LTE下行鏈路OFDM系統(tǒng)的MATLAB實現(xiàn).docx

clear all;% % % % % % % % % 參數(shù)設(shè)置部分 % % % % % % % % % %Nsp=52; %系統(tǒng)子載波數(shù)（不包括直流載波）Nfft=64; %FFT長度Ncp=16; %循環(huán)前綴長度Ns=Nfft+Ncp; %一個完整OFDM符號長度noc=53; %包含直流載波的總的子載波數(shù)Nd=6; %每幀包含的完整的OFDM符號數(shù)（不包括訓(xùn)練符號)M1=4; %QPSKM2=16; %16-QAM調(diào)制sr=250000; %OFDM符號速率EbN0=0:2:30; %歸一化信噪比Nfrm=100; %每種信噪比下的仿真幀數(shù)ts=1/sr/Ns; %OFDM符號抽樣時間間隔t=0:ts:(Ns*(Nd+1)*Nfrm-1)*ts; %抽樣時刻fd=100; %最大多普勒頻移h=rayleigh(fd,t); %生成單徑Rayleigh衰落信道*%訓(xùn)練符號頻域數(shù)據(jù)，采用802.11a中的長訓(xùn)練符號數(shù)據(jù)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); %訓(xùn)練符號重排后的數(shù)據(jù)Preamble1(39:end)=Preamble(1:26);preamble1=ifft(Preamble1); %訓(xùn)練符號時域數(shù)據(jù)preamble1=Preamble1(Nfft-Ncp+1:end) preamble1;%加入循環(huán)前綴% % % % % % % % % % 仿真循環(huán) % % % % % % % % % %for ii=1:length(EbN0)%*發(fā)射機部分* msg1=randsrc(Nsp,Nd*Nfrm,0:M1-1); %QPSK信息數(shù)據(jù) msg2=randsrc(Nsp,Nd*Nfrm,0:M2-1);%16-QAM信息數(shù)據(jù) data1=pskmod(msg1,M1,pi/4); %QPSK調(diào)制 data2=qammod(msg2,M2)/sqrt(10); %16-QAM調(diào)制并歸一化 data3=zeros(Nfft,Nd*Nfrm); %根據(jù)FFT要求，對數(shù)據(jù)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; %清除不需要的臨時變量 data3=ifft(data3); %IFFT變換 data4=ifft(data4); data3=data3(Nfft-Ncp+1:end,:);data3; %加入循環(huán)前綴 data4=data4(Nfft-Ncp+1:end,:);data4; spow1=norm(data3,fro).2/(Nsp*Nd*Nfrm); %計算數(shù)據(jù)符號能量 spow2=norm(data4,fro).2/(Nsp*Nd*Nfrm); data5=zeros(Ns,(Nd+1)*Nfrm); %加入訓(xùn)練符號 data6=data5; for indx=1:Nfrm data5(:,(indx-1)*(Nd+1)+1)=preamble1.; data5(:,(indx-1)*(Nd+1)+2:indx*(Nd+1)=data3(:,(indx-1)*Nd+1:indx*Nd); data6(:,(indx-1)*(Nd+1)+1)=preamble1.; data6(:,(indx-1)*(Nd+1)+2:indx*(Nd+1)=data4(:,(indx-1)*Nd+1:indx*Nd); end clear data3 data4; data5=reshape(data5,1,Ns*(Nd+1)*Nfrm); %并串轉(zhuǎn)換 data6=reshape(data6,1,Ns*(Nd+1)*Nfrm); sigma1=sqrt(1/2*spow1/log2(M1)*10.(-EbN0(ii)/10); %根據(jù)EbN0計算噪聲標(biāo)準(zhǔn)差 sigma2=sqrt(1/2*spow2/log2(M2)*10.(-EbN0(ii)/10); for indx=1:Nfrm dd1=data5(indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1);%當(dāng)前幀的發(fā)射數(shù)據(jù) dd2=data6(indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1); hh=h(indx-1)*Ns*(Nd+1)+1:indx*Ns*(Nd+1); %當(dāng)前幀對應(yīng)的信道參數(shù) % 信號通過單徑Rayleigh衰落信道，并加入高斯白噪聲 r1=hh.*dd1+sigma1*(randn(1,length(dd1)+j*randn(1,length(dd1); r2=hh.*dd2+sigma2*(randn(1,length(dd2)+j*randn(1,length(dd2); r1=reshape(r1,Ns,Nd+1); %串并轉(zhuǎn)換 r2=reshape(r2,Ns,Nd+1); r1=r1(Ncp+1:end,:); %移除循環(huán)前綴 r2=r2(Ncp+1:end,:); % % % % % % % % % % 理想信道估計 % % % % % % % % % % hh=reshape(hh,Ns,Nd+1); % 信道參數(shù)數(shù)據(jù)重排 hh=hh(Ncp+1:end,:); x1=r1(:,2:end)./hh(:,2:end); %信道補償 x2=r2(:,2:end)./hh(:,2:end); x1=fft(x1); %fft運算 x2=fft(x2); x1=x1(39:end,:);x1(2:27,:); %數(shù)據(jù)重排 x2=x2(39:end,:);x2(2:27,:); x1=pskdemod(x1,M1,pi/4); %數(shù)據(jù)調(diào)制 x2=qamdemod(x2*sqrt(10),M2); % 統(tǒng)計一幀中的錯誤比特數(shù) 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); % % % % % % % % % % 根據(jù)訓(xùn)練符號進行的信道估計 % % % % % % % % % % R1=fft(r1); %fft運算 R2=fft(r2); R1=R1(39:end,:);R1(2:27,:); % 數(shù)據(jù)重排 R2=R2(39:end,:);R2(2:27,:); HH1=(Preamble.)./R1(:,1); %信道估計 HH2=(Preamble.)./R2(:,1); HH1=HH1*ones(1,Nd); %根據(jù)信道估計結(jié)果進行信道補償 HH2=HH2*ones(1,Nd); x3=R1(:,2:end).*HH1; x4=R2(:,2:end).*HH2; x3=pskdemod(x3,M1,pi/4); % 數(shù)據(jù)解調(diào) x4=qamdemod(x4.*sqrt(10),M2); %統(tǒng)計一幀中的錯誤比特數(shù) 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); % 理想信道估計的誤比特率 ber2(ii)=sum(neb2)/(Nsp*log2(M2)*Nd*Nfrm); ber3(ii)=sum(neb3)/(Nsp*log2(M1)*Nd*Nfrm); % 根據(jù)訓(xùn)練符號信道估計的誤比特率 ber4(ii)=sum(neb4)/(Nsp*log2(M2)*Nd*Nfrm); endsemilogy(EbN0,ber1,-ro,EbN0,ber3,-rv,EbN0,ber2,-r*,EbN0,ber4,-rd);grid ontitle(OFDM系統(tǒng)誤比特率性能);legend(QPSK理想信道估計,QPSK訓(xùn)練符號信道估計,16-QAM理想信道估計,16QAM-訓(xùn)練符號信道估計);xlabel(信噪比(EbN0);ylabel(誤比特率);% 該程序給出了一個簡化的IEEE 802.11aOFDM系統(tǒng)的仿真，其中系統(tǒng)仿真中%