Parameterized Channel Feedback using Correlation-Based Channel Models for Multi-user MIMO Systems

Recent work has demonstrated that in multi-user systems employing multiple-input multiple-output (MIMO) technology, nonlinear dirty-paper coding (DPC) techniques using exact channel state information (CSI) at the transmitter maximize the broadcast channel sum capacity. Similarly, if the precoding is restricted to linear processing, the capacity under this constraint is maximized using a regularized channel inversion beamformer. The difficulty, however, is that in wireless propagation channels that vary in time due either to node motion or motion of scatterers within the environment, the performance of these techniques rapidly deteriorates since it becomes impractical to maintain accurate CSI at the transmitter.