You're absolutely right, Phil - when the network becomes very quiet, the
lowest duty cycle rate is optimal.  

Attached is a plot of the power consumption for a 'quiet' network - a
network that is listening the majority of the time.  You can see that the
curve previously located on the left side of the 'noisy' plot I previously
sent has dropped off the map, making power level 6 the most optimal.

David

-----Original Message-----
From: Philip Levis [mailto:[EMAIL PROTECTED] 
Sent: Tuesday, May 02, 2006 9:17 AM
To: David Moss
Cc: 'Gregory A. Moore'; [email protected]
Subject: Re: [Tinyos-help] Low power CC1000 Radio duty cycling


On Mon, 2006-05-01 at 10:22 -0700, David Moss wrote:
> Greg - 
>  
> The CC1000 radio power level 6 - the lowest duty cycling level - does
> not necessarily offer the lowest power consumption.  If your motes are
> talking to each other every once-in-awhile, power level 4 or 5 works
> pretty well.  
>  
> A lot of energy is consumed in sending the long preambles to wakeup
> nearby motes.  Attached is a plot detailing power consumption vs. duty
> cycle rates for the CC1000 radio in a 'noisy' network.

This is great. Thanks for posting it to the list. You're definitely
right about the tradeoff: for a given expected traffic rate, there's an
optimal setting. Joe Polastre goes into this a bit in his BMAC paper. 

I'm sure that if you pushed your traffic rate up, the bottom of the
curve would move right. Similarly, if you pushed it down, then the
bottom would shift left. Push it low enough, and the lowest duty cycle
setting will be optimal.

Phil

<<attachment: quiet_network.jpg>>

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