DSRC Roadside Unit

The United States Department of Transport (USDOT’s) is focusing on collision prevention through the incorporation of intelligent vehicles and intelligent infrastructure in its IntelliDrive. The Dedicated Short Range Communications operates around the 5.9 GHz frequency band. It is a secure and consistent form of communication between a vehicle and the roadside in specific positions like toll plazas. This way they can be used to support specific intelligent transport system applications like Electronic Fee Collection.

DSRC consists of RoadSide units (RSUs) and On Board Units (OBUs) that have transceivers and transponders. The RSU engages OBUs of travelling vehicles via the DSRC technology in order to acquire the necessary traffic information for instance time, speed and the location of the vehicle. The DSRC Roadside Unit then occasionally approximates the Start of Congestion (SoC) and Travel Time (TT) after acquiring the data. The information is then broadcasted to all the vehicles that are in its coverage range by the DSRC Roadside Unit. The DSRC Roadside Unit should be adapted with input parameters for the DSRC Roadside Unit monitoring before starting the communications with the On Board Units (OBUs). After the vehicle gets through the end of the congestion and the termination of the DSRC Roadside Unit monitoring range, it begins calculating the travel time and the beginning of the congestion. The RSU then updates this information in its DSRC broadcast which is then received by all OBUs in its range.

The main function of the DSRC RoadSide Unit is to facilitate the communication between vehicles and transportation infrastructure and other devices by transferring data over DSRC in accordance with the industry standards. The DSRC Roadside Unit can also be integrated with a backhaul system to enable distant management.

Applications of DSRC Roadside Unit

  • Traffic monitoring
  • Charging of congestions
  • Access and parking system
  • Enforcement systems
  • Multi-lane and single lane free flow systems.

The DSRC Road Side Unit can prevent collisions that are caused by traffic congestions. It can accurately estimate the travel time and the location of the Start of Congestion. DSRC Roadside Unit assists the drivers to slow down and make prepared decisions about changing lanes or rerouting.

DSRC Roadside Unit Input Parameters

Road direction

This parameter increases clockwise. It is used to check direction in the On Board Units (OBUs) to remove vehicles that are moving to the direction of the congestion on the same or another road.

Start of RSU Monitoring Range Location (SoRMR)

It is located right before the Start of Congestion location where the RSU coverage begins. Its purpose is to engage the vehicles with OBUs to take part in Vehicle to Infrastructure communications with the DSRC Roadside Unit.

Road size

This is the size for one direction travel.  Its purpose is to check the locations of approaching vehicles to engage them in the Vehicle to Infrastructure communication.

Road name and descriptive direction

It is an easily understood name for the road. This parameter is used to describe the direction that is broadcasted along with Travel Time (TT) and the Start of Congestion location by DSRC Roadside Unit for drivers.

End of Congestion Location

This is where the congestion ends and the lanes are once again open. It is used to check location of End of Congestion in the On Board Units to separate it from vehicle to infrastructure communications with DSRC Roadside Unit.

Features of DSRC Roadside Unit Devices and Antennas

The DSRC Roadside Unit operates in a specific microwave bands.  The devices can be installed in roadside poles or even inside a road side electronic cabinet. They contain an antenna system and a networkable computer.