关键词: 二进制指数退避算法（BEB）, 周期, 采样, 竞争窗口, 吞吐率, 碰撞, 公平性

Abstract: Aiming at the defects of backoff window adjustment mechanisms in Binary Exponential Backoff（BEB） algorithm and fairness of each node when data transmited, this paper proposes a Periodic Two-step sampling Exponential Backoff（PTEB） algorithm. PTEB firstly introduces the concept of the period sampling, on this basis, introduces a competitive channel parameters [Qc] and network congestion parameter [Qb]. [Qb] and [Qc] are calculated in the sampling period, and defines the contention window adjustment formula based on the values of these two parameters. Adjustment of the window needs to go through two stages, each stage corresponds to different formulas. Simulation results show that PTEB algorithm can effectively reduce the collision number of nodes, increase the network throughput rate and fairness between the nodes.

Key words: Binary Exponential Backoff（BEB）, periodic, sample, contention window, throughput rate, collision, fairness