Research On QoS Routing Of Wireless AdHoc Networks

AdHoc networks are mobile and wireless networks without the support of any preestablished infrastructure, which is typically characterized by self-organizing, no centralized access, rapid deployment, dynamic topology, multiple hops, and so on. Due to such characteristics, AdHoc networks have great potentials in many applications such as military combat readiness, disaster recovery, environment monitoring. Now, with the prevalence of multimedia applications, it has become an important research field to provide QoS in MANETs.Mobile AdHoc networks have a lot of characteristics such as multi-hops, limited bandwidth resource and dynamic network topology, which is difficult to discover and maintain routing path, especially in large scale networks building long routing path from the source to the destination that satisfies the QoS, it has brought the new challenge for the network researcher.This thesis is the extensive research on how to provide routing protocols with QoS guarantee in mobile AdHoc networks by analysing current relevant research contributions.Firstly, this thesis introduces the concept, characteristic and application of AdHoc networks, analyzes the current situation and the problem in the research,studies and analyzes the table driven protocols and on demand protocols supporting the QoS of AdHoc networks routing protocols deeply.And then, introduces QoS parameters, and gives a model of bandwidth and delay. The protocol chooses the QoS routing path mainly based on the bandwidth and takes the end-to-end delay of the link as optimization objective.At last, this thesis mainly researches about the AODV protocol, AODV protocol is considering mainly based on "the shortest path", on one hand, it may bring about the too busy nodes in some paths, which can make the network overcrowd and delay, on the other hand, the nodes are too busy, which can cause the energy of the nodes to consume quickly and shorten the life of the network to some extent; in addition, AdHoc networks have the characteristic of highly dynamic, topology structure changes frequently, which can make the path break easily. To solve these questions, this thesis lead into the concept of Leisure Degree and Link Expiration Time of the nodes, and take the weight of both as the condition for path choosing. On the condition of satisfing the bandwidth and delay, we choose the path with the largest weight as the path for transmission, and get the modified protocol-LLAODV.This thesis analyzes and compares the performance of LLAODV protocol and classic AODV protocol on the NS2 platform. Experimental results indicate that LLAODV which based on bandwidth and delay enhances the packet delivery rate, reduces the routing cost and delay,extend the life of networks.