k = 9.96&nbsp;Mb). A more common use however is to only grant the bandwidth when that much is needed. STDM does not reserve a time slot for each terminal, rather it assigns a slot when the terminal is requiring data to be sent or received.

In its primary form, TDM is used for [[circuit mode]] communication with a fixed number of channels and constant bandwidth per channel. Bandwidth reservation distinguishes time-division multiplexing from [[statistical multiplexing]] such as statistical time-division multiplexing. In pure TDM, the time slots are recurrent in a fixed order and pre-allocated to the channels, rather than scheduled on a packet-by-packet basis.

In [[dynamic TDMA]], a [[scheduling algorithm]] dynamically reserves a variable number of time slots in each frame to variable bit-rate data streams, based on the traffic demand of each data stream.<ref name=Miao>{{cite book|author1=Guowang Miao|author-link=Guowang Miao|author2=Jens Zander|author3=Ki Won Sung|author4=Ben Slimane|title=Fundamentals of Mobile Data Networks|publisher=[[Cambridge University Press]]|isbn=978-1107143210|year=2016}}</ref> Dynamic TDMA is used in:
* [[HIPERLAN/2]]
* [[Dynamic synchronous transfer mode]]
* [[IEEE 802.16a]]

Asynchronous time-division multiplexing (ATDM),<ref name="White" /> is an alternative nomenclature in which STDM designates synchronous time-division multiplexing, the older method that uses fixed time slots.