Re: [Discuss-gnuradio] Re: USRP2 questions

[Matt Ettus]

Quoc Lai wrote:
> Eric Blossom wrote:
>   
> > On Wed, Sep 17, 2008 at 01:48:34AM +0300, Juha Vierinen wrote:
> >     
> > > What does it mean that USRP2 can only do MIMO with eight receivers?
> > > What are the options for doing MIMO with, say 16 receviers?
> > >       
> > You would need to design and build some kind of hub that would provide
> > the clocks and synchronization for the 16 receivers using their MIMO
> > interfaces.  Depending on how you programmed the hub, you could just
> > send the control from there, and then send the sample data over the
> > ethernet interfaces on each of the 16 USRPs.
> >
> > You'd need some serious computational power to process 16 channels,
> > each streaming 100MB/s of data.  Sounds like fun :)
> >
> > Eric
> >     
>
> Hi Eric,
>
> Is the hub needed for any MIMO systems using USRP2? I want to build a 
> 4x4 MIMO. Do I have the synchronization problem?
>   

Each USRP2 can handle 1 antenna with most daughterboards, or 2 if you 
have your own external RF sections connected to the USRP2 at IF.

A dual USRP2 system does not need a hub, only a cable.  A quad USRP2 
system would need a hub unless you were willing to have 4 ethernet 
connections to the host computer.


Matt