An adaptive multiple access protocol for broadcast channels

A new adaptive multiple access protocol for time-slotted broadcast channels is presented. Slots are grouped into fixed-length time frame which can be dynamically assigned in either TDMA (time-division multiple access) or slotted-ALOHA mode. Initially, the users broadcast packets in the TDMA mode. If the number of unused slots in a frame exceeds a threshold value, the TDMA mode ceases in the next frame and users transmit packets in the slotted ALOHA mode. The mode of operation switches back to normal TDMA only when there is a collision in the previous frame. The performance of protocol is evaluated through a simulation study. The protocol behaves nearly the same as slotted ALOHA for light traffic; while at higher traffic intensities its performance approaches that of TDMA. The protocol is stable, adaptive to traffic load variations and it offers good delay-throughput characteristics.