[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] building carrier sense in the FPGA and UHD

From: George Nychis
Subject: Re: [Discuss-gnuradio] building carrier sense in the FPGA and UHD
Date: Sun, 4 Mar 2012 10:13:54 -0500

On Sun, Mar 4, 2012 at 10:01 AM, Marcus D. Leech <address@hidden> wrote:

I do think we need something like what you have suggested but I am still
a bit puzzled about the right way of implementing it.

Best regards,

I think a more fundamental issue is that "carrier sense" isn't actually defined in any kind of general way.  Certainly for *some* types of
 PHYs, you can do simple energy-presence detection.  But usually, it's more complicated than that, and it varies widely from PHY to
 PHY.  In some, you'll need to run a correlator before you even know whether the channel is busy or not.  In others, simple energy
 detection works.

I don't think there's a general-purpose way of doing this, but that's just my POV.

Definitely, there are MACs whose form of carrier sense is detecting preamble rather than detecting energy.  In my same piece of work, we put a matched filter in the FPGA and the host specifies the coefficients of the match filter, then you gate on that.  But, I don't think it's unreasonable to think basic energy detection is not general purpose enough?  I think supporting some basic form of energy detection would start to enable better MAC implementations...

and afterwards I have every intention of rolling a match filter in to the FPGA also.  So, maybe your suggestion is I build a separate FPGA implementation if people want MAC functionality.  I can do that if people believe that the functionality is not general enough.

reply via email to

[Prev in Thread] Current Thread [Next in Thread]