Capacity Gain from Multi-Mode Reconfigurable Antennas as a Function of Degrees of Control in Clustered MIMO Channels

Reconfigurable antennas can be beneficial in multiple-input-multiple-output (MIMO) systems where full digital control is infeasible such as in mmWave/THz frequency bands with a large of number of antennas. In this paper, we discuss the capacity enhancement of multi-mode reconfigurable antennas in clustered MIMO channels. Specifically, our focus is to investigate the relationship between the number of bits of control, complexity of channel, and overall capacity gain compared to single-mode linear arrays. We first compute the correlation matrix with a multi-mode reconfigurable circular patch antenna array (RCPA) and relate the instantaneous capacity with the degrees of control on RCPAs. We study the impact of the number of modes on antenna correlation in 2 ×2 MIMO channels. Then we evaluate the capacity gain of multi-mode antennas in various clustered MIMO systems. Simulation shows the capacity enhancement in 4 ×4 and 8 ×4 channels compared with single-mode baseline systems. The MIMO system based on reconfigurable antennas can be low-cost and thus has potential applications in real networks.