IEEE 802.11 MAC层中一种减小冲突的方法

A method to decrease contentions in IEEE 802.11 MAC layer

为了提高IEEE 802.11 DCF的性能,提出了一种应用于IEEE 802.11 DCF中减小冲突的方法.将2个时隙组合起来构成一个超时隙,站点的倒计数器以超时隙为单位减小,当一个站点在一个超时隙中发包时,它以概率q选择第一个时隙发包,以概率(1-q)选择第二个时隙发包.当多个站点同时在一个超时隙中发包时,仍然存在发包成功的可能,减小了冲突,提高了发包成功的概率.该方法可大大提高网络吞吐量和降低丢包率,并能减小网络中站点数目变化对吞吐量的影响,这种方法简单易行、效率高,较大幅度地提高了DCF的性能.

This paper proposes a method to decrease contentions in IEEE 802. 11 distributed coordination function（DCF）, in which two slots are assembled together to form a super slot, and the station＇s backoff counter is decreased in terms of super slot. When a station sends a frame in a super slot, the frame is sent at the first slot with the probability q and at the second slot with the probability （ 1 - q）. If more than one station sends a frame in a super slot all together, one of them may transmit a frame successfully without collision. Thus the possibility of successful transmission is increased. Applying this method in DCF can greatly improve the throughput and lower the frame dropping possibility. When the number of stations in a network is changed, this method can reduce the variance of network throughput. This method is easy to implement and can improve the performance of DCF greatly.