RIS-Assisted Communication with Known User Mobility

This thesis addresses the challenge of leveraging Reconfigurable Intelligent Surfaces (RIS) to enhance wireless communication performance by optimizing the average received power along a predefined receiver trajectory in near-field scenarios. Unlike previous studies, this work assumes a predefined movement trajectory provided by an external system, such as a localization system, and the RIS configuration remains fixed. The approach reduces the complexity of the network deployment. Numerical findings demonstrate an improved coverage distance in single input single-output (SISO) communication systems employing RIS in the millimeter wave (mmWave) band. Furthermore, the thesis explores the recently introduced Beyond-Diagonal RIS (BD-RIS) architecture in addition to the traditional diagonal RIS. For both architectures, a manifold-based optimization method is investigated. The performance of these algorithms and architectures is evaluated and compared to determine their effectiveness in providing adequate coverage along the trajectory of the user equipment.