Princeton-Rutgers Seminar Series in Information Sciences & Systems

Title: Iterative joint detection/decoding and estimation: algorithms and results

Speaker: Giuseppe Caire, Eurecon Institute, Sophia Antipolis, France

Date: March 26, 2004, 3:00 - 4:00pm

Location: WINLAB Conference Room, Rutgers University, Busch Campus, Piscataway, NJ


The factor-graph (FG) representation and the sum-product algorithm (SPA) have encountered an increasing success in digital communications as a common framework to interpret existing algorithms and developing new methods for signal detection and decoding. Perhaps the most celebrated applications of this framework is represented by the iterative decoding technique known as ``Belief-Propagation'', commonly used to decode low-density-parity-check codes, turbo-codes and other randomlike families of codes.

In this semi-tutorial talk, we review the application of the FG-SPA framework to the following problems: 1) joint decoding of users in a Gaussian multiple-access channel; 2) decoding of coded modulations in the presence of phase-noise. For both problems, we start from an axiomatic application of the FG and obtain the corresponding SPA. Interestingly, for both problems the brute-force implementation of the SPA is too complex for practical implementations. In the case of multiuser joint decoding, we shall develop approximations of the exact SPA and a performance analysis based on the Density-Evolution technique, which shows that the proposed approximations perform indeed very close to the ``locally optimal'' exact SPA at much lower complexity. In the case of decoding in the presence of phase-noise, we shall develop a number of new algorithms also obtained from the exact SPA by using the approach of ``canonical distributions'', and compare their performance by computer simulation. Remarkably, one of the new algorithms developed in this presentation perform as well as the locally optimal SPA at much lower complexity, and makes coherent detection even in the presence of strong phase noise practically achievable and easily implementable.


Giuseppe Caire (S '91 -- M '94) was born in Torino, Italy, on May 21, 1965. He received the B.Sc. in Electrical Engineering from Politecnico di Torino (Italy), in 1990, the M.Sc. in Electrical Engineering from Princeton University (USA) in 1992 and the Ph.D. from Politecnico di Torino in 1994. He was a recipient of the AEI G. Someda Scholarship in 1991, has been with the European Space Agency (ESTEC, Noordwijk, The Netherlands) in 1995, was a recipient of the COTRAO Scholarship in 1996 and a CNR Scholarship in 1997. He has been visiting the Institute Eurecom, Sophia Antipolis, France, in 1996 and Princeton University in summer 1997. He has been Assistant Professor in Telecommunications at the Politecnico di Torino and presently he is Professor with the Department of Mobile Communications of Eurecom Institute. He served as Associate Editor for the IEEE Transactions on Communications in 1998-2001 and he is presently Associate Editor of the IEEE Transactions on Information Theory since 2001. He is co-author of more than 50 papers in international journals and more than 80 in international conferences, and he is author of three international patents with the European Space Agency. His interests are focused on digital communications theory, information theory, coding theory and multiuser detection, with particular focus on wireless terrestrial and satellite applications.