OFDM.zip_OFDM信号_OFDM载波_QAM信号_ofdm子载波_qam-ofdm

clear all; close all; carrier_count=4;%子载波数 symbols_per_carrier=2;%每子载波含符号数 bits_per_symbol=4;%每符号含比特数,16QAM调制 IFFT_bin_length=512;%FFT点数 PrefixRatio=0;%保护间隔与OFDM数据的比例 1/6~1/4 GI=PrefixRatio*IFFT_bin_length ;%每一个OFDM符号添加的循环前缀长度为1/4*IFFT_bin_length 即保护间隔长度为128 beta=1/512;%窗函数滚降系数 GIP=beta*(IFFT_bin_length+GI);%循环后缀的长度20 SNR=15; %信噪比dB %================================================== %================信号产生=================================== baseband_out_length = carrier_count * symbols_per_carrier * bits_per_symbol;%所输入的比特数目 carriers = (1:carrier_count) + (floor(IFFT_bin_length/4) - floor(carrier_count/2));%共轭对称子载波映射 复数数据对应的IFFT点坐标 conjugate_carriers = IFFT_bin_length - carriers + 2;%共轭对称子载波映射 共轭复数对应的IFFT点坐标 baseband_out=round(rand(1,baseband_out_length));%输出待调制的二进制比特流 %==============16QAM调制==================================== complex_carrier_matrix=qam16(baseband_out);%列向量 complex_carrier_matrix=reshape(complex_carrier_matrix',carrier_count,symbols_per_carrier)';%symbols_per_carrier*carrier_count 矩阵 figure(1); plot(complex_carrier_matrix,'*r');%16QAM调制后星座图 title('16QAM调制后星座图') axis([-4, 4, -4, 4]); grid on %=================IFFT=========================== IFFT_modulation=zeros(symbols_per_carrier,IFFT_bin_length);%添0组成IFFT_bin_length IFFT 运算 IFFT_modulation(:,carriers ) = complex_carrier_matrix ;%未添加导频信号 ，子载波映射在此处 IFFT_modulation(:,conjugate_carriers ) = conj(complex_carrier_matrix);%共轭复数映射 %================================================================= signal_after_IFFT=ifft(IFFT_modulation,IFFT_bin_length,2);%OFDM调制 即IFFT变换 time_wave_matrix =signal_after_IFFT;%时域波形矩阵，行为每载波所含符号数，列ITTF点数，N个子载波映射在其内，每一行即为一个OFDM符号 %=========================================================== %=====================添加循环前缀与后缀==================================== XX=zeros(symbols_per_carrier,IFFT_bin_length+GI+GIP); for k=1:symbols_per_carrier; for i=1:IFFT_bin_length; XX(k,i+GI)=signal_after_IFFT(k,i); end for i=1:GI; XX(k,i)=signal_after_IFFT(k,i+IFFT_bin_length-GI);%添加循环前缀 end for j=1:GIP; XX(k,IFFT_bin_length+GI+j)=signal_after_IFFT(k,j);%添加循环后缀 end end time_wave_matrix_cp=XX;%添加了循环前缀与后缀的时域信号矩阵,此时一个OFDM符号长度为IFFT_bin_length+GI+GIP=660 %==============OFDM符号加窗========================================== windowed_time_wave_matrix_cp=zeros(1,IFFT_bin_length+GI+GIP); for i = 1:symbols_per_carrier windowed_time_wave_matrix_cp(i,:) = real(time_wave_matrix_cp(i,:)).*rcoswindow(beta,IFFT_bin_length+GI)';%加窗 升余弦窗 end %========================生成发送信号，并串变换================================================== windowed_Tx_data=zeros(1,symbols_per_carrier*(IFFT_bin_length+GI)+GIP); windowed_Tx_data(1:IFFT_bin_length+GI+GIP)=windowed_time_wave_matrix_cp(1,:); for i = 1:symbols_per_carrier-1 ; windowed_Tx_data((IFFT_bin_length+GI)*i+1:(IFFT_bin_length+GI)*(i+1)+GIP)=windowed_time_wave_matrix_cp(i+1,:);%并串转换，循环后缀与循环前缀相叠加 end %======================================================= Tx_data=reshape(windowed_time_wave_matrix_cp',(symbols_per_carrier)*(IFFT_bin_length+GI+GIP),1)';%加窗后 循环前缀与后缀不叠加 的串行信号 %================================================================= temp_time1 = (symbols_per_carrier)*(IFFT_bin_length+GI+GIP);%加窗后 循环前缀与后缀不叠加 发送总位数 figure (2) subplot(2,1,1); plot(0:temp_time1-1,Tx_data );%循环前缀与后缀不叠加 发送的信号波形 grid on ylabel('Amplitude (volts)') xlabel('Time (samples)') title('循环前后缀不叠加的OFDM Time Signal') temp_time2 =symbols_per_carrier*(IFFT_bin_length+GI)+GIP; subplot(2,1,2); plot(0:temp_time2-1,windowed_Tx_data);%循环后缀与循环前缀相叠加 发送信号波形 grid on ylabel('Amplitude (volts)') xlabel('Time (samples)') title('循环前后缀叠加的OFDM Time Signal') %===============加窗的发送信号频谱================================= symbols_per_average = ceil(symbols_per_carrier/5);%符号数的1/5，10行 avg_temp_time = (IFFT_bin_length+GI+GIP)*symbols_per_average;%点数，10行数据，10个符号 averages = floor(temp_time1/avg_temp_time); average_fft(1:avg_temp_time) = 0;%分成5段 for a = 0:(averages-1) subset_ofdm = Tx_data(((a*avg_temp_time)+1):((a+1)*avg_temp_time));%利用循环前缀后缀未叠加的串行加窗信号计算频谱 subset_ofdm_f = abs(fft(subset_ofdm));%分段求频谱 average_fft = average_fft + (subset_ofdm_f/averages);%总共的数据分为5段，分段进行FFT，平均相加 end average_fft_log = 20*log10(average_fft); figure (3) subplot(2,1,2) plot((0:(avg_temp_time-1))/avg_temp_time, average_fft_log)%归一化 0/avg_temp_time : (avg_temp_time-1)/avg_temp_time hold on plot(0:1/IFFT_bin_length:1, -35, 'rd') grid on axis([0 0.5 -40 max(average_fft_log)]) ylabel('Magnitude (dB)') xlabel('Normalized Frequency (0.5 = fs/2)') title('加窗的发送信号频谱') %====================添加噪声================================= Tx_signal_power = var(windowed_Tx_data);%发送信号功率 linear_SNR=10^(SNR/10);%线性信噪比 noise_sigma=Tx_signal_power/linear_SNR; noise_scale_factor = sqrt(noise_sigma);%标准差sigma noise=randn(1,((symbols_per_carrier)*(IFFT_bin_length+GI))+GIP)*noise_scale_factor;%产生正态分布噪声序列 Rx_data=windowed_Tx_data +noise;%接收到的信号加噪声 N1=length(Rx_data); M=15; L=N1; tx=1:1:N1; signal_r=Rx_data; signal_reconstruct=zeros(1,L); signal_reconstruct01=zeros(M,L); atomic01=zeros(M,L); yabs01=zeros(M,1); gabor01=zeros(M,L); yabs01=zeros(M,1); for ii=1:M ii proj=0; dic=0; a_base=2; j_min=1; j_max=ceil(log2(N1)); u_base=1/2; p_min=0; v_base=pi; k_min=0; w_base=pi/6; i_min=0; i_max=12; %signal_original=signal_original;((j_max)/5) proj_trans=0; proj=0; size_dic=0; for k1=1:1:10; s=N1/(1*k1); for k2=1:k1; for k3=0.2:(1/(s)):2 % for k4=i_min:i_max size_dic=size_dic+1; % s=N1/(1*k1); u=s.*(k2-1/2); v=v_base*k3*2; % w=w_base*k4; % t=1:N; % t=((t-u)/s); % g1=(1/sqrt(s))*exp(-pi*((tx-u)/s).*((tx-u)/s)).*cos(v*tx); % g1=g1./sqrt(sum(g1.*g1)); % g2=(1/sqrt(s))*exp(-pi*((tx-u)/s).*((tx-u)/s)).*sin(v*tx); % g2=g2./sqrt(sum(g2.*g2)); %window=0*((u-s/2)>tx)+1*(((u-s/2)<tx<(u+s/2)))+0*(tx>(u+s/2)); window=rectpuls((tx-u),s); g1=window.*cos(v*tx); g1=g1./sqrt(sum(g1.*g1)); g2=window.*sin(v*tx); g2=g2./sqrt(sum(g2.*g2)); proj_trans1=sum(signal_r.*g1); proj_trans2=sum(signal_r.*g2); proj_trans=sqrt(proj_trans1.*proj_trans1+proj_trans2.*proj_trans2); if abs(proj_trans)>abs(proj) proj=proj_trans; scale=s; translation=u; freq=v; phase=atan(-1*proj_trans2/proj_trans1); %end end end end end %window=0*((u-s/2)>tx)+1*(((u-s/2)<tx<(u+s/2)))+0*(tx>(u+s/2)); window=rectpuls((tx-translation),scale); g=window.*cos(freq*tx+phase); g=g/sqrt(sum(g.*g)); proj_3=sum(signal_r.*g); yabs01(ii)=(proj_3);%保存系数 yabs02(ii)=(freq);%保存系数 yabs03(ii)=(scale);%保存系数 yabs04(ii)=(translation);%保存系数 yabs05(ii)=(phase);%保存系数 signal_reconstruct=signal_reconstruct+proj_3.*g; signal_r=signal_r-proj_3.*g; gabor=proj_3.*g; signal_reconstruct01(ii,:)=signal_reconstruct; gabor01(ii,:)=g