[Tinyos-help] question on setNoise(node, mean, variance)

[Philip Levis]

On Jul 4, 2006, at 7:42 AM, Liu Haibin wrote:

> Hi,
>
> I have a question about the setNoise(node, mean, variance) in  
> TOSSIM 2.x. I found that the larger the mean is, the more noisy it  
> is. For example, setNoise(1, -100, 5.0) can make nodes receive  
> packets, but setNoise(1, -10, 5.0) cannot. I was expecting to see  
> that -100 would mean more noisy that -10. Did I get the concept  
> wrong? So what does the noise here mean? Many Thanks.
>

The noise is in dBm. So -10 is stronger noise than -100.

One note: the current noise model has a few issues. Since the  
distribution is bounded in the interval [mean - var, mean + var],  
then you see 100% links more suddenly than you often do in the real  
world. It really should be gaussian, with perhaps some greater  
complexities. We've been looking at some long-term traces for micaZ  
and telos networks in order to try to come up with a more  
representative noise model, and hope to have one by the end of the  
summer.

Phil