Research And Implementation Of Multi-interface OLSR Protocol In Wireless Mesh Network

The rapid development of wireless network technology enables people to access the Internet anytime and anywhere. Presently, more and more researchers contribute to the research on wireless network, providing a strong support to the development of wireless network. As a supplement and extension of wired networks, Wireless Mesh Network has become a hot topic in the field. With dynamic self-organizing, self-configuring, high capacity and other characteristics, Wireless Mesh Network can be a good solution to the "last kilometer" broadband access, caused an increased costs and other issues in order to cover "blind spots". However, the capacity constraints of the wireless Mesh network become the major factor restricting it development. In order to solve the capacity problem of Wireless Mesh network, we propose a multi-interface multi-channel protocol.In this paper, the OLSR protocol in wireless Mesh networks is studied, and the research is based on the multi-interface multi-channel expansion. After analyzing the research of a large number of multi interface multi-channel routing protocols, a new OLSR protocol is proposed, which is based on the research of multi interface and multi-channel. The purpose of improvement scheme is to use the features of proactive routing protocols, improving the protocol of the adaptability and the ability to automatically adjust of dynamic network structure, introducing multi-interface multi-channel strategy to reduce end to end delay, improving network throughput, and improving the reliability of data transmission further.First, the MobileNode model for NS2 is modified. Each node of the original MobileNode model in NS2 contains a link layer and physical layer components, the transmission of messages between nodes by calling the appropriate member. When a node has multiple interfaces, it will not reflect the advantages of multiple interfaces only in one group member, and therefore MobileNode model needed to be extended. To enable each interface of work independently, nodes need to copy a set of link layer and physical layer components, using multiple interfaces send and receive data simultaneously, for the purpose multi-interface extension, increasing network throughput.Secondly, some optimizations need to make for OLSR protocol. A scheme proposed in this paper, in a multi-interface OLSR network, each node is assigned only one IP address, and distinguish different interfaces on the same node by a new definition of the local interface index. OLSR protocol data structures also need to be extended. Link Set table and Routing table also need to distinguish the interfaces and, therefore, appropriate interface index needed to add the to these data structures. The data transfer mode of OLSR network in multi-interface multi-channel is different from situation of single interface, contains two transmission modes, transferring from a particular interface and transferring from all interface.Finally, through the modifications of the NS2 simulation programming, realize emulation of multi-interface multi-channel OLSR protocol completely. Under specific network environment, simulation experiments make comparative in multi-interface multi-channel OLSR protocol with single interface OLSR protocol, and multi-interface multi-channel OLSR protocol with multi-interface multi-channel AODV protocol. The data of experiments show the throughput of multi-interface multichannel OLSR protocol has been enhanced, the end to end delay decreased, the stability of the network also increased.