Optimized coordinated precoding in multicell MIMO wireless systems

This paper is concerned with downlink transmissions in coordinated multiple-input multi-output (MIMO) multicell wireless networks. The design of the transmit precoding matrices in this paper aims at the maximin optimization of user rates subject to realistic power constraints at the transmitters. This problem is a nonconvex objective function subject to convex constraints with respect to high-dimensional matrix variables. Up to date, a closed-form solution has not been properly proposed. Nevertheless, we show the objective functions can be analytically represented by d.c. (difference of two convex) functions. A simple but very efficient d.c. iterative algorithm (DCI) with guaranteed convergence is shown to locate the approximately optimal matrix solutions with the help of only a few converging semi-definite programs (SDP).