ABSTRACT
The introduction of intelligent reflecting surfaces (IRS) in communication systems has revolutionized the users' performance. IRS helps in controlling the scattering environment leading to better sensing and localization. This chapter discusses the interplay of IRS with different communication systems. In the multi-input multi-output cognitive system, IRS also helps in the signal transmission of secondary user (SU) by maximizing the achievable weighted sum rate of SUs. The non-orthogonal multiple access is a promising technique to serve the diverse demands of the 6G era. Device-to-Device communication is an additional technology for cellular networks to ensure ultra-low latency for the users. In terms of energy efficiency and spectral efficiency, IRS enhances the performance of the users in cognitive radio systems. There are various challenges in cognitive radio systems for efficient primary and SU signal transmissions. In this respect, IRS are deployed in cognitive radio systems for ensuring secure and efficient signal transmission of a SU.
