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SAE J2735-Draft-Rev18 [issued: 06-26-07]
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205 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
lower DSRC stack layers. The ‘no ID change’ state is managed by the dispatcher via applications and is
renewable.
3
Message Dispatcher Example
This section illustrates how the MD concept can be leveraged to efficiently construct a
message containing data elements requested by two different safety applications. The
safety applications discussed here are hypothetical and they are described with the only
intent of discussing the MD.
3.1 Required Data
This example assumes two distinct applications are running:
1.
The Severe Brake Warning (SBW) application warns the driver in case another
vehicle is performing a severe braking within some relevant area in front of the
driver’s vehicle.
2.
The Collision Avoidance Warning (CAW) application warns the driver if is there
is a potential for a collision in the near future.
The following table lists all the data elements that have been defined in this standard and
indicates which applications need to use them, as well as a frequency of update required.
The final column indicates what requirements the MD must satisfy in its transmission of
messages.
Applications
Data
SBW
CAW
Message Dispatcher
Message Composition
DF_AccelandYawPrecision
Yes (3 Hz)
Yes (3 Hz)
DF_AccelerationSet4Way
Yes (5 Hz)
Yes (5 Hz)
DF_AppContextMark
DF_BrakeSystemStatus
DF_DDate
DF_DDateTime
DF_DFullTime
DF_DMonthDay
DF_DTime
DF_DYearMonth
DF_FullPositionVector
DF_PositionLong
Yes (5 Hz)
Yes (10 Hz)
Yes (10 Hz)
DF_PositionPrecisionSet
Yes (3 Hz)
Yes (3 Hz)
Yes (3 Hz)
DF_PositionShort
Yes (5 Hz)
Yes (10 Hz)
Yes (10 Hz)
DF_PrecisionSet
DF_Snapshot
DF_SpeedandHeadingPrecision
Yes (5 Hz)
Yes (5 Hz)
Yes (5 Hz)
DF_Tail
DF_UpdateVector
Data Frames
DF_VehicleStatusDeviceType
Data Elements
DE_Acceleration
Yes (3 Hz)
No (included in DF_AccelarationSet4Way)