On the Mutual Information Distribution of OFDM-Based Spatial Multiplexing: Exact Variance and Outage Approximation

TL;DR

This paper derives exact variance formulas for the mutual information in OFDM-based MIMO channels, enabling precise distribution and outage capacity approximations across various system configurations.

Contribution

It introduces new closed-form variance expressions for mutual information in OFDM MIMO systems with arbitrary antennas and channel lengths, extending previous work.

Findings

Exact variance formulas for mutual information

Accurate outage capacity approximations

Applicability to arbitrary system configurations

Abstract

This paper considers the distribution of the mutual information of frequency-selective spatially-uncorrelated Rayleigh fading MIMO channels. Results are presented for OFDM-based spatial multiplexing. New exact closed-form expressions are derived for the variance of the mutual information. In contrast to previous results, our new expressions apply for systems with both arbitrary numbers of antennas and arbitrary-length channels. Simplified expressions are also presented for high and low SNR regimes. The analytical variance results are used to provide accurate analytical approximations for the distribution of the mutual information and the outage capacity.