Multiuser MIMO systems and interference avoidance

We present the application of interference avoidance methods to multiuser systems with multiple inputs and multiple outputs. A general signal space formulation is used which makes the approach applicable to any MIMO system model regardless of the choice of basis functions. Information is transmitted via multicode CDMA where symbols that comprise the data frame from a given user are "spread" over the available dimensions using a precoding matrix. Optimal precoding matrices that maximize signal-to-interference-plus-noise ratio for all symbols/users are then obtained by application of distributed greedy interference avoidance methods. Numerical simulations have been performed and the signal-to-noise ratio distribution for receiver antennas and complementary cumulative distribution functions for sum capacity with optimal precoding matrices are also presented.