Non linear space-time equalizer for single-user hybrid mmWave massive MIMO systems

Abstract

The aim of this manuscript is to propose a new hybrid iterative block space-time receiver structure for millimeter wave (mmW) systems, to efficiently separate the spatial streams. We consider that both the transmitter and the received are equipped with a large antenna array and the number of radio frequency (RF) chains is lower that the number of antennas. The analog and digital parts of the equalizer are jointly optimized using as a metric the mean square error (MSE) between the transmitted data vector and its estimate after the digital equalizer. The specificities of the analog domain impose several constraints in the joint optimization. To efficiently deal with the constraints the analog part is selected from a dictionary based on the array response vectors. Our performance results have shown that the performance of the hybrid iterative space equalizer is close to the fully digital counterpart after only a few iterations. Moreover, it clearly outperforms the linear receivers recently proposed for hybrid mmW massive MIMO architectures.