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.
History.
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). 
Singapore's Electronic Road Pricing scheme plans to use DSRC technology for road use measurement (ERP2) to replace its ERP1 overhead gantry method.
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:
Other short-range wireless protocols are IEEE 802.11, Bluetooth and CALM.
Standardization.
The European standardization organisation European Committee for Standardization (CEN), sometimes in co-operation with the International Organization for Standardization (ISO) developed some DSRC standards:
Each standard addresses different layers in the OSI model communication stack.