Re: Mac Layer

[Marcus Müller]

Hi Nick,

On 11.06.21 16:58, Nicholas Long wrote:
> Hi, so I have been wondering what people do to implement mac layer type 
> things with GNURadio?
> (for example automatic detection/handshaking type protocols before 
> transmitting digital
> data packets.)

Well, "we" (as in the community) have Basti Bloessl's gr-ieee802-11 project as 
an example
on how to approach that.

> From my perspective gnuradio is good for physical layer development, but less 
> so for state
> machine type work of mac layer...

Well, yes. Kind of.
GNU Radio definitely is a physical layer thing. It doesn't give you any tools 
to develop
MA controllers.
But: MACs are different. Pretty different, in fact. As you say, the common 
denominator is
"there's one or more state machines"; from there up, it's pretty variable.

Now, what GNU Radio *does* give you is a flexible architecture to implement 
your physical
receiver and transmitter, and a mechanism with which you can interchange 
messages with a
controller. I think (and I'm not alone with that, there's work ongoing on new 
concepts in
that space!) that we could do a bit better on the usefulness of that messaging 
system, but
it does work.

I think GNU Radio Companion as the visible front of the whole GNU Radio idea 
establishes
the impression that GNU Radio is a generator for stand-alone *applications*; 
it's not. GNU
Radio is a library, and the things you can create with it are *meant* to be 
used as the
signal processing side of other applications. Look at the success gqrx has: It 
uses GNU
Radio underneath, but none of its visualization blocks; satellite ground 
stations, video
transceivers, radiosonde receivers, emergency beacons and a myriad of other very
real-world applications are underpinned by GNU Radio. DARPA's spectrum 
challenge gave
teams a development kit based on GNU Radio as a starting point, and its whole 
point was to
demonstrate the ability to react to sudden interference and user constellation 
changes.

All these things use different approaches, clearly. There's good reason to 
assume the
project "should" have a goto MAC demo – but we don't. Too much to fiddle, 
probably.

Best regards,
Marcus