RIS-Aided Phase Noise Compensation in MIMO Frequency-Selective Systems

Phase noise (PN) generated from imperfect oscillators can destroy transmitted data, for instance, by random rotation of the received signal constellation, amplitude variation in multi-antenna systems, or spectrum regrowth. In this work, we develop a decision-directed PN compensation approach using recursive least squares (RLS) with a forgetting factor to compensate for independent local oscillator PN at a multi-antenna receiver in a frequency-selective system. We employ a single reconfigurable intelligent surface (RIS) configured offline and without PN knowledge via the power method. Simulation results show how RIS-only or RIS-aided links can improve PN estimation and detection over a direct link alone at lower signal-to-noise ratio (SNR) settings and motivate future PN estimation improvements in RIS-aided systems.