In mobile multiple-access communications, not only the location of active users, but also their number varies with time. In typical analyses, multiuser detection theory assumes that the number of active users is constant and known at the receiver, and coincides with the maximum number of users entitled to access the system. This assumption is often overly pessimistic, since many users might be inactive at any given time, and detection under the assumption of a number of users larger than the real one may impair performance.
This talk describes a different, more general approach to the problem of identifying active users and estimating their parameters and data in a dynamic environment where users are continuously entering and leaving the system. The goal is to lay the foundation of multiuser detection theory in an environment where the number and the parameters of active users are unknown at the receiver, and in addition may change from one observation time to the next following a known dynamic model.
Using a mathematical tool known as Random Set Theory (which will be described, along with its applications), I shall show Bayesian-filter equations which describe the evolution with time of the a posteriori probability density of the unknown user parameters, and use this density to derive optimum detectors. Possible applications to neighbor discovery in wireless networks will also be described.
Speaker Bio:
EZIO BIGLIERI is presently a professor with Universitat Pompeu Fabra, Barcelona, Spain. His previous positions include professorships with Universita` di Napoli (1975--1977), with UCLA (1987--1989), and with Politecnico di Torino (1977--1987 and 1990--2005). He has held visiting positions with the Department of System Science, UCLA, the Mathematical Research Center, Bell Laboratories, Murray Hill, NJ, the Bell Laboratories, Holmdel, NJ, the Department of Electrical Engineering, UCLA, the Telecommunication Department of The Ecole Nationale Superieure des Telecommunications, Paris, France, the University of Sydney, Australia, the Yokohama National University, Japan, the Electrical Engineering Department of Princeton University, the University of South Australia, Adelaide, the University of Melbourne, the Institute for Communications Engineering, Munich Institute of Technology, Germany, and the Institute for Infocomm Research, National University of Singapore.
He was elected three times to the Board of Governors of the IEEE Information Theory Society, and served as its President in 1999. He was the general co-chairman of the "IEEE 2000 International Symposium on Information Theory," Sorrento, Italy, June 2000, and the general co-chairman of ISITA 2004, Parma, Italy. He is a Fellow of the IEEE, and a Distinguished Lecturer for the IEEE Information Theory Society and the IEEE Communications Society. He was an Editor of the IEEE Transactions on Communications, the IEEE Transactions on Information Theory, the IEEE Communications Letters, the Journal on Communications and Networks, and the Editor in Chief of the European Transactions on Telecommunications. Since 2004 he has been the Editor-in-Chief of the IEEE Communications Letters. He has published 6 books and in excess of 120 journal papers on digital communications. Among other honors, he received the IEEE Third-Millennium Medal, the IEEE Donald G. Fink Prize Paper Award, and the IEEE Communications Society Edwin Howard Armstrong Achievement Award.