The optimal backoff window size and contention window size are given,and the transmission efficiency is calculated by analyzing the collision probability of contention request.

• 通过对竞争请求的冲突概率进行分析,推出了回退窗口和竞争窗口的最佳分配尺寸,并计算了不同业务流数量下系统可达到的最大传输效率。