移动自组网DSR协议路径缓存策略优化

Optimized Caching Strategies in DSR Routing Protocol for Wireless Ad Hoc Networks

移动自组网按需机制路由协议只是在有分组发送时,才启动路径发现机制搜索到达目的节点的路径。为了避免每发送一个分组都启动路由发现机制,必须利用路由保存机制将预先发现的路径缓存。对这些路径进行缓存、搜索、抛弃的管理策略极大地影响按需机制路由协议的性能。该文对多次性能测试中表现优越的DSR协议路由缓存策略进行分析,针对它的不足,提出改进算法。提出修正发送缓冲器的时限,根据最近路径失效时间和缓冲器中路径状况预测将来的路径失效时间,在缓存器中根据时间、能量参数搜索最佳路径、丢弃最差路径的策略。利用ns2对4组场景进行仿真,结果显示对DSR路径缓存策略进行优化后,比较明显改进了DSR协议性能。

An on-demand routing protocol for wireless ad hoc networks is one that searches for and attempts to discover a router to some destination node only when a sending node originates a data packet addressed to that node.In oder to to avoid the need for such a route discovery to be performed before each data packet is send,such routing protocols must cache routes previously discoved.The strategies of caching,searching,droping routes affect the performance of the on-demand routing protocol greatly.This paper analyzes the disadvantages of caching strategy in DSR which performed perfectly in many tests and presents the improved techniques of modifying the timeout of send buffer,predicting the future route timeout by using the recent route lifetime and link breakage time ,and searching the best route,droping the worst route according to time and energy parameters.Simulation results show that the combination of the proposed techniques not only result in improvement of delivery ratio abut also reduce the delay and the overheads.