Deploying Throwboxes to Enhance Fault-Tolerance Performance in Delay Tolerant Networks

Delay Tolerant Networks (DTNs) have attracted various interests these days. Since DTNs are subject to high loss rate, large delay, intermittent connection, and even no end-to-end connectivity, relay nodes, such as throwboxes, are deployed to enhance network performance. Internet-based systems have contemporaneous connectivity between location-distributed nodes, and this does not apply to DTNs. Thus, the traditional relay node deployment strategies are no longer suitable for DTNs. In this paper, we propose a novel strategy, named Connection-2 (CO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$CO_2$$\end{document}), to deploy throwboxes to enhance the fault tolerance of DTNs. CO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$CO_2$$\end{document} constructs a 2-connected DTN using an approximation algorithm. Every mobile node in the 2-connected DTN can reach another mobile node via two or more node-disjoint paths within its mobility range. While enhancing fault tolerance, the number of throwboxes that CO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$CO_2$$\end{document} requires is small. We conduct various experiments based on the simulation of the real Tuscaloosa bus transit system and compare its performance with two popular strategies. Experimental results show that CO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$CO_2$$\end{document} is effective.