ofdm.zip_ofdm调制解调_qam

echo on K=10;N=2*K;T=100;variance=1;%噪声方差 %noise=sqrt(variance)*randn(1,N); a=rand(1,36); a=sign(a-0.5); b=reshape(a,9,4); % Generate the 16 QAM points. XXX=2*b(:,1)+b(:,2)+j*(2*b(:,3)+b(:,4)); XX=XXX'; X=[0 XX 0 conj(XX(9:-1:1))]; xt=zeros(1,101); for t=0:100 for k=0:N-1 xt(1,t+1)=xt(1,t+1)+1/sqrt(N)*X(k+1)*exp(j*2*pi*k*t/T); echo off end end subplot(2,1,1); plot([0:100],abs(xt))%以上得到发送波形x（t） chan=rayleighchan(1,0.1,[0,1,2],[0,2,4]); y=filter(chan,xt); m = 1:5:100; yn = y(m); noise=sqrt(variance)*randn(1,length(yn)); %echo on %x=zeros(1,N); %for n=0:N-1 % for k=0:N-1 % x(n+1)=x(n+1)+1/sqrt(N)*X(k+1)*exp(j*2*pi*n*k/N); % echo off %end %end echo on r=yn+noise; Y=zeros(1,10); for k=1:9 for n=0:N-1 Y(1,k+1)=Y(1,k+1)+1/sqrt(N)*r(n+1)*exp(-j*2*pi*k*n/N); echo off end end subplot(2,1,2); plot([0:9],abs(Y))%得到接收波形 echo on %Detect the nearest neighbor in the 16 QAM constellation. for k=1:9 if real(Y(1,k+1))>0 if real(Y(1,k+1))>2 Z(1,k+1)=3; else Z(1,k+1)=1; end else if real(Y(1,k+1))<-2 Z(1,k+1)=-3; else Z(1,k+1)=-1; end end if imag(Y(1,k+1))>0 if imag(Y(1,k+1))>2 Z(1,k+1)=Z(1,k+1)+3*j; else Z(1,k+1)=Z(1,k+1)+j; end else if imag(Y(1,k+1))<-2 Z(1,k+1)=Z(1,k+1)-3*j; else Z(1,k+1)=Z(1,k+1)-j; end end echo off end echo on error=max(size(find(Z(1,2:10)-X(1,2:10))));