Bit-rate maximization for multiuser OFDM systems

OFDM (orthogonal frequency division multiplexing) is one of next-generation modulation techniques, which achieves high bandwidth efficiency and is robust to frequency selective fading. Bit-rate and bit error rate can be improved by utilizing adaptive modulation scheme on each subcarrier. Multiplexing is also possible by allocating subcarriers to multiple users. Since users have different channels, the quality of OFDM-based multiplexing systems depends on the subcarrier allocation. In this paper, we consider a subcarrier allocation and adaptive modulation for a multiuser OFDM system. We impose a transmission power constraint on each user to achieve a fair resource allocation. Under this condition, we propose a method to maximize the sum of each user's bit-rate. The effectiveness of the proposed method is numerically evaluated by simulation examples.