Communicating the sum of sources over a network

Aditya Ramamoorthy; Michael Langberg

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arXiv · 1001.5319

Communicating the sum of sources over a network

Aditya Ramamoorthy·Michael Langberg

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Abstract

We consider the network communication scenario, over directed acyclic networks with unit capacity edges in which a number of sources $s_i$ each holding independent unit-entropy information $X_i$ wish to communicate the sum $\sum{X_i}$ to a set of terminals $t_j$. We show that in the case in which there are only two sources or only two terminals, communication is possible if and only if each source terminal pair $s_i/t_j$ is connected by at least a single path. For the more general communication problem in which there are three sources and three terminals, we prove that a single path connecting the source terminal pairs does not suffice to communicate $\sum{X_i}$. We then present an efficient encoding scheme which enables the communication of $\sum{X_i}$ for the three sources, three terminals case, given that each source terminal pair is connected by {\em two} edge disjoint paths.

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Aditya Ramamoorthy, Michael Langberg. 2013-01-22. Communicating the sum of sources over a network. https://arxiv.org/abs/1001.5319

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