Research On Cross-layer Joint Optimization Technology Based On Network Coding And Opportunistic Routing In Wireless Mesh Networks

NCOR(Network Coding Opportunistic Routing),which eases the problem of high packet loss rate of wireless links by combining NC(Network Coding)technology with OR(Opportunistic Routing),is a transmission scheme to improve throughput and reliability of wireless mesh networks.In this thesis,network coding and opportunistic routing technology are introduced into wireless Mesh networks,then coordinated with transmission resource scheduling and rate control mechanism to achieve global network throughput maximization,and optimized delay performance.Firstly,NCOR is introduced into wireless Mesh network based on SIC technology,and the cross-layer optimization model is established.Then global maximization algorithm is designed.The maximization problem of global throughput rate is decomposed into three subproblems of source rate control of transmisstion layer,routing of network layer and scheduling of MAC layer.In routing problem,credit concept is introduced to implement CFS selection and forwarding responsibility assignment.A greedy scheduling algorithm based on queue length is proposed in scheduling problem.The problem of each layer is optimized independently,and the inter-layer coordination is realized through the interaction of node queue information to form a cross-layer optimization algorithm to achieve maximum global throughput.Secondly,based on the throughput maximization model,end-to-end delay constraint is added,and a global throughput maximization model with delay guarantee is proposed.Compared with previous model,the model has an additional method of controlling average end-to-end delay by delay weight in source rate control problem of transport layer.The problem of each layer is optimized independently,and achieves inter-layer coordination through information exchange,to optimize network throughput and provide delay protection.Finally,based on NS3 simulation platform,cross-layer joint optimization framework based on SIC and NCOR in wireless Mesh network is designed and implemented.Then simulation results of the proposed algorithm are analyzed.The experimental data shows that the proposed joint algorithm has better performance in terms of global throughput and average end-to-end delay,compared with traditional routing protocol MORE.