Dedicated short-range communications
Dedicated short-range communications (DSRC) are one-way or two-way short-range to medium-range wireless communication channels specifically designed for automotive use and a corresponding set of protocols and standards.
In October 1999, the United States Federal Communications Commission (FCC) allocated 75 MHz of spectrum in the 5.9 GHz band to be used by intelligent transportation systems (ITS). In August 2008, the European Telecommunications Standards Institute (ETSI) allocated 30 MHz of spectrum in the 5.9 GHz band for ITS.
By 2003, it was used in Europe and Japan in electronic toll collection. DSRC systems in Europe, Japan and the U.S. are not compatible and include some very significant variations (5.8 GHz, 5.9 GHz or even infrared, different baud rates, and different protocols).
In June 2017, the Utah Department of Transportation successfully demonstrated a Transit DSRC system on SR-68 (Redwood Road) for eleven miles, from 400 South in Salt Lake City to 8020 South in West Jordan City. This was in partnership with the Utah Transit Authority. Several UTA Transit buses were outfitted with the DSRC equipment to allow for signal cycle time extensions if the bus was running behind schedule.
In November 2020, the FCC reallocated all of DSRC's spectrum for other uses citing lack of adoption. Allocating 45 MHz to the neighboring 5.8 GHz ISM band and the remaining 30 Mhz to use by Cellular V2X. 
Other possible applications were:
- Emergency warning system for vehicles
- Cooperative Adaptive Cruise Control
- Cooperative Forward Collision Warning
- Intersection collision avoidance
- Approaching emergency vehicle warning (Blue Waves)
- Vehicle safety inspection
- Transit or emergency vehicle signal priority
- Electronic parking payments
- Commercial vehicle clearance and safety inspections
- In-vehicle signing
- Rollover warning
- Probe data collection
- Highway-rail intersection warning
- Electronic toll collection
The European standardization organisation European Committee for Standardization (CEN), sometimes in co-operation with the International Organization for Standardization (ISO) developed some DSRC standards:
- EN 12253:2004 Dedicated Short-Range Communication – Physical layer using microwave at 5.8 GHz (review)
- EN 12795:2002 Dedicated Short-Range Communication (DSRC) – DSRC Data link layer: Medium Access and Logical Link Control (review)
- EN 12834:2002 Dedicated Short-Range Communication – Application layer (review)
- EN 13372:2004 Dedicated Short-Range Communication (DSRC) – DSRC profiles for RTTT applications (review)
- EN ISO 14906:2004 Electronic Fee Collection – Application interface
Each standard addresses different layers in the OSI model communication stack.
- Harvey J. Miller and Shih-Lung Shaw (2001). Geographic Information Systems for Transportation. Oxford University Press. ISBN 978-0-19-512394-4.
- "Federal Communications Commission. News Release, October 1999". FCC. Retrieved 2009-08-16.
- "European Telecommunications Standards Institute. News release, September 2008". ETSI. Archived from the original on 2012-02-18. Retrieved 2009-08-16.
- "DSRC Standards: What's New?". ITS Standards Advisory number 3. US Department of Transportation. April 2003. Archived from the original on February 16, 2013. Retrieved September 9, 2013.
- "Traffic congestion pricing methodologies and technologies". doi:10.1016/j.trc.2011.02.010. Cite journal requires
- "FCC Modernizes 5.9 GHz Band to Improve Wi-Fi and Automotive Safety" (PDF).
- Performance Evaluation of Short-Range Communication Links for Road Transport & Traffic Telematics (in German)
- A comparison of different technologies for EFC and other ITS applications
- Connectsafe Wireless Vehicle Communication System - University of South Australia
- Dedicated Short-Range Communications (DSRC) Fact Sheet – U.S. Department of Transportation ITS JPO