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It is well known the OFDM systems suffer from PAPR given that the OFDM symbol is a combination of all of the subcarriers. Subcarrier voltages can add in-phase at some points within the symbol, resulting in very high instantaneous peak power—much higher than the average power.

I was thinking to myself which parts of a receiver communication system does the PAPR affect? For example does it affect the ADC, the LNA?

Here is my thinking: it should be the ADC, since it may drive out of the dynamic range of the ADC.. Does it also affect the LNA? I am not sure.

Another thing I was thinking of PAPR may affect the PA of the transmit side driving it beyond its linear range and operating in the saturation region. So here is my question, how does the transmitter know how much it should back off?

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  • $\begingroup$ general hint: if you notice that you have questions in your title, it's probably a good idea to not ask multiple questions in one question, but split them. In this case, your last question on its own would be too broad, already, so I'm removing it, seeing that otherwise your question would warrant a "close as in need of more focus". $\endgroup$ Sep 18 at 20:05
  • $\begingroup$ Feel free to ask a slightly more specific, separate question about OFDM PAPR reduction methods, but please do a bit of research in common thing cited by multiple papers in the field, as IEEExplore knows > 2200 of them $\endgroup$ Sep 18 at 20:07
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it should be the ADC, since it may drive out of the dynamic range of the ADC.

yes.

PAPR may affect the PA of the transmit side driving it beyond its linear range and operating in the saturation region

yes.

Does it also affect the LNA? I am not sure.

But you should be sure: see the consideration for the PA. An LNA also only has a limited linear range, and you'd always try to adjust gain such that you get the best noise figure without incurring too much nonlinearity.

So here is my question, how does the transmitter know how much it should back off?

That's the easiest part of all this: The transmitter is a device without many unknowns. The manufacturer can simply test it once and then program the device so that it won't operate outside of desirable regions.

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