摘要
自从IEEE802.15.4标准发布以来,低功耗、低速率传输的无线传感器网络的应用几乎涉及到现实生活的方方面面,而这个标准的CSMA/CA机制性能分析大部分都是基于均匀、饱和的传感器网络。针对非均匀、非饱和的CSMA/CA机制,提出了一种离散的性能评估方法,采用两个半马尔可夫链来分别表达两组节点的访问过程、一个宏观马尔可夫链来表达信道状态。最大的特点是两组节点被赋予了公平的机会来访问信道,而不存在优先权的问题。基于这个模型,分析了不饱和、无ACK的IEEE 802.15.4信标使能访问机制的数据包传送时间,包括数据包到达率、包大小、节点数量等参数对系统实时性的影响,并且这些分析结果与采用NS-2工具仿真的结果十分吻合。
Since the successful release of the IEEE 802.15.4 standard, a great convenience is offered to applications of low-power and low-rate wireless sensor networks which almost touch upon all aspects of our life. Analysis of the IEEE 802.15.4 Carrier Sense Multiple Access with Collision Avoidance（CSMA/CA） scheme with homogeneous or saturated tragic has received considerable attention recently. In this paper, it proposes stochastic analysis approach to evaluate the performance of CSMA/CA scheme with heterogeneous unsaturated traffic which is more realistic in our applications, adopt two modified semi-Markov chains and one macro-Markov chain to characterize such an asymmetric system, in which traffic arrivals and Packets accessing the channel are bestowed with nonpreemptive priority over each other instead of prioritization, predict packet delay of unsaturated, unacknowledged IEEE 802.15.4 beacon enabled networks based on these models, including impacts of different parameters such as packet arrival rate, packet size and the number of different kinds of nodes. Comprehensive simulation results are consistent with predictions of these models.
出处
《电子设计工程》
2011年第7期114-117,共4页
Electronic Design Engineering
