Date Added: Jan 2010
Linear precoding (beamforming) techniques provide simple processing methods with good performance at reduced signaling complexity compared with nonlinear precoding schemes. The beamforming technique that maximizes the achievable sum-rate in the multi-user, Multiple-Input Multiple-Output (MIMO) Broadcast Channel (BC) has the distinct form of a Regularized Channel Inversion (RCI). This paper adapts the method used for BC sum-rate maximization to maximize the sum-rate in the MIMO Multiple-Access Channel (MAC) under fixed, per-user power constraints. This beamformer is based on accurate Channel State Information (CSI) resulting in performance degradation when only erroneous CSI is available at the receiver.