Research And Development Of Local Repair Policy For Ad Hoc Network

With the continuous development of technology, the wireless communication will be the future development trends of communication technology. As a branch of wireless communications, mobile ad hoc networks, which can be quickly deployed and applied without existenting network infrastructures, especially applicable for battlefield environments, disaster relief, filed research and other situation. Therefore, Mobile Ad Hoc network is got more and more attention。Different with traditional wired and wireless networks, each node in Mobile Ad Hoc network not only sends and receives data as the host, but also runs route protocol as a router in order to forward data for other nodes. Besides, nodes'movements in Mobile Ad Hoc network can be random and arbitrary, which makes the topology of Mobile Ad Hoc network change frequently and unpredictablely, so routing protocols should take the responsibility for maintaining the effectiveness of the link, And, when necessary, reconstructing the broken routes. With some other special Features of Mobile Ad Hoc network, such as highly dynamic topology, make the traditional routing protocols like distance vector and link state routing protocol not applicable for MANET. So in order to support the operation of Ad Hoc networks, routing protocols must be appropriate, while the existing Ad Hoc routing protocols including on-demand routing protocols and table driven routing protocol, their performance are different, but can be compared and measured quantitatively.This thesis first reviews and outlines the recent proposed on-demand routing protocol and compares their performance. Then, makes a detailed analysis about the local repair strategy of AODV routing protocol, and points out the advantages and disadvantages, and for these deficiencies this thesis presents a improved protocol called AODV-BNS (AODV Based on Node Stability) routing protocol. the broadcast range of AODV local repair strategy is too large than needed, resulting in to many redundant routing overheads, AODV-BNS uses a repair strategy with smaller range called small area local repair to replace the local repair strategy, the using of small area local repair can reduce the control overheads of route repair. AODV local repair rely only on the upstream nodes to repair broken chain, the link may become instability after the repair, so the AODV-BNS proposes a measurement called node stability, intening to estimate whether a node is capable to repair the broken link. And if the upstream node can't meet the qualification of route repair, the AODV-BNS use back-hop routing strategy to repair the broken route. Then, using the Network Simulator NS2 (Network Simulator 2) to simulate the AODV routing protocol and AODV-BNS routing protocols. The results showed that AODV-BNS performs better than AODV at high load conditions.This work is supported by National Nature Science Foundation of China (NO.60970064), National Key Basic Research Program of China (NO.2011CB302601), Open Fund of the State Key Laboratory of Software Development Environment (Grant No.SKLSDE-2011KF-01), New Century Excellent Talents, China (No. NCET-08-0806), Fok Ying-Tong Education Foundation, China(Grant No.121067), the Fundamental Research Funds for the Central Universities(2011-Ⅱ-003) and the National High Technology Research and Development Program of China (863 Program) under Grant No.2009AA043303.