On Optimum End-to-End Distortion in Wideband MIMO Systems

This paper presents the impact of frequency diversity on the optimum expected end-to-end distortion (EED) in an outage-free wideband multiple-input multiple-output (MIMO) system. We provide the closed-form expression of optimum asymptotic expected EED comprised of the optimum distortion exponent and the multiplicative optimum distortion factor for high signal-to-noise ratio (SNR). It is shown that frequency diversity can improve EED though it has no effect on ergodic capacity. The improvement becomes slight when the frequency diversity order is greater than a certain number. The lower bounds related to infinite frequency diversity are derived. The results for outage-free systems are the bounds for outage-suffering systems and they are instructive for system design.