16QAM システム (送信機、チャネル、および受信機) と、結果の BER および PER 曲線を実行しています。ただし、受信機のノイズに問題があります。システムを 2 つのループ内で実行しています。すべての Eb/No 値とすべてのパケットに対して、200 個のシンボルと 1000 個のパケットを送信しましたが、これはまだ発生しています。このコードの結果が正しいかどうかを確認したい:
clear all
clc
numPkts=1000;
N = 200; % number of symbols
M = 16; % constellation size
k = log2(M); % bits per symbol
pv=4; %prefix length
% 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);
erTot=zeros(1,length(Eb_N0_dB));
% 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)
for pktX=1:numPkts
% 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;
s1 = k_16QAM*mod; % normalization of transmit power to one
s=[s1(length(s1)-pv+1:end) s1]; %add prefix
% noise
% -----
EsNo=10^(Es_N0_dB(ii)/10);
stanDevNoise=sqrt((1)/(2*EsNo));
n =stanDevNoise *[randn(1,length(s)) + j*randn(1,length(s))]; % white guassian noise, 0dB variance
h=(1/sqrt(2))*(randn+j*randn);
y1= conv(s,h) + n; % additive white gaussian noise
%removes prefix
y1(1:pv) = [];
y=y1/h;
% 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(pktX) = size(find([ipBitRe- ipBinHatRe]),1) + size(find([ipBitIm - ipBinHatIm]),1) ;
end
erTot(ii)=erTot(ii)+sum(nBitErr); %total errors in all packets
simBer(ii)=(erTot(ii)/(N*k*numPkts)); %bit error rate
totPktErRate(ii)=(erTot(ii)/(numPkts));
end
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')
ありがとう！
