On the Power of Cooperation: Can a Little Help a Lot? (Extended Version)

TL;DR

This paper introduces a novel indirect cooperation model for multiple access channels, demonstrating that small cooperative exchanges can lead to disproportionately large increases in channel capacity, surpassing prior models and network coding results.

Contribution

It presents a new cooperation framework through a larger network, showing significant capacity gains from minimal shared information, unlike previous direct cooperation models.

Findings

Existence of channels with large sum-capacity gains from small cooperation

Contrasts with prior cooperation models and network coding results

Demonstrates potential for substantial capacity improvements with limited cooperation

Abstract

In this paper, we propose a new cooperation model for discrete memoryless multiple access channels. Unlike in prior cooperation models (e.g., conferencing encoders), where the transmitters cooperate directly, in this model the transmitters cooperate through a larger network. We show that under this indirect cooperation model, there exist channels for which the increase in sum-capacity resulting from cooperation is significantly larger than the rate shared by the transmitters to establish the cooperation. This result contrasts both with results on the benefit of cooperation under prior models and results in the network coding literature, where attempts to find examples in which similar small network modifications yield large capacity benefits have to date been unsuccessful.