A Combined Fair Resource Scheduling and Adaptive Modulation Scheme for Clustered OFDMA Systems

Abstract

Orthogonal frequency division multiple access (OFDMA) is a promising technique for achieving high downlink capacities in next generation wireless communication system. An OFDM system has the advantage that multiple users can be scheduled at the same time in a frequency-selective channel. Proportional fair resource scheduling algorithm can guarantee the fairness among multiple users. Compared to the conventional fixed modulation, link adaptation modulation can select the most appropriate modulation scheme on each sub-carrier according to the current link qualify, this can be used to enhance system throughput. However, the overhead cost of feeding back channel state and modulation mode information of every sub-carrier for every user is very high. Cluster feedback scheme can greatly reduce the feedback overhead. In this paper, based on cluster feedback, an adaptive modulation with proportional fair scheduling algorithm is proposed. The analysis and simulation result verify that the introduced scheme is effective in improving system throughput and has fairness among users.