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Re: [Discuss-gnuradio] OFDM_TX_RX
From: |
Marcus Müller |
Subject: |
Re: [Discuss-gnuradio] OFDM_TX_RX |
Date: |
Sat, 25 May 2019 23:07:12 +0200 |
User-agent: |
Evolution 3.30.4 (3.30.4-1.fc29) |
After reading the original paper, you've meant "2D- or 3D-DCT" :)
On Sat, 2019-05-25 at 21:20 +0100, farid mihoub wrote:
> Hi,
> Discrete cosine transform
>
>
> 25.05.2019, 21:02, "Marcus Müller" <address@hidden>:
> > hi, what's 2DCT_or_3DCT?
> >
> > Best regards,
> > Marcus
> >
> > On Sat, 2019-05-25 at 19:38 +0100, farid mihoub wrote:
> > > My application is to broadcast a video using softcast approach.
> > > Video-->2DCT_or_3DCT-->Floating coefficients-->complex_mapping
> > > -->ofdm_phy
> > > My video quality (PSNR) will depend linearly to my SNR so no
> > > need to
> > > have an adaptive modulation.
> > >
> > >
> > > 25.05.2019, 18:27, "Marcus Müller" <address@hidden>:
> > > > 1- So, you have an SNR of best-case 16 dB; that's not high for
> > > an
> > > > OFDM
> > > > system.
> > > >
> > > > 2- No, there's no power normalization. Hint: you can look all
> > > this
> > > > up
> > > > by actually looking inside these blocks! This would make a lot
> > > of
> > > > sense, since it sounds you don't actually want to use tzhe
> > > OFDM
> > > > blocks
> > > > at all. The whole advantage of the OFDM blocks compared to
> > > just
> > > > doing
> > > > an IFFT of your transmit vector is that you get a header and
> > > > modulation
> > > > scheme.
> > > >
> > > > 3- Not quite sure what "information is linearly related to
> > > complex
> > > > symbols" means? Can you elaborate?
> > > > 3b- A case where you *don't* do FEC is either a non-
> > > communications
> > > > system (i.e. you don't actually want to do OFDM for the reason
> > > of
> > > > transmitting information) or the extremely-bad-SNR case (where
> > > FEC
> > > > makes your BER better). For both cases, the existing OFDM
> > > blocks
> > > > are
> > > > more of an obstacle than a solution.
> > > >
> > > > What are you building? What is your overall application.
> > > Please
> > > > paint
> > > > the bigger picture – it's a bit frustrating to try to help
> > > you, but
> > > > then only get told that "this is not how I want to do it".
> > > >
> > > > Best regards,
> > > > Marcus
> > > >
> > > > On Sat, 2019-05-25 at 18:39 +0200, Marcus Müller wrote:
> > > > > Dear Farid,
> > > > >
> > > > > please always respond on the mailing list.
> > > > > Thank you,
> > > > > Marcus Müller
> > > > >
> > > > > On Sat, 2019-05-25 at 17:36 +0100, farid mihoub wrote:
> > > > > > 1- For the noise : in the TX side the output is in the
> > > order
> > > > > of 2A,
> > > > > > the noise 0.05A.
> > > > > > 2-Second even without noise, the const does not affect the
> > > > > > transmission, is there any sort of power normalization?
> > > > > > 3-For the FEC and the modulation I want to try my custom
> > > > > mapping
> > > > > > where information is linearly related to complex symbols,
> > > and
> > > > > my
> > > > > > application doesn't require error correction.
> > > > > >
> > > > > > Thank you.
> > > > > >
> > > > > >
> > > > > > 25.05.2019, 17:06, "Marcus Müller" <address@hidden>
> > > :
> > > > > > > Hello Farid,
> > > > > > > On Sat, 2019-05-25 at 15:59 +0100, farid mihoub wrote:
> > > > > > > > Hello,
> > > > > > > >
> > > > > > > > In the OFDM_tx, rx examples in gr-digital :
> > > > > > > > 1- Why just a low level of noise affect the
> > > transmission
> > > > > and
> > > > > > > > cause it
> > > > > > > > to stop.
> > > > > > >
> > > > > > > "low" is relative. It seems it's high enough to cause
> > > packet
> > > > > > > losses,
> > > > > > > iff it's actually the noise.
> > > > > > >
> > > > > > > > 2- in the the Tx output and the Rx input no matter the
> > > > > value
> > > > > > > > of
> > > > > > > > the
> > > > > > > > multiply constant we apply
> > > > > > > > that would not affect our transmission.
> > > > > > >
> > > > > > > Then it's probably not only the noise!
> > > > > > >
> > > > > > > > 3- Is there any way to separate channel estimation and
> > > > > > > > tracking
> > > > > > > > from
> > > > > > > > data transmission, sometime I get the error "invalid
> > > > > packet
> > > > > > > > detected!" form the packet parser, also I need my data
> > > to
> > > > > > > > bypass
> > > > > > > > FEC
> > > > > > > > and QAM.
> > > > > > >
> > > > > > > Um, prior to QAM demodulation there is no data, and
> > > prior to
> > > > > FEC
> > > > > > > decoding there is no information bits, so I'm not sure
> > > what
> > > > > you
> > > > > > > want?
> > > > > > >
> > > > > > > > My purpose is to stream raw complex data to the I/Q
> > > > > > > > components
> > > > > > > > directly.
> > > > > > >
> > > > > > > Then it seems you don't want an OFDM transceiver but
> > > maybe
> > > > > just
> > > > > > > simply
> > > > > > > a single IFFT? Not quite sure what you have in mind.
> > > > > > >
> > > > > > > Best regards,
> > > > > > > Marcus
> > > > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Discuss-gnuradio mailing list
> > > > > address@hidden
> > > > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> > >
> > >
> > >
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
> > > address@hidden
> > > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
>
>
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- [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Message not available
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, Marcus Müller, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- Re: [Discuss-gnuradio] OFDM_TX_RX,
Marcus Müller <=
- Re: [Discuss-gnuradio] OFDM_TX_RX, farid mihoub, 2019/05/25
- [Discuss-gnuradio] OFDM / softcast / rate distortion theory (was:Re: OFDM_TX_RX), Marcus Müller, 2019/05/25