Date Added: Feb 2012
The authors propose an improved algorithm for optimizing the transmit covariance matrices for Successive Zero-Forcing (SZF) precoding in multiple-input multiple-output systems. They use a conjugate gradient projection method to solve the optimization problem. Their algorithm improves upon the existing method twofold. First, the existing covariance optimization method, with higher SNRs or more simultaneously supported users, can yield a lower sum rate than when using Block Diagonalization (BD), when theoretically SZF should never be inferior to BD. In comparison, their method consistently provides a higher throughput than BD.