Super Wideband MIMO Systems: Channel Modelling and Performance Analysis

This paper develops a physically-consistent framework for modeling and analyzing super wideband (SW) multipleinput-multiple-output (MIMO) communication systems that experience strong mutual coupling (MC). Starting from circuit theory, we derive a generalized MIMO model incorporating MC and physical noise sources, allowing a direct mapping to standard communication models. We develop a correlated Rician channel model with frequency-dependent spatial correlation, frequency correlation, and Rician K-factor, specifically tailored for SW systems. The performance of single and multiuser SW systems are analyzed using the developed channel model. Specifically, beamforming performance is evaluated under various receiver architectures, highlighting the impact of distorted steering vectors in beamforming due to high MC. Our studies show that strong MC inherently reduces the effective spatial correlations in SW MIMO arrays. Further, we explore uplink multiuser systems through both orthogonal scheduling and linear combining techniques. Numerical results show that tightly coupled arrays provide substantial signal-to-noise ratio (SNR) gains, particularly in endfire directions.