Power Allocation - Aided Spatial Modulation for 1 Limited - Feedback

Adaptive power allocation (PA) algorithms based on opti6 mization of the minimum distance dmin between signal points at the 7 receiver side are investigated in spatial modulation (SM) systems. First, a 8 closed-form solution of the optimal maximum-dmin-aided PA algorithm is 9 derived in the case of two transmit antennas (TAs). Moreover, for a higher 10 number of TAs, we propose a numerical approach, which appropriately 11 splits the power between the specific TA pair associated with dmin to 12 increase this distance. Furthermore, our PA-aided SM systems may be 13 readily combined with adaptive modulation (AM) to further improve 14 the system’s performance. Our numerical results show that the proposed 15 algorithms provide beneficial system performance improvements com16 pared with both the equal-gain PA-based SM and the identical-throughput 17 PA-aided spatial multiplexing systems. 18