机会网络中一种提高TCP性能的跨层改进算法  

A cross-layer design for improving TCP performance in opportunistic network

作　　者：左朝树[1] 雷仕英[2] 李云[2] 

机构地区：[1]保密通信重点实验室,四川成都610041 [2]重庆邮电大学无线信息网络研究中心,重庆400065

出　　处：《智能系统学报》2011年第2期152-159,共8页CAAI Transactions on Intelligent Systems

基　　金：国家自然科学基金资助项目(61071118;60702055);重庆市杰出青年科学基金资助项目(CSTC2010BA4010);重庆市科委自然科学基金资助项目(CSTC2009BB2279)

摘　　要：针对机会网络中TCP与传染路由结合时,传染路由的"洪泛"特性和机会网络的间断特性会使得TCP性能变差的问题,提出了一种基于传染路由协议和TCP/Reno协议的跨层改进算法——ACK-EPI.该算法对连接开始阶段的慢开始门限值进行修改,以避免因网络错误进入拥塞避免阶段而导致拥塞窗口增长速度过于缓慢.同时,为了避免网络中已经成功交付但仍存储在网络中其他节点的数据包的复本继续在网络中存在并扩散,造成网络资源浪费,算法还利用ACK作为到达通告来删除这些冗余数据包.通过深入的仿真分析和比较,结果表明ACK-EPI算法能明显改善TCP性能.In opportunistic networks,the infectivity of epidemic routing and intermittent connectivity of network would degrade the performance of TCP when TCP works with epidemic routing.In order to improve the performance of TCP in opportunistic networks,a cross-layer design,named ACK-EPI,which is based on epidemic routing and TCP/Reno,is proposed.The algorithm renews the threshold of slow-star at the beginning of TCP connection to prevent the network from incorrectly turning into congestion avoidance phase so that the network can keep the regular increment speed of congestion window.At the same time,to avoid the packets that have already been delivered being forwarded again in the network,the design makes use of ACK to delete the redundant packets.The stimulation results show that the proposed algorithm can ultimately increase TCP performance in opportunistic networks.

关 键 词：机会网络 TCP/Reno 传染路由协议 ACK-EPI 

分 类 号：TN929.5[电子电信—通信与信息系统]