Benefits of Spatial Correlation for Multi-Antenna Non-Coherent Communication over Fading Channels at Low SNR

For fading channels without channel state information (CSI) at the transmitter or the receiver, fundamental challenges arise for realizing efficient communication, especially under stringent constraints on average and peak input powers. To mitigate these challenges, in this paper we investigate the benefits of spatial correlation among multiple transmit and receive antennas. Based upon asymptotic analyses, we first show that spatially correlated antennas lead to both multiplicative rate gain as well as peak power reduction, at no cost of additional transmit power. Then we turn to a simple communication scheme employing on-off signaling with hard-decision demodulation. For this low-complexity scheme, we demonstrate that most of the benefits promised by the asymptotic analyses are realizable