Generalized-spatial-modulation-based reduced-RF-chain millimeter-wave communications

Generalized spatial modulation (GSM)-based millimeter-wave (mmWave) communications system is proposed. The GSM transmitter is characterized by a lower number of radio frequency (RF) chains than the number of transmit antennas, hence it is capable of reducing both the transmitter cost as well as the energy consumption. The antenna array alignment is optimized so as to maximize the rank of the channel matrix encountered. Furthermore, we employ an array of analog beamformers, which allows us to benefit both from the beamforming gain as well as from the GSM scheme’s high rate. It is demonstrated that the constrained capacity of the GSM transmitter equipped with as few as two RF chains is capable of approaching the performance of the full-RF spatial multiplexing having eight RF chains.