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The number of subcarriers = the size of the FFT?

The size may be the same or different depending on the document.

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The number of subcarriers including the null carriers is the size of the FFT since the complex value for each FFT bin represents the subcarrier modulation symbol (as a QAM waveform for example). You can also oversample by zero-padding out the FFT after subcarrier mapping to a larger FFT.

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  • $\begingroup$ Thanks. That is, with oversampling: FFT size > number of subcarriers (including null carriers). Please tell me what are the benefits of oversampling? $\endgroup$
    – Ryo Onishi
    Commented Oct 19, 2023 at 10:31
  • $\begingroup$ Oversampling in the transmitter allows for simpler analog filters after the D/A converter. It is also necessary to implement predistortion algorithms. (For operating power amplifiers further into compression resulting in better power efficiency- to the extent the power saved overcomes the power loss by sampling at a higher rate). $\endgroup$ Commented Oct 19, 2023 at 13:14

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