Demand Assigned Multiple Access

Demand Assigned Multiple Access (DAMA) is a technology used to assign a bandwidth to clients that don't need to use it constantly. DAMA systems assign communication channels or circuits based on requests issued from user terminals to a network control system. When the circuit is no longer in use, the channels are then returned to the central pool for reuse by others.

Channels are typically a pair of carrier frequencies (one for transmit and one for receive), but can be other fixed bandwidth resources such as timeslots in a TDMA burst plan. Once allocated to a pair of nodes this bandwidth is not available to other users in the network until their session is finished.

It allows utilizing of one channel (frequency band, timeslot, etc.) by many users at different times. This technology is mainly used by small clients, as opposed to PAMA (Permanently Assigned Multiple Access). By using DAMA technology the amount of users that can use a limited pool of circuits can be greatly increased.

DAMA and PAMA are related only to bandwidth assignment and are not to be mixed with the Multiple access methods intended to divide a bandwidth between several users at one time, which include FDMA, TDMA, CDMA and others. These systems typically allow a more determenistic near real time allocation of bandwidth based on demands and data priority.

DAMA is widely used in satellite communications, especially in VSAT systems. It is very effective in environments comprising multiple users each having a low to moderate usage profile.

DAMA is often used in military environments due to the relative simplicity of implementation, ease of modeling, and the fact that military usage profiles are a very good fit.

External links

A thumbnail overview can be found at http://www.defense-update.com/products/d/dama.htm

Comprehensive information on DAMA Technology is available at : http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=ADA336247&Location=U2&doc=GetTRDoc.pdf

A useful article with some interesting history can be found at http://www.birds-eye.net/definition/d/dama-demand_assigned_multiple_access.shtml