A Novel RIS-Aided EMF Exposure Aware Approach using an Angularly Equalized Virtual Propagation Channel

Abstract: Massive Multiple-Input Multiple-Output systems with beamforming are key components of the 5th and the future 6th generation of networks. However, in some cases, where the BS serves the same user for a long period, and in some propagation conditions, such systems reduce their transmit power to avoid creating unwanted regions of electromagnetic field exposure exceeding the regulatory threshold, beyond the circle around the BS that limits the distance between people and the BS antenna. Such power reduction strongly degrades the received power at the target user. Recently, exposition aware beamforming schemes aided by self-tuning reconfigurable intelligent surfaces derived from maximum ratio transmission beamforming, have been proposed: truncated beamforming. However, such scheme is highly complex. In this paper, we propose a novel and low complexity reconfigurable intelligent surface aided beamforming scheme called Equalized beamforming, which applies maximum ratio transmission to an angularly equalized virtual propagation channel. Our simulations show that our proposed scheme outperforms the reduced beamforming scheme, whilst complying with the exposition regulation.