Research On Network Coding Based Routing Technologies In Wireless Mesh Networks

Network coding was proposed by Rudolf Ahlswede et al. in 2000, which allows and encourages intermediate nodes to process packets. The great advantage of network coding is for transmission rate to reach the upper bound of network capacity determined by max-flow min-cut theory in multicast. Recently, network coding in wired networks which have stable topologies has been concerned extensively, but the research and application of network coding in wireless networks are still in the primary stage. Based on the characteristics of wireless network, this thesis researches network coding based routing in wireless mesh networks and critical technologies in practice. The major contents of this thesis are listed as follows:Chapter 1 mainly introduces the basic idea, advantages and disadvantages, and research significance of network coding, presents the system structures and routing in wireless mesh networks, and analyzes the characteristics for introducing network coding into wireless mesh networks.Chapter 2 analyzes the characteristics of wireless networks suitable for network coding, presents applications of wireless network coding in increasing network throughput, saving energy, enhancing robustness and security etc., analyzes the research significance of wireless network coding, and concludes the hot research directions in the present and future.Chapter 3 studies on network coding based routing in wireless networks for multicast and Unicast, based on the characteristics of wireless mesh networks. The main problem in multicast routing with network coding is choosing which packets to code together and using which coding strategy. On Unicast routing, this chapter analyzes three kinds of topologies in wireless mesh networks in which there may be network coding opportunities, studies two ideas of wireless network coding: opportunistic routing and coding aware routing, and describes several existing wireless routing protocols with network coding.Chapter 4 studies critical technologies in the implementation of network coding based routing in wireless networks. Queue scheduling with network coding in multicast and Unicast systems is the focal point of this chapter. This chapter proposes a CRP-based coding retransmission policy and an active network coding policy for queue scheduling, analyzes and compares the performance of each strategy. Chapter 5 proposes a flow based wireless network coding strategy (FNC), integrating with the structure and routing in wireless mesh networks. FNC uses hop-by-hop routing protocol to get prior paths, detects coding opportunities by using the information in each node's routing table, and continuously encodes those packets from different flows which satisfy the coding conditions during the period when the network is relatively stable. Simulation results show that FNC can get better throughput and packet delivery ratio than the strategy without network coding and COPE.Chapter 6 concludes the whole thesis and discusses the further work.