Detecting Angle of Arrival on a Hybrid RIS Using Intensity-Only Data

Reconfigurable reflective metasurfaces—or reconfigurable intelligent surfaces (RISs)—can redirect incident signals toward desired directions, an ability that allows for sculpting wireless communication channels with desired characteristics. This smart radio environment, however, necessitates the information about the transmitter(s) and the receiver(s) to be available at the RIS. One possible solution to this need is to add sensing capability to the RIS. However, sensing complex wireless signals (i.e., both amplitude and phase) often requires complicated setups. In this letter, we propose and numerically demonstrate a reconfigurable reflective metasurface that uses intensity-only samples of the incident signal to retrieve desired information about the propagation environment. To do that, we will randomly tune the metasurface elements to multiplex information incident on all of them. The phaseless multiplexed data are then processed using computational ghost imaging algorithm to retrieve the desired information. As a demonstrative example, we present the detection of the incident angle from a user in a free-space environment. This simplified sensing process can pave the way for incorporation of RISs with integrated sensing capabilities in future wireless communication or sensing systems.