[Tinyos-help] Collection: Loosing Connection to a Node

[Bulut ERSAVAS]

Hi Phil,

Thank you for your comments as well. Our application is based on
MultihopOscilloscope with no significant changes. We added LPL
functionality, would this cause any issues (sleep interval is 1000ms)? In
addition, we inserted Dissemination capability.

If, let's say, the RSSI worsens by about 10dB and a node looses its
neighbor; it will be able to re-discover the neighbor if RSSI get backs to
normal, right?

Thanks,
Bulut


On Sun, Apr 6, 2008 at 8:02 PM, Philip Levis <pal at cs.stanford.edu> wrote:

>
> On Apr 6, 2008, at 5:56 AM, Bulut ERSAVAS wrote:
>
> > Hi Omprakash,
> >
> > I can't really say that it is quite deterministic. In networks where we
> > collect measurements every 15 minutes, we lost path to some nodes within a
> > few hours to half a day. Our networks are generally small (i.e. 3 to 5 nodes
> > per network). There are cases where we lost the connection in a
> > single-hop-to-root setting. As we are experimenting, the nodes are not moved
> > around without our knowledge.
> >
> > This issue happens specifically at two locations. One is a greenhouse
> > with barely any obstacles. The other is a closed environment where there are
> > reflective metal walls. For the latter case, the motes are placed very close
> > to each other (about 10-15 meters).
> >
> > Would rebooting the motes periodically (e.g. every few hours) help ease
> > this problem? Is it possible for CTP to get stuck in a state where it can no
> > longer discover a path to root?
> >
>
> As long as there is a path to the root, CTP should be able to find it.
> That being said, there could be a bug in CTP or a bug in your application.
> Given how heavily CTP is tested, I'm leery of assuming it's a bug there.
>
> Stationary nodes does not mean the topology doesn't change. You can easily
> see significant signal strength shifts due to temperature and humidity. One
> study on ATPC showed RSSI vary by as up to 10dB for nodes sitting in on a
> lawn, over 24 hours.
>
> Phil
>
>
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