Performance Evaluation of Slotted ALOHA with Generalized Retransmission Backoff

This paper presents an analytical investigation of generalized retransmission backoff policies for slotted ALOHA random access channels. Backoff techniques, of which the well-known “exponential backoff” is a special case, are based on adaptation of average retransmission delay as a function of the number of collisions experienced by each message accessing the contention channel. An analytical model applicable to slotted ALOHA channels employing general backoff functions has been developed and used to assess the performance advantages offered by either exponential backoff or alternative policies motivated by heuristic considerations. Numerical results for an example satellite channel scenario are presented, demonstrating that the use of appropriate backoff policies can result in significant improvements in stable throughput-delay characteristics relative to nonadaptive systems.