How to get ber vs snr graph of received signal?

clc;

M =8; %here we initialize the number of constellation point of qam

no_of_data_bits=1024;

Fm=10^6;%Max freq

block_size = 16; %Size of each OFDM block to add cyclic prefix

cp_len = floor(0.1 * block_size); %Length of the cyclic prefix

data_source= abs(round(randn(1,no_of_data_bits)));%here we take random normal function

figure(1);

x=1:no_of_data_bits;

stem (x*(1/Fm),data_source);

grid minor;

xlabel('time(Microsecond)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

title('Transmitted Data','Fontsize',16);%here we plot that transmitted data

qam_modulated_data = qammod(data_source, M);%here we perform 8bit qam on the random normal function

nqdata = length(qam_modulated_data);

data = 0:M-1;

scatterplot(qam_modulated_data,1,0,'r*');

[udata, uidx] = unique(qam_modulated_data);

nudata = length(udata);

grid minor

for k=1:nudata

text(real(udata(k))-0.4,imag(udata(k))+0.4,num2str(data_source(uidx(k))));

end

axis([-4 4 -2 2])

qm = abs(qam_modulated_data);

figure(3);

stem(qm)

title('MODULATED TRANSMITTED DATA','Fontsize',16);%here we plot those constellation point

y=ifft(qam_modulated_data);

figure(4);

x=1:nqdata;

stem(x(2:end)*Fm,abs(y(2:end)));

grid minor;

xlabel('freq(Mhz)','Fontsize',16);

ylabel('amplitude of ifft','Fontsize',16);

title('without hermitian ifft','Fontsize',16);

udata1(1:(M/2))=qam_modulated_data(1:(M/2)); %here we introduce another array named qam_modulated_data1 where first four element is first four constellation point

udata1(((M/2)+1):M)=qam_modulated_data(1:(M/2));% in my qam_modulated_data1 array last four point is Hermitian of first four point

figure(5);

x=1:M;

stem (x*Fm,abs(udata1));

grid minor;

xlabel('frequency(MHZ)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

title('Hermitian symmetry','Fontsize',16);

y1=ifft(udata1); %here we apply fast Fourier transform on the data of udata1

figure(6);

x=1:M;

stem(x*Fm,abs(y1)); %here we plot that fft result

grid minor;

xlabel('Freq(Mhz)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

title('even frequency suppressed output','Fontsize',16);

y1c=conj(y1);

real_y1=y1.*y1c ;

figure(7);

x=1:M;

stem(x*Fm,real_y1);

grid on;

xlabel('Freq(Mhz)','Fontsize',16);

ylabel('amplitude of real values of ifft','Fontsize',16);

title('real value of ifft','Fontsize',16);

number_of_subcarriers=M;

assert(number_of_subcarriers <= M);

cp_start=block_size-cp_len;

ifft_Subcarrier = zeros(16, number_of_subcarriers);

cyclic_prefix = zeros(cp_len, number_of_subcarriers);

Append_prefix = zeros(16+cp_len, number_of_subcarriers);

for i=1:number_of_subcarriers

S2P = reshape(qam_modulated_data, no_of_data_bits/M,M);

ifft_Subcarrier(:,i) = ifft((S2P(:,i)),16);% 16 is the ifft point

for j=1:cp_len

cyclic_prefix(j,i) = ifft_Subcarrier(j+cp_start,i);

end

Append_prefix(:,i) = vertcat( cyclic_prefix(:,i), ifft_Subcarrier(:,i));

% Appends prefix to each subcarriers

end

A1=Append_prefix(:,1);

A2=Append_prefix(:,2);

A3=Append_prefix(:,3);

A4=Append_prefix(:,4);

A5=Append_prefix(:,5);

A6=Append_prefix(:,6);

A7=Append_prefix(:,7);

A8=Append_prefix(:,8);

figure(12), subplot(8,1,1),plot(real(A1),'r'),title('Cyclic prefix added to all the odd sub-carriers','Fontsize',16)

subplot(8,1,2),plot(real(A2),'y')

subplot(8,1,3),plot(real(A3),'b')

subplot(8,1,4),plot(real(A4),'g')

subplot(8,1,5),plot(real(A5),'m')

subplot(8,1,6),plot(real(A6),'k')

subplot(8,1,7),plot(real(A7),'c')

subplot(8,1,8),plot(real(A8),'g')

xlabel('frequency(MHZ)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

%Convert to serial from parallel

[rows_Append_prefix cols_Append_prefix]=size(Append_prefix)

len_ofdm_data = rows_Append_prefix*cols_Append_prefix;

% OFDM signal to be transmitted

ofdm_signal = reshape(Append_prefix, 1, len_ofdm_data);

figure(13),

plot(real(ofdm_signal)); xlabel('Time','Fontsize',16); ylabel('Amplitude','Fontsize',16);

title('OFDM Signal','Fontsize',16);grid on;

% Frequency selective channel with 4 taps

Ts = 1e-3; % Sampling period of channel

Fd = 0; % Max Doppler frequency shift

tau = [0 .2e-9 .5e-9 1.6e-9 2.3e-9 5e-9]; % Path delays

pdb = [0.189 0.379 0.239 0.095 0.061 0.037]; % Avg path power gains

h = comm.RayleighChannel('SampleRate', 1/Ts, ...

'MaximumDopplerShift', Fd, ...

'PathDelays', tau, ...

'AveragePathGains', pdb, ...

'PathGainsOutputPort', false);

reset(h); %ResetBeforeFiltering equivalent

channel = step(h, ofdm_signal(:,j).'); %second output is PathGains

after_channel = filter(channel, 1, ofdm_signal);

awgn_noise = awgn(zeros(1,length(after_channel)),0);

recvd_signal = awgn_noise+after_channel; % With AWGN noise

%Converts from serial back to parallel

figure(14),

plot(real(recvd_signal)),xlabel('Time','Fontsize',16); ylabel('Amplitude','Fontsize',16);

title('OFDM Signal after rayleigh fading passing through channel','Fontsize',16);grid on;

recvd_signal_paralleled = reshape(recvd_signal,rows_Append_prefix, cols_Append_prefix);

%now that the signal has passed through the channel we begin to work

%backawards, but we are first going to remove the CP

% Remove cyclic Prefix

%Now that the signal has already passed through the channel, we can get rid

%of the CP

recvd_signal_paralleled(1:cp_len,:)=[];

R1=recvd_signal_paralleled(:,1);

R2=recvd_signal_paralleled(:,2);

R3=recvd_signal_paralleled(:,3);

R4=recvd_signal_paralleled(:,4);

R5=recvd_signal_paralleled(:,5);

R6=recvd_signal_paralleled(:,6);

R7=recvd_signal_paralleled(:,7);

R8=recvd_signal_paralleled(:,8);

figure(15),plot((imag(R1)),'r'),subplot(8,1,1),plot(real(R1),'r'),

title('Cyclic prefix removed from the eight sub-carriers','Fontsize',16)

subplot(8,1,2),plot(real(R2),'y')

subplot(8,1,3),plot(real(R3),'g')

subplot(8,1,4),plot(real(R4),'b')

subplot(8,1,5),plot(real(R5),'k')

subplot(8,1,6),plot(real(R6),'c')

subplot(8,1,7),plot(real(R7),'m')

subplot(8,1,8),plot(real(R8),'b')

xlabel('frequency(MHZ)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

% Fourier Transofrm of the received signal

%Similarly to how we took the IFFT of the original signal, as we are back

%tracking we are now taking the FFT

for i=1:number_of_subcarriers

fft_data(:,i) = fft(recvd_signal_paralleled(:,i),16);

end

F1=fft_data(:,1);

F2=fft_data(:,2);

F3=fft_data(:,3);

F4=fft_data(:,4);

F5=fft_data(:,5);

F6=fft_data(:,6);

F7=fft_data(:,7);

F8=fft_data(:,8);

figure(16), subplot(8,1,1),plot(real(F1),'r'),title('Fourier Transform of all the eight sub-carriers','Fontsize',16)

subplot(8,1,2),plot(real(F2),'y')

subplot(8,1,3),plot(real(F3),'g')

subplot(8,1,4),plot(real(F4),'b')

subplot(8,1,5),plot(real(F5),'K')

subplot(8,1,6),plot(real(F6),'c')

subplot(8,1,7),plot(real(F7),'m')

subplot(8,1,8),plot(real(F8),'g')

xlabel('Time(microsec)','Fontsize',16);

ylabel('amplitude','Fontsize',16);

% Conversion to serial and demodulation

%The orignal data was in series, so we are taking the demodulated data

%which is still in parallel form and we are converting back into series to

%hopefully show the same data

recvd_serial_data = reshape(fft_data, 1,(16*8));

qam_demodulated_data = qamdemod(recvd_serial_data,M);

figure(17),

subplot(2,1,1),

x=1:no_of_data_bits;

stem(x*(1/Fm),data_source);

grid on;xlabel('Data Points(time in microsec)','Fontsize',16);ylabel('Amplitude','Fontsize',16);

title('Original Data','Fontsize',16)

subplot (2,1,2),

num_sent = length(data_source);

lie_about_the_time = linspace(x(1)/Fm, x(end)/Fm, length(qam_demodulated_data));

stem(lie_about_the_time, qam_demodulated_data);

grid on;xlabel('Data Points(time in microsec)','Fontsize',16);ylabel('Amplitude','Fontsize',16);

title('Received Data','Fontsize',16);

Now I want ber vs snr graph of qam_demodulated_data,can anyone please help?