[Tinyos-help] Maximum datarate on CC1000 radio

[Philip Levis]

On Jul 31, 2006, at 8:06 PM, venkatesh s wrote:

> Hi all,
>
> I am working on packet loss and delay measurements.  The fact is i  
> need to do this on multi-hop, for which i need to fix the  
> datarates.  It seems that when the application is sending 300  
> packets/minute, out of which i get around 5.2% loss.  The node  
> nearer to the base station has 0% loss.
> My network chosen was..
>
>    0 -------- 1---------------2
> The measurements were done on mica2 mote.  Also i observed that as  
> the number of motes increased in the range, losses also  
> increased..  Anyone who know the cause or what might be the  
> datarate for which there will be no loss, please let me know..
>

There is no data rate or distance for which there is no loss in all  
environments.

The cause is the signal-to-noise ratio. If noise doesn't vary much  
over space, then increasing distance decreases the signal strength,  
and lowers the SNR. When SNR gets low enough, you start losing packets.

In practice, noise is highly variable, as you can have all kinds of  
interferers. E.g., 802.11 interferes with much of the 802.15.4  
spectrum. So if you send a packet on 802.15.4 channel 11 while an  
802.11 node sends a packet on 802.11 channel 1, you might very well  
lose the packet.

Phil