Reconfigurable intelligent surface-centric communication networks: A comprehensive exploration of channel modeling and coverage extension

Reconfigurable intelligent surface (RIS)-empowered communication has received growing interest from the wireless research community due to its undeniable potential in extending the coverage, enhancing the link capacity, mitigating interference, deep fading, and Doppler effects, and increasing the physical layer security. RISs enable the control of wireless propagation through their unique electromagnetic functionalities and provide a new degree of freedom in the system design. Delving into the potential of RISs, this thesis unfolds across four detailed chapters, each contributing distinct insights into the deployment and application of RIS in enhancing wireless communication systems. Each chapter is crafted to provide a different perspective on RIS deployment and explain how this technology can be innovatively applied to support various aspects of wireless communication networks. This thesis takes a journey from the theoretical foundations of RIS to its envisioned practical applications and provides insights into how RIS can reshape wireless communication infrastructures to meet the demanding requirements of 6G networks. In the scope of this thesis, the RIS is introduced as a groundbreaking technology, reshaping the future of wireless communications by offering enhanced network capabilities, crucial for meeting the advanced requirements of next-generation applications. First, a comprehensive discussion of the intricacies of RISs in channel modeling is embarked on, which is a cornerstone for the effective deployment of sixth-generation (6G) wireless networks. In this regard, the physical channel modeling methodologies are provided for emerging RIS-empowered networks and aimed to fill an important gap in the open literature by providing an open-source and widely applicable physical channel model for mmWaves. Moreover, the open-source SimRIS Channel Simulator MATLAB package is introduced, which can be used in channel modeling and computer simulations of RIS-based communication systems with tunable operating frequency, terminal and RIS locations, number of RIS elements, and environments. The upcoming parts go beyond merely introducing the technology, delving into how RIS can be strategically employed to address some of the most challenging aspects of modern wireless communication, such as coverage extension, signal quality improvement, and network throughput enhancement. The following chapters build upon this foundation, each focusing on specific applications and implications of RIS in the realm of wireless communications. From intricate channel modeling to practical deployment strategies for coverage extension and advanced beamforming designs, the study offers a comprehensive and nuanced understanding of the multifaceted role of RIS in future wireless networks. This work stands as a testament to the transformative impact of RIS technology within the 6G landscape, offering an extensive exploration of its applications in channel modeling, coverage extension, and more. By weaving RIS into the fabric of various network design aspects, from sophisticated beamforming to coverage optimization, the study sets a robust framework for the advancement of future wireless communications, paving the way for the realization of the 6G vision.