Channel Estimation for Reconfigurable Intelligent Surface-Assisted Full-Duplex MIMO with Hardware Impairments

TL;DR

This paper develops an unbiased channel estimation method for RIS-assisted full-duplex MIMO systems with hardware impairments, providing closed-form expressions and pilot schemes, validated through simulations.

Contribution

It introduces a novel unbiased estimator that accounts for hardware impairments, extending the MLE framework to practical RIS-assisted FD MIMO systems.

Findings

Estimator performs well under hardware impairments

Closed-form expressions for estimator statistics

Pilot schemes effectively minimize MSE

Abstract

We consider the problem of channel estimation in a multiple-input-multiple-output (MIMO) full-duplex (FD) wireless communication system assisted by a reconfigurable intelligent surface (RIS) with hardware impairments (HI) occurring at the transceivers and RIS elements. We propose an unbiased channel estimator that requires knowledge of only the first and second order statistics of the HI, for which we derive closed form expressions. The proposed estimator reduces to the maximum likelihood estimator (MLE) in the case of ideal hardware. We also describe FD and HD orthogonal pilot schemes that minimize the mean square error of the MLE in the case of ideal hardware. We verify the performance of the estimator under varying conditions of transceiver and RIS HI via numerical simulations.