Performance Analysis of Active Intelligent Reflecting Surface-Assisted System: BER and Sum-Rate Evaluation

An active intelligent reflecting surface (IRS) has been introduced as a solution to address the double fading effect in passive IRS (PIRS)-assisted wireless systems, which is caused by a weak reflection link. The active IRS (AIRS) enhances the received signal strength by amplifying the reflected signal and applying a phase shift at the IRS panel. This paper presents the design and analysis of an AIRS-assisted wireless system, with a focus on examining the bit error rate (BER) and sum-rate performance of the system. Effect of imperfect channel state information, modulation order, the distance between IRS and the receiver, and the total reflected power at the IRS panel is studied. The simulation results demonstrate a significant performance improvement of AIRS compared to PIRS, with an improvement of around 15-20 dB. Unlike PIRS, which does not enhance system performance in the presence of a direct link, AIRS proves to be effective. Moreover, it is observed that a PIRS with an ultra-large number of reflecting elements may achieve performance comparable to AIRS when its total reflected power is lower.