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I'm studying OFDM modulation and trying to implement the Tx system on Simulink. I did what is shown in the picture.

I was expecting to see subcarriers but I got "nothing".

What am I doing wrong?

Also, when I do the ifft does that mean I take the nth symbol and "split" it into the mth subcarriers? If I expand the IDFT equation to 4 samples it turns out that the DC component is the sum of the 4 input symbols. So on and so forth. I am wrong?

enter image description here

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  • $\begingroup$ The IFFT of a QPSK signal is not OFDM. Maybe add more details about your approach? $\endgroup$
    – MBaz
    Oct 25, 2023 at 21:02
  • $\begingroup$ In the articles I found it seems that you need to find these modulated symbols and make the ifft of a length "n" equal to the number of subcarriers. Can you please explain to me how OFDM is done? $\endgroup$ Oct 26, 2023 at 7:21
  • $\begingroup$ No, but I'd recommend reading a book such as "Understanding LTE with Matlab" by Zarrinkboub -- it covers all this stuff. $\endgroup$
    – MBaz
    Oct 26, 2023 at 17:36
  • $\begingroup$ Also, I highly doubt that the IFFT sequence transmitted through in-phase and quadrature method is 'OFDM'. And that is because the IFFT sequence would need to be 'periodic' (ie. continually repeated sequence). Sending one unique IFFT non-periodic sequence is not going to give 'OFDM'. That is, the IFFT OFDM method appears to be very misleading. $\endgroup$
    – Kenny
    Dec 4, 2023 at 5:57

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