Message Passing Approach to Regularized Zero-Forcing Precoding in Multibeam Satellite Systems

Multibeam satellites allow for significant boost in capacity by reusing the available spectrum and regularized zero-forcing (RZF) precoding promises to be one efficient technique to manage the inter-beam interference in the forward link. In this paper, the RZF precoding problem is first cast within an equivalent Bayesian inference framework. Then, we propose two kinds of message passing based precoding approaches, namely variational message passing based RZF (VMP-RZF) and approximate message passing based RZF (AMP-RZF). Compared with evaluating RZF directly, our proposed methods circumvent the matrix inversion operation and thus enjoy a much lower complexity. Simulation results demonstrate that the normalized mean square errors of both VMP-RZF and AMP-RZF with respect to the true RZF are negligible while AMP-RZF converges faster than VMP-RZF.