Hi Mahamed,

First, note that you need use absolute square in calculation of PAPR. So,

use pbofdm = max(abs(ofdm_out).^2); and avbofdm = mean(abs(ofdm_out).^2).

The second thing is you need to give array for plotting cdf. So, find PAPR

for different realizations of data to obtain a vector of PAPR and use this.

Regards,

Nanda Kishore.

On Thu, Apr 10, 2008 at 12:00 PM, mohamed hussien

wrote:

> Hi,

> I'm trying to calculate the PAPR in OFDM system, but I

> don't know why there is no result? I know there is

> something wrong! Can any one help me to get it?

> this is my program code

> close all

> clear all

> clc;

> M = 64; % QAM Modulation Level

> N = 256; % IFFT Size

> % QAM 16 MODULATION

> data = qammod(randint(1,N,M),M);

> % CALCULATE PAPR OF BASELINE OFDM

>

> ofdm_out =sqrt(length(data))*ifft(data);

> pbofdm = max(abs(ofdm_out));

> avbofdm = mean(abs(ofdm_out));

> PAPRbofdm = pbofdm/avbofdm;

> %Rx.

> rxof = (1/sqrt(length(data)))*fft(ofdm_out);

> %PAPR CCDF CALCULATION

> [ofdm_ecdf, ofdmi]f(PAPRbofdm);

> ofdm_ccdf=1-ofdm_ecdf;

> %

> figure

> semilogy(abs(ofdmi), ofdm_ccdf);

> legend('OFDM');

> title('PAPR for OFDM');

> xlabel('PAPR_0 (dB)');

> ylabel('Probability (PAPR > PAPR_0)'); grid on;

> %

>

>