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Linear Network Coding for Two-Unicast-$Z$ Networks: A Commutative Algebraic Perspective and Fundamental Limits
Mohammad Fahim,Viveck R. Cadambe +1 more
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TLDR
In this paper, the authors consider a two-unicast-Z$ network over a directed acyclic graph of unit capacitated edges, and show that vector linear codes outperform scalar linear codes and non-linear codes in general, and develop a commutative algebraic approach to derive linear network coding achievability results.Abstract:
We consider a two-unicast-$Z$ network over a directed acyclic graph of unit capacitated edges; the two-unicast-$Z$ network is a special case of two-unicast networks where one of the destinations has apriori side information of the unwanted (interfering) message. In this paper, we settle open questions on the limits of network coding for two-unicast-$Z$ networks by showing that the generalized network sharing bound is not tight, vector linear codes outperform scalar linear codes, and non-linear codes outperform linear codes in general. We also develop a commutative algebraic approach to deriving linear network coding achievability results, and demonstrate our approach by providing an alternate proof to the previous results of C. Wang et. al., I. Wang et. al. and Shenvi et. al. regarding feasibility of rate $(1,1)$ in the network.read more
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An algebraic approach to network coding
Ralf Koetter,Muriel Medard +1 more
TL;DR: For the multicast setup it is proved that there exist coding strategies that provide maximally robust networks and that do not require adaptation of the network interior to the failure pattern in question.
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