The effect of intelligent reflecting surfaces on spectral efficiency in 6G wireless systems.

Intelligent Reflecting Surfaces (IRSs), comprised of numerous reflecting elements, offer a promising solution for enhancing wireless communication. By manipulating the wireless propagation environment, IRSs can mitigate the effects of non-line-of-sight propagation and extend signal coverage. This paper focuses on the performance of an IRS-aided wireless communication system when the direct link between the Base Station (BS) and receiver is obstructed, relying solely on the IRS for signal transmission, by using the pilot transmission and channel least square method in calculation of the received signal. We investigate the impact of IRS element components (effective capacitance [Formula: see text], bottom layer inductance [Formula: see text], top layer inductance [Formula: see text], and effective resistance R) and the frequency of the incident signal on system performance. These components significantly have an influence on reflection coefficients, where higher values of them leads to an increase in the amplitude response of reflection coefficient and hence, stronger reflected signals. The variation of those components can adjust the phase response of the reflected signal. In this paper, assessment of performance of IRS-aided 6G wireless communication system for single user is studied. The received power, SNR, and the spectral efficiency were estimated and used as metrics for the system performance. It has been cleared that the received power, SNR and the spectral efficiency are increased with increasing the size of IRS and transmitted power for both of the strongest and weakest configuration. Also, it has been shown that the received power, SNR and the spectral efficiency are decreased with increasing the AP-IRS horizontal distance. Higher degree of bandwidth improves the received power and the spectral efficiency whereas it reduces the SNR. The performance comparison between the spectral efficiency of system with IRS and without IRS at different values of transmitted power and bandwidth is introduced. It is shown that, at bandwidth = 5 MHz, the system with IRS achieves nearly 3 times the spectral efficiency of the system without IRS and at bandwidth = 25 MHz, the system with IRS achieves nearly 14 times the spectral efficiency of the system without IRS. Also, at transmitted power = 0.5 Watt, the system with IRS achieves nearly 5 times the spectral efficiency of the system without IRS and at transmitted power = 2.5 Watt, the system with IRS achieves nearly 5.7 times the spectral efficiency of the system without IRS. So, The IRS can be used and aided in improvement of the spectral efficiency in 6G wireless communication. The evaluation of performance of IRS-aided wireless communication system in a multi-user scenario is discussed. The data rate, spectral and energy efficiency were evaluated by using four different methods (power method, uniform metal surface method, IRS with best pilot method and with the case of no IRS). It has been shown that the received power method and the best pilot method give the best data rate, spectral and energy efficiency at any value for each of the transmitted power, the bandwidth, the size of IRS and AP-IRS horizontal distance and consequently, enhance the performance of IRS- aided 6G wireless communication system.