Generic Correlation Increases Noncoherent MIMO Capacity

TL;DR

This paper analyzes the high-SNR capacity of noncoherent MIMO Rayleigh block-fading channels, showing that generic temporal correlation significantly increases capacity pre-log compared to constant fading models.

Contribution

It demonstrates that generic correlation within each block enhances the capacity pre-log in noncoherent MIMO channels, especially for large block lengths.

Findings

Capacity pre-log is T(1-1/N) for T<N with generic correlation.

Generic correlation increases capacity pre-log by about four times over constant fading.

Large block length amplifies the capacity gains from generic correlation.

Abstract

We study the high-SNR capacity of MIMO Rayleigh block-fading channels in the noncoherent setting where neither transmitter nor receiver has a priori channel state information. We show that when the number of receive antennas is sufficiently large and the temporal correlation within each block is "generic" (in the sense used in the interference-alignment literature), the capacity pre-log is given by T(1-1/N) for T<N, where T denotes the number of transmit antennas and N denotes the block length. A comparison with the widely used constant block-fading channel (where the fading is constant within each block) shows that for a large block length, generic correlation increases the capacity pre-log by a factor of about four.