A novel rate-adaptation algorithm for multiple access OFDM systems

In this paper, a new scheme for adaptive subcarrier, bit and power allocation for downlink transmission of multiuser orthogonal frequency division multiplexing (OFDM) systems is presented. An adaptive algorithm is introduced to maximize the total data rate in a frequency selective channel, while satisfying the requirements on total transmit power, minimum data rate of each user, and desired BER that offer various quality of service (QoS) levels for different users. The performance and complexity of the proposed scheme is also compared with similar methods and other OFDM-based multiple access methods. Simulation results show that the proposed algorithm leads to higher performance in comparison with earlier sub-optimum methods, and yet requiring an acceptable computational complexity level.