 |
 |
 |
 |
|
 |
 |
SAE J2735-Draft-Rev28 [issued: 11-10-08]
-
275 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
Handle Packet Receipt
Is Packet ID
already in
Data Store
?
Store Packet ID
In Data Store
Handle Packet Contents
No
Yes
New Packet is
Received
Wait for Receipt of
New Packet
Figure 5: Handle Packet Receipt
Handling Newly Received Data Frames
Packets may contain geographically overlapping areas of advisories or road signs. As a result, a new
packet[RS18] can be received that contains advisories or road signs already received by the vehicle. If a
received Sign ID or Advisory ID is not a match to anything on the vehicle, then it is “new” and should
[RS19]be stored
11
. If there is a match for this ID, then the “Start Time” needs to be checked. If the stored
“Start Time” is newer, then this received data frame is “outdated”. Likewise, if the stored “Start Time” is
the same, then it is “repeated”. In both cases, the received data frame can be discarded. However, if the
stored “Start Time” is older, then the received advisory or sign is “updated”. The old one is deleted, and
the received one is stored in its place.
The following flowchart displays how each data frame can be parsed when receiving a new packet.
11
DCK: Is this strictly correct, if traveling in the other direction can not content be dropped?