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Deqiang Chen

Education

M.S.E.E., University of Notre Dame, 2004.

M.S., University of Science and Technology, Hefei.

B.S., University of Science and Technology, Hefei.

Research Summary

My research interests focus on detection and estimation theory, diversity techniques for fading channels, and signal processing for wireless communication. For the past two years, I have been working on cooperative diversity. Cooperative diversity is a new concept, which suggests users in a wireless network can relay information for each other and thereby increase reliability and reduce power consumption. Cooperative diversity combines spatial diversity techniques with relay methods.

Our work focuses on noncoherent communication theory for cooperative diversity. We develop a general framework for maximum likelihood (ML) demodulation in cooperative wireless communication systems. Piecewise-linear demodulators are proposed as an accurate approximation of the nonlinear ML detectors for coherent and noncoherent decode-and-forward (DF). The piecewise-linear detectors not only have certain implementation advantages over the nonlinear ML detectors, but also can lead to tight closed-form approximations for their error probabilities. High SNR approximations are derived based on the closed-form BER expressions. For noncoherent DF, the approximation suggests a different optimal location for the relay in DF than for the relay in amplify-andforward (AF). we also demonstrates that the DF does not achieve full diversity order. These observations are further extended to coherent and noncoherent DF with multiple relays. Comparison between DF and AF suggests that DF loses about half of the diversity order.

Publications