Capacity optimization using subspace method over multicell OFDMA networks

Capacity optimization in a multicell OFDMA system where each cell has multiple users is investigated in this work. The objective is to find an assignment of users to the sets of sub-carrier, their transmission rates for the sub-carrier, and power allocation such that the total system capacity is increased, while users meet a minimum total rate requirement and a power constraint. Since the optimal solution involves an exhaustive search or complex nonlinear integer programming, we develop sub-optimal low complexity algorithms. We propose a two-step scheme: First an initial channel and data rate allocations are determined by two initialization algorithms. Then we refine the assigned rates by an iterative algorithm. From simulation results, the proposed algorithms can efficiently allocate resources to increase the overall system capacity and reduce the allocation outages.