On the Sublinear Behavior of MIMO Channel Capacity at Low SNR

Abstract

We consider wideband wireless communication over a multiple-input, multiple-output (MIMO) Rayleigh fading channel where the transmitter has no channel state information (CSI). We study the channel with perfect receiver CSI (coherent channel) versus the channel with no CSI at the receiver (non-coherent channel). A channel with partial CSI at the receiver has a capacity between the coherent and non-coherent channels and in this paper, we study the two extremes.