关键词: Ad Hoc网络, 基于优先级概率统计的多址接入（SPMA）协议, 退避算法, 信道占用, 优先级

Abstract: For the backoff time problem of Ad Hoc network MAC protocol（SPMA protocol）, in order to reduce packet-to-packet collisions and improve channel utilization, a backoff algorithm based on channel occupancy and priority（A-COP algorithm） is proposed for the first time. Firstly, the impact of backoff time on system performance and the insufficient of existing backoff algorithm are analyzed. Then, the back-off algorithm model is established according to the characteristics of SPMA protocol and elementary function model. Finally, the system simulation based on OPNET is performed, and the protocol model is compared with the original algorithm model. The simulation result shows that the SPMA protocol based on this algorithm can make the system throughput more stable through the access control of low-priority services, and it can meet the requirement of high-priority services with high communication quality.

Key words: Ad Hoc network, Statistic Priority-based Multiple Access（SPMA） protocol, backoff algorithm, channel occupancy, priority