[Tinyos-help] bidirectional gain

[Philip Levis]

On Jun 9, 2009, at 10:03 AM, Rémi Villé wrote:

> 2009/6/8 Philip Levis <pal at cs.stanford.edu>
>
> On May 29, 2009, at 5:53 AM, Rémi Villé wrote:
>
> Hi,
>
> In the topology file of TOSSIM we can see that we can choose a gain  
> for a link from a node A to a node B and a different one for the  
> link from B to A, so it may imply that, in real world, we have  
> different gain from a mote A to a mote B and from B to A.
>
> I would like to know if it's indeed the case in reality, if having  
> two very different gain between two motes is a rarity, if we can say  
> the gain difference between two mote directed link is often in a  
> range of one value.
> If someone knows this value it would be perfect.
>
> Please read the work at USC on this.
>
> It is common in reality, due to hardware variations. While it is  
> very uncommon (but not impossible) for the actual RF attenuation to  
> be different in the two directions, the two transceivers can have  
> different frequency sensitivity.
>
> Phil
>
> Even between two telosb mote for example ?

Yes. There are variations in radio chip hardware.

>
> Have you got some publication title, key words, author names or  
> links to this subject ?

http://www.marcozuniga.com/professional/

has the two seminal papers:

"An Analysis of Unreliability and Asymmetry in Low-Power Wireless  
Links," and
"Analyzing the Transitional Region in Low Power Wireless Links."

SING tech report SING-08-03 has data on CC2420 nodes:

http://sing.stanford.edu/pubs/sing-08-03.pdf

Phil