Research On Opportunistic Routing In Wireless Mesh Network Based On Network Coding

With the rapid development of wireless networks and the rapid growth of demand for wirelessbroadband access network, the speed, quality and stability of wireless network communication have beenincreasing. Because of the advantages of low cost, high speed, easy networking and stable performance,Wireless Mesh Networks (WMN) becomes one of the very important technologies for broadband wirelessaccess network. Routing protocol is a key part of the network, which directly determines the overallperformance of the network. As research continues, opportunistic routing protocols based on networkcoding have been proposed by some scholars, which combine the network coding with routing mechanisms.Currently, using network coding and opportunistic routing technology to improve the overall performanceof WMN has become a new hotspot of current research.According to whether the packets involved in network coding come from the same data streamnetwork coding(NC) can be divided into opportunistic routing(OR) based on inter-flow networkcoding(Inter-NC) or intra-flow network coding(Intra-NC). MORE and CAOR are the typicalrepresentatives of these two types. Now researchers have made a lot of improvements based on these twoprotocols. Considering there are still some performance problems in the application of the network codingand opportunistic routing in wireless mesh network, in this thesis, we’ll study these issues combing thecharacteristics of WMN, The main research work includes the following aspects:1. We systematically introduce the background, meaning, basic concepts and the current state ofdomestic and foreign research of the routing protocol in wireless mesh network. The technology of networkcoding, opportunistic routing and the metrics of opportunistic routing are studied and analyzed separately.And the typical protocols in opportunistic routing based on network coding and their problems are thefocus of analysis. Considering that the probing cycle and the probing packet size are all fixed in the probingmechanisms of opportunistic routing based expected transmission count (ETX), we initially propose adynamic probing idea which can automatically adjust the probe cycle and probing packet size.2. On the basis of research and analysis on the route probe mechanism of MORE which is a typicalrepresentative of opportunistic routing based on intra-flow network coding and uses the fixed probingmechanisms,we introduces the dynamic probing idea into it. By monitoring the stability of theenvironment of data transmission, dynamically adjust probe cycle, reduce the impact of environmentalchange on the transmission network performance. By estimating the real packet size which is transportedby the node, dynamically adjust probe packet size, reduce the detection error of the probability of datasuccessful transmission. The dynamic probing mechanisms we proposed can not only detect the closernetwork performance to the real, improve network throughput, but also enhance the adaptability of routingprotocol on the dynamic nature of the wireless network.3. Aiming at the problem of the contradictions between coding opportunity and the number offorwarding nodes in combination of inter-flow network coding and opportunistic routing, we propose aforwarding node set selection algorithm(FNSA)in opportunistic routing based on inter-flow network coding. The algorithm gets more accurate successful transmission probability of data packets through the dynamicprobing mechanisms, and determines the optimal number of forwarding nodes through quantitative analysisof the relation among link delivery probability, transmission times and the number of forwarding nodes,and then determines the best forwarding node set. This algorithm can enhance the efficiency of datatransmission and effectively improve the throughput performance of the network.