基于竞争窗口递减因子自适应调整退避算法

包括IEEE802.11、802.15.4标准在内的许多无线网络协议都采用二进制指数退避机制管理数据的重发。在动态分布式的网络环境中,二进制指数退避算法固定的竞争窗口递减方式难以适应动态变化的网络规模。针对这一问题,提出了一种改进的回退机制,该机制通过引入竞争窗口递减因子,自适应地调整无线节点的等待时间,以实现网络吞吐量的最大化。同时,在算法实现上提出一种启发式算法以跟踪网络中竞争节点数量的改变。在IEEE 802.11DCF协议中以相同的物理层参数进行仿真,结果表明改进算法提高了网络吞吐量,降低了分组平均接入时延。

A self adaptive adjusting backoff algorithm based on contention window diminishment factor

Numerous wireless network protocols, including IEEE802.11 and 802.15.4, manage the retransmission of data frames with the binary exponential back off (BEB) mechanism. In a dynamic distributed environment, the fixed way the BEB adjusts contention window cannot adapt to the ever changing network size. To solve this problem, we propose an improved self adaptive adjusting back off algorithm based on contention window diminishment factor. By introducing the concept of contention window diminishment factor, the algorithm adaptively adjusts the waiting time of wireless nodes to realize the network throughput maximization. In addition, in order to track the changing number of competition nodes, we propose a heuristic algorithm when implementing our new back off scheme. Simulations on the same physical layer parameters of the IEEE 802.11 DCF protocol show that the proposed algorithm can improve the throughput and decrease the frame delay.