Simulation of MIMO_OFDM Communication System Based on MATLAB Space-time block Coding

%main_STBC_MIMO_OFDM. M % This is a simulation design of MIMO_OFDM communication system based on space-time block coding. This system includes QPSK modulation and demodulation, IFFT modulation, space-time codec, channel estimation based on training symbol and other communication modules. Clear all the close all CLC % + + + + + + + + + + + + + + + + + + + + + + + + + + + a variable + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + I =sqrt(- 1); 
IFFT_bin_length=512; % Number of Fourier transform sampling points carrier_count=100; % Number of subcarriers symbols_per_carrier=66; % Symbol number/carrier CP_length =10; % Loop prefix length addPrefix_length =IFFT_bin_length+cp_length; M_psk=4; bits_per_symbol=log2(M_psk); % digit/symbol %[x1 x2;-x2* x1*]1 2;2 -+j 1+j];   
%[x1 -x2 -x3;x2* x1* 0; x3*0 x1*;0-x3* x2*]1 2 - - 3;2+j 1+j 0;3+j 0 1+j;0 - 3+j 2+j];   
co_time=size(O,1);                                                                   
Nt=size(O,2); % Number of transmitting antennas Nr=2; % % receiving antenna number + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + % + + + + + + + + + + + + + + + + + + + + + + + + + + + transmitter + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + disp ('--------------start-------------------');
num_X=1; 
for cc_ro=1:co_time 
    for cc_co=1:Nt 
        num_X=max(num_X,abs(real(O(cc_ro,cc_co)))); 
    end 
end 
 
co_x=zeros(num_X,1); 
 
for con_ro=1:co_time    
    for con_co=1:Nt % is used to determine the positions, symbols, and conjugation of elements in the matrix "O"if abs(real(O(con_ro,con_co)))~=0 
            delta(con_ro,abs(real(O(con_ro,con_co))))=sign(real(O(con_ro,con_co)));  
            epsilon(con_ro,abs(real(O(con_ro,con_co))))=con_co; 
            co_x(abs(real(O(con_ro,con_co))),1)=co_x(abs(real(O(con_ro,con_co))),1) +1; 
            eta(abs(real(O(con_ro,con_co))),co_x(abs(real(O(con_ro,con_co))),1))=con_ro; 
            coj_mt(con_ro,abs(real(O(con_ro,con_co))))=imag(O(con_ro,con_co)); 
        end 
    end 
end 
 
eta=eta. ';                                                                            
eta=sort(eta); 
eta=eta. '; % coordinates: (1 to 100) + 14= (15:114)
carriers = (1: carrier_count) + (floor(IFFT_bin_length/4) - floor(carrier_count/2)); % coordinates:256 - (15:114) + 1= 257 - (15:114) = (242:143) 
conjugate_carriers=IFFT_bin_length-carriers+2;                                          
tx_training_symbols=training_symbol(Nt,carrier_count); 
baseband_out_length = carrier_count * symbols_per_carrier; 
 
snr_min=3; % Minimum SNR snR_max =15; % Maximum SNR graph_inf_bit=zeros(SNr_max-snr_min +1.2,Nr); % Graph_inf_SYm =zeros(SNr_max-SNr_min +1.2,Nr);  
 
for SNR=snr_min:snr_max                      
  clc 
  disp('Wait until SNR='); disp(snr_max); SNR n_err_sym=zeros(1,Nr); 
  n_err_bit=zeros(1,Nr); 
  Perr_sym=zeros(1,Nr); 
  Perr_bit=zeros(1,Nr); re_met_sym_buf=zeros(carrier_count,symbols_per_carrier,Nr); re_met_bit=zeros(baseband_out_length,bits_per_symbol,Nr); % Generate random number for simulation baseband_out=round(rand(baseband_out_length,bits_per_symbol)); % Binary to decimal conversion de_data=bi2de(baseband_out); PSK modulation data_buf % = pskmod (de_data M_psk,0); carrier_matrix=reshape(data_buf,carrier_count,symbols_per_carrier); % to prepare for null - time coding, where two consecutive numbers on each subcarrier are taken at a timefor tt=1:Nt:symbols_per_carrier                              
     data=[]; 
     for ii=1:Nt 
     tx_buf_buf=carrier_matrix(:,tt+ii- 1); 
     data=[data;tx_buf_buf]; 
     end 
     
     XX=zeros(co_time*carrier_count,Nt); 
     for con_r=1:co_time % space - time encodingfor con_c=1:Nt 
           if abs(real(O(con_r,con_c)))~=0 
             if imag(O(con_r,con_c))==0 
                XX((con_r- 1)*carrier_count+1:con_r*carrier_count,con_c)=data((abs(real(O(con_r,con_c)))- 1)*carrier_count+1:abs(real(O(con_r,con_c)))... 
                *carrier_count,1)*sign(real(O(con_r,con_c))); 
             else 
                XX((con_r- 1)*carrier_count+1:con_r*carrier_count,con_c)=conj(data((abs(real(O(con_r,con_c)))- 1)*carrier_count+1:abs(real(O(con_r,con_c)))... 
                *carrier_count,1))*sign(real(O(con_r,con_c))); XX=[tx_training_symbols;XX]; % add training sequence rx_buf=zeros(1,addprefix_length*(co_time+1),Nr); 
    for rev=1:Nr 
       for ii=1:Nt 
         tx_buf=reshape(XX(:,ii),carrier_count,co_time+1); 
         IFFT_tx_buf=zeros(IFFT_bin_length,co_time+1); 
         IFFT_tx_buf(carriers,:)=tx_buf(1:carrier_count,:); 
         IFFT_tx_buf(conjugate_carriers,:)=conj(tx_buf(1:carrier_count,:)); 
         time_matrix=ifft(IFFT_tx_buf); 
         time_matrix=[time_matrix((IFFT_bin_length-cp_length+1):IFFT_bin_length,:); time_matrix]; tx=time_matrix(:)'; % + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + % + + + + + + + + + + + + + + + + + + + + + + + + + + + channel + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + % d = randint (1, 4, [1, 7]); %4 multichannel analog %a=randint(1,4,[2,7])/10; tx_tmp=tx; D = [4,5,6,2; 4,5,6,2; 4,5,6,2; 4,5,6,2]; A = [0.2, 0.3, 0.4, 0.5, 0.2, 0.3, 0.4, 0.5, 0.2, 0.3, 0.4, 0.5, 0.2, 0.3, 0.4, 0.5]. for jj=1:size(d,2) copy=zeros(size(tx)) ; for kk = 1 + d(ii,jj): length(tx) copy(kk) = a(ii,jj)*tx(kk - d(ii,jj)) ; end tx_tmp=tx_tmp+copy; end txch=awgn(tx_tmp,SNR,'measured'); % Add gaussian white noise rx_buf(1,:,rev)=rx_buf(1,:,rev)+txch; end %+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ % + + + + + + + + + + + + + + + + + + + + + + + + + + + receiver + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + rx_spectrum = reshape (rx_buf (1,:,rev),addprefix_length,co_time+1); 
    rx_spectrum=rx_spectrum(cp_length+1:addprefix_length,:); 
    FFT_tx_buf=zeros(IFFT_bin_length,co_time+1); 
    FFT_tx_buf=fft(rx_spectrum); 
    spectrum_matrix=FFT_tx_buf(carriers,:); 
    Y_buf=(spectrum_matrix(:,2:co_time+1)); 
    Y_buf=conj(Y_buf'); 
  
    spectrum_matrix1=spectrum_matrix(:,1); 
    Wk=exp((2 -*pi/carrier_count)*i); 
    L=10; 
     
    p=zeros(L*Nt,1); 
    for jj=1:Nt 
         for l=0:L- 1 
             for kk=0:carrier_count- 1 
                  p(l+(jj- 1)*L+1.1)=p(l+(jj- 1)*L+1.1)+spectrum_matrix1(kk+1.1)*conj(tx_training_symbols(kk+1,jj))*Wk^(-(kk*l)); 
             end  
         end 
     end 
                      
     %q=zeros(L*Nt,L*Nt);             
     %for ii=1:Nt                        
     %   for jj=1:Nt 
     %      for l1=0:L- 1 
     %          for l2=0:L- 1 
     %             for kk=0:carrier_count- 1 
     %             q(l2+(ii- 1)*L+1,l1+(jj- 1)*L+1)= q(l2+(ii- 1)*L+1,l1+(jj- 1)*L+1)+tx_training_symbols(kk+1,ii)*conj(tx_training_symbols(kk+1,jj))*Wk^(-(kk*(-l1+l2))); 
     %             end  
     %         end 
     %      end 
     %   end 
     %end 
         
    %h=inv(q)*p; 
    h=p/carrier_count; 
     
    H_buf=zeros(carrier_count,Nt); 
    for ii=1:Nt 
       for kk=0:carrier_count- 1 
          for l=0:L- 1 
             H_buf(kk+1,ii)=H_buf(kk+1,ii)+h(l+(ii- 1)*L+1.1)*Wk^(kk*l); 
          end  
       end 
    end 
Copy the code

Version: 2014 a