Research Of Multi-Flow Transmission Technology Based On Network Coding Opportunistic Routing In Wireless Mesh Network And SDN Concept

NCOR (Network Coding Opportunistic Routing), which eases the problem of poor wireless link by combining advantages of NC (Network Coding) technology and multi-path transmission in OR (Opportunistic Routing), is a transmission solution to improve throughput and robustness in WMN (Wireless Mesh Network). Currently, the key issue of NCOR is how to select the CFS, and how many coded packets should each forwarder transmit, so that higher throughput can be achieved with lower forwarding cost. If there are multi-flows in parallel transmission, problems such as difficult to gather network topology and link quality, long convergence time of algorithm, adapt difficultly to dynamic network conditions and poor traffic scheduling in multi-flows exist in distributed solution.In this thesis, the thesis proposed a new way that apply centralized control of SDN (Software-defined Networking) to NOCR to solve the two problems, one is that overhead of gathering network topology and link quality is too large, the other one is that traffic scheduling in multi-flows is difficult. The thesis mainly works on the following issues:1. This thesis design a new algorithm to periodically gather network topology and link quality which using centralized control of wnSDN. And, the simulation results show the validity and superiority of the algorithm.2. Research how to select the CFS, and how many coded packets should each forwarder transmit in multi-flows, the author establish NCOR throughput maximization model and design a mechanism to select CFS and forwarding credit of each forwarder to improve network throughput.3. Research SDN technical in Wireless Mesh Networks. Because wireless channel is limited and fallible, implement of SDN in WMN is different from wire network. Therefore, characteristics of WMN should be considered, when implementing SDN in WMN, including the packet format for the communication between controller and general node, format of flow table, learning routing path from general node to controller, reliable method of sending control packets and guarantee of controller reliability.4. Multi-stream transmission system is designed and implemented in wmSDN. And, the simulation results show the validity and superiority of the multi-flows transmission in wmSDN.