Channel feedback reduction schemes for opportunistic scheduling in multicast OFDMA systems

In this paper, we present new feedback reduction schemes that reduce the feedback load needed for opportunistic scheduling in the multicast OFDMA system. Considering the characteristics of the multicast system that the feedback of the user with the poorest channel condition dictates the transmission rate, we designed the proposed schemes such that it can reduce the total feedback load by sacrificing the feedback of the users with good average channel condition. Specifically, the BS divides the users into two disjoint sets, i.e., the set consisting of the users with poor average channel condition and that consisting of the users with good average channel condition, and makes the users in the former set feed back fine-grained condition of the channels while the users in the latter set feed back coarse-grained condition of the channels. Numerical results reveal that the proposed schemes reduce the total feedback load substantially with a marginal loss of the throughput.