Network Coding Based Routing In Wireless Networks

With the rapid development of wireless communication techniques, an exciting era of wireless information comes into our lives. Wireless Ad-hoc networks have some promising properties in terms of non-infrastructure, self-configuration, self-healing and self-organization, which not only attract much attention in the field of military research, but also get promoted in the daily communications. Especially in recent years, the novel network frameworks, wireless mesh networks and wireless sensor networks, exhibit the great potential of multi-hop wireless networks in special wireless applications.As one of the most popular research areas in communication, network coding has overthrown the traditional store-and-forward relay method in routers by intro-ducing coding mechanism in the transmission of information, which efficiently uti-lizes the computational resources in the intermediate communication nodes and brings an extraordinary throughput gain for the whole network. In wireless networks, network coding can provide solutions to deal with the poor wireless communication environment and make an improvement on the network properties, such as raising network throughput, optimizing transmission delay, reducing transmission power, enhancing the security of network and so on.Based on the classic wireless routing mechanisms, in order to further increase the transmission efficiency, many up-to-date routing metrics and routing protocols have been proposed, which largely improve the conditions of wireless transmission. With the rapid development of network coding theory, many coding-aware routing mechanisms have been proposed. Compared with the passive coding mechanism in the network, coding-aware techniques can find more coding opportunities, which raise more throughput in the wireless networks.In this paper, under the background of network coding and related routing me-chanisms in wireless networks, we make the following contributions.Routing oblivious network coding mechanism makes the coding decisions on the opportunities in the network, and coding-aware routing can provide more opportunities of network coding. In multi-hop wireless networks, multi-hop network coding (MNC) rules are proposed, and their coding gains are analyzed in this paper. We also dig into the additional problems in MNC, and analyze the overheads when applying this mechanism. Traffic patterns in multi-hop wireless networks will affect the coding gains of MNC. So we analyze the typical wireless scenarios, make the abstraction of traffic flows into some traffic factors, and qualitatively analyze the rela-tions between the traffic factors and the gains of MNC. In addition, throughput boundary with MNC is formulated in the perspective of flows. Our evaluation also shows that particular MNC should be applied accord-ing to different traffic patterns to maximize network throughput and reduce the systematic overhead.Network coding based routing techniques focus on the coding opportuni-ties in the network, and make the strategy to find paths with more coding structures. In this paper, we proposed a novel network coding based flow aware routing protocol (FAR), which modifies AODV to provide coding aware and flow aware properties. When a new flow comes into the network, FAR will detect the exiting flows, and find a path with more coding op-portunities and less wireless contentions, on which the flow can achieve more throughput. During the period of routing maintenance, FAR will monitor the alteration of other flows, and make the flow reconstruction if necessary. At last, we conduct simulations in ns-3, and analyze the simula-tion results.