CC2420/LPL: shorten the inter-packet interval #341
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The inter-packet intervals in the packet trains are too long resulting in missed transmissions as the channel probing often happens between two packets when the channel is empty. This fix resolves the problem by shortening CC2420_ACK_WAIT_DELAY from 256 (7.8ms) to 50 (1.5ms). Lower values break software acknowledgements, larger may result in too long intervals. The fix was tested both in Cooja and real TMotes increasing the reliability of packet delivery significantly. Note that only acknowledged unicast transmissions are affected because broadcasts are sent much more densely (no need to wait for the ACK).
|
Could you describe the test a bit more on the hardware Tmotes? |
|
I use a modified TestLpl with one node sending 300 packets and the other one receiving. I attach the receiving node to the PC to log the serial output and put the sender right next to it. Without the fix, the PDR is around 80%, with the fix it is 100%. You can find the modified TestLpl here: |
MBradbury
added a commit
to MBradbury/tinyos-main
that referenced
this pull request
Jun 6, 2017
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
A fix for the issue #338 .
I tested it using the TestLpl application (which I had to fix as well) in both Cooja and real TMotes.
I've found the suitable value for CC2420_ACK_WAIT_DELAY = 50 (by trial and error), it works for both HW and SW acknowledgements.
According to my observations it increases the chances of successful packet delivery significantly.