[Tinyos-help] CTP with Low Power Listening

[Omprakash Gnawali]

On Mon, Mar 30, 2009 at 11:38 PM, Urs Hunkeler <uhu at gmx.ch> wrote:
> Hi,
>
> That question is probably of more general interest. I'm sorry if I bother
> you here. I vaguely remember that somebody once said that CTP does not
> support LPL, so I have a couple of questions:
>
> Could you briefly explain what you did to get low-power listening to work?
> Did you just have to setLocalDutyCycle()? What about setRXDutyCycle()? How
> could you set this on a per-message basis, or is it implicit when you
> setLocalDutyCycle() and only needs to be set if you want a different value?

You have to do this on a per packet basis - for all the packets sent
by/through CTP. This means, right now you have to hack CTP. I will
soon check in a TestNetwork application that shows how to use CTP with
LPL. But of course, only after core provides a firm guideline on how
to do this. Look for an update in the next few weeks.


> My impression was that the routing layer was sending a lot of messages to
> update the paths. So even if your application is only sending one message
> every 5 minutes, have you verified that you actually do get the duty-cycle
> that you set? I would be worried that the nodes just start sending very long
> preambles to send link probes and route updates and that thus the radio
> basically stays on all the time.

In my experiments I set receive interval and not duty-cycle. You
usually get higher numbers in achieved duty-cycles vs what you
specify.

- om_p