Utility Based Scheduling for Downlink OFDMA/SDMA Systems with Multimedia Traffic

This paper considers the scheduling and resource allocation problem for downlink OFDMA/SDMA systems with the objective to maximize the system capacity and guarantee each user´s QoS requirements. A mathematical formulation of the optimization problem is established based on utility function, and then the detailed proof of the equivalent optimal policy is given. The developed scheduling policy can decouple the complex joint space-time-frequency resource allocation problem into simple single-subcarrier optimization problem. Moreover, a low-complexity algorithm according to the spatial separability is proposed for practical implementation. Simulation results show that the proposed algorithm is able to better attain the tradeoff between system throughput and QoS requirement to employ different utility functions.