基于马尔可夫链的IEEE802.15.4网络防丢包信道访问机制研究

为了降低802.15.4MAC层数据帧丢包率，在分析丢包率的原因基础上，提出了一种基于Markov链的信道竞争机制模型。通过对网络发送、退避和信道检测状态的稳态概率进行数学推导，研究了信道碰撞和数据帧的丢包率分析式；最后研究了参数数据包到达速率、节点数量、误码率、后退指数、后退等待次数对碰撞概率和丢包率的影响。实验结果表明，与节点无休眠态的802.15.4网络相比，节点丢包率平均降低了23.7%，模型较好地描述了提出的MAC层信道访问机制，合理的网络参数设置能够优化数据帧丢包率，研究结果对无线传感网的应用提供可靠传输优化参考。

Research on channel access mechanism of anti packet loss for 802.15.4 network based on Markov chain

In order to reduce the packet lost rate in 802.15.4MAC layer, this paper raised a model of channel competition mechanism based on Markov chain by analyzing the reason of packet loss rate. Then, throught the mathematical derivations of the steady-state probability on the network transmission, backoff and the channel detection state based on the model of channel access, this paper?discussed the formulas of channel collision and the frame packet lost rate. Finally, this paper studied the impact of protocol parameters such as packet arrival rate, the number of nodes, bit error rate, backoff exponent, and number of backoffs on the collision probability and the packet lost rate. Experimental results show that, compared with 802.15.4 network without node sleep state, the packet lost rate was reduced by 23.7%. And the model describes the MAC layer channel access mechanism very well, and reasonable settings for parameters could optimize the frame packet lost rate. The research outcome could provide reference for the reliable transmission optimization in the practical application of wireless sensor network.