iii ACKNOWLEDGEMENTS Foremost, I wish to express my sincerest gratitude to my advisor, Professor Joel W Burdick, for his tremendous support during my last six years at Caltech. The keen scientific insight of Professor Burdick has incessantly shaped my horizon on the research subjects. It is his wise elicitations that pave the way for the final materialization of every detail in this thesis. Off the research field, Professor Burdick also encourages and guides me to explore diverse interesting topics, and provides kind support to my daily life. I feel so happy to have lived my past years in this fertile and liberal environment. I cannot thank my advisor enough for all he has done for me. Besides my advisor, I specially would like to thank Dr. Naoki Mitsumoto, who organized an absolutely enjoyable team research, and provided me valuable support and instructive suggestions all the way. The corporation with the talented team members in the radar project marks a happy memory for me. My special thanks go to Dr. Chris Assad, whose smart ideas resulted in an important radar signal preprocessing, and Dr. SangHyun Chang, from whom I gained understanding on multipath radar reflection. Additionally, I must thank Dr. Wissam Musallam and Dr. Eunjung Wang who kindly offered their experimental neural data, which granted me a precious algorithm test bed. I also thank my friends for their selfless help throughout my time at Caltech. Finally, my particular gratitude is owed to my parents and my wife, Hongying Sha. Their unconditional support, encouragement and patience accompany me all the way from the past to the future.