Hi, I have produced some results using Sentilla-JCreate and they are valid for Tmote if it behave similar (I guess so).
The round trip time (RTT) of Tmote for one byte long packet is around 17ms. That is if only one mote is sending and medium is totally free. The motes are placed only one foot apart from each other. I had written a small program that you can use to check RTT yourself. It is available from http://takatuka.sourceforge.net/TinyOSRTTCode.tar.gz. I know that is not exactly what you wanted but it might be helpful? Secondly, the Tmote can send at most around 124 packets in a second. You can also reproduce this result using anther program http://takatuka.sourceforge.net/fastestSendPossible.tar.gz -- Faisal Aslam University of Freiburg http://cone.informatik.uni-freiburg.de/people/aslam/ Paul Johnson wrote: > Somnath, > > There aren't really straightforward answers to your questions because > they both are non-deterministic to a degree. > > For the first question: What data rate are you talking about? The > raw number of bits(including headers/footers?) that can be > successfully delivered over the air using the hardware or the number > of payload bits that you can deliver? The CC2420 can support variable > length payload sizes. Are you talking about the default payload size, > or can modifications be made to increase it? Are there more than 1 > transmitter operating on the particular channel? Is there > interference from other wireless devices (baby monitors, WiFi, > Bluetooth, etc)? Are the transmissions broadcast (no ack) or unicast > (acks)? > > All of these effect the data rate. If you have the hardware, you can > just run a few simple tests to get some anecdotal results, but they > won't be able to fully describe every possibility mentioned. > > The second question also needs to be qualified. If you are using the > AMSenderC, it provides fair queuing between all concurrent instances > of AMSenderC. Are there any other instances of AMSenderC competing > for access to the radio? How often are interrupts occurring (timer > interrupts, adc done interrupts, etc)? These can significantly bog > down an attempt to use the radio. How many times does the sender have > to back-off because it detects that the medium is busy? > > As you can see there are many different variables that can impact the > answers to both of your questions. Aside from some anecdotal results, > I doubt anyone will be able to provide you better data than what you > could achieve by experimentally determining these answers yourself > using your own hardware/RF environment. > > Sorry I couldn't be more helpful, but the short answer is "it's hard > to calculate these for any generic situation, and you will get more > accurate results if you test these yourself using your own > hardware/software and RF environment" > > -Paul > > Somnath Mitra wrote: >> Hello , >> >> I need the exact data rate number that is achievable on a tmote >> (I do not mean CC2420 data rate - which is 250 kbps). I mean the data >> rate that is achievable taking into account the MAC layer. >> >> I would also like to know the time to transmit [probably a formula] a >> packet of n bytes, from the point an application calls SendMsg.send() >> on the sender mote to the point where the message is received by the >> application layer on the receiver mote. >> >> The motes are Tmotes running TinyOS 1.15 and the Boomerang TinyOS >> stack from MoteIV. >> >> Thanks, >> >> Somnath >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Tinyos-help mailing list >> [email protected] >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > ------------------------------------------------------------------------ > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
