Subcarrier and Power Allocation with Multiple Power Constraints in OFDMA Systems

This letter addresses the problem of subcarrier and power allocation over an OFDMA system with multiple power constraints. Each power constraint is related to sharing a power resource by a subset of users. Here, a framework based on time-sharing method is proposed that allows for approaching the optimum solution via using a low complexity iterative algorithm. The provided solution sets an upper bound on the performance of any resource allocation without time-sharing. The time-sharing based solution will be further utilized to derive suboptimum but efficient subcarrier and power allocation algorithms. Simulation results show negligible performance degradation in using suboptimum solutions. This framework generalizes downlink and uplink scenarios and also has applicability in multihop relay-enhanced cellular networks.