Can Negligible Cooperation Increase Network Reliability?

TL;DR

This paper proves that even negligible cooperation between transmitters in a two-user multiple access channel can equalize maximal- and average-error sum-capacities, showing small shared information can significantly improve network reliability.

Contribution

It demonstrates that minimal cooperation can eliminate capacity gaps in multiple access channels, revealing the non-continuity of sum-capacity with respect to cooperation capacity.

Findings

Negligible cooperation equalizes maximal- and average-error sum-capacities.

Networks with capacity gaps become continuous when minimal cooperation is introduced.

Sharing even a tiny amount of information can yield significant reliability benefits.

Abstract

In network cooperation strategies, nodes work together with the aim of increasing transmission rates or reliability. This paper demonstrates that enabling cooperation between the transmitters of a two-user multiple access channel, via a cooperation facilitator that has access to both messages, always results in a network whose maximal- and average-error sum-capacities are the same---even when those capacities differ in the absence of cooperation and the information shared with the encoders is negligible. From this result, it follows that if a multiple access channel with no transmitter cooperation has different maximal- and average-error sum-capacities, then the maximal-error sum-capacity of the network consisting of this channel and a cooperation facilitator is not continuous with respect to the output edge capacities of the facilitator. This shows that there exist networks where sharing even a negligible number of bits per channel use with the encoders yields a non-negligible benefit.