Intelligent Reflecting Surface with Discrete Phase Shifts: Channel Estimation and Passive Beamforming

Understand

In this paper, we consider an intelligent reflecting surface (IRS)-aided single-user system where an IRS with discrete phase shifts is deployed to assist the uplink communication.

• A practical transmission protocol is proposed to execute channel estimation and passive beamforming successively.
• To minimize the mean square error (MSE) of channel estimation, we first formulate an optimization problem for designing the IRS reflection pattern in the training phase under the constraints of unit-modulus, discrete phase, and full rank.
• This problem, however, is NP-hard and thus difficult to solve in general.