On Sep 24, 2007, at 9:34 PM, Iñigo Urteaga wrote:
Hi,
Thanks for the appreciation. However, I still have the compiling
errors related to Collection.
I thought it might be useful to make a few notes about the current
state of collection, because it's really the first time there's been
some cross-WG collaboration and we're trying to figure out the way to
handle CVS when there are some experimental extensions that look very
promising.
The net2 working group proposed adding a new interface to link-layer
communication, based on experiences developing link estimators for
collection. This interface provides the "white bit," which allows a
higher layer to ask if the channel had high quality during a packet.
Because this would be part of the packet HIL, it's core's
responsibility. So core and net2 started talking about the tradeoffs.
Core agreed that it sounded like a good idea, but wanted experimental
evidence that it helped before making it a HIL.
In a series of experiments, net2 showed that the white bit can
significantly improve link estimation. For the gory details, you can
read the technical report SING-07-00, which is a draft of a
submission to HotNets.[1] The short story is that, in comparison to
MultihopLQI, the new CTP link estimator reduces routing cost
(transmissions per packet delivered to base station) by 29% and is
much more effective in sparse topologies. Based on these results,
core gave the go-ahead to take the next step, which is to demonstrate
that the white bit can be implemented on different radio chips and
helps more than the CC2420.
Incorporating the white bit involves some significant changes to CTP
(the net2 collection protocol); trying to maintain a parallel CTP was
seen to be too big a deal, especially given the benefits we've seen
with CC2420-based platforms. So Om and Rodrigo checked in the new CTP
version. The recent collection problems are due to the need to iron
out some of the lingering issues. For example, since the white bit is
not yet an HIL, it's not part of ActiveMessageC; this means that the
link estimator needs #define statements to link to the right radio
chip. If the white bit joins the HIL, then this cruft will go away.
Anyways, that's the situation.
Phil
[1] http://sing.stanford.edu/singpubs.html
_______________________________________________
Tinyos-help mailing list
[email protected]
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
