On Mon, Apr 20, 2009 at 10:14 AM, Rémi Villé <[email protected]> wrote:
> Hi,
>
> I used TOSSIM to see how reacts TinyOS Collection (CTP) according to the
> gain (thanks to MultihopOscilloscopeApp example).
>
> First, after some difficulties I understood that gain and noise are negative
> values (between 0 and -100), and more the value is near than -100 more it's
> powerful (-100 for noise or 0 for gain prevent any communication).
>
> Second, I think that when gain becomes smaller than noise there's no
> possible communication.
>
> Am I wrong ?
>
> To have not any noise I choose -100 in every case.
>
> So I make some simulations to see the data path according to different gain
> values, with very good gain and very poor ones, but with a link between each
> nodes.
> And the data path don't change (the data go directly to the sink) !
>
> To see data paths I use "event bool  Intercept.forward(message_t* msg, void*
> payload, uint8_t len) " to add the intercepter node id in msg (and return
> TRUE in each case).
> In MultihopOscilloscopeAppC "MultihopOscilloscopeAppC.Intercept ->
> Collector.Intercept[AM_OSCILLOSCOPE];".
> The sink node print the path.
>
> So I wonder If Collection takes care of the gain, or only construct a tree
> with mote that can communicate with each other,
> so the routing gradient takes only care of paths with less hop than
> possible, and not faster ones ?
>
> I really don't understand, maybe I must search an energy reason... I will
> try other topologies...

Collection, like other routing protocols, determines the best next hop
to the destination from a list of candidate next hops. Collection does
not take care of gain - gain is used to define the link between two
nodes.

- om_p

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