Research On Key Technologies For Stability Routing In Mobile Ad-hoc Networks

The mobility of nodes is a main character of mobile ad-hoc networks, which can damage the connectivity of link and path and further decrease the performance of routing. Therefore aiming at this exsiting problem of mobile ad-hoc network, this thesis deeply studies the key technologies for stability routing in mobile ad-hoc networks, and proposes a series of effective solutions which can improve the robustness and the adaptability of routing to node’s motion. The study mainly contains three key technologies:the mobility-based stability evaluation, the optimized design of stability routing algorithm and the design of stability clustering algorithm.This thesis makes the following specific contributions:(1) Based on the evaluation of link stability which relies on the prediction of relative motion between nodes, a stability routing algorithm is proposed. This algorithm predicts relative motion between nodes, and then gains the relationship between distance and the average link expiration time with statistical method. Therefore, the average link expiration time can be calculated on the basis of distance. During route establishment process, the minimum average linke expiration time is used as the rule of route discovery, which ensures the route established has higher stability.(2) Aiming at the frequent route breakages of high speed nodes in nearspace mobile ad-hoc networks, a stability routing algorithm is proposed based on the prediction of the trajectory of node’s motion. It uses the semi-stillness backbone network, which is constructed by nodes with limited motion capacity in near space, to predict the trajectory of high-speed node, and then a signpost direction route mechanism is designed with the prediction results. Based on the setting and the updating of the signposts in this mechanism, the stability of route between other nodes and high-speed node is improved.(3) Due to stability routing lacks the effective adaptability to the mobility of node, a stability routing algorithm based on mobility-adaptive strategy is proposed. This mobility-adaptive strategy contains three key technologies:the bi-directional evaluations of stability, the asynchronous mobility information and link stability update, and the multipath-based route maintenance on the basis of link stability. This routing algorithm, which uses the mobility-adaptive strategy, effectively enhances the adaptability and the robustness to the mobility of node, and further improves the performance of routing..(4) The route establishment of stability routing algorithm produces many redundant RREQ packets which increases the routing overhead, so a game-based stability routing algorithm is proposed. In this algorithm, the RREQ reforwarding process is modeled as a mix strategy game which has many participants.In this game, using the link stability and the number of neighbor nodes as the parameters, the probability of RREQ reforwarding can be calculated with Nash equilibrium, so the probabilistic reforwarding of RREQ is realized which can decrease the routing overhead and improve the performance of stability routing.(5) The mobility of network topology is a key factor in affecting the route stability, so aiming at the dynamic topology of mobile ad-hoc network, a motion similarity evaluation-based stability clustering algorithm is proposed. The core of this algorithm is the motion similarity evaluation model. This algorithm uses it to evaluate the node stability, and chooses the nodes which have optimal stability to construct clusters.Furthermore, guest node and clusterhead competition threshold are set to reduce the frequency of clusterhead change. Based on all above technologies, the higher stable logic topologies can be constructed and benefit the stability routing.Above all, the proposals help promote the route stability in mobile ad-hoc networks, ensure the continuity of data transmission and improve thr routing performance.