An Outer Bound for Multiple Access Channels with Correlated Sources

Download Now Date Added: Jan 2013
Format: PDF

The capacity region of the multiple access channel with correlated sources remains an open problem. Cover, El Gamal and Salehi gave an achievable region in the form of single-letter entropy and mutual information expressions, without a single-letter converse. Cover, El Gamal and Salehi also suggested a converse in terms of some n-letter mutual information, which are incomputable. The authors have proposed an upper bound for the sum rate of this channel in a single-letter expression, by utilizing a new necessary condition for the Markov chain constraint on the valid channel input distributions. In this paper, they extend their results from the sum rate to the entire capacity region.