Phase-shift-based antenna selection for MIMO channels

This paper addresses the antenna subset selection in multiple antenna systems with full diversity transmission, for both correlated and uncorrelated channels. To reduce the severe performance degradation of traditional selection/combining schemes, we propose to embed phase-shift-only operations in the RF chains before selection. The resulting system shows a significant advantage in utilizing the multiple antenna diversity under almost any channel condition while incurring only a small hardware overhead. With the optimum phase shifter design given in analytical form, our analysis shows that with more than two branches allowed for selection, the new scheme can achieve the same SNR gain as the full-complexity MRC (maximum-ratio-combining). Even when only one branch is allowed, the performance is still well above the conventional selection scheme and near optimum.