Design and Analysis of Next Generation Wireless Networks

Abstract

Recent advancements in wireless communications have increased the demand for high data rates, massive connectivity, high spectral and energy efficiency, and low latency, which cannot be met by existing systems. The sixth-generation (6G) wireless network is envisioned as the next step to support these demands by integrating technologies, including intelligent reflecting surface (IRS), backscatter communication, non-orthogonal multiple access (NOMA), integrated sensing and communication (ISAC), and terahertz (THz) communications. Specifically, the IRS enhances the energy and cost efficiency by controlling the propagation environment through an array of reflecting elements. Backscatter communication enables passive battery-free devices to communicate using external RF signals, offering an energy-efficient and low-cost solution for the Internet of Things (IoT) paradigm. NOMA improves spectral efficiency and massive connectivity by allowing multiple users to share the same time-frequency resources, while ISAC combines sensing and communication functionalities into a single system for efficient spectrum and hardware usage. Finally, THz communication addresses the current limited spectrum by providing extensive bandwidth that supports ultra-high data rates. This thesis studies the integration of these technologies with a special focus on IRS and backscatter communications, considering various system models and realistic scenarios. It evaluates the performance of IRS-aided backscatter communication in both dedicated and ambient configurations using different detection techniques and transmission schemes. It also investigates IRS-assisted THz to serve multiple users through NOMA and wireless powered communication under various practical scenarios. Moreover, it explores the integration of ISAC with ambient backscatter communication. The thesis identifies the potential benefits of these technologies and examines the adverse impacts of practical factors such as beam misalignment, co-channel interference, imperfect successive interference cancellation, phase shift quantization errors, and hardware imperfection. Accurate analytical expressions are developed for key metrics, including bit error rate, ergodic capacity, and outage probability, under various system models and transmission schemes. Numerical and simulation results are provided to validate the accuracy of the theoretical analysis and provide valuable insights into the system design.