On the Impact of Oscillator Phase Noise in an IRS-assisted MISO TDD System

Intelligent reflecting surfaces (IRS) have great potential for achieving higher spectral and energy efficiency. However, the expected benefits depend strongly on the accuracy of the channel estimation. Most of the current work assumes perfect channel state information, which is impractical in real communication systems. Moreover, state-of-the-art IRS channel estimation algorithms are proposed under the assumption of perfect transceivers. These algorithms cannot be applied in the case of imperfect transceivers. In this work, we propose a novel channel estimation algorithm that takes into account phase noise from the local oscillator, which is the major contributor to the transceiver impairments. More specifically, we estimate the channel from uplink pilots transmission. Utilizing the obtained channel estimates the downlink ergodic rate is analyzed, where we find that the IRS-assisted system becomes more robust to phase noise as the number of reflective elements increases. Additionally, the impact of additive receiver noise in uplink vanishes when the number of reflective elements approaches infinity.