Palestrantes

Max H. M. Costa graduated as an Electrical Engineer at the University of Brasília in 1974. He received his Master Degree in Electrical Engineering from the University of Campinas (Unicamp) in 1977, the Master in Statistics from Stanford University in 1979, the Ph.D. in Electrical Engineering from Stanford University in 1983, and the “Livre Docência” in Electrical Engineering from Unicamp in 1998. He was a Researcher at the Brazilian National Institute of Space Research (INPE), in São José dos Campos, SP, Brazil, from 1983 to 1988 and at the General Electric Corporate Research and Development Center, in Schenectady, NY, USA, from 1988 to 1993. From 1993 to 1994 he was a Senior Research Associate at NASA’s Jet Propulsion Laboratory, in Pasadena, CA, USA. Since 1995 he has been a Faculty Member at Unicamp, where he is currently an Associate Professor. From April 2007 to April 2011 he was the Director of the School of Electrical and Computer Engineering (FEEC) of Unicamp. He is a Senior Member of the IEEE, and a Senior Member of the Brazilian Telecommunications Society (SBrT). In the period 2010-2012 he will be a member of the Board of Governors (BoG) of the IEEE Information Theory Society. He is currently a member of the External Nominations Committee and a Distinguished Lecturer of the Information Theory Society. His research interests lie in Shannon theory, information geometry, source and channel coding, and digital television. He is better known for his paper “Writing on dirty paper”, published in 1983, a recipient of over 2300 citations according to Google Scholar.

Interference Channels

The interference channel is one of the jewels of multiple user information theory and its capacity has stood as an open problem since the first considerations in the seventies, in the discrete memoryless version as well as in the Gaussian version. We consider the latter. The capacity region has been found in the very weak interference and in the strong interference regimes. When the crosstalk or interference gains are less than one, the channel is said to have weak interference and the capacity region is generally unknown. We review the cases in which the problem has been solved and consider two particular scenarios that have led to some recent progress. In the first, we consider the Z Gaussian interference channel, and propose a water-filling scheme to provide optimal power sharing among orthogonal dimensions. In this context the notion of noisebergs arises as a means to improve the allocation of power and degrees of freedom. The solution has been shown to equal the best known inner bound (the Han-Kobayashi region) to the capacity region with Gaussian signaling. In the second scenario, in joint work with Chandra Nair (CUHK, Hong Kong), we compute the exact rate sum of a symmetric Gaussian interference channel for the Han- Kobayashi region with Gaussian signaling for a subset of parameters in the weak interference regime. We identify a number of phase changes in this region, that justify denominations such as weak (revised), intermediate, moderate and almost strong interference conditions. We characterize a determined region of parameters, where we achieve exact computations of the rate sum, and a nebulous region, where our techniques do not yield the exact rate sum. However, we find schemes in this diffuse region that lead to rates above those prescribed by TDM (time division multiplex), even for values of interference gains that approach unity.