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# Phase Transition of Message Propagation Speed in Delay-Tolerant Vehicular Networks

## By: Little, T.D.C.; Starobinski, D.; Agarwal, A.;

2012 / IEEE

### Description

This item was taken from the IEEE Periodical ' Phase Transition of Message Propagation Speed in Delay-Tolerant Vehicular Networks ' Delay-tolerant network (DTN) architectures have recently been proposed as a means to enable efficient routing of messages in vehicular area networks (VANETs), which are characterized by alternating periods of connectivity and disconnection. Under such architectures, when multihop connectivity is available, messages propagate at the speed of radio over connected vehicles. On the other hand, when vehicles are disconnected, messages are carried by vehicles and propagate at vehicle speed. Our goal in this paper is to analytically determine what gains are achieved by DTN architectures and under which conditions, using the average message propagation speed as the primary metric of interest. We develop an analytical model for a bidirectional linear network of vehicles, as found on highways. We derive both upper and lower bounds on the average message propagation speed by exploiting a connection with the classical pattern-matching problem in probability theory. The bounds reveal an interesting phase transition behavior. Specifically, we find out that, below a certain critical threshold, which is a function of the traffic density in each direction, the average message speed is the same as the average vehicle speed, i.e., DTN architectures provide no gain. On the other hand, we determine another threshold above which the average message speed quickly increases as a function of traffic density and approaches radio speed. Based on the bounds, we also develop an approximation model for the average message propagation speed that we validate through numerical simulations.

**Related Topics**

Delay Tolerant Networks

Linear Network Analysis

Message Passing

Pattern Matching

Probability

Telecommunication Traffic

Numerical Simulations

Phase Transition

Message Propagation Speed

Delay Tolerant Vehicular Networks

Vehicular Area Networks

Radio Over Connected Vehicles

Dtn Architectures

Bidirectional Linear Network

Highways

Pattern Matching

Probability Theory

Approximation Model

Vehicles

Analytical Models

Road Transportation

Ad Hoc Networks

Computational Modeling

Computer Architecture

Network Topology

Vehicle Safety

Accident Prevention

Ad Hoc Networks

Algorithms

Automated Highways

Automotive Applications

Computer Networks

Industry Applications

Intelligent Transportation Systems

Intelligent Vehicles

Mathematics

Mobile Ad Hoc Networks

Protocols

Routing Protocols

Systems, Man, And Cybernetics

Vehicular And Wireless Technologies

Approximation Theory

Vehicular Ad Hoc Networks

Transportation

Engineering

Traffic Density Function