<p dir="ltr">Wireless technologies across various applications aim to improve further by developing intelligent systems, where the performance is optimized through adaptive policy selections that efficiently adjust to the environment dynamics. As a result, accurate observation on the surrounding conditions, such as wireless channel quality and relative target location, becomes an important task. Although both channel estimation and wireless positioning problems have been well studied, with advanced wireless communications relying on complex technologies and being applied to diverse environments, optimization strategies tailored to their unique architectures and scenarios need to be further investigated. In this dissertation, four key research problems related to channel estimation and wireless positioning tasks for intelligent wireless systems are identified and studied. First, a channel denoising problem in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems is addressed, and a Q-learning-based successive denoising scheme, which utilizes a channel curvature magnitude threshold to recover unreliable channel estimates, is proposed. Second, a pilot assignment problem in scalable open radio access network (O-RAN) cell-free massive MIMO (CFmMIMO) systems is studied, where a low-complexity pilot assignment scheme based on a multi-agent deep reinforcement learning (MA-DRL) framework along with a codebook search strategy is proposed. Third, sensor selection/placement problems for wireless positioning are addressed, and dynamic and robust sensor selection schemes that minimize the Cramér-Rao lower bound (CRLB) are proposed. Lastly, a feature selection problem for deep learning-based wireless positioning is studied, and a unique feature size selection method, which weights over the expected information gain and classification capability, along with a multi-channel positioning neural network is proposed.</p>

<div>Over the past few decades, the focus of wireless communication technology has been shrinking in terms of coverage area. It started with WMAN (Wireless Metropolitan Area Network), moved to WLAN (Wireless Local Area Network) and WPAN (Wireless Personal Area Network), and is soon expected to move to WBAN (Wireless Body Area Network). Wireless positioning/location services present a perfect analogy to wireless communication services. It started with the use of GPS (Global Positioning System), is moving to Local Area Positioning System (LPS) and will be soon moving to Personal and Body Area Positioning Systems (BPS) in the future.</div><div><br></div>This thesis presents the development of a high-speed and high-accuracy wireless magnetic positioning system which can locate the position and orientation of the sensor in real-time with a sub-mm level accuracy in body area. The system consists of an antenna (transmitter) and one or multiple sensors (receivers). The sensor module consists of a tri-axis AC magnetic field sensor, an orientation sensor, a micro-controller and a communication unit. The system is robust to multi-path, low-power, low-cost and provides complete location privacy to its users. Possible implementations of this technology could be in the field of gaming, media entertainment, security, robotics, bio medical, motion-capture and home-automation. The ultra-low latency of the system and its ability to track the sensor anywhere around the antenna without occlusion makes it a perfect candidate to be used as a Virtual/Augment Reality (VR/AR) input device.

<p>In this thesis, design and realization of a system which enables precise positioning of RFID tags in both azimuth and elevation angles is explained. The positioning is based on measuring the phase difference between four Yagi antennas placed in two arrays. One array is placed in the azimuth plane and the other array is perpendicular to the first array in the elevation plane. The phase difference of the signals received from the antennas in the azimuth array is used to find the position of RFID tag in the horizontal direction. For the position in the vertical direction, the phase difference of the signals received from the antennas in the elevation plane is used. After that the position of tag in horizontal and vertical directions is used to control the mouse cursor in the horizontal and vertical directions on the computer screen. In this way by attaching one RFID tag to a plastic rod, a wireless pen is implemented which enables drawing in the air by using a program like Paint in Windows. Simulated results show that the resolution of the tag positioning in the system is in the order of 3mm in a distance equal to 0.5 meter in front of the array with few number of averaging over the received phase data. Using the system in practice reveals that it is easily possible to write and draw with this RFID pen. In addition it is argued how the system is totally immune to any counterfeit attempt for faked drawings by randomly changing the transmitting antenna in the array. This will make the system a novel option for human identity verification.</p> / QC 20100920

In this thesis, design and realization of a system which enables precise positioning of RFID tags in both azimuth and elevation angles is explained. The positioning is based on measuring the phase difference between four Yagi antennas placed in two arrays. One array is placed in the azimuth plane and the other array is perpendicular to the first array in the elevation plane. The phase difference of the signals received from the antennas in the azimuth array is used to find the position of RFID tag in the horizontal direction. For the position in the vertical direction, the phase difference of the signals received from the antennas in the elevation plane is used. After that the position of tag in horizontal and vertical directions is used to control the mouse cursor in the horizontal and vertical directions on the computer screen. In this way by attaching one RFID tag to a plastic rod, a wireless pen is implemented which enables drawing in the air by using a program like Paint in Windows. Simulated results show that the resolution of the tag positioning in the system is in the order of 3mm in a distance equal to 0.5 meter in front of the array with few number of averaging over the received phase data. Using the system in practice reveals that it is easily possible to write and draw with this RFID pen. In addition it is argued how the system is totally immune to any counterfeit attempt for faked drawings by randomly changing the transmitting antenna in the array. This will make the system a novel option for human identity verification. / QC 20100920