matlab_MIMO多天线系统2*2、3*3、4*4的仿真，有信道容量计算

%STBC_MIMO_OFDM.m %这是一个基于空时分组编码的MIMO_OFDM通信系统的仿真设计。 %此系统包括QPSK调制解调，IFFT调制，空时编解码，基于训 %练符号的信道估计等通信模块。 clear all close all clc %+++++++++++++++++++++++++++变量++++++++++++++++++++++++++++++ i=sqrt(-1); IFFT_bin_length=512; %傅立叶变换抽样点数目 carrier_count=100; %子载波数目 symbols_per_carrier=66; %符号数/载波 cp_length=10; %循环前缀长度 addprefix_length=IFFT_bin_length+cp_length; M_psk=4; bits_per_symbol=log2(M_psk); %位数/符号 %[x1 x2;-x2* x1*] 二天线发送矩阵 O=[1 2;-2+j 1+j]; %[x1 -x2 -x3;x2* x1* 0;x3* 0 x1*;0 -x3* x2*] 三天线发送矩阵 %O=[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); %发射天线数目 Nr=2; %接收天线数目 %+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ %+++++++++++++++++++++++++++发射机++++++++++++++++++++++++++++++ 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 %用于确定矩阵“O”中元素的位置，符号以及共轭情况 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.'; % 坐标： (1 to 100) + 14=(15:114) carriers = (1: carrier_count) + (floor(IFFT_bin_length/4) - floor(carrier_count/2)); % 坐标 ：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=2; %最小信噪比 snr_max=13; %最大信噪比 graph_inf_bit=zeros(snr_max-snr_min+1,2,Nr); %绘图信息存储矩阵 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); %生成随机数用于仿真 baseband_out=round(rand(baseband_out_length,bits_per_symbol)); %二进制向十进制转换 de_data=bi2de(baseband_out); %PSK调制 data_buf=pskmod(de_data,M_psk,0); carrier_matrix=reshape(data_buf,carrier_count,symbols_per_carrier); %取数为空时编码做准备，此处每次取每个子载波上连续的两个数 for 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 %进行空时编码 for 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))); end end end end %空时编码结束 XX=[tx_training_symbols;XX]; %添加训练序列 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(:)'; %+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ %+++++++++++++++++++++++++++信道++++++++++++++++++++++++++++++ %d=randint(1,4,[1,7]); %4多经信道模拟 %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'); %添加高斯白噪声 rx_buf(1,:,rev)=rx_buf(1,:,rev)+txch; end %+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ %+++++++++++++++++++++++++++接收机++++++++++++++++++++++++++++++ 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 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 H_buf=conj(H_buf'); RRR=[]; for kk=1:carrier_count Y=Y_buf(:,kk); H=H_buf(:,kk); for co_ii=1:num_X for co_tt=1:size(eta,2) if eta(co_ii,co_tt)~=0 if coj_mt(eta(co_ii,co_tt),co_ii)==0 r_til(eta(co_ii,co_tt),:,co_ii)=Y(eta(co_ii,co_tt),:); a_til(eta(co_ii,co_tt),:,co_ii)=conj(H(epsilon(eta(co_ii,co_tt),co_ii),:)); else r_til(eta(co_ii,co_tt),:,co_ii)=conj(Y(eta(co_ii,co_tt),:)); a_til(eta(co_ii,co_tt),:,co_ii)=H(epsilon(eta(co_ii,co_tt),co_ii),:); end end end end RR=zeros(num_X,1); for iii=1:num_X %接收数据的判决统计 for ttt=1:size(eta,2) if eta(iii,ttt)~=0 RR(iii,1)=RR(iii,1)+r_til(eta(iii,ttt),1,iii)*a_til(eta(iii,ttt),1,iii)*delta(eta(iii,ttt