Performance Evaluation of a Modified Aloha Protocol for Tactical RadioCommunications

摘要

A performance evaluation of a modified Aloha protocol for the MAC layer ispresented. The modifications are that frames are not constrained to be fixed length, and frames are assigned a waiting time for their first attempt rather than only after collisions. Equations are derived that predict the throughput and average delay for a finite user systems with a Poisson arrival process. These expressions can be used in a higher layer protocol so that channel use is maximized while still meeting application layer requirements. Next, an analysis for Logical Link Control or higher protocol layers is presented for the case where several priority queues are used. The MAC layer receives the frames at intervals from these queues, which are emptied from highest to lowest priority. It is shown that if either channel utilization of traffic rate is held constant, there is no benefit through the use of priority queues.