Study Of Network Coding And Fault Tolerance

Network coding is introduced by Ahlswede in 2000, which is based on the conception of network information flow. If coding is permitted by the network vertices, the max-flow bound of network multicast can be achieved, i.e. the theoretical upper bound of netwoek resource utilization, which can not always be achieved by traditional copying and routing. Furthermore, through network coding, we can obtain the benefits of saving in bandwidth, load balancing, optimizing the energy usage of energy-limited networks and so on. Now, the research of network coding has received great interests and has become one of the most attractive fields in network information theory.This thesis investigates some aspects of netwok coding with emphasis on the application of network coding to guard against link failures of multicast network. The main results and contents are as follows.1. Based on directed graph, the basic principle of network coding is addressed, especially linear network coding, and the performance of multcast based on network coding and that of traditional IP multicast are compared.2. Two algorithms of network recoding and decoding are introduced, and implementation issues of network coding in actual environment are discussed.3. The methods of traditional link-failure recovery and that based on network coding are studied. From the idea of erasure codes, we show how to construct network codewords to withstand the effect of link failures to the robustness of the multicast information transmission.Now, the study of network coding is still in its theoretical stage. Through multicast based on network coding, many advantages can be achieved, however, if network coding is used in actual environment, there are still many issues to resolve. Through the link-failure recovery based on network coding, the robustness of multicast information transmission will greatly enhanced, but we only have little work on this title, and great effort will be done to this problem.