异构网络中基于MPTCP的协作拥塞控制方案

提出了一种基于MPTCP的协作拥塞控制方案。在拥塞避免阶段,该方案首次以马尔科夫链模型为基础,对异构网络中各条路径上未被确认的数据包个数进行预测,进而计算出各条路径所能承载的最大数据量。若网络拥塞窗口值大于各条路径所能承载的最大数据量中最小值的2倍,则启动协作拥塞控制机制。在协作拥塞控制机制下,根据AIMD算法的加性增加准则调整拥塞窗口,若网络拥塞窗口值大于各条路径所能承载数据量之和,则结束协作拥塞控制机制,执行传统的TCP慢启动算法。为了提高慢启动阶段的带宽利用率,对TCPW(TCP Westwood)带宽估计算法进行改进,使路径可用带宽的估计更准确,从而提高慢启动阈值设置的合理性。仿真结果表明,在保证异构网络负载均衡及单条TCP流公平性的前提下,该方案能够增加成功传输数据包的数量。

Cooperative Congestion Control Scheme Based on MPTCP in Heterogeneous Network

A cooperative congestion control scheme based on MPTCP was proposed.At the stage of avoiding congestion,the unconfirmed data packets transferred in each route in heterogeneous network are predicted based on the Mar-kov Model,and then the sender calculates the maximum amount of data that each route can carry.If the network congestion window is more than two times higher than the minimum of the maximum amount of data that every path can carry,the mechanism of cooperative congestion control will be started.Under the cooperative congestion control mechanism,the network congestion window should be adjusted according to the norm of additive increase of AIMD algorithm.If the sum of the carrying capacity of each path is less than the network congestion window,the cooperative congestion control mechanism should be ended,and then traditional slow start of TCP algorithm is implemented.To enhance broadband utilization at the slow start stage,this paper modified the broadband estimation algorithm of TCPW(TCP Westwood) to make the estimation of available broadband in each path more accurate and improve the reasonability of slow start threshold setting.Simulation results demonstrate that the proposed scheme can increase the number of successful transmission data packets while guaranteeing the load balance and fairness between single TCP flow and MPTCP flow.