ofdm-ml.rar_Doppler in OFDM_ML_OFDM ML _OFDM多普勒_似然同步 算法

m1=3;c1=zeros(m1,2048); for zhen1=1:m1 M1=1992; a1=rand(1,7968); a1=sign(a1-0.5); b1=reshape(a1,1992,4); xxx1=2*b1(:,1)+b1(:,2)+j*(2*b1(:,3)+b1(:,4)); xx1=ifft(xxx1')*1992; geshu1=length(xx1); s11=1;s21=56;s31=1; w11=s11:s31:s21; addcp1=ones(1,geshu1+s21); for i1=w11 addcp1(1,i1)=xx1(1992-s21+i1); end w21=1:1:geshu1; for k1=w21 addcp1(1,s21+k1)=xx1(k1); end c1(zhen1,1:2048)=addcp1; c11=c1'; addcp11=reshape(c11,1,6144); end for n=1:3 for m=1:2048 addcp11((n-1)*2048+m)=addcp11((n-1)*2048+m)*exp(i*2*pi*0.5*m/2048); %加入频偏V以后的各样点值 end end %信道模型：带多普勒频移的瑞利衰落信道 fade=[0 0 0.2 0.3]; %多径的幅度 Len=length(addcp11); f_Len=length(fade); sch=addcp11; for m=1:f_Len sch(1+m:Len)=sch(1+m:Len)+fade(m)*addcp11(1:Len-m); end fd=0.25;%多普勒频移 for m=1:length(sch) addcp11(m)=sch(m)*exp(i*2*pi*fd*m/2048); %加入频偏V以后的各样点值 end SNR=15; noise=awgn(addcp11,SNR); addcp11=addcp11+noise; n1=length(addcp11); for h1=1:n1-1992 as1=0; if h1<4098 for l1=h1:h1+s21-1 as1=as1+abs(addcp11(l1)*conj(addcp11(l1+M1)))-0.5*(abs(addcp 11(l1))^2+abs(addcp11(l1+M1))^2); div1=-1./(2*pi)*angle(addcp11(l1)*conj(addcp11(l1+M1))); end else for y1=h1:s21+4096 as1=as1+abs(addcp11(y1)*conj(addcp11(y1+M1)))-0.5*(abs(addcp11(y1) )^2+abs(addcp11(y1+M1))^2); div1=-1./(2*pi)*angle(addcp11(y1)*conj(addcp11(y1+M1))); end end p1(h1)=as1; ff(h1)=div1; end figure(1) plot(p1); figure(2) t=1:30:4096; plot(t,ff(t)); %寻找定时同步的准确位置 % max1=0; % for m=1:2000 % if p1(m)>max1 %条件判断，如果数组前面的数比其后的小，执行以下语句 % max1=p1(m); % dml=m; % end % end % fprintf('定时偏差d1的估计值为:%f\n',dml); %