With the growing computing power of mobile devices and increasingly sophisticated applications, mobile computing and wireless communication are nowadays pervasive. However, since mobile devices have limited energy storage and sporadic energy supply, energy management remains a critical issue in mobile networks. To address the problem, a few approaches have been introduced to develop intelligent and optimal energy management for mobile networks. Firstly, wireless energy charging can be employed to replenish batteries of mobile devices. The mobile devices can harvest or receive energy to charge its battery Upon the completion of this thesis, I would like to express the greatest gratitude to my supervisor Prof. Dusit Niyato, for offering me the opportunity to research and pursue my doctorate degree in Nanyang Technological University. Without his guidance and advices, my work on optimizations and mobile energy management topics would not have started. Prof. Dusit Niyato is among the most insightful and vigorous researchers I have ever seen, who always "stays hungry" in learning, creating and contributing to the academic community. From him, I still have too much to learn on becoming a real qualified researcher for now, and for the rest of my career whatever it will be. I would like to thank my co-supervisor Prof. Ping Wang, who has help me a lot in the progress of completing my research during these years as a PhD student. She is a strict and serious researcher, who has pointed out hidden problems and flaws in my research papers for countless times, which I have always failed to discover. I would also like to thank Prof. Dong In Kim from Sungkyunkwan University, Korea, for offering me an opportunity to visit and collaborate to complete a research paper as a part of this thesis. I had a very pleasant stay in Korea. As paraphrased from his words, it is always good to go out to meet different people. I would like to express my very sincere thankfulness to my wife Zhou Yi, who also spent four struggling years as a PhD student in the same university with me. Comparing with our peers and friends at our own age, we have not been living a fantastic and fruitful life for the past years since our marriage. There were even times that we feel frustrated and lost. She never blamed me for the choices I made. The words always come to my mind that charity suffereth long, and is kind. Together we will make it through. We also would like to thank our family for the everlasting support and prompt help whenever we are in need. Besides that, I wish to thank all the current and previous members of our research group for all the collaborations and discussions both in research and daily life. I would like to thank all the staffs and students of Parallel and Distributed Computing Centre (PDCC), the place where this thesis has been done, and most time of my four years has been spent.