Research On Channel Assignment In Multi-channel Wireless Mesh Networks

As the development of wireless technology, wireless networks have been gradually applied to many aspects of social life for different purposes. Wireless mesh networks is an emerging multi-hop wireless network architecture that can effectively improve the capacity and coverage of wireless network,which is now the focus of academic and industry. Unlike the traditional wireless network, wireless mesh networks can be the wireless backbone networks that connect traditional wireless networks and the Internet, as well as the self-organized networks for users'personal purposes. Therefore how to improve the network capacity of wireless mesh networks is the practical problem that should be solved as soon as possible. Multi-interface multi-channel technology is one of effective measures to enhance the network capacity, but in these networks, the actual situation is that the number of total network interfaces is more than that of the available channels, and the number of interfaces per node is less than that of the available channels. So how to allocate channels among the interfaces is the difficulty with application of the multi-interface multi-channel technology. Main works of this paper are summarized as follows:1. A interference estimation method is proposed for assigning fixed channel per node. In this method, we model a two-way network connection graph and a node confliction graph according to the communications in hybrid channel assignment. Then a weighted two-way connection graph is established using the models with the concept of probability, upon which the computation of link interference estimation and node estimation is depended.2. A coordination mechanism is proposed for communications based on time slots, which does not need a special control interface and can minimize the complexity of channel synchronization. The mechanism divides the time for dynamic interface into broadcast slots and data slots, while the former is just for broadcast packets in broadcast slots and the latter is used for general data packets. This method not only brings down the complexity, but also guarantees the timeliness of broadcast information.3. A channel assignment protocol is accomplished upon the interference estimation and the coordination mechanism. We have improved the structure of wireless node,and expanded the NS2 to support multi-interface multi-channel communication in wireless mesh networks, which can be the foundation for next research.4. At last, the limitation is pointed out and some corresponding solutions are proposed with the direction of future research.The simulations show that both the proposed channel assignment for fixed interface per node and the hybrid channel assignment protocol can effectively improve the throughput of wireless mesh networks and reduce the end-to-end delay of data packets, while the expanded NS2 supporting the multi-interface multi-channel network is convenient for these networks.