Researches On Technology Of Multicast And Broadcast In MAC Layer Of Broadband Wireless Multimedia System

BWM Networks constructs the networks based on the characters of Mobile Video Networks and the Broadband Wireless Access Networks, in order to find the technical way of operating efficiently and costing lowly, realizing the "combination of three networks" from all the directions and sides which contains air interface, wireless access networks, core networks, service flat and terminals. The MAC layer of BWM system plays an important role in managing and allocating up-layer resources and enhancing the transmitting efficiency. In MAC layer of the BWM networks, using multicast and broadcast which belongs to the transmitting mode of point to multipoints can save more frequency band resources and more transmitting power than the point to point communication, and is the main trend of future communication development. Based upon the research and analyze of the basic theory and key technology of multicast and broadcast in the MAC layer of BWM in the existing domestic and abroad research, this paper designed innovative resolving schemes of key technology in the multicast scheme, multicast data scheduling and broadcast scheme of the MAC layer of BWM. In the multicast scheme, we design the novel Algorithm of Dynamic Allocation of the Multicast Connection, voting to generate the multicast base-station group, making all the base-stations use the same connection identity on the same channel and one connection undertake several channels at one time dynamically, looking forward to reduce the number of the connections; In the multicast data scheduling, we propose the created Optimized Equity scheduling algorithm and scheduling algorithm of Frequency and time First, aiming separately to approach the absolute equity infinitely and to reduce the difference between cold and hot programs in the waiting time. In the broadcast scheme, we design the novel Timing and Counting algorithm in the broadcast on demand, alternate checking several timers and counters to find the idle slots of the broadcast to provide service for communication of data, enhancing the utilizing efficiency of the resources. We carried out the simulation on the opnet and matlab in windows for these algorithms, after analyzing the result of the experiment, we found that algorithm of Dynamic Allocation of the Multicast Connection can save the resources of connections on a certain degree, both of the two multicast data scheduling algorithms can reach its goal, and the Timing and Counting algorithm in the broadcast on demand can enhance the utilizing efficiency of the resources.