On Mon, April 2, 2007 11:52 am, Bibudh Lahiri said: > One scheme I can suggest for measuring the end-to-end delay (round-trip) > is, once the message reaches the destination from the src by the multi-hop > path, send some kind of reply/ACK message all the way back to the sender, > following the same route. Notice the time when this reply/ACK reaches the > original src, and take the time difference with the time the message was > sent out from this sender, divide it by 2. > > My approach may sound too naive, let's see if someone else comes up with > some better idea. > > Bibudh >
I would agree calculating on the ACK (by setting auto-ACK) and dividing by 2 is your best bet short of lots of hardware monitoring equipment. BTW-Round-trip would be the full time from send to ACK. End-to-end would be approximately round-trip/2. There may be some computing time in between on round-trip, but it is likely trivial, and in the "real world" the amount of time it takes the MAC to signal receive or to transmit is part of the delay. Pure signal timing assumes infinitely fast code in all parts of the MAC, which will never happen. Draw your lines appropriately. -- The difference between the right word and the almost right word is really a large matter- it's the difference between a lightning bug and the lightning. -Twain _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
