Home Forums SYSTEM Peak to average power ratio

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    • #28212
      Dr. Dhiman Kakati
      Participant

      What is peak to average power ratio (PAPR), how it effect the communication system. If we consider OFDM using quadrature phase shift keying (QPSK) modulation technique it decreases PAPR but when there is a abrupt amplitude variation the higher order terms of the phase modulated signal, will make each data to spread over multiple carrier and it induces a large Inter-carrier Interference (ICI). so how to encounter this problem. Thanks in advance.

      Regards,
      Dhiman

    • #28218
      alistu
      Participant

      Hi Dhiman,

      As its name implies, it is the ratio of the peak power to average power (which you can set in OptiSystem 13 OFDM transmitter component) in OFDM. OFDM has rather high PAPR. So for a signal with average power, at some instants the power becomes high and this causes problem by letting nonlinear effects to kick in when the signal is launched into fiber.

      Regards

      • #28221
        Dr. Dhiman Kakati
        Participant

        Hi Alistu, Thanks for the reply, So how to handle the problem as you mentioned in the last line, any suggestion please.. ” So for a signal with average power, at some instants the power becomes high and this causes problem by letting nonlinear effects to kick in when the signal is launched into fiber.”

        Regards

        +2
        • #28224
          alistu
          Participant

          You’re welcome Dhiman. There have been many suggestions regarding PAPR, but in different systems. For example, I have seen suggestions about MIMO OFDM, some for CO-OFDM, etc. And suggestions include mathematical methods in many cases. If you are interested in any particular area and you want me to introduce a paper, you can let me know. BTW, do you want more explanation about the part of my statement that you have repeated in your comment?

          Regards

        • #28237
          Dr. Dhiman Kakati
          Participant

          Hi Alistu, The line i put from your reply, I can understand the meaning of it but unable to imagine exactly the scenario, a littlebit expalnation will be helpful. Thanks.

          Regards,
          Dhiman

        • #28244
          alistu
          Participant

          As you know, signal with high power being injected into the optical fiber causes signal degradation due to nonlinearities. At the same time, if we send a low-power signal into the line, we may not be able to get the desired BER due to low SNR. So there should be a trade-off. Let’s say we have to launch a signal with average power into the fiber. Now for OFDM, even this average power signal has some instants with high power because of its high PAPR. So for a signal with average power, we might still have nonlinearities in an OFDM system (Of course, the terms AVERAGE, HIGH and LOW are relative) which contribute to signal corruption.

          +1
        • #28251
          Dr. Dhiman Kakati
          Participant

          Thank you So much Alistu for the explanation. Its helping.

          Regards

        • #28256
          alistu
          Participant

          You’re welcome.

          Cheers!

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