中文摘要：

在无线传感器网络中,各节点采集的信息以多跳的方式传送到汇聚点.从各节点到汇聚点形成一棵以汇聚点为根的传输树.文中在对无线传感器网络传输特点分析的基础上,剖析了基于CSMA/CA（载波多路监听/冲突避免）的MAC协议在树状结构无线传感器网络中的弊端,提出了一种基于CSMA/CA的MAC协议优化算法.算法基于节点在传输树中的位置信息调整其MAC信道接入分配,将CSMA/CA采用的各节点均等竞争信道的方法优化为各节点依据在传输树中的位置情况竞争信道的方式,这一优化提高了节点公平性,使MAC信道接入分配与树状结构的无线传感器网络传输特点相契合,解决了基于CSMA/CA的MAC协议与树状结构无线传感器网络不匹配的问题,从而减少了信道资源浪费,提高了网络传输效率,降低了能耗.实验结果表明该算法在网络丢包率、吞吐量和能耗方面的性能均有较大改进.

英文摘要：

In wireless sensor networks（WSNs）,data converges to sinks via multi-hop transmission,which can be described by a transmission tree.In this paper,we analyzed the conflict between Carrier Sense Multiple Access with Collision Avoidance（CSMA/CA） based MAC protocols and the tree structured transmission in WSNs.Based on the address of the transmission feature of WSNs,we proposed a MAC layer optimization algorithm based on the CSMA/CA.The optimization algorithm improves the equal channel access strategy in CSMA/CA and adjusts the channel access strategy based on the location of the nodes in the transmission tree to fit the transmission feature of WSNs,which enhances the network fairness.The objective of the algorithm is to improve MAC efficiency,including loss ratio,throughput and energy consumption.The performances on data loss,throughput and energy consumption of the algorithm are verified via the simulation results.