Pillay, Narushan.Xu, Hongjun.Morar, Yashil.2026-01-222026-01-2220232023https://hdl.handle.net/10413/24241Masters Degree. University of KwaZulu-Natal, Durban.The demand for increased link reliability, higher data rates, improved error performance (EP) and increased spectral efficiency (SE) in wireless communications systems (WCS) is increasing exponentially year after year. Furthermore, the overall data traffic and number of mobile users is growing, and continues to grow, rapidly each year. In theory, multiple-input multiple-output systems can achieve these goals, but not without their drawbacks and challenges. These drawbacks include low energy efficiency, high computational complexity and increased harmful radiation emission. Hence, it is evident that to meet the current and future wireless demands and standards, the next generation of wireless networks can no longer be an extension of the previous generation. Rather, the next generation of wireless networks requires totally novel concepts, implementations and foundations from which to build upon. As such, reconfigurable intelligent surfaces (RISs) provide a completely new paradigm in this respect. RISs are man-made electromagnetic (EM) surfaces with adjustable parameters capable of modifying the impinging signal to enhance signal strength and quality. In other words, RISs allow control over what was previously assumed to be the uncontrollable wireless propagation environment. The key principle in using the RIS is that its adjustable parameters may be reconfigured to effect a change on the EM wave, thereby improving various aspects of WCS. RISs hold attractive advantages which make them a key competitor of MIMO systems. Firstly, RISs are nearly passive surfaces, meaning they do not require additional energy sources to operate. Secondly, RISs are cost-effective as they operate on low-power electronics and do not require converters or power amplifiers. Thirdly, they are easily deployable on walls, ceilings, buildings, facades, billboards, vehicles and even clothes. Lastly, RISs are environmentally friendly, and meet the requirements of green communications. Motivated by this, this dissertation presents a study on RIS-aided WCS. In particular, this dissertation provides an investigation into how RISs may improve the EP of WCS. This dissertation investigates the effect of both passive and active RIS elements on the EP and SE of WCS by considering hybrid RISs to assist data transmission. This dissertation also provides a study on RIS-aided systems in Rician fading channels to investigate the impact of the line-of-sight component of the RIS on the EP of WCS. The theoretical average bit error probability of each scheme is provided and validated by Monte-Carlo simulations. The findings in this dissertation illustrate that hybrid RIS-aided systems can achieve significant improvements in EP over conventional RIS-aided systems, and that Rician fading channels have a distinct impact on the EP of RIS-aided WCS due to the line-of-sight component associated with Rician fading.enCC0 1.0 Universalhttp://creativecommons.org/publicdomain/zero/1.0/Error Performance (EP).Spectral Efficiency (SE).Wireless Communications Systems (WCS).Thesis