Transportation dynamics on coupled networks with limited bandwidth

TL;DR

This paper studies transportation dynamics on coupled networks with limited bandwidth, revealing how different coupling mechanisms affect capacity, congestion, and bandwidth efficiency, and provides a theoretical method to determine congestion points.

Contribution

It introduces a model for transportation on coupled networks with bandwidth sharing and analyzes the impact of various coupling mechanisms on network capacity and congestion.

Findings

Transportation capacity depends on coupling mechanism.

Disassortative coupling preserves capacity better.

Bandwidth sharing mechanisms influence congestion and travel time.

Abstract

The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly.