Comparative analysis of single versus multi-IRS-assisted multi-user for 6 G wireless communication systems

Intelligent Reflecting Surfaces (IRSs) are emerging as a key enabler technology for advancing wireless communications in 6G networks, serving as a complementary solution alongside massive MIMO and terahertz (THz) communication. IRSs are engineered electromagnetic (EM) surfaces integrated with electronics that are capable of passively reflecting signals to improve coverage and reduce power consumption compared to traditional relays. However, to fully exploit the potential, optimizing IRS-assisted wireless communication requires advanced signal processing techniques. In this work, we present a comparative analysis of single versus multi-IRS-assisted multi-user wireless communication systems, with a focus on energy efficiency (EE) and spectral efficiency (SE). By using a fixed number of reflecting elements per IRS ( $$N = 400$$ ), the deployment of multiple IRS units( up to six) demonstrates significant performance improvements. The simulation results show that at a user distance of 100 meter, the energy efficiency increases from 10 bits/Joule (1-IRS) to 50 bits/Joule (with 6-IRS), and with SNR of 50 dBm, the six-IRS setup achieves up to 65 bits/Joule which is nearly $$3\times$$ the performance of a single IRS system. In terms of spectral efficiency, increasing the number of IRS elements boosts the performance that can achieve up to 50 bps/Hz when $$N = 800$$ . Overall, the results confirm that the proposed multi-IRS-assisted system significantly outperform single-IRS configurations, particularly in challenging propagation environments, offering a promising solution for energy and spectral-efficient communication in future 6G wireless networks.