stbc_sm_Alamouti_sm_

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Alamouti code STBC-SM % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % Script for computing the BER for M-QAM modulation in a % Rayleigh fading channel with Alamouti Space Time Block Coding spatial modulation % 4 transmit antenna, 4 Receive antenna % %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% clc clear all Nt=4; Nr=4; M=4; E=1; k_QAM=sqrt(E)*sqrt(2); k_b=log2(M); % 信号位数 small=0.7; big=sqrt(2-small^2); angle1=pi/8; Nt1=(Nt*(Nt-1)/2); ss=0; while(2^ss<Nt1) ss=ss+1; end ss=ss-1; %ss为天线对选择位数 ss:total number of STBC-SM codewords sss=2^ss; no=k_b*2+ss; %总数 N =1000; % number of bits or symbols Es_N0_dB = 0:2:13; % multiple different Eb/N0 values BER = zeros(1,length(Es_N0_dB)); bit_errors = zeros(1,length(Es_N0_dB)); sq=sqrt(-1); %虚数单位i %% 以下为核心代码 %% for ii = 1:length(Es_N0_dB) for aa=1:N %% transmitter %% active_antenna = round(rand(1,ss)); %选择被激活天线，激活的用1表示 ip1 = round(rand(1,k_b)); %等概率生成0和1 ip2 = round(rand(1,k_b)); ip3 = round(rand(1,k_b)); bin_ip=[ip1;ip2]; %调制符号对信息 bin_ip1=[active_antenna,ip1,ip2]; %生成要传输的信息比特，包含激活天线对信息和调制符号对信息 dec_ip=zeros(1,3); for a=1:ss %选天线参数十进制化 if active_antenna(a)==1 %哪一个天线被选中 dec_ip(1,1) = dec_ip(1,1) + 2^(ss-a); %将其十进制化 end end bin_ip3=zeros(1,k_b); for jj=1:2 bin_ip3=bin_ip(jj,:); for a=1:k_b % Convert to Decimal Input 两个传输信号十进制化 if bin_ip3(a)==1 dec_ip(1,jj+1) = dec_ip(1,jj+1) + 2^(k_b-a); end end end sin=zeros(1,2); for i=1:2 sin(1,i)=pskmod(dec_ip(i+1),M); %产生x1和x2 end pairs=[floor(rand(1,16)*4+1);floor(rand(1,16)*4+1)].'; %生成天线组合矩阵 dec_choose=dec_ip(1,1); %dec_choose是随机的 tx_ant_no=dec_choose+1; tx=pairs(tx_ant_no,:); %从pairs中选取行参数,即选出了激活天线对 x=zeros(1,Nt); x(tx(1))=(sin(1,1)); % 输出信号 和给定的程序相比少了一个+1，如果加1了就不在0到M-1范围内了吧 x(tx(2))=(sin(1,2)); % Alamouti STBC编码过程 sCode=zeros(2,Nt); sCode(1,:)=x; sCode(2,tx(1))=(conj(x(tx(2)))*(-1)); % 双时间间隔传输信号矩阵 sCode(2,tx(2))=(conj(x(tx(1)))); if tx_ant_no>2 scode=sCode*exp(angle1*sq)*big; %乘以一个优化旋转角 else scode=sCode*small; end %% 经过信道传输 H = 1/sqrt(2)*(randn(Nt,Nr) + sq*randn(Nt,Nr)); %瑞利信道矩阵 sigma=10^(-Es_N0_dB(ii)/20)*k_QAM; n = sigma*1/sqrt(2)*(randn(2,Nr) + sq*randn(2,Nr)); %高斯白噪声, 0dB variance y=scode*H+n; %不能用hMod代替x进行Alamouti变换，因为天线对很多 %% ML Detection Scheme %% symbolsDetect = zeros(2 , N) ; dml = zeros(M ,M ,N) ; %得到M*M种组合 for i1 = 1:M for i2 = 1:M dml(i1, i2, aa) = ( norm( y - sCode * H , 'fro') ) ; % 共16种组合 end end dml_min = min( reshape(dml( :, :, aa ) .' , 1, M*M) ) ; %找到最合适的 然后译码 for j1 = 1: M for j2 = 1:M if dml(j1 , j2, aa) ==dml_min symbolsDetect(1, aa) = j1; symbolsDetect(2, aa) = j2; end end end end %计算误码率 samp=10000; snr(ii)=Es_N0_dB(ii)+10*log10(k_b)-10*log10(samp); %信噪比 yn=awgn(y,snr(ii),'measured'); %加入高斯白噪声 yd=qamdemod(yn,M); %此时解调出来的是64进制信号 z=de2bi(yd,'left-msb'); %转化为对应的二进制比特流 z=reshape(z.',numel(z),1'); % [num_of_err(ii),sym_err_rate(ii)]=symerr(xsym,yd.'); [number_of_errors(ii),bit_error_rate(ii)]=biterr(x,z.'); % 一个信噪比结束 统计SER SER(ii) = sum ( reshape(symbolsDetect , 1, N * Nt) ~= reshape (symbols , 1, N *Nt) )/ (N * Nt); BER(ii)=bit_errors(ii)/(no*N) % BER BER(ii)=bit_errors(ii)/(N); % SER end %% semilogy(Es_N0_dB,BER,'bd-.','LineWidth',2); hold on grid on xlabel('Es/No, dB') ylabel('Bit Error Rate')