Controlled Wireless Channel using Multi-Antenna Multi-IRS Assisted Communication System: A Comprehensive Performance Analysis

Abstract

To address societal demands, upcoming communication systems must manage multiple tasks simultaneously, thereby increasing circuit complexity and error rates. These challenges can be mitigated with intelligent reflecting surface (IRS) by utilizing cost-effective reconfigurable metamaterials to manipulate wireless propagation channels. The study investigates the performance analysis of a multi-antenna multi-IRS assisted communication system in a generalized fading channel assuming non-line-of-sight (NLOS) scenario between the base station (BS) and the user equipment (UE) using the moment-generating function (MGF) approach. The theoretical expressions for the bit error rate (BER), and Ergodic capacity (EC) are derived for the system model under consideration. Energy efficiency (EE) was also evaluated for completeness. A mean Monte-Carlo (MC) transceiver simulation test bed is provided to validate the obtained theoretical expressions. The derived theoretical formulae cover Nakagami-m, Nakagami-q, and Rayleigh channels as corner cases to cover the practical indoor and outdoor scenarios. Improved performance is observed with more antennas at the BS and UE, more IRSs, more reflecting elements, IRS placement near BS or UE, high , and low values. It was noticed that the triple-IRS system offers better BER, enhanced EC, more energy efficient than the single-IRS system, and achieves 8 dB gain at BER point of 105, 2.82 (b/s/Hz) improvement in EC, and 3.5 times energy efficient at average achievable rate 25 (b/s/Hz). Moreover, employing multiple antennas achieves 6 dB improvement at BER value of 105, enhanced achievable rate, and in turn improves energy efficiency. Lastly, placing the IRS either near BS or UE is more beneficial than setting it at mid-way where the BER reduces from 102 to 109, EC of 2 (b/s/Hz) gain, and can design a 3 times better energy efficient system.