Research On Channel Assignment In Multi-radio And Multi-channel Wireless Mesh Networks

As a new network structure,wireless mesh networks have some characteristics suchas high transfer rate,wide coverage, flexibility and lower cost etc,which have a distinctadvantage in the “last mile”wireless broadband access. Multi-interface and mul-ti-channel technology can further increase the capacity of wireless mesh net-work,however, due to the limit of radio spectrum resources,there are many constraintsin the process of channel assignment. How to make full use of the limited spectrum re-sources to improve network transmission performance become an important part ofwireless mesh network research. This paper pays more attention to improving the net-work capacity of the wireless mesh networks and the utilization of the radio channel,mainly discusses the problem of channel assignment in multi-Radio and multi-Channelwireless mesh networks.Main works of this paper are summarized as follows：Firstly, an innovative interference model is proposed for multi-interface and mul-ti-channel wireless mesh network. Due to the broadcast nature of wireless media,thereare a lot of inter interference and intra interference. If we consider the use of otherwireless devices in the same frequency, interference will become more complex.In thispaper, The interference model permits to take into account the actual signal power re-ceived from each interference source, the interference produced by sources external tothe wireless mesh network, the link utilization factor and directive antennas.The esti-mate result is more close to reality and has strong adaptability.Secondly, Starting from this new model, we propose a centralized rank based in-terfence and traffic aware channel assignment algorithm for multi-interface and multi-channel wireless mesh network.The rank of each node is computed based on the aggre-gate traffic,the degree of node,from the gateway,and the number of NICs per node.Then，once the rank of each node has been computed, the algorithm traverses the mesh net-work in decreasing order of rank(node), assigning channels to the radios of node. Eachnode select the channel with minimum interference according to the interference modeland using the greedy algorithm.so that the aggregate interference is minimal and get lo-cal optima.Thirdly,we extend the NS2simulation software so that it support multi-interfacesand multi-channel network simulation.we simulate and evaluate the proposed channelallocation algorithm on the extended the NS2simulation platform,and analysis the resultcompared with the CCA and CLICA algorithms from throughput and end-to-end delay.Experiments show that the proposed channel assignment algorithm can improve thenetwork throughput and utilization of channel to a large extent.