Active intelligent reflecting surfaces for sum-rate and coverage enhancement in B5G/6G multi-user wireless networks

The rapid growth of mobile technologies has driven the demand for high-speed, reliable, and energy-efficient wireless communication systems (WCSs). Intelligent reflecting surfaces (IRSs) have emerged as a key enabling technology for beyond fifth-generation (B5G) and sixth-generation (6G) networks by enhancing coverage, spectral efficiency (SE), sum rate (SR), and energy-efficiency (EE). However, conventional passive IRSs suffer from limited coverage, lack of signal amplification, and sensitivity to blockages, which restrict their practical performance. To address these limitations, this work investigates active IRS-assisted multi-user wireless systems, where IRS elements amplify incident signals using integrated amplifiers. A realistic signal model is developed by incorporating signal amplification and noise effects, and system performance is evaluated under Rician fading channels with variations in transmit power, transmission distance, and the number of IRS elements. The results demonstrate that active IRS significantly outperforms passive IRS. In weak-link scenarios, the sum rate increases from 19.68 to 35 bps/Hz (77.7% gain), while in strong-link scenarios it rises from 12 to 47 bps/Hz (147.4% gain). At a transmit power of 40 dBm, active IRS achieves 66–70 bps/Hz, providing transmit power savings of up to 13 dB in weak links and 8 dB in strong links compared to passive IRS. These results indicate that active IRS effectively mitigates multiplicative fading, enhances spectral and energy-efficient, extends coverage, and improves interference management, making it a promising solution for high-performance and energy-efficient B5G and 6G wireless networks.