Research On Topology Control And Channel Assignment Algorithm For Multi-radio Multi-channel Wireless Mesh Networks

Wireless Mesh Networks has the characteristics of multi-hop and self-organizing,so that it can effectively provide users with flexible wireless broadband access service.At the same time, due to advantage of the wide coverage, low construction costs andnetwork robustness, more and more attention has been attracted.However, in the traditional single radio WMNs, nodes can only work in the samechannel, making the network be low capacity and large delay because of the conflict.Based on this, scholars put forward a direct and efficient way which is to configure amultiple of RF interfaces for each mesh node, so that it can simultaneously use amultiple of non-interfering channel for communication.Multi-radio Multi-channel Wireless Mesh Networks can increase network capacityand reduce delay, but a lot of new problems have been brought up. For example, thenetwork topology becomes more complex because of the introduction of multi radios.And it causes the channel assignment problem because of the multi channels. So how tomake full use of the advantages of multi channels and multi radios becomes the criticalsolution to the current problems of WMNs.In response to above situations, the paper carried out the research work of thefollowing three aspects.Firstly, from a theoretical point of view, the multi-radio multi-channel WMN hasbeen analyzed and researched in the thesis. According to discussion on how the numberof RF interface and channel number impacting on network capacity, the maximumcapacity about toO (min(k, m2/t))was drawn, where k is the channel number, mrefers to the number of RF and t is average node degree per neighbor. On this basis,the power control for the impact of network capacity was analyzed. When the amount ofchannel is limited, in order to acquire the maximum network capacity, the power shouldbe as low as possible.Secondly, based on the above analysis, we modified a based power controltopology control and channel assignment joint algorithm (BPTCA) in the thesis. Thealgorithm can ensure the network topology connectivity, and minimize interference between links by adjusting the transmission power, to optimize the network topology.And based on the optimized network topology, by calculating the load level and theinterference index of the channel, the channel assignment problem is solved. TheBPTCA does not need to know the link’s load. According to computing the interferenceindex of the channel, it could guarantee the interference between the links as low aspossible.Lastly, the BPTCA algorithm was compared to CCA. The simulation results showthat the BPTCA can effectively improve network capacity and reduce network latency.Then, the BPTCA algorithm was compared to similar centralized channel assignmentalgorithm C-HYA and BFS-CA. In the same simulation environment, the networkcapacity of the BPTCA algorithm was12.5%higher than the network capacity of theC-HYA. The network capacity of the BPTCA algorithm was10.6%higher than thenetwork capacity of the BFS-CA.