A fast suboptimal subcarrier, bit, and power allocation algorithm for multiuser OFDM-based systems

In this paper, we propose a real-time subcarrier, bit, and power allocation algorithm for OFDM-based multiuser communication systems in downlink transmission. Assuming that base stations know the channel gains of all subcarriers of all users, the proposed loading algorithm tries to minimize the required transmit power while satisfying the rate requirement and data error rate constraint of each user. The novel algorithm determines subcarrier, bit, and power allocation simultaneously by enhancing the suboptimal algorithm in [1] while having the same computational complexity. The proposed scheme offers better performance in terms of transmit power than [1], as demonstrated in the simulation results, wherein the performance of the scheme in [1] was close to that of the optimal solution.