A Research And Implementation Of An AODV Routing Protocol Based On Relative Mobility And Links’ Stability

A mobile Ad Hoc Network (MANET) is made up of a set of wireless nodes, with a frequently changedtopology. The communication of neighboring nodes does not depend on any fixed network infrastructures.It uses a distributed management mode, and is aware of dynamic links with a high degree of autonomy.MANET has broad application areas, so in recent years MANET has become one of the hot topics at homeand abroad, especially the routing algorithm researches about it. Because of the characteristic of thenetwork’s architecture with dynamic topology, so the traditional routing protocols do not perform verywell. So providing a stable and efficient routing algorithm for mobile Ad Hoc network is of significancefor us, thus creating the Ad Hoc On-demand Distance Vector Routing protocol. AODV has been widelyused for many reasons. However, growing end-to-end delay, excessive consumption of single node’senergy and a bad routing architecture has drawn attention to researchers. Therefore, improving AODV tomake it more adapted to the mobile situations is of great importance.This thesis concerns on the routing algorithms for MANET, proposing an effective AODV routingalgorithm based on relative mobility and links’ stability, and combined with backup strategy, withconsideration of relative mobility and nodes’ remaining energy, which are the main reasons for adding upnetwork burden and affecting communications. As a mature protocol, AODV draws lessons from manyother algorithms. This modified routing protocol takes comparatively stable and more energetic routes, aswell as backups for the responding mechanism, which guarantees the stability of the network to a certainextent. The main tasks in this thesis are:(1)The architecture for choosing routes based on relative mobility and backup routes. In mobile AdHoc network, the relative mobility between neighboring nodes causes its moving out of communicationrange, which is a major cause of link breakage. Therefore, the quantization of relative mobility can help uschoose more stable route, which is significant for network’s communication quality. At the same time, toensure links’ healthy, our algorithm will back up a route for emergency in every necessary route discovery process as responsive actions. Meantime, regular update algorithm for back up route guarantees it’sreal-time.(2) Links’ stability. The energy of nodes in mobile Ad Hoc network is limited. If the energy depleted,nodes will lead to the interruption of the communication link, resulting in instability. In this algorithm,when a node receives a route request packet, it needs to judge the level of its remaining energy to decidewhether deliver it or not. If the remaining energy is below a certain threshold, the packet is not forwardedto reduce flooding effect. If a node is able to forward route request packet, it needs to maintain theminimum remaining energy field of a RREQ, which reflects the average remaining energy of the wholelink for reference. The purpose of choosing the route with a bigger minimum remaining value is to ensurethe links’ stability when the differences of relative mobility are narrow.(3) Simulation using OPNET modeler. According to the three layer modeling mechanism of OPNET,we simulate the modified algorithm and compare with other relevant protocols under the same simulationenvironment.