Research Of Channel Assignment And Efficiently Usage Of Channel Resource Based On Wireless Mesh Network

As the development of wireless access technology, WMN(Wireless Mesh Network) has attracted more and more attention due to its low cost and efficiency. WMN usually works as access network, which makes it has the feature of aggregated load. Number of mesh clients is also changeable. Multi-radio Multi-channel has brought WMN great improve in network capacity, which also makes channel assignment problem vital. Method to make use of the finite channel resource and partially overlapped channels to improve network performance has attracted much more attention.Since the scarcity of channel resource, only assign orthogonal channels to links will result in waste of channel resource. In this paper, usage of partially overlapped channels is considered to make full use of channel resource and thus improve network capacity. ALPOCA(Aggregate Load based Partially Overlapped Channel Assignment) is designed firstly. A connected tree-based topology based on the original topology is constructed in ALPOCA. Then interference is analyzed and partitioned into near interference and far interference. Near interference is also partitioned into different kink and bandwidth loss of each situation as well as far interference is analyzed. At the same time, measurement of interference also takes amount of flow into consideration, which fits more with the real network situation and makes the channel assignment result more accurate.LAPOCA(Load Aware Partially Overlapped Channel Assignment) is then proposed. LAPOCA is the improved version of ALPOCA. Since ALPOCA is static channel assignment algorithm, it cannot fit well with change of load. LAPOCA grades the variety of load into different hierarchies and set two threshshould. When a node detects the change of node value has exceeded the first threshould and within the second threshould, it will adjust its contention window; when vital nodes detects the change of node value has exceeded the second threshould, it will trigger channel switch on the path. If the proportion of number of nodes that need to switch its channel to number of all nodes has exceeded a particular value, then the network will start channel-reassignment process.MATLAB and NS2 are used to do the simulation. Simulation results proved that ALPOCA can measure interference in network efficiently and thus improve network thourghput and reduce delay; simulations results also proved that LAPOCA can response to change of load efficiently with the methods of adjusting contention window and partially channel switching.