IEEE 802.15.4 protocol is proposed to meet the low latency and energy consumption needs in low-rate wireless applications, however, few analytical models are tractable enough for comprehensive evaluation of the protoc...IEEE 802.15.4 protocol is proposed to meet the low latency and energy consumption needs in low-rate wireless applications, however, few analytical models are tractable enough for comprehensive evaluation of the protocol. To evaluate the IEEE 802.15.4 slotted CSMA/CA channel access mechanism in this paper, we propose a practical and accurate discrete Markov chain model, which can dynamically represent different network loads. By computing the steady-state distribution probability of the Markov chain, we obtain an evaluation formula for throughput, energy consumption, and access latency. Then we further analyze the parameters that influence performance including packet arrival rate, initial backoff exponent and maximum backoff number. Finally, NS2 simulator has been used to evaluate the performance of the 802.15.4 CSMA/CA mechanism under different scenarios and to validate the accuracy of the proposed model.展开更多
针对IEEE 802.15.4MAC协议中的标准时隙CSMA/CA(carrier sense multiple access with collision avoidance)机制不能提供数据流区分服务的问题,提出了一种基于优先级的网络负载动态自适应参数调整DAPA-CSMA/CA算法.该算法根据应用实时...针对IEEE 802.15.4MAC协议中的标准时隙CSMA/CA(carrier sense multiple access with collision avoidance)机制不能提供数据流区分服务的问题,提出了一种基于优先级的网络负载动态自适应参数调整DAPA-CSMA/CA算法.该算法根据应用实时性的需求为不同的节点分配不同的优先级,优化协议参数配置以实现区分服务,并通过动态调整退避指数来自适应网络流量变化,在此基础上,结合马尔可夫原理对DAPA-CSMA/CA算法的信道竞争过程进行理论分析.仿真结果表明:该算法具有较强的网络自适应能力,可以降低节点间的碰撞,降低丢包率、时延及能耗,更好地满足无线传感器网络在实时监测环境中对高服务质量的要求.展开更多
基金National Basic Research 973 Program of China under Grant No.2006CB303000the National Natural Science Foundation of China under Grant Nos.60673187,60702009,and 60872055
文摘IEEE 802.15.4 protocol is proposed to meet the low latency and energy consumption needs in low-rate wireless applications, however, few analytical models are tractable enough for comprehensive evaluation of the protocol. To evaluate the IEEE 802.15.4 slotted CSMA/CA channel access mechanism in this paper, we propose a practical and accurate discrete Markov chain model, which can dynamically represent different network loads. By computing the steady-state distribution probability of the Markov chain, we obtain an evaluation formula for throughput, energy consumption, and access latency. Then we further analyze the parameters that influence performance including packet arrival rate, initial backoff exponent and maximum backoff number. Finally, NS2 simulator has been used to evaluate the performance of the 802.15.4 CSMA/CA mechanism under different scenarios and to validate the accuracy of the proposed model.
文摘针对IEEE 802.15.4MAC协议中的标准时隙CSMA/CA(carrier sense multiple access with collision avoidance)机制不能提供数据流区分服务的问题,提出了一种基于优先级的网络负载动态自适应参数调整DAPA-CSMA/CA算法.该算法根据应用实时性的需求为不同的节点分配不同的优先级,优化协议参数配置以实现区分服务,并通过动态调整退避指数来自适应网络流量变化,在此基础上,结合马尔可夫原理对DAPA-CSMA/CA算法的信道竞争过程进行理论分析.仿真结果表明:该算法具有较强的网络自适应能力,可以降低节点间的碰撞,降低丢包率、时延及能耗,更好地满足无线传感器网络在实时监测环境中对高服务质量的要求.
