Two independent PC+USRP nodes. All the ACK related logic was implemented at the Python layer.
Another thing that I tried was to connect the two nodes via Ethernet (I have two Ethernet NICs in each of the PCs) and then use USRPs for data and Ethernet for ACKs. I still couldn't get good results, although I had some issues with the OFDM decoding latency, so I can't really say where the bottleneck was. Veljko 2010/4/6 Jeff Brower <jbro...@signalogic.com>: > Veljko- > >> I tried with a stop-and-wait ARQ and two USRP2s with XCVR2450s, but >> the delay was too long and inconsistent. I can't remember the exact >> figures, but definitely up to milliseconds. > > Do you mean two USRP2s back-to-back? Or both connected to motherboard ports? > > -Jeff > >> 2010/4/6 George Nychis <gnyc...@cmu.edu>: >>> >>> >>> On Tue, Apr 6, 2010 at 10:07 AM, Charles Irick <cir...@gmail.com> wrote: >>>> >>>> Thanks for the reply George. I'm still looking for a little more >>>> information on this topic. >>>> >>>> - What is PMT >>> >>> http://gnuradio.org/redmine/wiki/1/TypePMT >>> >>>> >>>> - Why was m-block removed >>> >>> http://osdir.com/ml/discuss-gnuradio-gnu/2010-01/msg00066.html >>> >>>> >>>> - Has anyone measured latency with the USRP2 and GigE >>> >>> I'm not sure. >>> >>>> >>>> - Is GigE alone not capable of handling MAC turnaround times or is >>>> software to blame for this >>> >>> I think the latency is on hundreds of microseconds, which is greater than, >>> say, an 802.11 ACK turnaround time (24us). >>> >>>> >>>> - Is the scheduler the main issue in the way it handles i/o between blocks >>> >>> There are some details of this in the second link I gave. >>> >>> - George >>> >>> >>> _______________________________________________ >>> Discuss-gnuradio mailing list >>> Discuss-gnuradio@gnu.org >>> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>> >>> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> Discuss-gnuradio@gnu.org >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> > > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
