Alzheimer's Disease (AD) Diagnosis with Functional Brain Connectivity Analysis
Functional connectivity is defined as statistical dependencies among remote neurophysiological events. The study is based on functional magnetic resonance imaging (fMRI), which is a functional neuroimaging procedure using MRI technology that measures brain activity by detecting associated changes in blood flow. In this research, machine learning and data analysis algorithms are developed to discover the underlying neurological changes that happen to AD patients and mild cognitive impairment (MCI) subjects.
Security and Efficiency Enhancement in Multicarrier/Multiband Communications
Along with the widespread application of orthogonal frequency division mulplexing (OFDM) in wireless communications, people are relying more and more on multicarrier/multiband communications for information transmission. Nevertheless, security has become an urgent issue considering potential threats from malicious users and/or unknown interference. There is always a trade off between the communication security and the efficiency, although people want to sacrifice neither of them in their desired communications. This research is devoted to developing new security schemes for multicarrier/multiband communications with minimum efficiency cost, as well as other schemes in balancing the communication efficiency against the security. Moreover, game theory is exploited to enhace the security of multicarrier/multiband communications when a smart and fast adapting jammer is present.
Direct-Sequence Code Division Multiple Access (DS-CDMA) and Navigation
In DS-CDMA systems, each user is assigned a specific pseudo-random code (also known as the signature) to spread its signal over a bandwidth N times larger. Due to the processing gain resulted from the spread spectrum technique, DS-CDMA is especially robust under narrow band jamming and works very well under low SNR levels. DS-CDMA signals cannot be recovered unless the user signature is known at the receiver, and can be hidden within the noise floor, making it difficult to be detected. This research involves a wide variety of topics, including non-binary spreading code design and anti-jamming techniques under disguised jamming (where the jammer mimics the authorized signal using the cracked or public coding information), and expands to the application of DS-CDMA in GPS navigation.