A real-time joint subcarrier, bit, and power allocation scheme for multiuser OFDM-based systems

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 Wong et al. (1999) while having the same computational complexity. The proposed scheme offers better performance in terms of transmit power than Wong´s, as demonstrated in the simulation results, wherein the performance of the scheme in Wong was close to that of the optimal solution.