Detecting Abrupt Channel Changes for IRS-Assisted MIMO Communication

This letter aims to detect abrupt changes in the base station to intelligent reflecting surface (BS-IRS) channel for IRS-assisted communications. Specifically, we first propose a centralized channel change detector, where the BS enables a fusion change detection based on the log-likelihood ratios (LLRs) obtained from all the user equipments. Next, to curtail the feedback overhead, we propose a decentralized channel change detector, where each UE independently detects channel changes and conveys a 1-bit outcome signal to the BS enabling a change detection. Numerical results validate that the proposed change detectors can promptly detect the change with low false alarm rate.