Survivability in Time-Varying Networks

Abstract

Abstract-Time-varying graphs are a useful model for networks with dynamic connectivity such as vehicular networks, yet, despite their great modeling power, many important features of time-varying graphs are still poorly understood. In this paper, we study the survivability properties of time-varying networks against unpredictable interruptions. We first show that the traditional definition of survivability is not effective in timevarying networks, and propose a new survivability framework. To evaluate the survivability of time-varying networks under the new framework, we propose two metrics that are analogous to MaxFlow and MinCut in static networks. We show that some fundamental survivability-related results such as Menger's Theorem only conditionally hold in time-varying networks. Then we analyze the complexity of computing the proposed metrics and develop approximation algorithms. Finally, we conduct trace-driven simulations to demonstrate the application of our survivability framework in the robust design of a real-world bus communication network.

Routing in Delay-Tolerant Networks under Uncertain Contact Plans

“…In order to model a time-evolving and uncertain DTN network, the timevarying graph proposed in [32] is extended by uncertainty functions into an Uncertain Time-Varying Graph defined as follows.…”

“…Rerouting after effective detection of a failed contact or transmission attempt is a fundamental practical aspect to model the overall data flow in DTNs under uncertain contact plans. Single route reliability estimations such as those in [32] can result inaccurate in practice when nodes detect and act upon unexpected failures. However, the phenomena is not trivial.…”

“…Previous Works. Previous works have addressed the survivability properties of time-varying networks [32], as well as the problem of reliable topology design in DTN [33]. However, to the best of the authors' knowledge, the problem of reliable route determination based on uncertain contact plans has been overlooked.…”

Survivability Analysis on a Cyber-Physical System

“…On the other hand, the study of survivability varies with researchers' fields. Liang et al [17] studied the survivability of time-varying networks and proposed a new survivability framework for time-varying networks. Wan et al [18] researched the node survivability of a sensor network and considered how to schedule each sensor between active and sleep modes to maximize the network lifetime while meeting survival requirements.…”