Statistical Precoding for Dual-Polarized narrowband and wideband mmWave Systems

In this paper, we consider precoding for hybrid millimeter wave (mmWave) systems with dual-polarized arrays, which are known to allow more antennas to be packed into the same physical space. In practice, the precoder is typically designed based on periodic feedback of channel state information (CSI) from the receiver and the feedback is not instantaneous. We design the precoders using statistics of the user channels, without instantaneous channel information. We show that, given the channel statistics, channel covariance matrices can be derived in a closed-form. The closed-form lends itself to the design of statistical precoders. As the statistical precoder is designed based on statistics, the performance is less sensitive to fading caused by user movement. Simulations over realistic channels show that when mobile speed exceeds 1.5 km/hr, statistical precoding outperforms a precoder that is designed using periodic full CSI feedback for a commonly used feedback period.