Vehicle to Vehicle or Vehicle to Roadside Communications?

Nov. 1, 2006
It will take both to achieve ITS America's vision of "Zero Fatalities. Zero Delays."

Within the last few years, a number of changes have occurred with the vision and future plans for Intelligent Transportation Systems (ITS). For example, General Motors' recent demonstration of vehicle-to-vehicle (V2V) communications using global positioning system (GPS) technology and wireless dedicated short-range communication (DSRC) at 5.9 GHz put the technology in vehicles without requiring any roadside infrastructure. As a result, the technology and its implementation could dramatically change from previous forecasts. This report will explore some of the recent philosophy changes and their impact on automotive electronics technology.


In the landmark demonstrations at the 1997 SAE Future Transportation Technologies Conference in San Diego, much of the technology was implanted in the road. “We came away from that seeing that it is possible to do all kinds of incredible technology that automates the driving process and makes cars safer and assist drivers in doing what they need to be doing,” said Neil Schuster, president & CEO of Intelligent Transportation Society of America (ITS America). Since then, ITS America has looked at alternatives to modifying every mile of every road. With more technology in vehicles, the installation cost on the roadway is far less. This avoids digging up roadways to install sensors and the associated lane closures that would be required to make it happen. With technology in vehicles, roadway maintenance and upgrades could be avoided.

Fresh from attending the 13th World Congress on ITS, which was held Oct. 8-12, in London, UK, Schuster provided the latest perspective on ITS and vehicle infrastructure integration (VII). “We've got two sets of systems — those that are in the roadway and those that are in the car,” said Schuster. According to the current plan, a decision will be made near the end of 2008 regarding deploying a system nationwide that would bring the two together. A number of technologies have already been demonstrated.

More than 20 potential systems today that were not part of the equation in 1997 were demonstrated at the 12th World Congress on Intelligent Transport Systems, Nov. 6-10, 2005 in San Francisco. For example, a vehicle going into a skid alerted the vehicle behind it regarding a potentially dangerous situation, cars that park themselves, self-docking buses, communication between vehicles and communication with flashing rear lights. Communication between vehicles includes information such as how fast the vehicle is moving, if it is turning, and sensing of the roadway including information regarding the roadway temperature, the presence of ice on the roadway, or if it is raining. “It can even determine where potholes are,” said Schuster. The pilot vehicles communicate the location (latitude and longitude) of a threshold-level pothole that impacts the suspension to the central database so other drivers can be aware of the pothole and avoid swerving or losing control.

A vehicle equipped with ITS capability provides a benefit to the driver justifying the driver to invest in the technology. By maintaining the vehicle, the driver pays part of the maintenance cost of the data-collection system. The transition from roadway to vehicle has been happening since 1997; however, the automated roadway is still a part of the total solution.

Every major city has some sort of transportation system manager. Collecting, analyzing and distributing the data from these projects are among ITS America's efforts. The data from separate systems can be shared, consolidated, and then delivered to customers. “The emerging challenge in ITS is taking all these disparate systems and bringing them closer and closer together into one network,” said Schuster. By having a network of networks, travelers will be fully connected anywhere.

One of the enabling technologies for network communication is dedicated short-range communication (DSRC). The Federal Communications Commission (FCC) allocated radio spectrum at 5.9 GHz specifically for transportation applications to provide enhanced safety and improved mobility. DSRC uses modified Wi-Fi technology to provide communication rates from 3 Mbps to 54 Mbps and a range up to 1000 meters. A sample of some of the applications from ITS 12th World Congress that took advantage of DSRC was demonstrated at Convergence 2006, Oct. 16-18, 2006 in Detroit, MI.


Several of the Innovative Mobility Showcase demos at 12th World Congress on Intelligent Transport Systems, Nov. 6-10, 2005 communicated with Econolite's Intelligent Intersection System. Using a DSRC network, intersection status information was broadcast by Econolite's ASC/3-2100 traffic controller to specially equipped test vehicles as shown in Figure 1. A priority message from a vehicle to the traffic controller using the DSRC network requested a green light simulating an emergency situation. Once the traffic controller identified the request, it changed the red traffic light to green to allow the vehicle to proceed.


General Motors' V2V communication puts the technology inside vehicles instead of in the highway infrastructure. Using the DSRC and GPS technologies, the host vehicle receives communications from another vehicle that could be up to one-quarter mile away. GM has demonstrated the technology in a wireless instantaneous driver advisory system and a wireless automated collision avoidance system.

As shown in Figure 2, with the lane change and blind zone advisor, the host vehicle receives a steady amber warning when a vehicle is in the blind zone. If the driver activates the turn signal while a vehicle is in the blind zone, a flashing amber vehicle icon light and vibrating seat warn of the potential danger.

In the forward collision avoidance with auto-brake mode, the system in the host vehicle monitors signals from other vehicles in the same lane as far as 150 meters away, as shown in Figure 3. The vehicle-ahead indicator progresses from green indicating a safe distance to yellow to red for a dangerous situation and then applies the brakes if the driver does not respond. In both systems, a haptic warning from a vibrating seat provides an additional alerting mechanism to the driver.

Using a communications approach to monitoring vehicle proximity and identifying dangerous situations, both of the V2V modes reduce the cost and complexity of functions that typically require several sensors to detect the same events. The V2V system uses a simple antenna, computer, a GPS receiver, and transponder. V2V communications can avoid chain reactions and provide additional warnings by flashing the rear lights of the vehicle(s) ahead.


Established to determine the feasibility of widespread deployment and to establish an implementation strategy, the National VII Coalition consists of automobile manufacturers, the American Association of State Highway and Transportation Officials (AASHTO), 10 state departments of transportation, and the U.S. Department of Transportation. As shown in Figure 4, equipment on the vehicle communicates with the infrastructure using the wireless access in vehicular environments (WAVE) software and radio module hardware. Service providers and probe data users receive data from the infrastructure.

With the first DSRC radio available for coalition testing last April and vehicle-infrastructure-network integration beginning in late 2006, the coalition expects to complete proof of concept testing in 2007 and initiate field operational tests in 2008. From the technology side, the feasibility has been proven and the initial architecture developed. The draft DSRC standard is complete, prototype DSRC units are available, and overall system design is under way. As shown in Figure 5, the 5.9 GHz DSRC in the VII communicates between onboard equipment, roadside equipment, and a regional message switch as well as between vehicles.

As part of the VII effort in June 2006, DaimlerChrysler, Econolite and Raytheon, and TechnoCom demonstrated communication technology in the kick off of the Innovative Mobility Showcase road show sponsored in part by the American Association of State Highway and Transportation Officials (AASHTO)[4]. The demonstration used TechnoCom's multiband configurable networking unit (MCNU) (shown in Figure 6), a DSRC platform for either in-vehicle or roadside equipment in VII applications. Besides 5.9 GHz DSRC, the MCNU also supports Wi-Fi and 4.9 GHz public safety communications. TechnoCom and Raytheon jointly developed application software used in the road show and the MCNU.


Evolving technology will allow both V2V and VII to complement each other and expand. With ITS goals that match personal travel goals of arriving on time and with-out any fatalities, Schuster is optimistic about short-term improvements. In the last few years, ITS applications have benefited from consumer products provided on cell phones, PDA or in-vehicle navigation/real-time technologies. Lo-cation-based services are proliferating. Schuster notes that navigation systems with increased communication capability are getting useful while the vehicle is moving. Until recently, many of the vehicle systems were either theoretical or only in development vehicles, such as cars that park themselves.

Navigation systems and real-time information have the inside track to become mainstream applications. While emergency response vehicles such as fire, police and ambulances and public transportation vehicles could be among the first to benefit from DSRC technology with the capability for signal light rescheduling, other changing vehicle technologies could provide ITS synergy. With new fuel sources offered in limited locations, such as diesel fuel today and in the future hydrogen, infrastructure to vehicle communication can help drivers avoid running out of fuel.


  1. 12th World Congress on Intelligent Transport Systems, Nov. 6-10, 2005 Econolite Intelligent Intersection, (

  2. VIIC and VII program overview.




Randy Frank is president of Randy Frank & Associates Ltd., a technical marketing consulting firm based in Scottsdale, AZ. He is an SAE and IEEE Fellow and has been involved in automotive electronics for more than 25 years. He can be reached at [email protected].

Sponsored Recommendations


To join the conversation, and become an exclusive member of Electronic Design, create an account today!