CSMA/CA算法的退避失败概率的分析

ANALYSING BACKOFF FAILURE PROBABILITY FOR CSMA/CA ALGORITHM

当网络节点采用CSMA/CA算法竞争访问信道时,会引起退避失败,停止发送数据。针对退避失败概率的问题,提出一种基于马尔可夫链的分析方法。首先,建立饱和负载状态下的离散马尔可夫链数学模型,然后推导退避失败概率与退避次数、退避指数、节点数量之间的关系,最后分析CSMA/CA算法的参数和网络规模对退避失败概率的影响。实验结果表明,利用NS-2仿真器评价的结果和数学模型分析的结果大致相同,该数学模型能够有效分析退避失败概率。

When the network nodes contending for channel access using CSMA /CA algorithm,the backoff failure is caused,and data transmission is stopped as well.Aiming at the problem of backoff failure probability,we proposed a Markov chain-based analysis method. First,we built the discrete Markov chain model in saturated traffic scenarios,and then deduced the relations between the backoff failure probability and the backoff times,the backoff indices and the node numbers.Finally we analysed the impact of the CSMA /CA algorithm parameters and wireless sensor network scale on backoff failure probability.Experimental result showed,it was almost the same in the results evaluated by the NS-2 simulator and analysed by the mathematical model respectively,the mathematical model can effectively analyse the backoff failure probability.