Intelligent reflecting surface (IRS) that enables the control of the wireless propagation environment has been looked upon as a promising technology for boosting the spectrum and energy efficiency in future wireless communication systems. Prior works on IRS are mainly based on an ideal phase shift model with full reflection regardless of phase shift, which, however, is practically difficult to realize. In contrast, we propose in this letter a practical phase shift model that captures the phase dependent amplitude in the reflection coefficient. Applying this new model to an IRS-aided wireless system, we formulate a problem to maximize its achievable rate by jointly optimizing the transmit beamforming and the IRS reflect beamforming. The formulated problem is non-convex and difficult to be optimally solved in general, for which we propose a low-complexity suboptimal solution based on the alternating optimization (AO) technique. Simulation results unveil a substantial performance gain achieved by the joint beamforming optimization based on the proposed phase shift model as compared to the conventional ideal model. Index Terms-Intelligent reflecting surface, passive array, beamforming optimization, phase shift model.
For a phase dependent amplitude in the reflection coefficient, in REF , the transmit beamforming and the RIS reflect beamforming are jointly optimized based on an alternating optimization technique to achieve a low-complex sub-optimal solution.
Intelligent Reflecting Surface: Practical Phase Shift Model and Beamforming Optimization
ArXiv
ArXiv
Computer Science Engineering Mathematics