This thesis is the culmination of my journey of PhD which was just like climbing a high peak step by step accompanied with encouragement, hardship, trust, and frustration. At this moment of accomplishment, I realized though only my name appears on the cover of this dissertation, a great many people including my family members, my friends, colleagues and many more have contributed to accomplishing this journey. First and foremost, I would like to thank my supervisor Quang-Cuong Pham, who has gone above and beyond anything I could have expected from an advisor. I am thankful for his support, guidance in life and research during these years. Thanks to the good friends I have here in CRI group-Puttichai Lertkultanon, Francisco Suarez-Ruiz, Ahmad Bin Anwar, Tien Hung Pham and many more. You made my experience in the lab special and unforgettable. We have had a lot of great discussions about both research and non-research. I cherish all the good times that we have spent together. Also thanks to all Vietnamese friends I have here in NTU for the stimulating discussions, for all the badminton matches and for all the fun we have had in the last four years. Last but not least, I am eternally grateful to my Mom, Dad, Brother and my beloved in-laws for always believing in me and encouraging me to follow my dreams. Most importantly, a very special thanks to my loving wife, Chau Phan, for your unconditional, persistent love, for your support and understanding during my pursuit of PhD degree that made the completion of thesis possible. You were always around at times I thought that it was impossible to continue, you helped me to keep things in perspective. Without you, I would not have come this far.