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SAE J2735-Draft-Rev29 [issued: 12-11-08]
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255 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
Handle Packet Contents
Read next Data Frame
More
Data Frames in
packet
?
Is
Sign ID in
data
store
?
No
Yes
Yes
Is
“Start Time”
Newer than Data
Store
?
Yes
No
No
New
Sign
Updated
Sign
Sign
Or
Advisory
?
Store
New
Sign
sign
Repeated or
Outdated Sign
Is
Advisory ID in
data
store
?
Is
“Start Time”
Newer than Data
Store
?
advisory
Delete
Old
Advisory
Store
New
Advisory
New
Advisory
Updated
Advisory
No
Yes
Yes
No
Delete
Old
Sign
Repeated or
Outdated Advisory
Figure 6: Handle Packet Contents
Replacement Policy for Locally-Stored Messages
Pruning Messages by In-vehicle Housekeeping
Housekeeping will need to be performed on the vehicle to delete stale messages. The most obvious method
is to delete messages with an “Duration Time” that has been exceeded. However, the OBU will have
limited physical memory and will likely need to employ some additional type of replacement policy when
the memory limit is reached. This may be based on priority, heading, distance from vehicle, FIFO, start
time, etc.