Asymptotic Orthogonal Space Shift Keying in Massive MIMO Systems

We investigate space shift keying, which is a simple form of spatial modulation. The bit error rate performance of line-of-sight (LOS) multiple-input and multiple-output (MIMO) was obtained in the literature with orthogonal subchannels for indoor millimeter-wave (mmWave) communications. It is essential to impose a rigid restriction on the distance between the transmitter and the receiver and antenna spacing to maintain orthogonal subchannels. However, in wireless communications, it is not viable to meet the strict distance requirements since user equipment is portable. We propose asymptotic orthogonal space shift keying with mobile stations. The asymptotic orthogonal space shift keying approaches orthogonal subchannels for a large number of transmitter and receiver antennas in correlated subchannels. This result is valuable for future wireless MIMO communications in mmWave frequencies. The massive MIMO renders the subchannel correlation symmetrical so that they can cancel each other. The example correlation model is employed for a numerical illustration. The proposed performance analysis is based on a large number of miniaturized antennas available in mmWave frequencies.