Re: wimax chain

[CEL]

Hi Eitan,

> specifically - mimo-ofdm over wimax

As I said, it's unlikely someone else wrote exactly what you're
supposed to build before.

I'm currently not taking development projects, but: it's a pretty
normal thing to pay for contract GNU Radio development, so I'm sure we
can help you find someone to work for you!

Of course, the mailing list is always open to your questions, so if you
have any questions to what I (or others) have written here before, do
not hesitate to ask about specifics!

Best regards,
Marcus

On Sun, 2019-12-22 at 14:17 +0200, Eitan Hetzroni wrote:
> specifically - mimo-ofdm over wimax
> 
> On Sun, Dec 22, 2019 at 1:13 PM Eitan Hetzroni <address@hidden>
> wrote:
> > anyone with any progress on the wimax?will to even pay for a
> > working chain - cant figure out where to find a grc chain.
> > 
> > On Wed, Nov 20, 2019 at 3:29 PM Müller, Marcus (CEL) <
> > address@hidden> wrote:
> > > Hi,
> > > ah! OK, yeah, that's unfortunate. 
> > > 
> > > So, the easy thing about OFDM: as soon as you know where your
> > > symbol
> > > starts, all you need to do is apply an FFT – and you're done.
> > > (you will
> > > still have to "equalize" your reception, but that is a point-wise
> > > multiplication at the output of the FFT.)
> > > 
> > > So, if I was to recommend a methodology for solving this: Start
> > > with
> > > building a fixed-lag correlator to find the beginning of
> > > symbols. 
> > > You're not the first person to have to do that:
> > > The gr-dab module [1] contains one such, that you'd only have to
> > > parameterize to use the length and sizes of OFDM symbols in WiMaX
> > > instead of these in DAB+. (I actually recommend looking at gr-
> > > dab's
> > > receiver; it's a nice display of how to demodulate OFDM
> > > downlinks.)
> > > You'll be getting output that you can threshold to get the
> > > beginnings
> > > of symbols, then you just start taking FFTs at these positions,
> > > and in
> > > those, you look for the preamble symbols to get the equalizer
> > > taps.
> > > 
> > > Best regards,
> > > Marcus
> > > 
> > > [1] https://github.com/kit-cel/gr-dab
> > > On Wed, 2019-11-20 at 15:19 +0200, Eitan Hetzroni wrote:
> > > > hello,
> > > > it is an ofdm system, but i could not get to tweak the ofdm_Rx
> > > example to find the preamble in the transmission i was looking to
> > > capture.
> > > > 
> > > > On Wed, Nov 20, 2019 at 3:16 PM Müller, Marcus (CEL) <
> > > address@hidden> wrote:
> > > > > Hi Eitan,
> > > > > 
> > > > > please keep replies on the list!
> > > > > I don't think there's a readymade solution for you. 
> > > > > 
> > > > > I'm not quite sure what you mean with "resemble OFDM": could
> > > you
> > > > > elaborate? I really thought that IEEE802.16 is a pure OFDM
> > > system, so
> > > > > this comes as a surprise. In which way is it not?
> > > > > 
> > > > > Best regards,
> > > > > Marcus
> > > > > 
> > > > > On Wed, 2019-11-20 at 15:13 +0200, Eitan Hetzroni wrote:
> > > > > > thanks for the rapid reply,
> > > > > > it does resemble ofdm, however as a beginner in the field i
> > > was hoping to find a readymade chain to tweak with?
> > > > > > 
> > > > > > 
> > > > > > On Wed, Nov 20, 2019 at 3:11 PM Müller, Marcus (CEL) <
> > > address@hidden> wrote:
> > > > > > > Hi Eitan,
> > > > > > > 
> > > > > > > it's been a while since I've looked into IEEE802.16, but
> > > that's a very
> > > > > > > regular OFDM system, isn't it, with a fixed OFDM symbol
> > > as short
> > > > > > > preamble (for the downlink bursts), and a 2-symbol
> > > preamble for the
> > > > > > > start of frame?
> > > > > > > 
> > > > > > > A simple correlation detector might do in that case; a
> > > bit nicer on the
> > > > > > > acquisition speed per computational effort might be a
> > > fixed-length
> > > > > > > correlator that detects the position of cyclic prefixes
> > > and could be
> > > > > > > applied to a whole burst or even frame to get a good
> > > timing estimate
> > > > > > > before you start decoding OFDM symbols.
> > > > > > > 
> > > > > > > Best regards,
> > > > > > > Marcus
> > > > > > > 
> > > > > > > PS: Your email signature is kinda funny on a publicly
> > > archived mailing
> > > > > > > list :D
> > > > > > > 
> > > > > > > 
> > > > > > > On Wed, 2019-11-20 at 14:43 +0200, Eitan Hetzroni wrote:
> > > > > > > > Hi,
> > > > > > > > any solution to the reception (rx) or tx of wimax using
> > > gnuradio?
> > > > > > > > could not find any proper chain that finds the
> > > preamble.
> > > > > > > > 
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