一种基于数据重传率的无线自组织网络TCP公平性策略

IEEE 802.11 MAC协议被广泛应用于多跳无线网络的研究与示范网中，802.11协议采用RTS/CTS策略减少了隐终端 问题对无线TCP性能的影响。但在多条并行链路间，隐终端问题的存在使得中间链路节点不能有效的接入到信道，导致TCP性能和公平性严重下降。该文提出了一种新的基于传输层数据重传率方法，对于受到严重干扰的中间链路不断获取它的数据重传率，在重传率增加时动态减少802.11退避计时器竞争窗口大小，增加其接入信道能力，从而提高其TCP性能和公平性。仿真结果证明，使用基于传输层数据重传率方法，不仅能基本上保证并行链路TCP的稳定性，还可以极大地提高中间链路TCP公平性。

A Fair Algorithm for Wireless Ad hoc Networks Based on Data Retransfer Ratio

The 802.11MAC protocol has been used widely in static multihop wireless network.It reduces the effect of hidden terminal for TCP performance,but it does not remove the effect of hidden terminal fully.But,the fairness of middle links will be affected due to the hidden terminal and make the throughput badly descend.This paper proposes a new way based on data retransfer ratio.When the data retransfer ratio increase,dynamic reduce the size of contention window of backofftimer,enhance the probability of use channel and improvement the TCP fairness.The simulational results show that the proposed algorithm can ultimately avoid the instability of TCP flow and increase the fairness of middle links.