The Research Of Key Technologies On Ad Hoc Network

Ad Hoc network with the features of distributed, no-center, self-organization,multi-hop routing and flexible networking is one of the hotspots in current wirelesscommunication field, and has very broad application prospects. This dissertationcarries out deep researches in several important techniques of mobile Ad Hoc network,which include the mechanism of repair route, cross-layer multi-channel assignmentprotocol and a dynamic feedback power control method for Ad Hoc network. Themain contributions of this dissertation are as follows:(1)Based on the AOMDV protocol, the dissertation puts forward an algorithm forrepairing routing. Add information “the second hop” in the route table which obtainedthrough the packet of RREP and RREQ. Upstream node of breakpoint can build up abypass path with the downstream node of breakpoint according to this informationwhen path failed，data can be transmitted normally through this bypass around thebreakpoint. Simulation results show that this strategy can improve packet delivery rateand meanwhile effectively reduce the normalized routing overhead and the frequencyof route discovery.(2)A protocol of cross-layer multi-channel assignment CMA-AOMDV wasimplemented through exchanged channel status message between MAC layer androute layer. In this protocol, nodes collected status of data channels and establishedavailable channel list at MAC layer; routing protocol putted this list into route controlmessages directly, then assigning data channels for link between nodes when buildingroute. Compared with existing multi-channel assignment protocol, this protocolimproves the performances of network throughput, packet dropped rate and controlmessage overhead.(3)Traditional Ad Hoc networks transmit data with fixed power, this workingmode seriously affected the node and the network’s lifetime which is limited by theenergy stored in mobile node. To address this issue, this dissertation proposes toobserve the linear change of SIR (signal to interference ratio) of receiving node tocalculate the required transmitting power of sending node, so as to dynamically adjust the transmitting power. Simulation results show that this method can effectivelyreduce the energy loss of nodes and increase the network lifetime.