The paths will change, and as such, you won't receive full LQI reports
for those paths.  You only receive LQI reports for the top three links
of each node, and that's only for a single hop link quality; the full
path quality is only reported for a single parent as the message
travels the network to the base station.

-Joe

On 11/30/06, Frank  Christian <[EMAIL PROTECTED]> wrote:






Dear all,



I am working with the Link Quality Indicators (LQI) reported in Trawler
(Boomerang) based on a Tmote Sky network running Delta. I am currently
logging every LQI data point shown in Trawler to a file with the purpose of
using the link qualities observed in the real network as input for a network
configuration algorithm I would like to test.



Now my question: What are the semantics of a data point shown in Trawler,
for example for the link 0 -> 20?



Example of my raw data (Trawler's data points) for the link 0->20:



LQI at 12:41:33 on 26.11.2006 is 189.

LQI at 12:41:39 on 26.11.2006 is 189.

LQI at 12:41:43 on 26.11.2006 is 189.

LQI at 12:41:49 on 26.11.2006 is 189.

LQI at 12:41:54 on 26.11.2006 is 189.

LQI at 12:41:54 on 26.11.2006 is 189.

LQI at 12:41:58 on 26.11.2006 is 420.

LQI at 12:42:03 on 26.11.2006 is 420.

LQI at 12:42:08 on 26.11.2006 is 420.*

LQI at 12:50:28 on 26.11.2006 is 144.

LQI at 12:50:33 on 26.11.2006 is 144.

LQI at 12:50:38 on 26.11.2006 is 144.



As I understood, the LQI is measured "per message" by the CC2420 radio. I
wonder about the 8 minutes (*) in which values are missing. My question is:
What are the semantics of such a "data missing" period?



a) Does this imply that the link was dead at this time?

b) Or just that no messages were sent along 0->20 in the Delta routing tree
(different route was chosen)?

c) Or that no MultiHopMessages reporting on the link 0->20 have reached the
basestation?



In my logs, there are many such "data missing" slots, even for very good
links which are regularly part of the routing tree. What would be the best
strategy to ensure that Trawler receives LQI values periodically at least
for good links? I assume one could extend Delta to send some periodic
broadcast message on each mote, is this true?



Many thanks!

Christian
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