Antenna Design and Channel Characterization for Mobile MIMO Systems

One significant difficulty associated with the implementation of multiple-input multiple-output (MIMO) technology is that communication node mobility leads to a time-varying channel which can limit the achievable system throughput [1]. This paper quantifies the degradation in channel capacity resulting from channel temporal variation using novel information theoretic metrics, and demonstrates that proper antenna element radiation properties can reduce the impact of this variability. Furthermore, for rapidly fading channels when channel covariance information is used to construct the transmit signaling, recent studies have suggested that capacity is maximized when the transmit antenna spacing is small [2]. This paper shows that this observed phenomenon results from increased radiated power arising from mutual coupling effects. When the radiated power is constrained, the analysis shows that a conventional array design (approximately λ/2 element spacing) is optimal.