OFDM基于IEEE 802.11a仿真.zip

tic %参数设置 Nsp=52; %子载波数 Nfft=64; %FFT长度 Ncp=16; %循环前缀长度 Ns=Nfft+Ncp; %一帧OFDM数据长度 noc=53; %包含直流载波的子载波数 Nd=6; %一个数据包所包含的帧数 M1=4; %QPSK调制 M2=16; %16QAM调制 sr=2500; %码元速率 EbNo=0:2:30; %归一化信噪比 Nfrm=10000; %数据包数目 ts=1/sr/Ns; %码元抽样时间间隔 t=0:ts:(Ns*(Nd+1)*Nfrm-1)*ts; %抽样时刻 fd=100; %最大多普勒频移 h=rayleigh(fd,t); %生成单径Rayleigh衰落信道 h1=sqrt(2/3)*h; %生成2径衰落信道 h2=sqrt(1/3)*rayleigh(fd,t); h2=[zeros(1,4) h2(1:end-4)]; %长训练符号频域数据 Preamble=[1 1 -1 -1 1 1 -1 1 -1 1 1 1 1 1 1 -1 -1 1 1 -1 1 -1 1 1 1 1 ... 1 -1 -1 1 1 -1 1 -1 1 -1 -1 -1 -1 -1 1 1 -1 -1 1 -1 1 -1 1 1 1 1]; Preamble1=zeros(1,Nfft); Preamble1(2:27)=Preamble(27:end); Preamble1(39:end)=Preamble(1:26); preamble1=ifft(Preamble1); preamble1 = [preamble1(Nfft - Ncp + 1:end) preamble1]; %仿真循环 for ii=1:length(EbNo) %发射机部分 msg1=randsrc(Nsp,Nd*Nfrm,[0:M1-1]); %QPSK信息数据 msg2=randsrc(Nsp,Nd*Nfrm,[0:M2-1]); %16QAM信息数据 data1=pskmod(msg1,M1,pi/4); %QPSK调制 data2=qammod(msg2,M2)/sqrt(10); %16QAM调制 data3=zeros(Nfft,Nd*Nfrm); %数据重排 data4=zeros(Nfft,Nd*Nfrm); data3(2:27,:)=data1(27:end,:); data3(39:end,:)=data1(1:26,:); data4(2:27,:)=data2(27:end,:); data4(39:end,:)=data2(1:26,:); clear data1 data2; data3=ifft(data3); %IFFT变换 data4=ifft(data4); data3=[data3(Nfft-Ncp+1:end,:);data3]; %加入循环前缀 data4=[data4(Nfft-Ncp+1:end,:);data4]; spow1=norm(data3,'fro').^2/(Nsp*Nd*Nfrm); %计算符号能量 spow2=norm(data4,'fro').^2/(Nsp*Nd*Nfrm); data5=zeros(Ns,(Nd+1)*Nfrm); %加入训练符号 data6=data5; for index=1:Nfrm data5(:,(index-1)*(Nd+1)+1)=preamble1.'; data5(:,(index-1)*(Nd+1)+2:index*(Nd+1))=data3(:,(index-1)*Nd+1:index*Nd); data6(:,(index-1)*(Nd+1)+1)=preamble1.'; data6(:,(index-1)*(Nd+1)+2:index*(Nd+1))=data4(:,(index-1)*Nd+1:index*Nd); end clear data3 data4 data5=reshape(data5,1,Ns*(Nd+1)*Nfrm); %串并变换 data6=reshape(data6,1,Ns*(Nd+1)*Nfrm); data51=zeros(1,length(data5)); data61=zeros(1,length(data6)); data51(5:end)=data5(1:end-4); data61(5:end)=data6(1:end-4); sigma1=sqrt(1/2*spow1/log2(M1)*10.^(-EbNo(ii)/10)); %根据EbNo计算噪声标准差 sigma2=sqrt(1/2*spow2/log2(M2)*10.^(-EbNo(ii)/10)); for indx=1:Nfrm dd1=data5((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); dd2=data6((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); dd3=data51((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); dd4=data61((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); hh=h((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); %当前数据包的单径信道参数 hh1=h1((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); %当前数据包的2径信道参数 hh2=h2((indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1)); %信号通过单径衰落信道，并加入高斯白噪声 r1=hh.*dd1+sigma1*(randn(1,length(dd1))+j*rand(1,length(dd1))); r2=hh.*dd2+sigma1*(randn(1,length(dd2))+j*rand(1,length(dd2))); %信号通过2径衰落信道，并加入高斯白噪声 r11=hh1.*dd1+hh2.*dd3+sigma1*(randn(1,length(dd1))+j*rand(1,length(dd1))); r21=hh1.*dd2+hh2.*dd4+sigma1*(randn(1,length(dd2))+j*rand(1,length(dd2))); r1=reshape(r1,Ns,Nd+1); %并串变换 r2=reshape(r2,Ns,Nd+1); r11=reshape(r11,Ns,Nd+1); r21=reshape(r21,Ns,Nd+1); r1=r1(Ncp+1:end,:); %移除循环前缀 r2=r2(Ncp+1:end,:); r11=r11(Ncp+1:end,:); r21=r21(Ncp+1:end,:); %根据训练符号进行的信道估计 R1=fft(r1); %FFT变换 R2=fft(r2); R11=fft(r11); R21=fft(r21); R1=[R1(39:end,:);R1(2:27,:)]; %数据重排 R2=[R2(39:end,:);R2(2:27,:)]; R11=[R11(39:end,:);R11(2:27,:)]; R21=[R21(39:end,:);R21(2:27,:)]; HH1=(Preamble.')./R1(:,1); %信道估计 HH2=(Preamble.')./R2(:,1); HH11=(Preamble.')./R11(:,1); HH21=(Preamble.')./R21(:,1); HH1=HH1*ones(1,Nd); HH2=HH2*ones(1,Nd); HH11=HH11*ones(1,Nd); HH21=HH21*ones(1,Nd); x1=R1(:,2:end).*HH1; %信道补偿 x2=R2(:,2:end).*HH2; x3=R11(:,2:end).*HH11; x4=R21(:,2:end).*HH21; x1=pskdemod(x1,M1,pi/4); %数据解调 x2=qamdemod(x2.*sqrt(10),M2); x3=pskdemod(x3,M1,pi/4); x4=qamdemod(x4.*sqrt(10),M2); %统计一帧中的错误比特数 [neb1(indx),temp]=biterr(x1,msg1(:,(indx-1)*Nd+1:indx*Nd),log2(M1)); [neb2(indx),temp]=biterr(x2,msg2(:,(indx-1)*Nd+1:indx*Nd),log2(M2)); [neb3(indx),temp]=biterr(x3,msg1(:,(indx-1)*Nd+1:indx*Nd),log2(M1)); [neb4(indx),temp]=biterr(x4,msg2(:,(indx-1)*Nd+1:indx*Nd),log2(M2)); end ber1(ii)=sum(neb1)/(Nsp*log2(M1)*Nd*Nfrm); %理想信道的误比特率 ber2(ii)=sum(neb2)/(Nsp*log2(M2)*Nd*Nfrm); ber3(ii)=sum(neb3)/(Nsp*log2(M1)*Nd*Nfrm); %2径信道的误比特率 ber4(ii)=sum(neb4)/(Nsp*log2(M2)*Nd*Nfrm); end semilogy(EbNo,ber1,'-ro',EbNo,ber3,'-rv',EbNo,ber2,'-r*',EbNo,ber4,'-rd') grid on title('OFDM系统误比特率性能') legend('QPSK单径信道','QPSK2径信道','16-QAM单径信道','16-QAM2径信道') xlabel('信噪比（EbNo）') ylabel('误比特率') toc