MMAC: an efficient wmATM MAC for multicast communications

Some future broadband multimedia services will require special wireless network features. Especially, the higher the bandwidth each mobile terminal (MT) requires, the more important the capability of multicasting in the radio part comes to be. Legacy wmATM (wireless mobile ATM) MACs have not efficiently supported multicast services. In this paper, we propose an efficient multicast mechanism for the wmATM MAC layer, named MMAC (multicast MAC). We design the system architecture of MMAC, MAC frame format and slot structure. We adopt GSA (group selection agent) by which base stations can reasonably perform the multicast connection admission control and resource allocation in terms of three factors: service classes (e.g., CBR, VBR, ABR/UBR), the number of group members and the requested bandwidth for the multicast channels. Another essential feature of MMAC is to support heterogeneous QoS demand of each MT by filtering cells. This cell filtering is performed by a cell-filter module. On error recovery, one backup channel is used for all multicast channels. Its size is dynamically allocated according to the condition of MMAC. Finally we give a performance evaluation of MMAC by using the OPNET network simulator.