co ofdm matlab,ofdm matlab程序

% Vinay Mohan Jonnakuti

% Wireless Communication:

% BPSK modulation and demodulation with increased bit rate

%BPSK simulation using a carrier cosine wave with increased bit rate

clc;

close all;

clear all;

% no of sub carrier channels

channels=6;

c=6;

% bits per channels

bits=54

% total no of bits to be transmitted

n=324;

for i=1:n

data(i)= 2*round(rand)-1;

end

% Converting the series into parallel for the channels

s = reshape(data,c,bits);

% BPSK modulation for a single channel

signal1 = s(1,:);

%first expand the bit stream

exdata1=[];

exdata2=[];

exdata3=[];

exdata4=[];

exdata5=[];

exdata6=[];

for i=1:length(signal1)

for rep=1:2

exdata1= [exdata1 signal1(i)];

end

end

signal2 = s(2,:);

%first expand the bit stream

exdata=[];

for i=1:length(signal2)

for rep=1:2

exdata2= [exdata2 signal2(i)];

end

end

signal3= s(3,:);

%first expand the bit stream

exdata=[];

for i=1:length(signal3)

for rep=1:2

exdata3= [exdata3 signal3(i)];

end

end

signal4= s(4,:);

%first expand the bit stream

exdata=[];

for i=1:length(signal4)

for rep=1:2

exdata4= [exdata4 signal4(i)];

end

end

signal5= s(5,:);

%first expand the bit stream

exdata=[];

for i=1:length(signal5)

for rep=1:2

exdata5= [exdata5 signal5(i)];

end

end

signal6= s(6,:);

%first expand the bit stream

exdata=[];

for i=1:length(signal6)

for rep=1:2

exdata6= [exdata6 signal6(i)];

end

end

% Bpsk modulation

m=10*n;

% Generating the carrier signal

ts=.1;

tp=1:ts:11.79;

carrier1=cos(2*pi*tp);

% Generating the modulated signal 1

bpsk_sig1=exdata1.*carrier1;

% Generating the modulated signal 2

carrier2=cos(4*pi*tp);

bpsk_sig2=exdata2.*carrier2;

% Generating the modulated signal 3

carrier3=cos(6*pi*tp);

bpsk_sig3=exdata3.*carrier3;

% Generating the modulated signal 4

carrier4=cos(8*pi*tp);

bpsk_sig4=exdata4.*carrier4;

% Generating the modulated signal 5

carrier5=cos(10*pi*tp);

bpsk_sig5=exdata5.*carrier5;

carrier6=cos(12*pi*tp);

% Generating the modulated signal

bpsk_sig6=exdata6.*carrier6;

% taking the iFFT of each of these signals

if_sig1=ifft(bpsk_sig1);

if_sig2=ifft(bpsk_sig2);

if_sig3=ifft(bpsk_sig3);

if_sig4=ifft(bpsk_sig4);

if_sig5=ifft(bpsk_sig5);

if_sig6=ifft(bpsk_sig6);

fin(1,:)=if_sig1;

fin(2,:)=if_sig2;

fin(3,:)=if_sig3;

fin(4,:)=if_sig4;

fin(5,:)=if_sig5;

fin(6,:)=if_sig6;

transmit=reshape(fin,1,648);

% generating the noise

% p=rand(1,800)*2*pi;

p=rand*2*pi;

snr=10;

r=sqrt(-1*(1/snr*log(1 - rand)));

% no = 5*(r.* exp(j*p));

no = (r.* exp(j*p));

% value of alpha

al=rand+j*rand;

%al=1;

% Spreading channel with the alpha as the variable

for k=2:2:646

for l = 1:2

%al=round(rand)+j*round(rand)

rec(k+l)=transmit(k+l)+al*transmit(k-2+l);

end

end

rxdata=rec+ no ;

% Converting from serial to parallel

myrec=reshape(rxdata,6,108)

rxdata1=fft(myrec(1,:));

rxdata2=fft(myrec(2,:));

rxdata3=fft(myrec(3,:));

rxdata4=fft(myrec(4,:));

rxdata5=fft(myrec(5,:));

rxdata6=fft(myrec(6,:));

% taking the FFT

%begin demodulation

%first multiply recieved bitstream by cosine wave with carrier frequency

uncarry1=rxdata1.*carrier1;

uncarry2=rxdata2.*carrier2;

uncarry3=rxdata3.*carrier3;

uncarry4=rxdata4.*carrier4;

uncarry5=rxdata5.*carrier5;

uncarry6=rxdata6.*carrier6;

%plot(uncarry)

%demodulate by integrating

dec1=[];

dec2=[];

dec3=[];

dec4=[];

dec5=[];

dec6=[];

for inc=1:2:length(uncarry1)

dec=trapz(inc:inc+1,uncarry1(inc:inc+1));

dec1=[dec1 dec];

end

%2

for inc=1:2:length(uncarry2)

dec=trapz(inc:inc+1,uncarry2(inc:inc+1));

dec2=[dec2 dec];

end

%3

for inc=1:2:length(uncarry3)

dec=trapz(inc:inc+1,uncarry3(inc:inc+1));

dec3=[dec3 dec];

end

%4

for inc=1:2:length(uncarry4)

dec=trapz(inc:inc+1,uncarry4(inc:inc+1));

dec4=[dec4 dec];

end

%5

for inc=1:2:length(uncarry5)

dec=trapz(inc:inc+1,uncarry5(inc:inc+1));

dec5=[dec5 dec];

end

%6

for inc=1:2:length(uncarry6)

dec=trapz(inc:inc+1,uncarry6(inc:inc+1));

dec6=[dec6 dec];

end

final_rec(1,:)=dec1;

final_rec(2,:)=dec2;

final_rec(3,:)=dec3;

final_rec(4,:)=dec4;

final_rec(5,:)=dec5;

final_rec(6,:)=dec6;

fin_rec_parallel=reshape(final_rec,1,324)

%make decision with a threshold of zero

demod=[];

for i=1:length(fin_rec_parallel)

if fin_rec_parallel(i)>0

demod=[demod 1];

else

demod=[demod -1];

end

end

%stem(demod)

%calculate errors

error=0;

for i=1:length(demod)

if data(i)~=demod(i)

error=error+1;

end

end

error;

ber=error/324

figure(3)

stem(data)

hold

stem(demod,'rx')