Digital Communication Projects Using Matlab

Digital Communication Projects using Matlab.

1. Multiple Input Multiple Output(MIMO) using Matlab

clc;
close all;
clear all;
mT = 2; % No.of transmitters
mR = 2; % No.of receivers
ITER = 1000; % number of iterations.
SNRdB = [0:25]; % SNR maximum scale
SNR = 10.^(SNRdB/10); % SNR in decibels

C_SISO = zeros(1,length(SNR));
C_SIMO = zeros(1,length(SNR));
C_MISO = zeros(1,length(SNR));
C_MIMO = zeros(1,length(SNR));

for ite = 1:ITER
h_SISO = (randn +1i*randn)/sqrt(2);
h_SIMO = (randn(mR,1)+1i*randn(mR,1))/sqrt(2);
h_MISO = (randn(1,mT)+1i*randn(1,mT))/sqrt(2);
h_MIMO = (randn(mR,mT)+1i*randn(mR,mT))/sqrt(2);

for K = 1:length(SNR)
C_SISO(K) = C_SISO(K) + log2(1+ SNR(K)*norm(h_SISO)^2);
C_SIMO(K) = C_SIMO(K) + log2(1+ SNR(K)*norm(h_SIMO)^2);
C_MISO(K) = C_MISO(K) + log2(1+ SNR(K)*norm(h_MISO)^2/mT);
C_MIMO(K) = C_MIMO(K) + log2(abs(det(eye(mR)+SNR(K)*h_MIMO*h_MIMO'/mT)));
end
end

C_SISO = C_SISO/ITER;
C_SIMO = C_SIMO/ITER;
C_MISO = C_MISO/ITER;
C_MIMO = C_MIMO/ITER;

plot(SNRdB,C_SISO,'r',SNRdB,C_SIMO,'b',SNRdB,C_MISO,'m',SNRdB,C_MIMO,'k')
%legend('SISO','SIMO','MISO','MIMO')
xlabel('SNR in dB')
ylabel('Capacity (b/s/Hz)')
title('Capacity Vs. SNR')
grid;

Output

2. Pulse Width Modulation(PWM) working Principal using Matlab

clc;
clear all;
close all;
F2=input('Messsage frequency=');
F1=input('Carrie Sawtooth Frequency=');
A=5;
t=0:0.001:1;
c=A.*sawtooth(2*pi*F1*t);
subplot(3,1,1)
plot(t,c);
xlabel('time')
ylabel('Amplitude');
title('Carrier Sawtooth Wave');
grid on;
m=0.75*A.*sin(2*pi*F2*t);
subplot(3,1,2);
plot(t,m);
xlabel('Time');
ylabel('Amplitude');
title('Message Signal');
grid on;
n=length(c);
for i=1:n
if (m(i)>=c(i))
pwm(i)=1;
else
pwm(i)=0;
end
end

subplot(3,1,3);
plot(t,pwm);
xlabel('Time');
ylabel('Amplitude');
title('plot of PWM');
axis([0 1 0 2]);
grid on;

Output

3. Quadrature Amplitude Modulation(QAM)

Fd=1;Fs=1;
nsamp=1;
M=32;
k = log2(M);
n = 30000;
x = randi([0 1],n,1);
stem(x(1:40),'filled');
title('Random Bits');
xlabel('Bit Index');
ylabel('Binary Value');
xsym = bi2de(reshape(x,k,length(x)/k).');
figure;
stem(xsym(1:10));
title('Random Symbols');
xlabel('Symbol Index');
ylabel('Integer Value');
y=qammod(xsym,M);
title('modulated');
xlabel('Symbol Index');
ylabel('Integer Value');
ytx = y;
stem(y(1:10));
EbNo=10;
snr = EbNo + 10*log10(k) - 10*log10(nsamp);
pinput=std(ytx);
noise = (randn(1,n/k)+sqrt(-1)*randn(1,n/k))*(1/sqrt(2));
Noisestd = (pinput*10^(-snr/20));
ynoisy = ytx + (Noisestd*noise);
yrx=ynoisy;
figure;
plot(real(yrx(1:5e3)),imag(yrx(1:5e3)),'b*');
hold on;
plot(real(ytx(1:5e3)),imag(ytx(1:5e3)),'y.');
title('Signal Constellation');
legend('Received Signal', 'Transmitted Signal');
axis([-5 5 -5 5]);
hold off;

Output

4. MATLAB code for Binary Frequency Shift Keying(BFSK) Modulation and Demodulation

clc;
clear all;
N=8;
b=round(rand(1,N));
subplot(4,1,1);
stem(b,'filled')
xlabel('Bits index')
ylabel('transmitted bits')
NRZ_out=[];
Vp=1;
for index=1:size(b,2)
if b(index)==1
NRZ_out=[NRZ_out ones(1,200)*Vp];
elseif b(index)==0
NRZ_out=[NRZ_out zeros(1,200)*(-Vp)];
end
end
subplot(4,1,2);
plot(NRZ_out)
t=0.005:0.005:8;
f2=3;
f1=5;
A=5;
mod_sig=[];
for(i=1:1:length(NRZ_out))
if(NRZ_out(i)==1)
y=A*cos(2*pi*f1*t(i));
else
y=A*cos(2*pi*f2*t(i));
end
mod_sig=[mod_sig y];
end
subplot(4,1,3);
plot(t,mod_sig)
xlabel('Time in seconds')
ylabel('Modulated signal')
demod_branch_1=mod_sig.*(cos(2*pi*f1*t));
demod_branch_2=mod_sig.*(cos(2*pi*f2*t));
y_1=[];
for i=1:200:size(demod_branch_1,2)
y_1=[y_1 trapz(t(i:i+199),demod_branch_1(i:i+199))];
end
y_2=[];
for i=1:200:size(demod_branch_2,2)
y_2=[y_2 trapz(t(i:i+199),demod_branch_2(i:i+199))];
end
rec_sig=y_1>y_2;
subplot(4,1,4);
stem(rec_sig,'filled','r')
xlabel('Bits index')
ylabel('Received bits')

Output

5. Pulse Code Modulation (PCM)

P=5;
t = [0:0.1:1*pi];
sig = 4*sin(t);
Vh=max(sig);
V1=min(sig);
N=3;M=2^N;
S=(Vh-V1)/M;
partition = [V1+S:S:Vh-S];
codebook = [V1+S/2:S:Vh-S/2];
[index,quantized_sig,distor] = quantiz(sig,partition,codebook);

codedsig=de2bi(index,'left-msb');
codedsig=codedsig;
txbits=codedsig(:);
errvec=randsrc(length(txbits),1,[0 1;(1-P/100) P/100]);

rxbits=rem(txbits+errvec,2);
rxbits=reshape(rxbits,N,length(sig));
rxbits=rxbits';
index1=bi2de(rxbits,'left-msb');
reconstructedsig=codebook(index1+1);

figure,
subplot(2,2,1);
stem(t,sig);
xlabel('Time');
title('original signal');

subplot(2,2,2);
stem(t,quantized_sig);
xlabel('time)');
title('quantized signal');
tt=[0:N*length(t)-1];

subplot(2,2,3);
stairs(tt,txbits);
xlabel('time');
title('PCM Waveform');

subplot(2,2,4);
stem(t,reconstructedsig);
xlabel('time');
title('received signal');

6. Quadrature Phase Shift Keying (QPSK), Matlab Code

clc;
clear al;
close all;
Tb=1;
t=0:(Tb/100):Tb;
fc=1;
c1=sqrt(2/Tb)*cos(2*pi*fc*t);
c2=sqrt(2/Tb)*sin(2*pi*fc*t);

subplot(3,2,1);
plot(t,c1);
title('Carrier Signal-1');
xlabel('t ----->');
ylabel('c1(t)');
grid on;

subplot(3,2,2);
plot(t,c2);
title('Carrier Signal-2');
xlabel('t ----->');
ylabel('c2(t)');
grid on;

N=16;
m=rand(1,N);

t1=0;
t2=Tb;
for i=1:2:(N-1)
t=[t1:(Tb/100):t2];

if m(i)>0.5
m(i)=1;
m_s=ones(1,length(t));
else
m(i)=0;
m_s=-1*ones(1,length(t));
end
odd_sig(i,:)=c1.*m_s;

if m(i+1)>0.5
m(i+1)=1;
m_s=ones(1,length(t));
else
m(i+1)=0;
m_s=-1*ones(1,length(t));
end
even_sig(i,:)=c2.*m_s;

Qpsk =odd_sig + even_sig;

subplot(3,2,3);
stem(m);
title('Binary Data of Message Signal');
xlabel('n ----->');
ylabel('b(n)');
grid on;

subplot(3,2,4);
plot(t,Qpsk(i,:));
title('QPSK Modulated Signal');
xlabel('t ------>');
ylabel('s(t)');
grid on;
hold on;
t1=t1+(Tb+0.01);
t2=t2+(Tb+0.01);
end
hold off;

t1=0;
t2=Tb;
for i=1:N-1
t=[t1:(Tb/100):t2];

x1=sum(c1.*Qpsk(i,:));
x2=sum(c2.*Qpsk(i,:));

if (x1>0 && x2>0)
demod(i)=1;
demod(i+1)=1;
elseif (x1>0 && x2<0)
demod(i)=1;
demod(i+1)=0;
elseif (x1<0 && x2<0)
demod(i)=0;
demod(i+1)=0;
elseif (x1<0 && x2>0)
demod(i)=0;
demod(i+1)=1;
end

end

subplot(3,2,5);
stem(demod);
title('QPSK Demodulated Signal');
xlabel('n ------>');
ylabel('b(n)');
grid on;

Output

7. Differential Phase Shift Keying (DPSK), Matlab code

clc;
clear al;
close all;
N=10;
bk=round(rand(1,N));

br=10^6;
f=br;
T=1/br;

grid on;
subplot(4,1,1);
stem(bk,'linewidth',1.5);
title('INFORMATION BITS TO BE TRANSMITTED');
axis([0 11 0 1.5]);

dk=1;
coded =[dk];
for i=1:length(bk)
temp=~xor(dk,bk(i));
coded=[coded temp];
dk=temp;
end

subplot(4,1,2);
stem(coded,'linewidth',1.5);
grid on;
title('Differentially encoded signal');
axis([0 11 0 1.5]);

coded_PNRZ=2*coded-1;
mod_sig=[];
t=T/99:T/99:T;
for i=1:length(coded)
temp=coded_PNRZ(i)*sqrt(2/T)*cos(2*pi*f*t);
mod_sig=[mod_sig temp];
end

subplot(4,1,3);

tt=T/99:T/99:(T*length(coded));
plot(tt,mod_sig,'linewidth',1.5);
title('dpsk modulation signal');
grid on;

rec_sig=mod_sig;
rec_data=[];
for i=1:length(coded)-1
y_in=rec_sig((i-1)*length(t)+1:i*length(t)).*rec_sig((i)*length(t)+1:(i+1)*length(t));
y_in_intg=trapz(t,y_in);
if (y_in_intg>0)
temp=1;
else
temp=0;
end
rec_data=[rec_data temp];
end

subplot(4,1,4);
stem(rec_data,'linewidth',3);
title('received information bits');
axis([0 11 0 1.5]);

8. BPSK(Binary Phase Shift Keying) Matlab Project code

clc;
clear all;
close all;
%fine Transmitted Signal=
N=10;
x_inp=round(rand(1,N)); % Message Signal
Tb=0.0001; % Bit Period

%Represent Input Signal as Digital Signal
x_bit=[];
nb=100;

for n=1:1:N
if x_inp(n)==1
x_bitt=ones(1,nb);
else
x_bitt=zeros(1,nb);
end
x_bit=[x_bit x_bitt];
end
t1=Tb/nb:Tb/nb:nb*N*(Tb/nb);
f1=figure(1);
set(f1,'color',[1 1 1]);
subplot(3,1,1);
plot(t1,x_bit,'LineWidth',2);
grid on;
axis([0 Tb*N -0.5 1.5]);
ylabel('Amplitude(volt)');
xlabel('Time(sec)');
title('Input Signal as Digital Signal');

%fine BPSK Modulation
Ac=10;
mc=4;
fc=mc*(1/Tb);
fi1=0;
fi2=pi;
t2=Tb/nb:Tb/nb:Tb;
t2L=length(t2);
x_mod=[];
for i=1:1:N
if x_inp(i)==1
x_mod0=Ac*cos(2*pi*fc*t2+fi1);
else
x_mod0=Ac*cos(2*pi*fc*t2+fi2);
end
x_mod=[x_mod x_mod0];
end

t3=Tb/nb:Tb/nb:Tb*N;
subplot(3,1,2);
plot(t3,x_mod);
xlabel('Time(sec)');
ylabel('Amplitude(volt)');
title('Signal of BPSK modulation');

%Transmitted Signal x
x=x_mod;
h=1;
w=0;

%Received Signal
y=h.*x+w;

%BPSK Demodulation
y_dem=[];
for n=t2L:t2L:length(y)
t=Tb/nb:Tb/nb:Tb;
c=cos(2*pi*fc*t);
y_dem0=c.*y((n-(t2L-1)):n);
t4=Tb/nb:Tb/nb:Tb;
z=trapz(t4,y_dem0);
A_dem=round((2*z/Tb));
if(A_dem>Ac/2)
A=1;
else
A=0;
end
y_dem=[y_dem A];
end
x_out=y_dem;

%Represent output signal as Digital Signal

xx_bit=[];
for n=1:length(x_out)
if x_out(n)==1
xx_bitt=ones(1,nb);
else
xx_bitt=zeros(1,nb);
end
xx_bit=[xx_bit xx_bitt];
end
t4=Tb/nb:Tb/nb:nb*length(x_out)*(Tb/nb);
subplot(3,1,3)
plot(t4,xx_bit,'LineWidth',2);
grid on;
axis([0 Tb*length(x_out) -0.5 1.5]);
ylabel('Amplitude(volt)');
xlabel('Time(sec)');
title('Output Signal as Digital Signal');

Output

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1. Multiple Input Multiple Output(MIMO) using Matlab

2. Pulse Width Modulation(PWM) working Principal using Matlab

3. Quadrature Amplitude Modulation(QAM)

4. MATLAB code for Binary Frequency Shift Keying(BFSK) Modulation and Demodulation

5. Pulse Code Modulation (PCM)

6. Quadrature Phase Shift Keying (QPSK), Matlab Code

7. Differential Phase Shift Keying (DPSK), Matlab code

8. BPSK(Binary Phase Shift Keying) Matlab Project code

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Multiple Input Multiple Output(MIMO) using Matlab

Pulse Width Modulation(PWM) working Principal using Matlab

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