Demand Assigned Multiple Access (DAMA) is a competitive method for multiple access to frequency channels, especially used in satellite communications. In this method, which is a special type of Time Division Multiple Access (TDMA), idle channels are grouped together in a pool. When a channel request is received, an idle channel with the corresponding bandwidth is selected and allocated to the requesting party. In satellite
radio, several earth stations compete for a radio frequency, whereas another multiple access method used in satellite transmission, Preassigned Multiple Access (PAMA), works with reservation techniques.