Save Variable in for Loop

Here is the code for M-ary PSK modulation and demodulation:

custMap = [0 2 4 6 8 10 12 14 15 13 11 9 7 5 3 1];

pskModulator = comm.PSKModulator(16,'BitInput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);

pskDemodulator = comm.PSKDemodulator(16,'BitOutput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);

constellation(pskModulator)

awgnChannel = comm.AWGNChannel('BitsPerSymbol',log2(16));
errorRate = comm.ErrorRate;
ebnoVec = 6:18;
ber = zeros(size(ebnoVec));

for k = 1:length(ebnoVec)
    
    % Reset the error counter for each Eb/No value
    reset(errorRate)
    % Reset the array used to collect the error statistics
    errVec = [0 0 0];
    % Set the channel Eb/No
    awgnChannel.EbNo = ebnoVec(k);
    
    while errVec(2) < 200 && errVec(3) < 1e7
        % Generate a 1000-symbol frame
        data = randi([0 1],4000,1);
        % Modulate the binary data
        modData = pskModulator(data);
        % Pass the modulated data through the AWGN channel
        rxSig = awgnChannel(modData);
        % Demodulate the received signal
        rxData = pskDemodulator(rxSig);
        % Collect the error statistics
        errVec = errorRate(data,rxData);
    end
    
    % Save the BER data
    ber(k) = errVec(1);
end

berTheory = berawgn(ebnoVec,'psk',16,'nondiff');

figure
semilogy(ebnoVec,[ber; berTheory])
xlabel('Eb/No (dB)')
ylabel('BER')
grid
legend('Simulation','Theory','location','ne')

From that code we can save the BER data, my question is how to save "rxData" variable like BER data in the for loop function above?

Answer 1

[VBBV]

K = 1 % place this outside the for loop
while errVec(2) < 200 && errVec(3) < 1e7
      % Generate a 1000-symbol frame
      data = randi([0 1],4000,1);
      % Modulate the binary data
      modData = pskModulator(data);
      % Pass the modulated data through the AWGN channel
      rxSig = awgnChannel(modData);
      % Demodulate the received signal
      rxData(K,k) = pskDemodulator(rxSig);
      % Collect the error statistics
      errVec = errorRate(data,rxData);
K = K +1;
  end

[VBBV]

You can add a loop counter inside the while loop.

[Ibnu Darajat]

After I try like this:

custMap = [0 2 4 6 8 10 12 14 15 13 11 9 7 5 3 1];
pskModulator = comm.PSKModulator(16,'BitInput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);
pskDemodulator = comm.PSKDemodulator(16,'BitOutput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);
constellation(pskModulator)
awgnChannel = comm.AWGNChannel('BitsPerSymbol',log2(16));
errorRate = comm.ErrorRate;
ebnoVec = 6:18;
ber = zeros(size(ebnoVec));
K=1;
for k = 1:length(ebnoVec)
    
    % Reset the error counter for each Eb/No value
    reset(errorRate)
    % Reset the array used to collect the error statistics
    errVec = [0 0 0];
    % Set the channel Eb/No
    awgnChannel.EbNo = ebnoVec(k);
    
    
    while errVec(2) < 200 && errVec(3) < 1e7
        % Generate a 1000-symbol frame
        data = randi([0 1],4000,1);
        % Modulate the binary data
        modData = pskModulator(data);
        % Pass the modulated data through the AWGN channel
        rxSig = awgnChannel(modData);
        % Demodulate the received signal
        rxData(K,k) = pskDemodulator(rxSig);
        % Collect the error statistics
        errVec = errorRate(data,rxData);
        K = K+1;
    end
    
    % Save the BER data
    ber(k) = errVec(1);
end

I got this error:

Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right

side is 4000-by-1.

Error in Untitled2 (line 32)

rxData(K,k) = pskDemodulator(rxSig);

[VBBV]

rxData(:,k) = pskDemodulator(rxSig);

[VBBV]

Can you check again with the above change

[Ibnu Darajat]

I just tried it:

custMap = [0 2 4 6 8 10 12 14 15 13 11 9 7 5 3 1];
pskModulator = comm.PSKModulator(16,'BitInput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);
pskDemodulator = comm.PSKDemodulator(16,'BitOutput',true, ...
    'SymbolMapping','Custom', ...
    'CustomSymbolMapping',custMap);
constellation(pskModulator)
awgnChannel = comm.AWGNChannel('BitsPerSymbol',log2(16));
errorRate = comm.ErrorRate;
ebnoVec = 6:18;
ber = zeros(size(ebnoVec));
K=1;
for k = 1:length(ebnoVec)
    
    % Reset the error counter for each Eb/No value
    reset(errorRate)
    % Reset the array used to collect the error statistics
    errVec = [0 0 0];
    % Set the channel Eb/No
    awgnChannel.EbNo = ebnoVec(k);
    
    
    while errVec(2) < 200 && errVec(3) < 1e7
        % Generate a 1000-symbol frame
        data = randi([0 1],4000,1);
        % Modulate the binary data
        modData = pskModulator(data);
        % Pass the modulated data through the AWGN channel
        rxSig = awgnChannel(modData);
        % Demodulate the received signal
        rxData(:,k) = pskDemodulator(rxSig);
        % Collect the error statistics
        errVec = errorRate(data,rxData);
        K = K+1;
    end
    
    % Save the BER data
    ber(k) = errVec(1);
end

and got this error:

>> Untitled2

Error using ErrorRate

Multichannel operation is not supported.

Error in Untitled2 (line 34)

errVec = errorRate(data,rxData);

did i missing something? Thanks before

[VBBV]

errVec = errorRate(data,rxData(:,k));

Ok. Then you need to pass the vector for the rxData data as shown above

[Ibnu Darajat]

Oke thanks that worked.

And the value result is 4000x13 double (because size Eb/No is 6:18) as shown below:

My last question, how can I retrieve data from specific row?

[VBBV]

rxData(1,:) = pskDemodulator(rxSig);

This retrieves all data from row 1

[VBBV]

Please accept the answer if it worked well

[Ibnu Darajat]

Thankyou very much