Uniquely factorable space-time modulation for two-user uplink massive MIMO systems

In this paper, we propose a new space-time modulation scheme using quadrature amplitude modulation division for a two-user massive multiple-input multiple-output (MIMO) uplink system, in which channel state information (CSI) is unavailable at both the transmitter and the receiver. It is proved that our proposed transmission scheme enables both the large scale channel coefficients and the transmitted symbols to be uniquely and explicitly determined in a noise-free case when the number of the receiver antennas tends to infinity. For a noisy channel with a limited number of the receiver antennas, three different detectors including a simple closed-form detector, a minimum Euclidean distance detector, and a minimum Riemannian distance detector, are investigated. In addition, when the distribution of the large scale channel coefficients is known to the transmitter, a power loading algorithm is proposed. Finally, computer simulations demonstrate that our proposed communication scheme performs very well in terms of bit error rate (BER) with a moderate number of base station (BS) antennas.