16QAM比特误差率(BR)中推导出基于AWLU的灰色编码星座映射Matlab代码.rar

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % All rights reserved by Krishna Pillai, http://www.dsplog.com % The file may not be re-distributed without explicit authorization % from Krishna Pillai. % Checked for proper operation with Octave Version 3.0.0 % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Bit Error Rate for 16-QAM modulation using Gray modulation mapping clear N = 10^5; % number of symbols M = 16; % constellation size k = log2(M); % bits per symbol % defining the real and imaginary PAM constellation % for 16-QAM alphaRe = [-(2*sqrt(M)/2-1):2:-1 1:2:2*sqrt(M)/2-1]; alphaIm = [-(2*sqrt(M)/2-1):2:-1 1:2:2*sqrt(M)/2-1]; k_16QAM = 1/sqrt(10); Eb_N0_dB = [0:15]; % multiple Es/N0 values Es_N0_dB = Eb_N0_dB + 10*log10(k); % Mapping for binary <--> Gray code conversion ref = [0:k-1]; map = bitxor(ref,floor(ref/2)); [tt ind] = sort(map); for ii = 1:length(Eb_N0_dB) % symbol generation % ------------------ ipBit = rand(1,N*k,1)>0.5; % random 1's and 0's ipBitReshape = reshape(ipBit,k,N).'; bin2DecMatrix = ones(N,1)*(2.^[(k/2-1):-1:0]) ; % conversion from binary to decimal % real ipBitRe = ipBitReshape(:,[1:k/2]); ipDecRe = sum(ipBitRe.*bin2DecMatrix,2); ipGrayDecRe = bitxor(ipDecRe,floor(ipDecRe/2)); % imaginary ipBitIm = ipBitReshape(:,[k/2+1:k]); ipDecIm = sum(ipBitIm.*bin2DecMatrix,2); ipGrayDecIm = bitxor(ipDecIm,floor(ipDecIm/2)); % mapping the Gray coded symbols into constellation modRe = alphaRe(ipGrayDecRe+1); modIm = alphaIm(ipGrayDecIm+1); % complex constellation mod = modRe + j*modIm; s = k_16QAM*mod; % normalization of transmit power to one % noise % ----- n = 1/sqrt(2)*[randn(1,N) + j*randn(1,N)]; % white guassian noise, 0dB variance y = s + 10^(-Es_N0_dB(ii)/20)*n; % additive white gaussian noise % demodulation % ------------ y_re = real(y)/k_16QAM; % real part y_im = imag(y)/k_16QAM; % imaginary part % rounding to the nearest alphabet ipHatRe = 2*floor(y_re/2)+1; ipHatRe(find(ipHatRe>max(alphaRe))) = max(alphaRe); ipHatRe(find(ipHatRe<min(alphaRe))) = min(alphaRe); ipHatIm = 2*floor(y_im/2)+1; ipHatIm(find(ipHatIm>max(alphaIm))) = max(alphaIm); ipHatIm(find(ipHatIm<min(alphaIm))) = min(alphaIm); % Constellation to Decimal conversion ipDecHatRe = ind(floor((ipHatRe+4)/2+1))-1; % LUT based ipDecHatIm = ind(floor((ipHatIm+4)/2+1))-1; % LUT based % converting to binary string ipBinHatRe = dec2bin(ipDecHatRe,k/2); ipBinHatIm = dec2bin(ipDecHatIm,k/2); % converting binary string to number ipBinHatRe = ipBinHatRe.'; ipBinHatRe = ipBinHatRe(1:end).'; ipBinHatRe = reshape(str2num(ipBinHatRe).',k/2,N).' ; ipBinHatIm = ipBinHatIm.'; ipBinHatIm = ipBinHatIm(1:end).'; ipBinHatIm = reshape(str2num(ipBinHatIm).',k/2,N).' ; % counting errors for real and imaginary nBitErr(ii) = size(find([ipBitRe- ipBinHatRe]),1) + size(find([ipBitIm - ipBinHatIm]),1) ; end simBer = nBitErr/(N*k); theoryBer = (1/k)*3/2*erfc(sqrt(k*0.1*(10.^(Eb_N0_dB/10)))); close all; figure semilogy(Eb_N0_dB,theoryBer,'bs-','LineWidth',2); hold on semilogy(Eb_N0_dB,simBer,'mx-','LineWidth',2); axis([0 15 10^-5 1]) grid on legend('theory', 'simulation'); xlabel('Eb/No, dB') ylabel('Bit Error Rate') title('Bit error probability curve for 16-QAM modulation')