[Tinyos-devel] Tossim - node receives packet althought sending other

Philip Levis pal at cs.stanford.edu
Wed Feb 11 06:58:45 PST 2009


On Feb 11, 2009, at 2:30 PM, Lumir Honus wrote:

> 1->0 starts at 107522761719, finishes at 107542750616
> 3->1 starts at 107540209259, finishes at 107560198156
>
> collision is from 107540... to 107542....
>
> I presume that radio on mote 1 is busy while sending in whole  
> interval,
> and for successful receive has to be free from the beginning. (from
> 107540209259).

Oh, whoops!

I think this might be due to the ack interval. While packet  
transmissions in terms of sendDone completes after an ACK wait period  
(34 symbols, or 500us), the actual radio transmission does not include  
the ACK wait period. The values I see there suggest that 3->1 is  
starting 200us before 1->0 issues a sendDone. So it could be that 3->1  
is occuring *after* the transmission 1->0 but before the ack wait  
period has completed.

Phil


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