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

Wireless mesh network expanding the coverage of wireless local area networks and having the flexibility of ad-hoc networks, is a new kind wireless network with high-capacity and high-bandwidth, which is the integration of the advantages of wireless local area networks and wireless ad-hoc networks. Currently, the focus of the study of wireless mesh network is routing, and many scholars in our country at home and abroad are also carrying out researches in this area. Among researches, the opportunistic routing proposed breaks the transmission mode of traditional fixed next-hop of routing, which uses set of the forwarding nodes as the "next hop" to enhance the utilization of spectrum space. The more influtial is opportunistic routing based on network coding. It exploits processing capacity of coding nodes for transmiting data, which improves the performance of opportunistic routing in routing metric. However, the study of opportunistic routing based on network coding is not very mature, there are many places to improve.First,we give a detailed analysis and study in opportunistic routing protocols based on network coding,and propose a opportunistic routing algorithm BNC_OR (Blanced Network Coding and Opportunistic Routing) with Coding-Aware,which takes into account coding opportunities of forwarding nodes and considers how to select forwarding nodes.Unlike existing algorithms, it uses number of expected transmission as a basis of selecting forwarding nodes and adds Coding-aware in transmission number.we can also adjust the coefficients A and8to ensure the weight of network coding in routing metric,which make BNCOR achieve the highest throughputs at the same time to improve coding opportunities as much as possible.NS-2(Network Simulation-2) simulation results also show that the proposed algorithm,which is relative to the CORE, increases throughputs of system and reduces the end-to-end delay.Subsequently, we analyze the potential benefits of the combination of opportunistic routing and network coding with the bit-rate selection mechanism. We develop a model for finding the optimal forwarding scheme for a multi-rate combination of opportunistic routing and network coding in a given network. Our model consists of two parts:one is the framework for the calculation of expected opportunistically coded transmission time (ExOCTT), it reflects not only coding decisions and opportunistic forwarding but also the selection of a proper bit-rate. The other is the algorithm for finding the optimal forwarding scheme to minimize ExOC_TT in a given topology. NS-2simulation results also show that considering bit-rate selection in combination with opportunistic routing and network coding has substantial benefits in terms of the expected transmission time compared to multi-rate opportunistic routing, multi-rate network coding, and a fixed-rate combination approach.