Continue to Site

# papr reduction using slm and clipping method

Status
Not open for further replies.

#### victory.dj96

##### Newbie level 3
i am working on papr reduction in ofdm using slm and clippping method, please help me in understanding the matlab code for these techniques.

thanks!

Please let us know what exactly you are not able to understand in the code

Code:
clc;
clear all;
close all;

L=input('Enter the L factor(1 to 1.5)= ');
N=input('Enter the number of transmitted symbols= ');
M=input('Enter the alphabet size= ');

k=[0:0.5:10];
k1=[1:N];

r=floor(M*rand(N,1));
modulated_data=qammod(r,M);

LN=floor(L*N);
parallel_data=modulated_data';

x_mag=abs(ifft_data);
papr=max(x_mag.^2)/mean(x_mag.^2);

figure(1)
plot(x_mag),title('Normal OFDM signal');
xlabel('time'),ylabel('amplitude')

y=abs(ifft_data).^2;
y1=sort(y,'descend');
y3=y1./mean(x_mag.^2);
y4=10*log10(y3)

[d,k] = hist(y4,k);
figure(2)
semilogy(k,1-cumsum(d)/max(cumsum(d)),'-r')

CR=5;

x_max=(10^(CR/20))*mean(x_mag);

for j=1:LN
if(x_mag(j,1)>x_max)
x_mag1(j,1)=x_max;
else
x_mag1(j,1)=x_mag(j,1);
end;
end;

figure(3)
plot(x_mag1),title('Clipped OFDM signal with CR=5 dB');
xlabel('time'),ylabel('amplitude')

papr1=max(x_mag1.^2)/mean(x_mag1.^2);

c=abs(x_mag1).^2;
c1=sort(c,'descend');
c2=c1./mean(x_mag1.^2);
c3=10*log10(c2)

[dc,k] = hist(c3,k);

CR1=1;

x_max1=(10^(CR1/20))*mean(x_mag);

for j=1:LN
if(x_mag(j,1)>x_max1)
x_mag2(j,1)=x_max1;
else
x_mag2(j,1)=x_mag(j,1);
end;
end;

c21=abs(x_mag2).^2;
c22=sort(c21,'descend');
c31=c22./mean(c21);
c34=10*log10(c31);

[c35,k]=hist(c34,k);

papr2=max(x_mag2.^2)/mean(x_mag2.^2);

figure(4)
plot(x_mag2),title('Clipped OFDM signal with CR=1 dB');
xlabel('time'),ylabel('amplitude')

figure(5)
semilogy(k,1-cumsum(dc)/max(cumsum(dc)),'-k')

figure(6)
semilogy(k,1-cumsum(c35)/max(cumsum(c35)),'-k')

figure(7)
semilogy(k,1-cumsum(d)/max(cumsum(d)),'-sr',k,1-cumsum(dc)/max(cumsum(dc)),'-+b',k,1-cumsum(c35)/max(cumsum(c35)),'-<g')
xlabel('PAPR (dB)');ylabel('CCDF');
title('CCDF VS PAPR');grid on;hold on;
hleg=legend('ORIGINAL','clipping with CR=5 dB','clipping with CR=1 dB');

Last edited by a moderator:

how the papr is reduced when we multiplied with phase sequence in slm method.. please explain me.

Last edited by a moderator:

Status
Not open for further replies.