OFDM_pilot_ch_est.rar_LMMSE pilot_LMMSE插值_LS线性插值_ofdm interpolat

%% clear the workspace clear all; close all; %% Set paraments pilot_inter=6; %导频符号间隔为5 pilot_bit=[0 0 0 1]; cp_length=144; SNR_dB=0:20; OFDM_symbol_num=100; Subcarriers=2048-cp_length; %子载波个数，即FFT_Len modOrd=4; %采用16QAM调制 ls_err_ber=zeros(1,length(SNR_dB)); lmmse_err_ber=zeros(1,length(SNR_dB)); svd_mmse_err_ber=zeros(1,length(SNR_dB)); for index=1:length(SNR_dB) loop_num=10; ls_bit_num=0; lmmse_bit_num=0; svd_mmse_bit_num=0; total_bit_num=0; for l=1:loop_num %% % *****************TRANSMITTER********************************** msg=randint(modOrd*Subcarriers,OFDM_symbol_num,2); [nbit,mbit]=size(msg); total_bit_num=total_bit_num+nbit*mbit; % ===================modulation==================================== h=modem.qammod('M', 2^modOrd, 'PhaseOffset', 0, 'SymbolOrder', 'binary',... 'InputType','bit'); hdemod=modem.qamdemod(h); y_out=modulate(h,msg); % ===================insert pilot================================ [insert_pilot_out,pilot_num,pilot_sequence]=insert_pilot(pilot_inter,pilot_bit,y_out); %====================作FFTLen点逆FFT运算，完成ofdm调制============= ofdm_modulation_out=ifft(insert_pilot_out,Subcarriers); %====================insert CP==================================== ofdm_cp_out=insert_cp(ofdm_modulation_out,cp_length); %% %====================以下过程为ofdm符号通过频率选择性多径信道======== num_path=3; %假设功率延迟谱服从负指数分布~exp(-t/trms),trms=(1/4)*cp时长； %t在0~cp时长上均匀分布 %若cp时长为16e-6s，可以取5径延迟如下 delay=[0 50e-9 120e-9];% 8e-6 12e-6]; t_interval=32.55e-9; %采样间隔为1us t_cp=cp_length*t_interval; trms=t_cp/4; t_max=t_cp/t_interval; trms_a=trms/t_interval; %信道各径的平均延时，一般取为1/4CP长 var_pow=[-1 -1 -1]; fd=0;%最大doppler频率为0Hz %信道采样点数，每个调制符号采一个点 passchan_ofdm_symbol=multipath_chann(ofdm_cp_out,num_path,var_pow,delay,t_interval); %====================加高斯白噪声=================================== snr=10^(SNR_dB(index)/10); [nn,mm]=size(passchan_ofdm_symbol); signal_power=0; for i=1:nn for j=1:mm signal_power=signal_power+real(passchan_ofdm_symbol(i,j))^2+imag(passchan_ofdm_symbol(i,j))^2; end end signal_power_per=signal_power/(nn*mm); sgma=sqrt(signal_power_per/(2*snr)); receive_ofdm_symbol=add_noise(sgma,passchan_ofdm_symbol); %% %===================去循环前缀====================================== cutcp_ofdm_symbol=cut_cp(receive_ofdm_symbol,cp_length); %===================作FFT运算，ofdm信号解调========================= ofdm_de_symbol_output=fft(cutcp_ofdm_symbol,Subcarriers); %===================对信号进行信道估计============================== ls_output=ls_estimation1(ofdm_de_symbol_output,pilot_inter,pilot_sequence,pilot_num); lmmse_output=lmmse_estimation1(ofdm_de_symbol_output,pilot_inter,pilot_sequence,pilot_num,trms_a,t_max,snr); svd_mmse_output=svd_mmse_estimation1(ofdm_de_symbol_output,pilot_inter,pilot_sequence,pilot_num,trms_a,t_max,snr,cp_length); %===================demodulation=================================== ls_output_receive=demodulate(hdemod,ls_output); lmmse_output_receive=demodulate(hdemod,lmmse_output); svd_mmse_output_receive=demodulate(hdemod,svd_mmse_output); %===================count the wrong number========================= ls_err_num=error_count(msg,ls_output_receive); lmmse_err_num=error_count(msg,lmmse_output_receive); svd_mmse_err_num=error_count(msg,svd_mmse_output_receive); ls_bit_num=ls_bit_num+ls_err_num; lmmse_bit_num=lmmse_bit_num+lmmse_err_num; svd_mmse_bit_num=svd_mmse_bit_num+svd_mmse_err_num; end % 计算各SNR下错误比特的数目 ls_err_ber(index)=ls_bit_num/total_bit_num; lmmse_err_ber(index)=lmmse_bit_num/total_bit_num; svd_mmse_err_ber(index)=svd_mmse_bit_num/total_bit_num; end %% % 画图 semilogy(SNR_dB,ls_err_ber,'b-*') hold on semilogy(SNR_dB,lmmse_err_ber,'r-o') hold on semilogy(SNR_dB,svd_mmse_err_ber,'g-s') grid on