MATLAB: Bit eror rate

berfft

hello lets say i have this random bits bits= randint(1,1000)

and after few math functions i get x=(1,1000) how do i calculate and make a plot of the ber when i make this math function 10 times for 10 diffrents snr? thanks!

Best Answer

SNR = [1, 2, 5, ... whatever]
N = length(SNR);
ber = zeros(N,1);
for K = 1:N
  x = ApplySNR(bits, SNR(K));
  ber(K) = mean(x ~= bits);
end
plot(SNR, ber);

Where ApplySNR is your function for transforming the bits according to the given SNR.

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MATLAB: Index exceeds matrix dimensions ?

Hi Ali,

please try to run the following code:

%%Setup
% Define parameters.
M = 16;                 % Size of signal constellation
k = log2(M);            % Number of bits per symbol
n = 3e4;                % Number of bits to process
nsamp = 1;              % Oversampling rate
hMod = modem.qammod(M); % Create a 16-QAM modulator
%%Signal Source
% Create a binary data stream as a column vector.
x = randint(n,1); % Random binary data stream
% Plot first 40 bits in a stem plot.
stem(x(1:40),'filled');
title('Random Bits');
xlabel('Bit Index'); ylabel('Binary Value');
%%Bit-to-Symbol Mapping
% Convert the bits in x into k-bit symbols.
xsym = bi2de(reshape(x,k,length(x)/k).','left-msb');
%%Stem Plot of Symbols
% Plot first 10 symbols in a stem plot.
figure; % Create new figure window.
stem(xsym(1:10));
title('Random Symbols');
xlabel('Symbol Index'); ylabel('Integer Value');
%%Modulation
y = modulate(modem.qammod(M),xsym); % Modulate using 16-QAM.
%%Transmitted Signal
ytx = y;
%%Channel
% Send signal over an AWGN channel.
EbNo = 10; % In dB
snr = EbNo + 10*log10(k) - 10*log10(nsamp);
ynoisy = awgn(ytx,snr,'measured');
%%Received Signal
yrx = ynoisy;
%%Scatter Plot
% Create scatter plot of noisy signal and transmitted
% signal on the same axes.
h = scatterplot(yrx(1:nsamp*5e3),nsamp,0,'g.');
hold on;
scatterplot(ytx(1:5e3),1,0,'k*',h);
title('Received Signal');
legend('Received Signal','Signal Constellation');
axis([-5 5 -5 5]); % Set axis ranges.
hold off;

After you have run the code you should have the following variables in your workspace:

whos
  Name            Size             Bytes  Class           Attributes
    EbNo            1x1                  8  double                    
    M               1x1                  8  double                    
    h               1x1                  8  double                    
    hMod            1x1                     modem.qammod              
    k               1x1                  8  double                    
    n               1x1                  8  double                    
    nsamp           1x1                  8  double                    
    snr             1x1                  8  double                    
    x           30000x1             240000  double                    
    xsym         7500x1              60000  double                    
    y            7500x1             120000  double          complex   
    ynoisy       7500x1             120000  double          complex   
    yrx          7500x1             120000  double          complex   
    ytx          7500x1             120000  double          complex

Please compare these values with yours in order to hunt down the issue.

I hope I could help,

Friedrich

MATLAB: Whats wrong with this code

Trying to run it, I get--
...
Error using chi2inv (line 22)
Requires two input arguments. 
>>

Don't know what the intent is and with, as you note Stephen, no explanations, I'm not going to try to divine but need a DOF argument as the second argument to chi2inv

Whether that should be N or perhaps count OP will have to determine...

Best Answer

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MATLAB: Index exceeds matrix dimensions ?

MATLAB: Whats wrong with this code

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