ofdm_multichal_junheng_ofdm.asv

好东西

%%%新方案，接收端先进行合并，将受到jamming影响的子载波去除

clear all
clc
format long
%本次仿真载频为2GHz，带宽1MHz，子载波数64个，cp为8
%子载波间隔为15.625kHz
%一个ofdm符号长度为64us，cp长度为8us
%系统调制级别定为QPSK
%最大doppler频率为50Hz,信道是慢变的
%多径信道为4径，功率延迟谱服从负指数分布~exp(-t/trms),trms=(1/5)*tmax＝1.2us时长，各径延迟取为delay=[0 3e-6 6e-6]
t0=clock;
cp_length=16;%cp长度为16
N_carrier=64;%OFDM子载波个数
bandwidth=1000000;%系统带宽为1MHz
t_interval=(1/bandwidth)*N_carrier/(cp_length+N_carrier);%采样间隔64/72us，加上循环前缀后，采样率增加
delta_f=bandwidth/N_carrier;%Hz
% SNR_dB=[0 4 8 12 16 20 24 28 32 35];%Eb/N0
% SJR_dB=[-10 -5 -3 0 3 5 10 15 20 25];%符号信干比
SNR_dB=[2 4 6 8 10];
%SNR_dB=[10];
% Pe=1e-3;
% groupnumber1=[4 16 32];
% ber_snr_persjr_ofdm=zeros(length(groupnumber1),length(SNR_dB)); 
% ber_snr_reallocatpow=zeros(length(groupnumber1),length(SNR_dB)); 
% for kk=1:length(groupnumber1)
%     groupsize=N_carrier/groupnumber1(kk);
%     groupnumber=groupnumber1(kk);
    for i=1:length(SNR_dB)%每个SNR点上仿真若干次
    snr=10^(SNR_dB(i)/10);
    error_bit_ofdm=0;
    error_bit_ofdm1=0;
    total_bit_num=0;%发送总比特数统计
%     error_bit_ofdm1=0;%for 二次功率分配
%     total_bit_num1=0;%for 二次功率分配
    loop_num=10; %共仿真1000次

     for l=1:loop_num
    ofdm_symbol_num=12;%每次仿真产生10个ofdm符号,则每次仿真共有200×64个星座映射符号；QPSK调制下，1个星座映射符号包含2个bit
    map_flag=4;
    bit_source=rand(map_flag*N_carrier,ofdm_symbol_num)>0.5;
    [m,n]=size(bit_source);
    total_bit_num=total_bit_num+m*n;
    map_out=map_module(bit_source,map_flag);      
            
   ofdm_modulation_out=sqrt(N_carrier)*ifft(map_out,N_carrier);%作64点逆FFT运算，完成ofdm调制,前面乘系数sqtr(64)是为了保持ifft前后的符号能量不变
   
      ofdm_cp_out=insert_cp(ofdm_modulation_out,cp_length);%插入循环前缀 
      %%%%%%%%以下计算噪声方差%%%%%%%%%%
            [nn,mm]=size(ofdm_cp_out);
            spow2=0;
            for k=1:nn
                for b=1:mm
                    spow2=spow2+real(ofdm_cp_out(k,b))^2+imag(ofdm_cp_out(k,b))^2;
                end
            end
            spow1=spow2/(nn*mm);%信号平均能量
            
%             map_flag=sum(bit_num_ofdmsig)/(N_carrier*ofdm_symbol_num);
           sgma=sqrt(spow1/(2*snr)/map_flag);
        %%%%信道参数%%%%%%
%         num=1;
%         delay=[0];
%         trms=1.5e-6;
%         var_pow=10*log10(exp(-delay/trms));
%         
    num=6;

    delay=[0 1e-6 2e-6 3e-6 4e-6 6e-6];
    trms=1.5e-6;
    var_pow=10*log10(exp(-delay/trms));%各径功率衰减,以dB形式给出
    fd=50;%最大doppler频率为50Hz
    %t_interval=0.8889e-6;%采样间隔64/72us，加上循环前缀后，采样率增加
    counter=10000;%200000000;%各径信道的采样点间隔，应该大于信道采样点数。由以上条件现在信道采样点数
    count_begin=(l-1+100000000)*5*counter;%每次仿真信道采样的开始位置
    %%%%%%以上为信道参数%%%%%%
    [passchan_ofdm_symbol,Hk]=multipath_chann(ofdm_cp_out,num,var_pow,delay,fd,t_interval,counter,count_begin,cp_length);
            
    sig_temp=cut_cp(passchan_ofdm_symbol,cp_length);
    ofdm_demodulation_out1=fft(sig_temp,N_carrier)/sqrt(N_carrier);
    HHk=ofdm_demodulation_out1./map_out;
    HHk1=HHk./abs(HHk);
    
    passnoise_ofdm_symbol=add_noise(sgma,passchan_ofdm_symbol);%加入随机高斯白噪声，receive_ofdm_symbol为最终接收机收到的ofdm符号块
  
     
    cutcp_ofdm_symbol=cut_cp(passnoise_ofdm_symbol,cp_length);%去除循环前缀
    
    ofdm_demodulation_out=fft(cutcp_ofdm_symbol,N_carrier)/sqrt(N_carrier);%作128点FFT运算，完成ofdm解调
   %receive_ofdm_symbol=ofdm_demodulation_out;
    receive_ofdm_symbol=ofdm_demodulation_out./HHk;
    receive_ofdm_symbol1=ofdm_demodulation_out./HHk1;
 
    receive_bit_sig=de_map_module(receive_ofdm_symbol,map_flag);
    receive_bit_sig1=de_map_module(receive_ofdm_symbol1,map_flag);
    %以下过程统计接收信号中的错误比特数
           [mn,nn]=size(bit_source);
           err_num=sum(sum(rem(bit_source+receive_bit_sig,2)));
           error_bit_ofdm=error_bit_ofdm+err_num;
           err_num1=sum(sum(rem(bit_source+receive_bit_sig,2)));
           error_bit_ofdm=error_bit_ofdm+err_num;
 %%%%%%%%%以上为不做二次功率分配，原参考文献方法%%%%%%%%%%%%         
           
           
           
           
           
           

end%for l=1:loop_num

ber_snr_persjr_ofdm(i)=error_bit_ofdm/total_bit_num;
%ber_snr_reallocatpow(kk,i)=error_bit_ofdm1/total_bit_num1;
% fre_eff_persnr(kk,i)=total_bit_num/(loop_num*ofdm_symbol_num*(1/bandwidth)*N_carrier)/bandwidth;
% fre_eff_persnr_reallocatpow(kk,i)=total_bit_num1/(loop_num*ofdm_symbol_num*(1/bandwidth)*N_carrier)/bandwidth;

save bitalloc_data ber_snr_persjr_ofdm 
end%for i=1:length(SNR_dB)

% end %for kk
elapse_time=etime(clock,t0);
% figure(1)
% % semilogy(SNR_dB_theo,ber_theo(1,:),'b')
% % hold on
semilogy(SNR_dB,ber_snr_persjr_ofdm(1,:),'b-*')
grid on
% semilogy(SNR_dB,ber_snr_persjr_ofdm(2,:)/2,'g-o')
% semilogy(SNR_dB,ber_snr_persjr_ofdm(3,:)/6,'m-+')
% hold off
% xlabel('SNR(dB)');
% ylabel('仿真结果，实际Pe=1e-3');
% 
% figure(2)
% plot(SNR_dB,fre_eff_persnr(1,:),'r-*'),hold on
% % plot(SNR_dB,fre_eff_persnr(1,:),'r-*',SNR_dB,fre_eff_persnr(2,:),'g-o',SNR_dB,fre_eff_persnr(3,:),'m-+')
% plot(SNR_dB,fre_eff_persnr(2,:),'g-o')
% plot(SNR_dB,fre_eff_persnr(3,:),'m-')
% xlabel('SNR(dB)');
% ylabel('Spectral Efficiency(bps/Hz)');
% hold off