Spectral Efficiency Optimization for Absorbable IRS-Based Wireless Communications with Strong Interferences

We design an absorbable intelligent reflecting surfaces (IRS)-based wireless communication system with two modes, where a wave-absorption structure is embedded into a wave-reflection structure. This is the vital work to investigate the dual function of IRS to switch between the wave-absorption mode and the wave-reflection mode, which improves the degree of freedom in terms of optimization. We formulate the spectral efficiency problem with respect to discrete phase shifts and wave-absorption function for the designed absorbable IRS-based wire-less communication system with strong interferences. In order to maximize spectral efficiency, we propose an iterative grouping optimization (IGO) algorithm, to enhance the desired signal power and reduce interference, based on the wave-absorption mode and the wave-reflection mode. The proposed algorithm achieve low complexity, requiring no exhaustive search, while providing spectral efficiency higher than the existing method with no wave-absorption.