OFDM无线大作业.zip

clc clear %q1:ifft点数难道不是应该等于子载波数吗？子载波数与ifft点数的关系？ %a:ifft点数等于子载波数 %q2：对矩阵进行fft？ %a:y可以是一向量或矩阵，若y为向量，则Y是y的FFT，并且与y具有相同的长度。若y为一矩阵，则Y是对矩阵的每一列向量进行FFT。 %image_data_generator(); %数据子载波数128 %fft点数512 snr = 0:1:20%dB 高斯信道的SNR cdata_number = 128; fft_n = 128; %OFDM码元个数 500 %生成数据随机序列 cdata_length = 500; cdata = rand_bit(cdata_number*cdata_length*2); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(cdata(1,1:200),"信源序列时域图",'B'); subplot(2,1,2); frequency_response(cdata(1,1:200),"信源序列频谱图",'B'); %-------------------------------------------------------------------------- %导频长度256 %插入导频间隔为5 %生成随机的的导频序列 pilot_inter = 5; pilot_length = 256; pilot_bit = rand_bit(pilot_length); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(pilot_bit(1,1:200),"导频序列时域图",'B'); subplot(2,1,2); frequency_response(pilot_bit(1,1:200),"导频序列频谱图",'B'); %-------------------------------------------------------------------------- %进行qpsk调制 输出复数矩阵 qpsk_bit = modulator_QPSK(cdata); scatterplot(qpsk_bit); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(qpsk_bit(1:100)),"信源序列QPSK",'B'); hold on; time(imag(qpsk_bit(1:100)),"信源序列QPSK",'R'); subplot(2,1,2); frequency_response(qpsk_bit(1:100),"信源序列QPSK频谱图",'B'); %-------------------------------------------------------------------------- %串并转换 128*1000 paradata = reshape(qpsk_bit,cdata_number,cdata_length); %-------------------------------------------------------------------------- %插入导频 inserted_bit = insert_pilot(paradata,pilot_bit,pilot_inter); %-------------------------------------------------------------------------- %逆傅里叶变换 ifft_data = ifft(inserted_bit,fft_n,1)*sqrt(fft_n); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(ifft_data(1:100)),"逆傅里叶变换时域图",'B'); hold on; time(imag(ifft_data(1:100)),"逆傅里叶变换时域图",'R'); subplot(2,1,2); frequency_response(ifft_data(1:100),"逆傅里叶变换频域图",'B'); %-------------------------------------------------------------------------- %生成OFDM频谱图 figure; for i = 1:600 hold on; frequency_response_deshift(inserted_bit(:,i)',"OFDM频域图",'B'); end %-------------------------------------------------------------------------- %插入循环前缀 symbol_cp_pro = cyclic_prefix(ifft_data); %-------------------------------------------------------------------------- [row,column] = size(symbol_cp_pro); %-------------------------------------------------------------------------- %经过高斯信道 awgn_err_plot(cdata,symbol_cp_pro); %-------------------------------------------------------------------------- %ls多径信道 ERR1 = ls_err_plot(cdata,symbol_cp_pro,pilot_bit); %-------------------------------------------------------------------------- %并串转换 symbol_cp = reshape(symbol_cp_pro,1,[]); %-------------------------------------------------------------------------- figure; time(real(symbol_cp(1:160)),"加入CP时域图",'B'); hold on; time(imag(symbol_cp(1:160)),"加入CP时域图",'R'); %-------------------------------------------------------------------------- %信道 %ts采样间隔 %fdDoppler频偏，HZ %tau多径延时 %pdb各径功率 %---------------------------------------------多径信道--------------------- fs = 15000; ts = 1/fs; fd = 0; tau = [0,50,120,200,230,500,1600,2300,5000]/(10^9); pdb = [-1.0,-1.0,-1.0,0,0,0,-3.0,-5.0,-7.0]; chan = rayleighchan(ts,fd,tau,pdb); chan.ResetBeforeFiltering = 0; chan_symbol_s = filter(chan,symbol_cp); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(chan_symbol_s(1:100)),"过多经信道时域图",'B'); hold on; time(imag(chan_symbol_s(1:100)),"过多经信道时域图",'R'); subplot(2,1,2); frequency_response(chan_symbol_s(1:100),"过多经信道频谱图",'B'); %--------------------------------------------多径信道----------------------- %------------------------------------------叠加高斯信道--------------------- SNR = 20;%单位dB chan_symbol_s = awgn(chan_symbol_s,SNR); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(chan_symbol_s(1:100)),"过多经信道叠加高斯信道时域图",'B'); hold on; time(imag(chan_symbol_s(1:100)),"过多经信道叠加高斯信道时域图",'R'); subplot(2,1,2); frequency_response(chan_symbol_s(1:100),"过多经信道叠加高斯信道频谱图",'B'); %-------------------------------------------------------------------------- figure; for i=1:100 plot(chan_symbol_s(i),'b*'); title('QPSK调制经过高斯信道后的信号星座图'); xlabel('I(t)'); ylabel('Q(t)'); hold on; end %-------------------------------------------------------------------------- %串并转换 chan_symbol_p = reshape(chan_symbol_s,row,length(chan_symbol_s)/row); %-------------------------------------------------------------------------- %去循环码 re_symbol_cp = re_cyclic_prefix(chan_symbol_p); %-------------------------------------------------------------------------- %fft fft_symbol = fft(re_symbol_cp,fft_n,1)./sqrt(fft_n); %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(fft_symbol(:,1)'),"傅里叶变换时域图",'B'); hold on; time(imag(fft_symbol(:,1)'),"傅里叶变换时域图",'R'); subplot(2,1,2); frequency_response(fft_symbol(:,1)',"傅里叶变换频谱图",'B'); %-------------------------------------------------------------------------- %去除导频 [output,pilot_symbol] = re_insert_pilot(fft_symbol,pilot_inter); % %----------------导频位置信道响应LS估计----------------------------------- pilot_qpsk = modulator_QPSK(pilot_bit); pilot_patt=repmat(pilot_qpsk',1,100); pilot_esti=pilot_symbol./pilot_patt; % Y = H*X + S [r,c] = size(output); h = zeros(r,c); for i = 1:100 h(:,(1+(i-1)*5):i*5) = repmat(pilot_esti(:,i),1,pilot_inter); end output = output./h; %-------------------------------------------------------------------------- figure; subplot(2,1,1); time(real(output(1:100)),"接收序列QPSK",'B'); hold on; time(imag(output(1:100)),"接收序列QPSK",'R'); subplot(2,1,2); frequency_response(output(1:100),"接收序列QPSK频谱图",'B'); %-------------------------------------------------------------------------- figure; for i=1:100 plot(output(i),'b*'); title('经过信道均衡后的信号星座图'); xlabel('I(t)'); ylabel('Q(t)'); hold on; end %-------------------------------------------------------------------------- %并串转换 output = reshape(output,1,[]); re_modulated =re_modulatorQPSK(output); figure; subplot(2,1,1); time(re_modulated(1,1:200),"接收端序列时域图",'B'); subplot(2,1,2); frequency_response(re_modulated(1,1:200),"接收端序列频谱图",'B'); %-------------------------------------------------------------------------- % err = 0; % for n = 1:length(cdata) % if cdata(n) ~= re_modulated(n) % err = err + 1; % end % end % err = err/length(cdata); % n = 1:20; % ERR = repmat(err,1,20); % figure; % semilogy(n,ERR,'-*b') % legend('OFDM仿真误码率') % xlabel('符号信噪比 (dB)'); % ylabel('误符号率/误比特率'); %输入随机序列 function sr = rand_bit(L) sr = round(rand(1,L)); end %输入信号进行QPSK调制 function pilot_modulated = modulator_QPSK(pilot) length_pilot = length(pilot); ip = zeros(1,floor(length_pilot/2)); for ii = 1:floor(length_pilot/2) ip(ii) = 1/sqrt(2)*1i*(2*pilot(2*ii) - 1) + 1/sqrt(2)*(2*pilot(1 + 2*(ii - 1)) - 1); end pilot_modulated = ip; end %QPSK解调 function output =re_modulatorQPSK(input)%序列 length_input = length(input); output = zeros(1,2*length_input); for ii = 1:length_input