Information Theory Seminar

TITLE: Broadcast channels: new results

SPEAKER: Chandra Nair (Chinese University of Hong Kong)

DATE: 2:00 - 3:00 PM, Thursday, February 19, 2009

LOCATION: Tioga, 3U

ABSTRACT:
In this talk, we will present three new results that were obtained last year on the broadcast channel. The broadcast channel refers to a communication scenario where one sender (cell-phone towers) sends different messages to two or more receivers (subscribers in its cell). The set of achievable rates under this setting is a long standing open problem, and this talk presents partial optimality results for various classes of channels.

Result 1 answers the following question: What is the capacity region for the 2-receiver broadcast channel when one of the channels is the binary symmetric channel and the other is a binary erasure channel.

Result 2 (joint with my student Zizhou "Vincent" Wang) concerns a study of the inner and outer bounds for a class of 3-receiver broadcast channels with 2-degraded messages. We will produce an example where the bounds differ and use a "new" argument to show the tightness of the inner bound.

Result 3 establishes an information theoretic inequality for the binary skew-symmetric broadcast channel. This produces the first example where the best known inner and outer bounds differ for the 2-receiver broadcast channel. The way the inequality is proved (and the only known proof of this) is very non-standard.

The ordering of the results is based on the techniques involved: from the traditional to the novel.

BIOGRAPHY:
Chandra Nair is an assistant professor with the Information Engineering Department at the Chinese University of Hong Kong. His research interests include "random" problems in combinatorial optimization, networks, and information theory.

Chandra Nair was a Stanford graduate fellow (00-04) and Microsoft graduate fellow (04-05) during his graduate studies at Stanford university. Subsequently, he was a post-doc with the theory group at Microsoft research, Redmond. He joined the faculty of the Iinformation Engineering Department at the Chinese university of Hong Kong during Fall 2007.