Connected Vehicle Infrastructure University Transportation Center

Virginia Connected Vehicle Test Bed System Performance

Final Report

Abstract

If the Virginia Connected Vehicle Test Bed is to support a full-scale regional deployment, the environment must be able to effectively handle the connected vehicle volume. In such an environment, the benefits of vehicle-to-vehicle/infrastructure (V2X) systems hinge on the ability to securely, transmit, receive, and process information. Synonymous to actual traffic jams, a similar situation may exist on the Vehicle-to-Infrastructure (V2I) ‘information super highway’. Considering the traffic distribution along I-66 and arterials, a common occurrence is stop and go traffic. If all of the vehicles were instrumented with V2X technologies, spectral channels and network devices may become locally congested due to the amount of over the air (OTA) transmissions. This may result in interruption of key V2X applications if not properly understood and handled.

Network congestion may occur from a multitude of different sources, chiefly connected vehicle transmission density. Considering the physical traffic distribution along I-66 and arterials, a common occurrence is traffic jams. If all of the vehicles were instrumented with V2X technologies, localized spectrum congestion may occur. This is due to the number of vehicles transmitting messages OTA. In addition to spectral congestion, networked devices may also be put under extreme processing load and backhaul networks may reach bandwidth limitations, as each interconnected device that processes network data may become a bottleneck.

Based on hourly traffic distribution provided in a Federal Highway Administration (FHWA) I-66 West Bound Traffic Density Research Project [FHWA 132-133], a projection of data transmitted by vehicles and processed by the infrastructure can hit peaks in upwards of 1TB of data per hour. The projection assumes that all vehicles are transmitting 378 byte messages OTA at a rate of 10 Hz per Crash Avoidance Metrics Partnership (CAMP) research parameters [NHTSA 65]. In addition, the total projected data throughput is calculated by accounting for all other RSEs in the network.

Research in vehicle-to-vehicle (V2V) communications scalability has already been performed by entities such as CAMP. On the other hand, V2I based research results are not readily available or incomplete due to the lack of equivalent connected vehicle test bed environments. Much can be gained in implementing a similar research methodology performed by CAMP and adapting it for V2I. Such results can better serve the research community, but more importantly verify the functionality of the Virginia Connected Vehicle Test Bed.

In an effort to identify system limitations, the project will run experimental studies focusing on stressing the wireless and backhaul networks on the Virginia Connected Vehicle Test Bed. By understanding what links break between equipped vehicles, roadside equipment, and network infrastructure, limitations can be characterized and improvements can be made when feasible.

Execution of the project plans to facilitate:

  • Identification of Network Bottlenecks
  • Identification of Load Shedding Strategies (i.e. data suppressing, message sequencing, or formatting)
  • Understand Impact of RSSI, Packet Error Rate, Inter Packet Gap as a function of Range, Speed, Elevation, Heading under various scalability test scenarios
  • Support USDOT NHTSA Affiliated Test Bed Research and Deployment Requirements

Highlights

  • Evaluated the performance by assessing three standard communication parameters: Packet Error Rate, Latency and Inter-Packet Gap.
  • Associated with several intrinsic and extrinsic factors including heading, speed, ahead, across, range, roundabouts.
  • Initial results indicate that physical obstacles in the roadway may be impacting communication performance between vehicles and RSEs. Such obstacles include overpasses, underpasses, highway barrier walls, and/or tree foliage.

Sponsor Organization

Research and Innovative Technology Administration
University Transportation Centers Program
Department of Transportation
1200 New Jersey Avenue, SE
Washington, DC 20590
USA

UTC Grant Manager

Harwood, Leslie
Phone: 540-231-9530
Email: lharwood@vtti.vt.edu

Performing Organization

Virginia Polytechnic Institute and State University, Blacksburg
Virginia Tech Transportation Institute
3500 Transportation Research Plaza
Blacksburg, Virginia 24061
USA

Research Investigators

Viray, Reginald
Doerzaph, Zac
Gorman, Tom

More Information

RiP URL
Project Poster
TriD Format