802.11a Hits the Road, Jack

So what is DSRC? DSRC is Dedicated Short Range Communications. What does is it have to do with 802.11? In August 2001, the DSRC standards committee (ASTM 17.51) selected 802.11a as the underlying radio technology for DSRC applications. The IEEE 802.11a standard was modified to meet DSRC deployment requirements. This standard is to apply to all vehicles in North America (USA, Canada, and Mexico).

What impact will this have on 802.11 markets?

With the introduction of DSRC, an emerging market for 802.11 is telematics. Considering that there are over 17 million new vehicles sold each year, this is a very large market opportunity for the 802.11 community. Several years ago, Congress authorized 75 MHz of spectrum from 5.850 to 5.925 GHz for DSRC. Similar spectrum has been allocated in Canada and Mexico for this purpose. As this spectrum is just above the UNII band, one can expect deployment of radios that can operate in both UNII and DSRC bands.

For market potential comparison, consider that an estimated 150 million PCs are in use the USA, whereas there are currently more than 200 million vehicles in use in the USA. PCs may connect via wired networks, while moving vehicles essentially have only a wireless option. As DSRC is poised to be the primary method of connecting into ITS (Intelligent Transportation Systems) applications, the potential for 802.11 chipsets in telematics may exceed that for conventional PC and PDA markets.

The goal of Congress and the Department of Transportation is to have a standard, interoperable, platform to deploy ITS (Intelligent Transportation Systems) applications. Current DSRC systems such as toll tags operate in the 900 MHz spectrum, but as no single standard was established, several proprietary systems were deployed. With the current system, a car traveling through the US can’t communicate with all DSRC systems. In this revision of DSRC, interoperability is a key requirement. If all the vehicles can’t communicate with each other, one can’t effectively deploy ITS applications.

What are the types of applications that can be deployed with this new generation of DSRC? The new generation of DSRC is a vehicle-powered two-way communication link with data rates ranging from 6 to 27 Mbps. This platform will greatly enhance the applications that can be deployed. Some example DSRC applications:

  • Emergency Vehicle Warning – Currently, emergency vehicles only have sirens and lights to notify of their approach. With DSRC, the emergency vehicle can have the traffic system change traffic lights to clear traffic along it’s intended route. Also, this route information can be broadcast to other cars to provide user/vehicle specific directions to reduce collisions.

  • Traffic congestion data can be exchanged between vehicles. On-coming traffic exchanges information on traffic status ahead so that vehicle navigation systems can dynamically provide the best route to a destination. No recurring cost to the consumer, just a cooperative software application integrated into automobile navigation systems.

  • An industry standard interoperable tolling platform could expand the use of toll systems or processing payments at parking lots, drive-through establishments (food, gas), etc. A new revenue source for toll road operators?

  • Safety applications could benefit the most in the long term. The DSRC automaker consortium (DaimlerChrysler, GM, Ford, Toyota, Nissan, & VW) are seeking ways to enhance passenger safety with DSRC communications. For example, in a typical collision, a car has only 10 milliseconds to tighten seatbelts, deploy airbags, etc. If an additional advance warning of 5 milliseconds was provided, one could tighten seatbelts, warm-up the airbags, etc. to prepare the car for collision. Using radar, GPS data, etc. a car can determine that a collision is imminent, and it can then notify the car about to be hit to prepare for collision. The automakers believe that even this small advance warning will provide the opportunity to significantly reduce the severity of injuries.

As the radios that will be installed will most likely operate in both DSRC and UNII bands, one can anticipate 802.11 hotspots at many more locations to provide vehicles with location-specific traveler information services along with many other categories of services that can be provided over DSRC/802.11 systems.

Mohan Pundari [email protected] is an independent technology consultant and is the Chairman of the DSRC Vehicle Taskforce within the DSRC ASTM standards committee.

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