Downlink OFDMA Resource Allocation Under Partial Channel State Information

The problem of resource allocation (RA) in a downlink OFDMA system is examined under the realistic assumption of imperfect channel state information (CSI) at the base station. In this case, there is a nonzero outage probability that the assigned rate at a particular subcarrier/user pair will not be supported by the true channel realization, which may lead to a significant waste of the system's available resources. It is therefore necessary to obtain RA algorithms that take into account the effect of imperfect CSI. By exploiting the statistical description of the imperfect CSI, various algorithms are proposed that tradeoff complexity versus performance, aiming at maximizing the system's successfully transmitted rate.