Direction-of-Arrival (DoA) Estimation Performance in Next-Generation Wireless Systems (5G and Beyond)

The Direction-of-Arrival (DoA) estimation method facilitates the accurate identification of signal origins, significantly enhancing the efficiency of communication systems. The need for precise and efficient DoA methods has increased due to their complex nature and broad applicability, which arise from varied signal environments, different source counts, and distinctive signal properties that impact accuracy. Evaluation techniques for DoA differ by application in methodology, efficiency, computational requirements, and accuracy, with specific approaches favoring speed and others emphasizing precision at more significant resource expense. Grasping these variations is essential for the optimization of communication system outputs. This thesis evaluates the performance of DoA estimation methodologies inVehicleto- Everything (V2X) and Satellite Communication systems, emphasizing their application in Next-Generation Wireless technologies (5G and Beyond). The research focuses on integrating Multiple Antenna Systems and millimeter-wave (mm-wave) technologies, demonstrating how these innovations enhance the accuracy of DoA estimation, which is vital for effective localization, beamforming, and tracking functionalities. The work rigorously evaluates how adapting DoA estimation to high-frequency environments improves communication efficiency. It meticulously addresses the challenges of significant path-loss and shadowing effects in these domains, employing advanced beamforming techniques to ensure accurate DoA estimations of transmitting/receiving devices. The thesis is methodically divided into four segments, providing essential insights for advancing communication systems. In the thesis’s first segment, the research identifies the critical obstacles in implementing the DoA estimation method for V2X applications within a multipath environment. Emphasis is placed on the necessity for precise channel-phase estimation and the consideration of spatial correlation amongst antenna elements, which can significantly enhance the performance of DoA estimations. As such, this initial part evaluates the performance of DoA estimation methods for V2X applications using 5G mm-wave frequency. The environment is characterized by multipath propagation, envelope fading, and spatial correlation. The assessment mainly aims at a single receiver system equipped with multiple antennas. In the thesis’s second segment, the research is expanded to a system with multiple receivers equipped with multi-antennas and leveraging the distinct traits of channel multipath propagation. The proposed model in this segment incorporates the receive diversity techniques and fuses the channel phase modeled as a random variable from the multi-receiver systems. This comprehensive approach markedly enhances the performance of DoA estimation for V2X applications by improving the signal-to-noise ratio (SNR). In the thesis’s third segment, the investigation pivots to DoA estimation methodologies applicable to different satellite communications, such as Low Earth Orbits (LEO) and Geostationary Earth Orbits (GEO) systems. This part features the application of a closed-form expression that aids in accurately modeling the DoA angle. Besides, the research adapts a correlation model in the signal adapted explicitly to the study of DoA estimations. In the thesis’s fourth segment, the study’s scope extends to exploring DoA Root Mean Square Error (RMSE) performance in satellite downlinks involving multiple targets. A vital aspect of this analysis is the consideration of spatial correlation effects, which have been identified as adversely impacting RMSE performance in multi-target DoA estimation methods for closely spaced targets. A comprehensive model of a multi-target system incorporating spatial correlation within a satellite downlink scenario is presented. Moreover, the research examines how the accuracy of the DoA method, as quantified by RMSE, is affected by the varying distances between targets, particularly under different Signal-to-interference-plus-noise ratio (SINR) conditions. These investigations are crucial to understanding the precision of error estimation in multi-target DoA estimations for satellite communication systems. This thesis introduces innovative advancements in DoA estimation by exploring various system configurations that enhance the robustness and scalability of techniques across diverse environments. It focuses on improving accuracy and efficiency, which is crucial for advancing modern communication systems. The findings, validated through computer simulations and Monte Carlo analysis, contribute significantly to DoA estimation performance, particularly in Next-Generation Wireless Systems (5G and beyond). Additionally, the findings presented in this thesis have been published in peer-reviewed journals, presented at conferences, or are currently under review, as detailed in the respective chapters of the thesis. Lastly, The authors hope this work will provide valuable insights and contribute meaningfully to the advancement of DoA estimation in 5G Networks and future wireless technologies.