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SAE J2735-Draft-Rev15 [issued: 01-30-07]
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168 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
The warning presented to the driver may be different depending upon the proximity of the emergency vehicle to their
vehicle. The closer the emergency vehicle is, the more severe the warning. If pre determined emergency route
information is available from a public safety vehicle, the information may be sent via other applications.
Other emergency vehicles that are responding, receiving the message may use the data to analyze if they may
encounter the responding vehicle. The warning can advise the driver to be prepared to take actions to stay out of
the path of the responding vehicle. The warning could include information about:
The type of emergency vehicle
The location or proximity of the emergency vehicle
Instructions on action that the driver may want to take
The warning presented to the driver may be different depending upon the proximity of other emergency vehicle to
their vehicle and the use of sirens by both other responding vehicles and their vehicle. The closer the emergency
vehicle is, the more severe the warning will be communicated to the operator.
5.
Application use with DSRC
The messages in this application are transmitted using the Wave Short Message Protocol (WSMP) stack in a
periodic broadcast mode on a high power channel to other devices (typically other mobile OBEs) who have
determine to receive this type of message (based on ACID value and running a suitable application). Upon
reception of such messages they are examined for message content and relevance regardless of the ACM of the
sender.
Therefore, this is a provider application that does not employ a Wave Basic Service Set (WBSS) as per IEEE
1609.4 Clause 5.3 and there is no confirm and join operations. Receivers of these messages are expected to
process all such message regardless of the ACM found (typically each vehicle running a provider application will
have its own ACM for its transmissions).
This application shall transmit its messages using an ACID value of “19” [the “emergency-warning” service] as
defined by IEEE 1609.4 or its successors. The Application Context Mark (ACM) shall be a 2 byte unique value for
each instance of the application. Multiple applications, each with their own ACM are expected to be found
operating in overlapping local coverage areas. Based on the data exchanged in this application, devices may
determine the need to initiate other services or applications using other ACID values. The application priority of
this application shall be set to the highest possible value for devices found on vehicles defined as emergency
responder who are actively engaged in a response. The expected repetition rate for the messages broadcast in
this application is nominally to be one new message every one second.
Additional information on this application is being developed and will be added at this point.
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