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
我国电力工业迅速发展,智能电网规模不断扩大,需要在线监控的设备和对象也越来越多,传统的监控与数据采集(Supervisory Control And Data Acquisition,SCADA)系统已无法满足电力信息化的要求。文章将ZigBee技术应用于SCADA的数据采集系...我国电力工业迅速发展,智能电网规模不断扩大,需要在线监控的设备和对象也越来越多,传统的监控与数据采集(Supervisory Control And Data Acquisition,SCADA)系统已无法满足电力信息化的要求。文章将ZigBee技术应用于SCADA的数据采集系统,针对系统节点业务不断变化对网络性能的影响,提出了一种网络负荷判断和最小二乘线性拟合的退避策略。在每次载波监听多路访问/冲突避免(Carrier Sense Multiple Access with Collision Avoidance,CSMA/CA)开始时,根据上一时刻的网络负荷和数据包是否发送成功预测下一时刻的网络负荷,并用最小线性拟合法实时调整退避指数。仿真结果表明,与IEEE802.15.4标准协议算法比较,该算法提高了网络吞吐量,减小了数据包的丢包率,同时还降低了能耗。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.
文摘我国电力工业迅速发展,智能电网规模不断扩大,需要在线监控的设备和对象也越来越多,传统的监控与数据采集(Supervisory Control And Data Acquisition,SCADA)系统已无法满足电力信息化的要求。文章将ZigBee技术应用于SCADA的数据采集系统,针对系统节点业务不断变化对网络性能的影响,提出了一种网络负荷判断和最小二乘线性拟合的退避策略。在每次载波监听多路访问/冲突避免(Carrier Sense Multiple Access with Collision Avoidance,CSMA/CA)开始时,根据上一时刻的网络负荷和数据包是否发送成功预测下一时刻的网络负荷,并用最小线性拟合法实时调整退避指数。仿真结果表明,与IEEE802.15.4标准协议算法比较,该算法提高了网络吞吐量,减小了数据包的丢包率,同时还降低了能耗。
