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

[Omprakash Gnawali]

On Mon, Apr 7, 2008 at 6:09 AM, Bulut ERSAVAS <bfersavas at gmail.com> wrote:
> Omprakash,
>
> Thanks for your detailed comments.
>
> Interesting point about the LPL. I believe the nodes are sleeping looking
> into the low power consumption  (which is still more than what we
> calculated/estimated and this may be the reason). I'll take the multimeter
> and measure the amount of current drawn by nodes which are a hop away from
> the root. So, what is your suggestion here? Increase the root beacon
> interval? We tried that (increase to 10 and 20 sec) and the amount of losses
> seemed to increase (no hard numbers though). We keep the root plugged into
> the electricity so no concerns for its power consumption.

How are you increasing the root beacon interval?

> Other than the power issue you pointed out, have you ever observed
> reliability problems with CTP when LPL was enabled? What were the numbers
> (i.e. sleep interval etc.) you used for testing?

We haven't done rigorous experiments to evaluate this but we have
measured about 10% less reliability when you use CTP with LPL. Have
you done your experiments without LPL?

> As for the snooping, what should I expect to see if I snoop next to the lost
> node? Could you refer me to a document describing the LEEP frame?

http://tinyos.cvs.sourceforge.net/tinyos/tinyos-2.x/doc/txt/tep124.txt?revision=1.5&view=markup


>
> We are using a platform with msp430 and cc2420. Minor modification of
> TelosB.

Do you have a name for this platform or a document describing the platform?

> Finally, about the packet loss when the nodes are multi-hops away: we
> definitely observe packet loss much more than just 1%. It is more like
> 30-40%. Still no hard numbers though. Any idea how we can debug this
> problem?

If you have a way to leave your laptop in the field for several hours,
I would connect your mote that is getting "disconnected" to your
laptop and log the debug messages. Then we can look at the debug
messages to see why you are losing the messages. It is likely that the
links are bad but we can get a better understanding with the log
messages.

- om_p