关键词: IEEE802.15.4, 载波监听多路访问/冲突避免, 指数加权滑动平均, 吞吐量, 碰撞概率

Abstract: Concerning the impact on network performance of the mobile nodes and the constantly changing data transmission rate, the authors proposed a new backoff scheme for IEEE802.15.4, which used Probability Judgment based on Network Load and Exponentially Weighted Moving Average (PJNL_EWMA) method. According to a realtime monitoring of current network status by probability judgment of network load, this method dynamically adjusted backoff exponent by EWMA when Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) began. Compared with the IEEE802.15.4 standard protocol and MBS (Memorized Backoff Scheme)+EWMA algorithm, the simulation experiments on NS2 platform show that the PJNL_EWMA algorithm not only improves the throughput of the network, but also reduces the packet loss rate and the collision ratio, significantly improving the network performance.

Key words: IEEE802.15.4, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), Exponentially Weighted Moving Average (EWMA), throughput, collision ratio