matlab-16QAM调制解调误码率仿真,对比Star-16QAM,Square-16QAM以及Square-16QAM-Gr

function ber = qamm_func( snr ) %Star-16QAM % Random bit sequence numberOfBits = 1e4; x = rand(1, numberOfBits); x( x < 0.5 ) = 0; x( x >= 0.5 ) = 1; % Radius of inner and outer circle r1 = sqrt(4.88); r2 = r1*1.76; % Define mapping table applying Gray mapping mappingTable(1) = r1 * exp(1i* 0); mappingTable(2) = r1 * exp(1i* pi/4); mappingTable(3) = r1 * exp(1i* 3*pi/4); mappingTable(4) = r1 * exp(1i* pi/2); mappingTable(5) = r1 * exp(1i* 7*pi/4); mappingTable(6) = r1 * exp(1i* 3*pi/2); mappingTable(7) = r1 * exp(1i* pi); mappingTable(8) = r1 * exp(1i* 5*pi/4); mappingTable(9:16) = mappingTable(1:8) ./ r1 .* r2; if mod(numberOfBits, 4) ~= 0 error('numberOfBits must be a multiple of 4.'); end mappedSymbols = zeros(1, numberOfBits / 4); % Map bits to symbols for i = 1:4:length(x) symbolBits = x(i:i+3); symbolIndex = 2^3 * symbolBits(1) + 2^2 * symbolBits(2) + 2^1 * symbolBits(3) + 2^0 * symbolBits(4); % Mapping mappedSymbols((i - 1)/4 + 1) = mappingTable( symbolIndex + 1); end % Add white Gaussian noise meanSignalPower = (r1^2 + r2^2)/2; snr_lin = 10^(snr/10); % linear scale meanNoisePower = meanSignalPower ./ snr_lin; receivedSignal = mappedSymbols + randn(1, length(mappedSymbols)) * sqrt(meanNoisePower/2) +... 1i * randn(1, length(mappedSymbols)) * sqrt(meanNoisePower/2); % Decision and demapping receivedBits = zeros(1, numberOfBits / 4); for i = 1:length(receivedSignal) [mindiff minIndex] = min(receivedSignal(i) - mappingTable); symbolIndex = minIndex - 1; bitString = dec2bin(symbolIndex, 4); receivedBits((i-1)*4 + 1) = str2double(bitString(1)); receivedBits((i-1)*4 + 2) = str2double(bitString(2)); receivedBits((i-1)*4 + 3) = str2double(bitString(3)); receivedBits((i-1)*4 + 4) = str2double(bitString(4)); end numberOfBitErrors = nnz( x - receivedBits ); ber = numberOfBitErrors / numberOfBits; % bit error rate disp(['SNR: ' num2str(snr) ' dB']); disp(['Bit error rate (BER): ' num2str(ber)]); % figure; % plot( real(receivedSignal), imag(receivedSignal), '.'); hold on; % absLim = max( max(real(receivedSignal)), max(imag(receivedSignal))); % xyLimits = [-absLim*1.1 absLim*1.1]; % xlim( xyLimits ); % ylim( xyLimits ); % plot( real(mappedSymbols), imag(mappedSymbols), '.r'); hold off; % xlim( xyLimits ); % ylim( xyLimits ); % xlabel('In-Phase'); % ylabel('Quadrature'); % legend('received', 'transmitted'); end