Abstract: Adaptive resource allocation is crucial to improving the spectrum efficiency for OFDM systems. A novel resource
allocation algorithm is developed here to assign subcarriers and power to each user. According to the users rate
requirement, the subcarriers are allocated with proportional fairness. The improved multiuser water-filling algorithm, with
the consideration of the bit error rate, is used to determine the power on each subcarrier. The results show that the
proposed algorithm can obtain a high spectrum efficiency and that the bit error rate and the fairness among the users are
considered simultaneously.

Key words: multiuser, OFDM, water-filling algorithm, resource allocation, fairness