Resource Allocation Algorithm Based on Bandwidth Demands for OFDMA Systems with Imperfect Channel Quality Information

For the problem to maximize spectral efficiency of OFDMA-TDD systems while satisfying bandwidth demands and the average bit error rate (BER) constraints of users, a resource allocation algorithm based on bandwidth demands of users is proposed. The user weights are introduced and the Max weighted-SNR scheduling strategy based on bandwidth demands of users is proposed. Based on this strategy,the closed expression of average BER with channel estimation error and Channel Quality Information (CQI) delay is achieved, and above problem is decomposed into the subchannel allocation problem and the problem of rate adaptation threshold vector optimization. The proposed Max weighted-SNR scheduling strategy is used to allocate subchannel to satisfy bandwidth demands of users. By Lagrange multiplier approach, this (J-1) dimensional optimization problem of rate adaptation threshold vector is transformed into one-dimensional optimization problem, resulting in optimal solution. This algorithm not only can satisfy bandwidth demands of users,but also adapt to the change of Imperfect Channel Quality Information (ICQI) accuracy and provides the corresponding optimal rate adaptation threshold vector so as to maximize spectral efficiency while satisfying the average BER constraints of users. Copyright © 2014 IFSA Publishing, S. L.