一种ZigBee网络自适应退避机制

An Adaptive Backoff Mechanism of Zig Bee Networks

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。

With the rapid development of power industry in China, more and more objects are need to be monitored in smart grid, traditional supervisory control and data acquisition（SCADA） system can not meet the information requirement of smart grid. This paper uses Zig Bee technique in the SCADA system and proposes a new backoff strategy using predicting the network load and least squares linear fi t（PNL_LS） method to cope with the impact on network performance of the constantly changing data transmission. When carrier sense multiple access with collision avoidance（CSMA/CA） begins, the next time network load is predicted based on the past network load and data packet sending status, and the value of backoff exponent is dynamically adjusted by LS. Compared with the IEEE802.15.4 standard protocol, the simulation results show that the PNL_LS algorithm not only improves the throughput of the network, but also reduces the packet loss rate and energy consumption, signifi cantly improves the network performance.