Spectral Efficiency of Multi-pair Two-Way Massive MIMO Relay With Correlated Hardware Distortion

Most of the existing works on massive multi-input multi-output (MIMO) relaying consider the hardware distortion to be uncorrelated across antennas. We consider multi-pair two-way half-duplex massive MIMO relaying with correlated hardware distortion. We study the effect of distortion correlation on the spectral efficiency (SE) in two scenarios when i) relay is equipped with low-quality hardware; and ii) both relay and users are equipped with low-quality hardware. We numerically show that the distortion correlation considerably affects the SE in the former case, especially for small number of users and/or large number of relay antennas. We also numerically show that when the user has low-quality hardware, the hardware distortion correlation can be neglected for moderate number of users and/or number of relay antennas.