Optimal beamforming in wireless multiuser MIMO-relay networks

Abstract

This paper deals with optimal beamforming in wireless multiple-input-multiple-output (MIMO) relay networks that involves multiple concurrent source-destination pairs with imperfect channel state information (CSI) at relays. Our aim is the optimization of the MIMO relay weights that minimize the total relay transmit power subject to signal-to-interference-plus-noise ratio (SINR) of all destinations to be kept above a certain threshold. Since power minimization is a non-convex quadratically constrained quadratic program (QCQP), we use semi-definite programming (SDP) relaxation of above mentioned problem by using a randomization technique.