Correlation Analysis of Instantaneous Mutual Information in 2 × 2 MIMO Systems

In this paper, the second-order statistics such as the autocorrelation function and correlation coefficient of the instantaneous mutual information (IMI) are studied, in 2times2 multiple-input multiple-output (MIMO) time-varying Rayleigh flat fading channels, assuming general non-isotropic scattering environments. Exact closed-form expressions are derived, as well as asymptotic approximations in low- and high-SNR regimes. Monte Carlo simulations are provided to verify the accuracy of those derived analytical results.