What is PAPR? and its relationship to OFDM

Explains the Peak to Average Power Ratio (PAPR) and shows why it is important for OFDM digital communications. Sometimes this is also called Peak to Average Ratio (PAR).

Note that when discussing the OFDM case (top right hand drawing showing the five waveforms), I wanted to keep the diagram simple, so that I could explain the "phase alignment" problem, so I didn't draw waveforms for all the carriers. I probably should have mentioned it, but I only drew waveforms for the following multiples of the base frequency: 1, 2, 4, 8, 16. It was too complicated to draw all the other multiples (3, 5, 6, 7, 9, 10 ...). Also note that the diagrams I showed are "baseband". In other words, I didn't show them after they are up-converted to the carrier frequency

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[AbuSousPR]

you make what is difficult... very easy and fun to learn

[ankitsinha]

Your videos are pure delight to watch. Thanks a lot

[zeeshanahmad]

I think PAPR mostly impact TX PA efficiency, that was a must aspect to explain

[rushabhpatel]

Thanks iain. J have never liked signals nd systems in my college. But your videos have made me fall in love with it.❤️

[ananthakrishnank]

I'm glad that I found your channel ;)

[YGurin-gwsu]

Thanks! So how to deal with that? Is CFR will be enought? How artifical reduction of the peak affect the signal?

[刘新-et]

Thanks for your sharing! But I have a problem. How does the PAPR affect the digital beamforming process? Looking forward to your detailed answer.

[werdasize]

So just to clarify, when you say perform IDFT you mean that we first add all the carrier signals in the frequency domain and then take it back to time domain to see the combination (something like that peak you draw). The diagram with carriers is in the time domain, that’s why I got confused.

[TurbidSugar]

But didnt we use fixed point FFT and choose "power window" relative to noise floor? (FFT shifts)
In that case we at risk of saturation inject "colour noise" to whole symbol, instead of compression problem

[yasserothman]

Thanks for sharing may I know how did single carrier fdma solved this problem by adding n point dft block before the m point ifft where n<m ?

[tasheido]

How would variable gain affect the OFDM system? I mean using compression enhancing the signal near the average and compressing the peaks. And doing the opposite at the receiver side.. ?

[kpranati]

Greetings sir, can u plz teach us the "PAPR TECHNIQUES" le, PTS, SLM, CODING.... etc waiting for ur all further classes

[mohamed-rayanelakehal]

please sir, could you talk about the frequency offset in a video ... ? thank you

[dahlia]

Thanks for the post... One query..in ofdma the subcarrier division is equal ryt...like say LTE each subcarrier will be 15KHz so this c1, C2, c3 waveforms u mentioned will not be applicable ..so how PAPR explains for ofdma? For this reason Uplink uses SC -Fdma ryt

[malisettyjyothi]

Sir could you please give a real time example to reduce PAPR by using PTS. For better understanding purpose.