correct for these codes and help me to get running codes

% System parameters
M = 50; % Number of antennas
K = 3;  % Number of terminals
SNR_dB = 20; % SNR in dB
numSymbols = 1e4; % Number of symbols for simulation
L_prime = 5; % L' = 5

% QPSK Modulator and Demodulator
qpskMod = comm.QPSKModulator('BitInput', false);
qpskDemod = comm.QPSKDemodulator('BitOutput', false);

% Generate random data symbols
dataSymbols = randi([0 3], K, numSymbols);

% Generate transmitted symbols (QPSK)
txSymbols = step(qpskMod, dataSymbols(:)); % Corrected input format
txSymbols = reshape(txSymbols, [], K);

% Channel matrix
H = (randn(M, K) + 1i*randn(M, K))/sqrt(2);

% Received signal with AWGN
rxSignal = awgn(H .* txSymbols, SNR_dB, 'measured'); % Transpose to match dimensions

Arrays have incompatible sizes for this operation.

% MRC Combining
combiner_MRC = conj(H);
rxCombined_MRC = combiner_MRC * rxSignal;

% ZF Combining
combiner_ZF = pinv(H);
rxCombined_ZF = combiner_ZF * rxSignal;

% Demodulate received symbols
rxDataSymbols_MRC = step(qpskDemod, rxCombined_MRC(:));
rxDataSymbols_ZF = step(qpskDemod, rxCombined_ZF(:));

% Decision threshold (for QPSK, it's zero)
detected_MRC = rxDataSymbols_MRC > 0;
detected_ZF = rxDataSymbols_ZF > 0;

% Reshape for plotting
rxCombined_MRC = reshape(rxCombined_MRC, [], 1);
rxCombined_ZF = reshape(rxCombined_ZF, [], 1);

% Plotting
figure;
subplot(1, 2, 1);
scatterplot(rxCombined_MRC);
title('MRC Receiver');
xlabel('In-Phase');
ylabel('Quadrature');
axis equal; % Equal scaling on both axes
grid on;
subplot(1, 2, 2);
scatterplot(rxCombined_ZF);
title('ZF Receiver');
xlabel('In-Phase');
ylabel('Quadrature');
axis equal; % Equal scaling on both axes
grid on;
sgtitle('Constellation of Estimated Symbols for K=3, M=50, L''=5, and \rho=20 dB');

[Steven Lord]

What makes you think this code is incorrect?

• Do you receive warning and/or error messages? If so the full and exact text of those messages (all the text displayed in orange and/or red in the Command Window) may be useful in determining what's going on and how to avoid the warning and/or error.
• Does it do something different than what you expected? If so, what did it do and what did you expect it to do?
• Did MATLAB crash? If so please send the crash log file (with a description of what you were running or doing in MATLAB when the crash occured) to Technical Support so we can investigate.

[Sam Chak]

@PROSPER, You can check the size of the arrays.

% Generate transmitted symbols (QPSK)
txSymbols = step(qpskMod, dataSymbols(:)); % Corrected input format
txSymbols = reshape(txSymbols, [], K);
size(txSymbols)

ans = 1x2

10000 3

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% Channel matrix
H = (randn(M, K) + 1i*randn(M, K))/sqrt(2);
size(H)

ans = 1x2

50 3

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% Received signal with AWGN
rxSignal = awgn(H .* txSymbols, SNR_dB, 'measured'); % Transpose to match dimensions

Arrays have incompatible sizes for this operation.

Answer 1

[sai charan sampara]

Hello,

I made the following changes to the code to make the array sizes compatible.

rxSignal = awgn(H * txSymbols', SNR_dB, 'measured'); % Transpose to match dimensions
% MRC Combining
combiner_MRC = conj(H)';

The following code post changes might help you:

M = 50; % Number of antennas
K = 3;  % Number of terminals
SNR_dB = 20; % SNR in dB
numSymbols = 1e4; % Number of symbols for simulation
L_prime = 5; % L' = 5
% QPSK Modulator and Demodulator
qpskMod = comm.QPSKModulator('BitInput', false);
qpskDemod = comm.QPSKDemodulator('BitOutput', false);
% Generate random data symbols
dataSymbols = randi([0 3], K, numSymbols);
% Generate transmitted symbols (QPSK)
txSymbols = step(qpskMod, dataSymbols(:)); % Corrected input format
txSymbols = reshape(txSymbols, [], K);
% Channel matrix
H = (randn(M, K) + 1i*randn(M, K))/sqrt(2);
% Received signal with AWGN
rxSignal = awgn(H * txSymbols', SNR_dB, 'measured'); % Transpose to match dimensions
% MRC Combining
combiner_MRC = conj(H)';
rxCombined_MRC = combiner_MRC * rxSignal;
% ZF Combining
combiner_ZF = pinv(H);
rxCombined_ZF = combiner_ZF * rxSignal;
% Demodulate received symbols
rxDataSymbols_MRC = step(qpskDemod, rxCombined_MRC(:));
rxDataSymbols_ZF = step(qpskDemod, rxCombined_ZF(:));
% Decision threshold (for QPSK, it's zero)
detected_MRC = rxDataSymbols_MRC > 0;
detected_ZF = rxDataSymbols_ZF > 0;
% Reshape for plotting
rxCombined_MRC = reshape(rxCombined_MRC, [], 1);
rxCombined_ZF = reshape(rxCombined_ZF, [], 1);
% Plotting
scatterplot(rxCombined_MRC);
title('MRC Receiver');
xlabel('In-Phase');
ylabel('Quadrature');
axis equal; % Equal scaling on both axes
grid on;

scatterplot(rxCombined_ZF);
title('ZF Receiver');
xlabel('In-Phase');
ylabel('Quadrature');
axis equal; % Equal scaling on both axes
grid on;
sgtitle('Constellation of Estimated Symbols for K=3, M=50, L''=5, and \rho=20 dB');