Adaptive Rate and Power Allocation Schemes for OFDM/SDMA Systems

In this paper, adaptive resource allocation approaches, which jointly adapts power distribution and subcarrier allocation according to instantaneous channel conditions, is proposed for uplink OFDM/SDMA-based multiuser system. The first scheme utilizes adaptive algorithm to reduce symbol-error rate. The closed-form algorithm is derived for this idea. The second contribution in this paper deals with constant-rate transmissions over a spatial multiuser OFDM system. In the proposed system, the receiver jointly optimizes rate and power assignments for each user and then informs them to the transmitter via a low-rate feedback channels.