Campus Units

Electrical and Computer Engineering

Document Type

Conference Proceeding


2009 IEEE International Symposium on Information Theory

Publication Version

Accepted Manuscript

Link to Published Version

Publication Date


Journal or Book Title

IEEE International Symposium on Information Theory, 2009. ISIT 2009.

First Page


Last Page




Conference Title

2009 IEEE International Symposium on Information Theory

Conference Date

June 28-July 3, 2009


Seoul, South Korea


We consider the network communication scenario in which a number of sources si each holding independent information Xi wish to communicate the sum ∑Xi to a set of terminals tj. In this work we consider directed acyclic graphs with unit capacity edges and independent sources of unit-entropy. The case in which there are only two sources or only two terminals was considered by the work of Ramamoorthy [ISIT 2008] where it was shown that communication is possible if and only if each source terminal pair si/tj is connected by at least a single path. In this work we study the communication problem in general, and show that even for the case of three sources and three terminals, a single path connecting source/terminal pairs does not suffice to communicate ∑Xi. We then present an efficient encoding scheme which enables the communication of ∑Xi for the three sources, three terminals case, given that each source terminal pair is connected by two edge disjoint paths. Our encoding scheme includes a structural decomposition of the network at hand which may be found useful for other network coding problems as well.


This is a manuscript of a proceeding from the IEEE International Symposium on Information Theory (2009): 2121, doi:10.1109/ISIT.2009.5205758. Posted with permission.


Copyright 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Copyright Owner




File Format


Published Version


Article Location