[Tinyos-devel] Re: [Tinyos-help] CVS update and Collection problems

[Andreas Koepke]

The experiments with an adapted MultiHopLqi for eyesIFX look pretty
promising. I based this adaptation on the SNR in [dB] and use the same
idea to adjust the link estimator as the CC2420 version.

I'd vote for go ahead with an interface for the white bit, this platform
should also benefit. I added the necessary support to the CSMA.
Suggestions for an accessor interface?

As a side note: it seems that in some situations the SNR and the LQI on
the CC2420 are somewhat the same, so if it works for LQI it should work
on any platform where RSSI can be converted to SNR in dB using a simple
linear function.

Best, Andreas

Philip Levis wrote:
> 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
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