Beamforming Optimization for Intelligent Reflecting Surface with Discrete Phase Shifts

Understand

Intelligent reflecting surface (IRS) is a promising technology for achieving high spectrum efficiency in future wireless networks by leveraging massive low-cost reflecting elements with each reflecting the incident signal with a proper phase shift.

• However, prior works on IRS are mainly based on the optimization of infinite-resolution phase shifters which are practically infeasible due to hardware imperfections.
• In contrast, we study in this paper an IRS-aided wireless network, where an IRS with only finite-resolution phase shifter available at each element is deployed to assist in the communication from a multi-antenna access point (AP) to a single-antenna user.
• We aim to minimize the transmit power at the AP by jointly optimizing the transmit beamforming at the AP and reflect beamforming at the IRS, subject to the signal-to-noise ratio (SNR) constraint and practical discrete phase shift constraints.