Dedicated versus Shared Element-Allotment in IRS-aided Wireless Systems: When to Use What?

While conventional communication systems sufficiently meet the demands of human-to-human (H2H) information exchange, they cannot support the seamless mass-scale inclusion of non-human communication entities for next generation technological applications. In this context, intelligent reflecting surfaces (IRS) appear as a promising eco-friendly disruptive technology for the extremely dense practical realizations of wireless infrastructures required for futuristic cyber-physical systems. To better exploit IRS to enable ultra-massive connectivity, this work employs element-sharing between multiple users in a practical reflection model enabled IRS-aided wireless system. The element-sharing paradigm of allotment provides spectral efficiency gains while keeping the scale of IRS panels in feasible physical deployment and cost constraints. We investigate the dedicated and shared element-sharing schemes for IRSs under different operating conditions. Simulation results show that element-sharing outperforms dedicated element-allotment in systems with a higher number of served users and a limited number of reflecting elements while also being more robust to channel estimation and phase optimization errors.