Adaptive Resource Allocation in Multicast OFDMA Systems

Orthogonal frequency-division multiple access (OFDMA) exploits the frequency selective property of a wireless communication channel by allocating subchannels to individual users. Conventional multicast systems, however, suffer from diversified channel conditions among users. The main contribution of this paper is to maximize the multicast rate of one multicast session while being fair among users and build a general framework for resource allocation for multi multicast sessions. By assuming availability of channel state information, we study resource allocation in a multicast OFDMA system. We first study one multicast session system and solve the resource allocation problem in two steps. We first propose a novel subchannel allocation algorithm by allocating each subchannel to a group of users in the multicast session based on their subchannels gains. Second, a bit loading algorithm is also proposed. We further study multiple multicast transmission systems and propose a greedy algorithm for resource allocation to achieve proportional fairness among sessions. Finally, we numerically show that proposed algorithms outperform conventional multicast schemes and previous works for one multicast scenario and conventional multicast schemes for multi multicast scenario.