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i want to generate an fft signal in below ofdm signal code ?????

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Jayesh Nakum
Jayesh Nakum 2016-4-8
评论： Rick Rosson 2016-4-8
% OFDM Code % Author: Ihsan Ullah, % Ms-55 Electrical, % College of EME, % NUST Pakistan % No.of Carriers: 64 % coding used: Convolutional coding % Single frame size: 96 bits % Total no. of Frames: 100 % Modulation: 16-QAM % No. of Pilots: 4 % Cylic Extension: 25%(16)
close all clear all clc
%% % Generating and coding data t_data=randint(9600,1)'; x=1; si=1; %for BER rows %% for d=1:100; data=t_data(x:x+95); x=x+96; k=3; n=6; s1=size(data,2); % Size of input matrix j=s1/k;
%% % Convolutionally encoding data constlen=7; codegen = [171 133]; % Polynomial trellis = poly2trellis(constlen, codegen); codedata = convenc(data, trellis); %% %Interleaving coded data
s2=size(codedata,2); j=s2/4; matrix=reshape(codedata,j,4);
intlvddata = matintrlv(matrix',2,2)'; % Interleave. intlvddata=intlvddata';
%% % Binary to decimal conversion
dec=bi2de(intlvddata','left-msb');
%% %16-QAM Modulation
M=16; y = qammod(dec,M); % scatterplot(y);
%% % Pilot insertion
lendata=length(y); pilt=3+3j; nofpits=4;
k=1;
for i=(1:13:52)
pilt_data1(i)=pilt;
for j=(i+1:i+12);
pilt_data1(j)=y(k);
k=k+1;
end
end
pilt_data1=pilt_data1'; % size of pilt_data =52
pilt_data(1:52)=pilt_data1(1:52); % upsizing to 64
pilt_data(13:64)=pilt_data1(1:52); % upsizing to 64
for i=1:52
pilt_data(i+6)=pilt_data1(i);
end
%% % IFFT
ifft_sig=ifft(pilt_data',64);
%% % Adding Cyclic Extension
cext_data=zeros(80,1); cext_data(1:16)=ifft_sig(49:64); for i=1:64
cext_data(i+16)=ifft_sig(i);
end
%% % Channel
% SNR
o=1;
for snr=0:2:50
ofdm_sig=awgn(cext_data,snr,'measured'); % Adding white Gaussian Noise % figure; % index=1:80; % plot(index,cext_data,'b',index,ofdm_sig,'r'); %plot both signals % legend('Original Signal to be Transmitted','Signal with AWGN'); %% % RECEIVER %% %Removing Cyclic Extension
for i=1:64
rxed_sig(i)=ofdm_sig(i+16);
end
%% % FFT
ff_sig=fft(rxed_sig,64);
%% % Pilot Synch%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
for i=1:52
synched_sig1(i)=ff_sig(i+6);
end
k=1;
for i=(1:13:52)
for j=(i+1:i+12);
synched_sig(k)=synched_sig1(j);
k=k+1;
end
end
% scatterplot(synched_sig)
%% % Demodulation dem_data= qamdemod(synched_sig,16); %% % Decimal to binary conversion
bin=de2bi(dem_data','left-msb'); bin=bin';
%% % De-Interleaving
deintlvddata = matdeintrlv(bin,2,2); % De-Interleave deintlvddata=deintlvddata'; deintlvddata=deintlvddata(:)';
%% %Decoding data n=6; k=3; decodedata =vitdec(deintlvddata,trellis,5,'trunc','hard'); % decoding datausing veterbi decoder rxed_data=decodedata;
%% % Calculating BER rxed_data=rxed_data(:)'; errors=0;
c=xor(data,rxed_data); errors=nnz(c);
% for i=1:length(data) % % % if rxed_data(i)~=data(i); % errors=errors+1; % % end % end BER(si,o)=errors/length(data); o=o+1;
end % SNR loop ends here
si=si+1;
end % main data loop
%% % Time averaging for optimum results
for col=1:25; %%%change if SNR loop Changed ber(1,col)=0; for row=1:100;
ber(1,col)=ber(1,col)+BER(row,col);
end
end
ber=ber./100;
%% figure i=0:2:48; semilogy(i,ber); title('BER vs SNR'); ylabel('BER'); xlabel('SNR (dB)'); grid on

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