Research On Relay Cooperative MAC Protocol Based On Network Coding For Wireless Ad Hoc Network

Wireless Ad hoc Networks have a broad application prospects in the fields of war communications,environmental monitoring and medical care.Nodes can cooperate with each other for distributed data processing and transmission,which can form a virtual multiple input multiple output(MIMO)system,so as to ensure the reliability of the wireless link and obtain diversity gain.Network coding technology can increase the amount of information transmitted in a unit time slot.Its main idea is that the relay node encodes the data that is intercepted or cached and then forwards it to other nodes until it reaches the destination terminal.The effective combination of network coding technology and cooperative communication technology can improve the overall performance of the communication system,and the cooperative transmission process itself provides favorable conditions for the application of network coding.If the intermediate node performs network coding operation,encoding the cached data of the source node and its own data,and then sending the coded frame to the destination node,it can effectively solve the problem of low relay efficiency during cooperative retransmission.Therefore,how to efficiently assist the source node to transmit data for improving the transmission efficiency of the wireless network,which has become a hot topic in recent years.In this thesis,the cooperative MAC protocols were studied deeply based on network coding for the current wireless Ad hoc network.Two new protocols are proposed for the problem of relay inefficiencies.The specific achievements and innovation include the following two aspects.First,to deal with the problem that the transmission energy consumption of nodes does not be considered and unnecessary candidate cooperative relay nodes participate in competition and the control message cannot make other nodes give up competition in the current Network Coding Aware Cooperative MAC(NCAC-MAC)protocol,an high efficiency MAC protocol based on cooperative network coding(HECNC-MAC)is proposed.First of all,the candidate cooperative relay node can predict in advance whether the destination node can effectively decode the data through the design of the predictive decoding mechanism which not only can reduce the numbers of competing nodes but also ensure the successful decoding of its destination node.Second,thetransmission energy consumption of the node is considered when selectting the relay node.Finally,the redundant ETH control message relay node is removed in the process of selectting the best cooperative and the frame format of the confirmation message is modified so that the destination node can confirm the best collaborative relay node,which ultimately reduces overhead and improve the throughput of networks.Second,to address the problem that the selected cooperative relay nodes fail to make full use of coding opportunities and the destination node do not use corrupted packets to optimize the diversity gain in bidirectional cooperative MAC based on network coding,a novel bidirectional cooperative MAC protocol based on adaptive double decoding(ADD-BCMAC)is proposed.In this protocol,a coding compensation mechanism is proposed when the destination node has no data that is sent to the source node.The cooperative relay node encodes the listening data with its own data,proposing a cooperative relay node selection mechanism based on the priority of the number of frames,to improve the efficiency of selecting cooperative relay nodes;An adaptive multiple decoding method is proposed,which greatly improves the decoding success rate of the destination node,which can achieve the purpose of improving the throughput of networks?delivery success rate and end-to-end delay of date frame.At the end of the article,the full text is summarized and the further research direction is given.