supervisor, Assoc. Prof. Xu Yan, for his guidance, encouragement, and advice. It has been a great privilege and joy to study under his guidance and supervision. His rigorous academic attitude, infectious enthusiasm, and gentle personality always inspire me in my research and life journey. It is him who makes my Ph.D. journey fulfilling, and it is also him who always encourages me to explore life's possibilities. The limited words hardly express my deep feelings, but I still want to say the Ph.D. journey under his supervision is the best time of my life. Also, I would like to thank my co-supervisor at NTU, Assoc. Prof. Tan Rui, my mentor, Prof. Wang Peng, and my co-supervisor at the Technical University of Denmark, Assoc. Prof. Wu Qiuwei. They provide very valuable suggestions and guidance and give me many supports in my Ph.D. journey. Dr. Wang Yu, Research Fellow of EEE, NTU, has my heartfelt gratitude. He always supports me when I was in tough situations. The research experience shared by him inspires me to pursue more in this field. He teaches me a lot about the detailed algorithms, models, skills, and knowledge, and I really enjoyed the time discussing research issues with him. He is an excellent academic role model for me, and his steady, practical, diligent, and modest qualities will always be worth my lifelong learning.Moreover, I also want to thank my seniors and colleagues, Dr.