[Tinyos-devel] timestamps in seriallisten/sflisten etc.

[Vlado Handziski]

On Thu, Jun 26, 2008 at 21:35, Razvan Musaloiu-E. <razvanm at cs.jhu.edu>
wrote:

> Hi!
>
>
>> One way to use the field can be as follows. The original handshake between
>> the SF and the mote can be extended to enable estimation of the RTT over
>> the
>> serial line.
>>
>
> I'm a little confused. There is a handshake (the 'U ' thing) over the TCP
> connections between SF clients and SFs but the serial protocol between a
> mote and a SF is different. There is no handshake there but each packet the
> SF is sending to the mote is acked by the mote with an explicit ACK frame.
>
>
Yes, there is currently no proper hanshake apart from the possibility of
selecting an ACKed or not ACKed packet. I don't think we have a rule about
this, it is just a convention that one direction was ACKed and the other was
not. But by using only 2 symmetric ACKed packet exchanges (one mote->PC, the
other PC->mote) we can get a very good estimate of the propagation time.

Vlado
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