Tunneling Under Interference With Reconfigurable Intelligent Surfaces

Reconfigurable intelligent surface (RIS) technology is gaining significant attention from academia and industry due to its potential to greatly enhance coverage, spectral and energy efficiency, and security in next-generation (NextG) wireless communication systems. In this letter, we present a novel framework to avoid interference near a NextG receiver with the installation of an RIS. In particular, first we minimize the smallest eigenvalue of the locally-sensed interference-plus-noise covariance matrix (INCM) by optimizing phase shifts of the RIS to open a new “clean” eigen-mode of communication. Then, we carry out optimal design of a multiple-input multiple-output (MIMO) transmit waveform that takes advantage of the reconfigured wireless environment around the receiver and maximizes the pre-detection signal-to-interference-plus-noise ratio (SINR). Extensive simulation studies included in this letter illustrate our theoretical developments and show that phase optimizing an RIS near the receiver can reduce the smallest eigenvalue of INCM by up to 90% or more leading to remarkably enhanced pre-detection SINR by subsequently optimized MIMO waveforms.