Adaptive subchannel allocation in multiuser MC-CDMA systems

We treat the multiuser scheduling problem in MC-CDMA systems. To reduce the implementation complexity, we present an efficient structure for the multiuser scheduler. Given the active users and the channels, the subchannel allocator then aims at maximizing the instantaneous system throughput. We develop a stochastic-ruler based algorithm to achieve the subchannel allocation, and prove its global convergence. We also extend the algorithm to track the time-varying optimum in non-stationary channels. We present simulation results to show the performance of the proposed schemes in terms of the throughput maximization with fast convergence, the excellent tracking capability in time-varying channels, and the small throughput loss of the multiuser scheduler.