When I read this, pCell comes in mind: http://www.rearden.com/artemis/An-Introduction-to-pCell-White-Paper-150224.p df
Quite exciting stuff! Ralph. > -----Original Message----- > From: discuss-gnuradio-bounces+ralph=schmid....@gnu.org > [mailto:discuss-gnuradio-bounces+ralph=schmid....@gnu.org] On Behalf Of > Martin Braun > Sent: Tuesday, March 3, 2015 5:26 PM > To: Pengyu Zhang > Cc: Discuss-gnuradio@gnu.org > Subject: Re: [Discuss-gnuradio] mimo beam forming on USRP > > Can you give us some details (frequency, number of antennas) that you want > to have? > > A lot of people have done MIMO with USRPs, up to 100x100 antennas, so > there is some precedent. For beam forming, you'll need very good phase > alignment, depending on what you're planning to set up. This is always > difficult, because all sorts of things affect phase. You should, in any case, > have a way to test phase alignment. > > Cheers, > Martin > > On 03.03.2015 08:18, mle...@ripnet.com wrote: > > If you use the phase-resynch feature of the SBX card, and you have > > common refclock and 1PPS across all your USRPs in the array, > > then you should be OK. > > > > In *general*, synthesized downconverters use fractional-N synthesizers > > where their starting phase after a re-tune is random with respect to > > any other synthesizer using the same reference clock. That's just the > > way > > fractional- N synthesis works. It happens that SBX uses an ADF4351 > > synthesizer, which has a (rare!) hardware feature to allow > > phase-resynch after tuning. In order to make this work, all SBXes in your > "array" > > must be tuned at exactly the same time, so the timed_commands feature > > must be used to do the tuning. > > > > See: > > > > http://files.ettus.com/manual/page_sync.html > > > > On 2015-03-03 11:05, Pengyu Zhang wrote: > > > >> Hi Guys, > >> I am planning to build a mimo system which supports beam forming. Is > >> USRP a good platform for my target? I do not want to use WARP because > >> I need to operate at frequencies lower than 2.4GHz. > >> A potential problem of USRP is phase alignment. As the following doc > >> suggests, phase alignment can be done by MANUALLY tuning the phase. > >> This process can be labor intensive when the number of antennas > >> increases. I am also worried about the problem that the manual phase > >> calibration might need to be done each time you use the mimo system. > >> Is there any approach that can make this process much easier? > >> > http://www.ettus.com/content/files/kb/mimo_and_sync_with_usrp_updat > ed > >> .pdf Would be great if you can give me some suggestions about what > >> devices should I use for building a mimo system for beam forming. > >> Thanks. > >> Pengyu > >> > >> _______________________________________________ > >> Discuss-gnuradio mailing list > >> Discuss-gnuradio@gnu.org <mailto:Discuss-gnuradio@gnu.org> > >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > > _______________________________________________ > > Discuss-gnuradio mailing list > > Discuss-gnuradio@gnu.org > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
