Research On Video Multicast Transmission Technologies Over Wireless Mesh Networks

Wireless multicast has much difference to the means of communication of traditional unicast.Wireless multicast needs to use wireless broadcast advantage(WBA) to construct efficient multicast tree for the multicast transmission.However,the broadcast nature of wireless transmission also cause some troubles while it meets the needs of the wireless multicast.So, how to improve the time slot utilization of co-channel 802.16 Wireless Mesh Network(WMN) multicast and the system throughputs, reducing the interference of multi-channel 802.11 WMN multicast,are key problems.For multicast in co-channel WMN, we analyze the interference relationship firstly among the transmissons by introducing a gragh transformation method based on the multicast topology.Then, with consideration of intererence relaionship and the time-varying characteristics of wireless channel,an adaptive greedy capacity algorithm is designed to provide simultaneous trasmission,which meets the requirements of time slot of each transmission.Next, we study the multicast in multi-channel WMN.Firstly, for the ideal wireless link quality, we utilize a method of constructing multicast tree, which needs shortest paths and least relay nodes.In the case of wireless packets loss, we improve the original multicast tree into the minimum loss ratio multicast tree.Secondly, multi-channel WMN multicast needs effective channel allocation(CA) algorithm to determine which channel should be used for a link to transmit the data to maximize the network throughput.We propose a minimum interference multicast CA algorithm(MI_CA)(in wireless packet loss environment,as MLMI_CA), to minimize the interference among nodes which in multicast routing tree.We use both orthogonal and overlapping channels such as those in IEEE 802.11b/g networks.Simulation results show that the proposed transmission scheduling mechanism significantly improved system throughput, channel assignment algorithm can reduce the interference, improve the network throughput, reduce end-to-end delay and increase the packet delivery ratio, and it can provide QoS guarantee for the video streaming.