Multi-cell H-inf Precoding in Massive MIMO Systems

We consider downlink transmission in time-division duplexing (TDD) Massive multiple input multiple output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over frequency selective fading channels. A simple multi-cell H-inf precoding method is proposed in order to achieve good suppression to pilot contamination (PC). This precoding is developed virtually by an intuitive optimization problem under H-inf performance criterion, and calculated by performing a J-spectral factorization. Based on some conditions, we obtain a simple closed-form solution to this J-spectral factorization. For a large number of base station (BS) antennas, an approximate expression of this solution could also be derived. It is shown that the approximate solution can achieve the same performance as the proposed H-inf precoding in Massive MIMO systems. Furthermore, significant performance gains compared to certain popular precoding methods are shown.