High-SNR power offset in multiantenna communication

In this paper, the high-SNR multiantenna capacity with coherent receivers on the multiplexing gain, i.e., the multiplicative increase as function of the number of antennas is analyzed. For most channels of interest, such multiplexing gain equals the minimum of the number of transmit and receive antennas. This traditional characterization, however, is unable to quantify the impact of many relevant channel features. As a function of SNR, the capacity is very well approximated, from moderate SNR on, as an affine function. The impact of the various channel features is captured in the power offset (in dB) or zero-order term in the affine expansion.