Dedicated Short Range Communication at 915 MHz Standards Group


Dedicated Short Range Communications (DSRC) is a general purpose RF communications link between the vehicle and the roadside, or between two vehicles. The set of standards developed to support this interface provide a short to medium range communications service for a variety of applications, including public safety (obstacle detection, collision warnings and avoidance, intersection safety), commercial vehicle applications (weigh-in-motion/inspection clearances, border crossing), electronic toll collection, parking lot payment, in-vehicle signing, and many others.  

There are two groups of standards supporting DSRC applications, each operating in a different frequency band: 915 MHz and 5.9 GHz. A set of 915 MHz DSRC standards was completed several years ago and is primarily used in commercial vehicle applications, electronic toll collection, and other applications. The set of 5.9 GHz DSRC standards, the majority of which were approved in 2006 or have been voted on and are undergoing revision for approval, are designed to support a larger variety of applications, including collision avoidance, advanced vehicle control, traveler information, increased freight/cargo transport support, transit, parking, and traffic management as well as supporting other private applications (see DSRC 5GHz Standards Group).  

The DSRC 915MHz Standards Group includes standards covering the rules for communicating between in-vehicle ITS systems and roadside equipment, and are common across all of the vehicle-to-roadside interfaces in the National ITS Architecture. The standards that describe the "vocabulary" (called data elements and messages) are specific to certain architecture flows, and are therefore only mapped to the relevant flows.  

In commercial vehicle (CVO) applications, this standards group covers the interface between commercial vehicles and roadside equipment and includes the following standards:  

ASTM E2158-01: Standard Specification for Dedicated Short Range Communication (DSRC) Physical Layer using Microwave in the 902-928 MHz Band 
ASTM Draft Standard for Dedicated Short Range, Two-Way Vehicle to Roadside Communications Equipment, Draft 6, 23 February 1996, Layer 2 Data Link Layer 

In the CVO community, these two standards together with "IEEE Std 1455-1999: Standard for Message Sets for Vehicle/Roadside Communications" are commonly known as the "sandwich spec", and are the de facto standards for many current CVO programs, particularly CVO electronic screening. The physical layer is used in active mode and the data link layer in synchronous mode to facilitate national interoperability. Although the ASTM E2158-01 standard has been recently withdrawn by the standards development organization, ASTM, the “sandwich spec” is still widely deployed, and therefore will be retained as a standard for CVO programs. Alternative standards are currently under consideration for future deployments. 

For non-commercial vehicle (CVO) applications, the 915 MHz standards group includes the following Standards Activities: 

ASTM E2158-01: Standard Specification for Dedicated Short Range Communication (DSRC) Physical Layer using Microwave in the 902-928 MHz Band