 Prof. Milica Stojanovic, Northeastern University, USA
Personal profile: Professor, Department of Electrical Engineering, Northeastern University, Affiliated Faculty, Department of Bioengineering, Northeastern University, Permanent Guest Investigator, Woods Hole Oceanographic Institution (WHOI),Visiting Scientist ( affiliated with AUV Laboratory), Massachusetts Institute of Technology, millitsa@ece.neu.edu
Milica Stojanovic graduated from the University of Belgrade, Serbia, in 1988, and received the M.S. and Ph.D. degrees in electrical engineering from Northeastern University in Boston, in 1991 and 1993. She was a Principal Scientist at the Massachusetts Institute of Technology, and in 2008 joined Northeastern University, where she is currently a Professor of electrical and computer engineering. She is also a Guest Investigator at the Woods Hole Oceanographic Institution. Her research interests include digital communications theory, statistical signal processing and wireless networks, and their applications to underwater acoustic systems. Milica is a Fellow of the IEEE, an Associate Editor for the IEEE Journal of Oceanic Engineering, a past Associate Editor for the IEEE Transactions on Signal Processing, IEEE Transactions on Vehicular Technology, and a Senior Editorial Board Member of the IEEE Signal Processing Magazine. She chairs the IEEE Ocean Engineering Society’s (OES) Technical Committee for Underwater Communication, Navigation and Positioning, and is an IEEE OES Distinguished Lecturer. Milica is the recipient of the 2015 IEEE/OES Distinguished Technical Achievement Award, the 2019 IEEE WICE Outstanding Achievement Award, and the 2023 IEEE Communications Society’s Women Stars in Computer Networking and Communications Award. In 2022, she was awarded an honorary doctorate from the Aarhus University in Denmark and was elected to the Academy of Engineering Sciences of Serbia.
Presentation title: Underwater acoustic communications: Feedback-based techniques and transmit beamforming
Abstract: Feedback-based communication allows the receiver to send channel state information back to the transmitter, which in turn adjusts the signal parameters to best suit the propagation conditions. The adjustment enables various system design concepts, ranging from simple power control to more sophisticated adaptive modulation and spectrum shaping techniques, as well as transmit beamforming and spatial-division multiple access. While such techniques are finding widespread use in terrestrial radio communications, their application to underwater acoustic communications has been limited. The main difficulty in applying these techniques to the acoustic channel arises from the fact that sound propagates relatively slowly, allowing the channel response can change significantly over the time it takes to close the feedback loop.
In this presentation, we focus on feedback-based transmit beamforming, explaining its fundamental principles and outlining solutions suitable for acoustic channels with delayed feedback. Transmit beamforming is beneficial on point-to-point links as it offers power efficiency and avoidance of unintended listeners, while in networked systems it offers the additional possibility to separate the multiple users’ signals spatially. The latter is particularly important for acoustic systems whose bandwidth is notoriously limited, as it allows multiple users to be separated without reducing the transmission rate.
Within the framework of broadband beamforming, we discuss multi-carrier signal processing algorithms for both uplink and downlink transmission, with coherent and differentially coherent signal detection. We demonstrate the full multi-user system proof-of-concept using experimental signals in an in-air acoustic communications testbed.
|