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SAE J2735-Draft-Rev18 [issued: 06-26-07]
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181 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
on the data exchanged in this application area, devices may determine the need to initiate other services or
applications using other ACID values.
The expected repetition rate for the MSG_BasicSafetyMessageFrame, Part I messages broadcast in this
application is expected to be consistent with the scan rates for on-board sensors used for vehicle safety
systems. Based on this expectation, the repetition rate is nominally considered to be one new message
every 100 milliseconds. However, to help prevent the possibility of vehicle broadcast messages overloading
the control channel bandwidth, the frequency of transmissions may need to be adjusted in dense traffic
environments and may be adjusted based on speed, number of vehicles in close proximity or other
parameters in dense traffic environments where many vehicles are stopped or close to being stopped (e.g., a
toll plaza).
The nominal expectation for the inclusion of a MSG_BasicSafetyMessageFrame, Part II broadcast message
along with Part I is every 10th Part I transmission, or whenever requested by another vehicle or roadside
unit.
In all seven of the following application scenarios, a GPS unit and a connection to the vehicle data bus, in
addition to a DSRC radio unit, are necessary to send out the correct information to, and receive the
necessary information from, other vehicles.
Annex A-1 Intersection Collision Warning
Application Description
This application warns drivers when a side-impact or straight crossing path collision at an intersection is
probable. DSRC communications can be used to allow a vehicle approaching an intersection to detect all
nearby vehicles, their position, velocity, acceleration, and turning status. The in-vehicle unit analyzes these
parameters for the other vehicles as contained in their MSG_BasicSafetyMessageFrame, Part I and
MSG_BasicSafetyMessageFrame, Part II messages and projects expected future vectors for these vehicles.
If this analysis determines that a collision is likely, an appropriate warning is issued to the driver.
Flow of Events
Flow of events
1.
Vehicle “A” sends MSG_BasicSafetyMessageFrame, Part I.
2.
Vehicle “B” receives message
3.
Vehicle “B” recognizes that Vehicle A’s message is relevant (crossing road
segment via map and/or heading)
4.
Vehicle “B” alerts its driver to a straight crossing path hazard.
Hardware Devices:
DSRC radio
Positional Sensors
Human-Machine Interface
Occupant
Vehicle
System
Driver
Passenger
Service
Provider
Road
Department
Actors: (What entities
play an active role in use)
X
X