the matlab code is on using two transmit and two receive antenna diversity to mitigate attenuation. the code is not running on my system can any guy correct it for me

frmLen = 100;       % frame length
numPackets = 1000;  % number of packets
EbNo = 0:2:20;      % Eb/No varying to 20 Db
N = 2;              % maximum number of Tx antennas
M = 2;              % maximum number of Rx antennas
% Create  omm..BPSKModulator and  omm..BPSKDemodulator System objects
P = 2;        % modulation order
hMod = comm.BPSKModulator;
hDemod = comm.BPSKDemodulator('OutputDataType','double');

% Create  comm.OSTBCEncoder and  omm..OSTBCCombiner System objects
hAlamoutiEnc =  comm.OSTBCEncoder;
hAlamoutiDec =  comm.OSTBCCombiner;

% Create two  omm..AWGNChannel System objects for one and two receive
% antennas respectively. Set the NoiseMethod property of the channel to
% ‘Signal to noise ratio (Eb/No)’ to specify the noise level using the
% energy per bit to noise power spectral density ratio (Eb/No). The output
% of the BPSK modulator generates unit power signals; set the SignalPower
% property to 1 Watt.
Hawgn1Rx =  comm.AWGNChannel('NoiseMethod', 'Signal to noise ratio (Eb/No)',...
                            'SignalPower', 1);
Hawgn2Rx = clone(Hawgn1Rx);

% Create  omm..ErrorRate calculator System objects to evaluate BER.
HErrorCalc1 =  comm.ErrorRate;
hErrorCalc2 =  comm.ErrorRate;
hErrorCalc3 =  comm.ErrorRate;

% Since the  omm..AWGNChannel System objects as well as the RANDI function
% use the default random stream, the following commands are executed so
% that the results will be repeatable, i.e., same results will be obtained
% for every run of the example. The default stream will be restored at the
% end of the example.
S = RandStream.create('mt19937ar', 'seed',55408);
prevStream = RandStream.setGlobalStream(s);

% Pre-allocate variables for speed
H = zeros(frmLen, N, M);
ber_noDiver  = zeros(3,length(EbNo));
ber_Alamouti = zeros(3,length(EbNo));
ber_MaxRatio = zeros(3,length(EbNo));
ber_thy2     = zeros(1,length(EbNo));
% Set up a figure for visualizing BER results
h = gcf;
grid on;
hold on;
ax = gca;
ax.Yscale = 'log';
xlim([EbNo(1), EbNo(end)]);
ylim([1e-4 1]);
xlabel('Eb/No (Db)');
ylabel('BER');
h.NumberTitle = 'off';
h.Renderer = 'zbuffer';
h.Name = 'Transmit vs. Receive Diversity';
title('Transmit vs. Receive Diversity');

% Loop over several EbNo points
for idx = 1:length(EbNo)
    reset(hErrorCalc1);
    reset(hErrorCalc2);
    reset(hErrorCalc3);
    % Set the EbNo property of the AWGNChannel System objects
    Hawgn1Rx.EbNo = EbNo(idx);
    Hawgn2Rx.EbNo = EbNo(idx);
    % Loop over the number of packets
    for packetIdx = 1:numPackets
        % Generate data vector per frame
        data = randi([0 P-1], frmLen, 1);

          % Modulate data
          modData = step(hMod, data);

          % Alamouti Space-Time Block Encoder
          encData = step(hAlamoutiEnc, modData);

          % Create the Rayleigh distributed channel response matrix
          %   for two transmit and two receive antennas
          H(1:N:end, :,:) = (randn(frmLen/2, N, M) + ...
                           1i*randn(frmLen/2, N, M))/sqrt(2);
          %   assume held constant for 2 symbol periods
          H(2:N:end, :, :) = H(1:N:end, :, :);

          % Extract part of H to represent the 1x1, 2x1 and 1x2 channels
          H11 = H(:,1,1);
          H21 = H(:,:,1)/sqrt(2);
          H12 = squeeze(H(:,1,:));

          % Pass through the channels
          chanOut11 = H11 .* modData;
          chanOut21 = sum(H21.* encData, 2);
          chanOut12 = H12 .* repmat(modData, 1, 2);

          % Add AWGN
          rxSig11 = step(Hawgn1Rx, chanOut11);
          rxSig21 = step(Hawgn1Rx, chanOut21);
          rxSig12 = step(Hawgn2Rx, chanOut12);

          % Alamouti Space-Time Block Combiner
          decData = step(hAlamoutiDec, rxSig21, H21);

          % ML Detector (minimum Euclidean distance)
          demod11 = step(hDemod, rxSig11.*conj(H11));
          demod21 = step(hDemod, decData);
          demod12 = step(hDemod, sum(rxSig12.*conj(H12), 2));

          % Calculate and update BER for current EbNo value
          %   for uncoded 1x1 system
          ber_noDiver(:,idx)  = step(hErrorCalc1, data, demod11);
          %   for Alamouti coded 2x1 system
          ber_Alamouti(:,idx) = step(hErrorCalc2, data, demod21);
          %   for Maximal-ratio combined 1x2 system
          ber_MaxRatio(:,idx) = step(hErrorCalc3, data, demod12);

      end % end of FOR loop for numPackets

      % Calculate theoretical second-order diversity BER for current EbNo
      ber_thy2(idx) = berfading(EbNo(idx), 'psk', 2, 2);

      % Plot results
      semilogy(EbNo(1:idx), ber_noDiver(1,1:idx), 'r*', ...
               EbNo(1:idx), ber_Alamouti(1,1:idx), 'go',... 
               EbNo(1:idx), ber_MaxRatio(1,1:idx), 'bs',...
               EbNo(1:idx), ber_thy2(1:idx), 'm');
      legend('No Diversity (1Tx, 1Rx)', 'Alamouti (2Tx, 1Rx)',...
             'Maximal-Ratio Combining (1Tx, 2Rx)', ...
             'Theoretical 2nd-Order Diversity');

      drawnow;
  end  % end of for loop for EbNo
  % Perform curve fitting and replot the results
  fitBER11 = berfit(EbNo, ber_noDiver(1,:));
  fitBER21 = berfit(EbNo, ber_Alamouti(1,:));
  fitBER12 = berfit(EbNo, ber_MaxRatio(1,:));
  semilogy(EbNo, fitBER11, 'r', EbNo, fitBER21, 'g', EbNo, fitBER12, 'b');
  hold off;

% Restore default stream
RandStream.setGlobalStream(prevStream);

Answer 1

[ABDULLAHI MOHAMMAD]

Line 32, the variable s isn't defined (prevStream = RandStream.setGlobalStream(s)).

[Mahdi A. Atiyah]

Write S no s