Energy Efficient Transmit-Receive Hybrid Spatial Modulation for Large-Scale MIMO Systems

We consider a point to point large-scale multiple-input multiple-output (MIMO) system operating in the millimeter wave (mmWave) band and an outdoor scenario. Novel transmit and receive spatial modulation (SM) schemes are proposed for uplink (UL) and downlink (DL) data transmission phases based on a novel energy efficient hybrid user terminal architecture. The analog circuitry of the proposed hybrid architecture is divided into two stages: phase shifters and analog switches. The phase shifting stage assures high gain and overcomes the severe path-loss caused by outdoor mmWave propagation. The analog switching stage smartly allocates the antennas to be used at the phase shifting stage and combats the spatial correlation. We provide the analysis of the spectral efficiency $({{SE}})$ of the UL and DL systems. Next, we propose a reduced complexity algorithm that jointly optimizes the analog beamformer and combiner design of the UL and DL circuitry to maximize the energy efficiency $({{EE}})$ . Finally, we compare and evaluate the performance of the proposed algorithm in terms of the ${{SE}}$ and ${{EE}}$ assuming both stochastic and realistic channel models.