多用户检测MATLAB程序

%MMSE多用户检测 %由发送序列－>调制－>扩频－>AWGN－>解调－>解扩－>MMSE检测 clear all; K=7; N=1000; goal_user=1; M=2; %PSK调制进制 E=1; %每符号能量 %——产生gold序列—— fbconnection1=[0 0 1 0 1]; fbconnection2=[0 1 1 1 1]; mseq1=m_sequence(fbconnection1); mseq2=m_sequence(fbconnection2); L=2^length(fbconnection1)-1; for shift_amount=0:L-1 shift_mseq2=[mseq2(shift_amount+1:L) mseq2(1:shift_amount)]; %对第二个m序列进行循环移位 goldseq(shift_amount+1,:)=mod(mseq1+shift_mseq2,2); %m1序列和循环移位后的m2序列模2加后即为gold序列 end ind1=find(goldseq==0); %将gold序列的0变为-1； goldseq(ind1)=-1; %——归一化互相关矩阵(扩频信号)—— R=zeros(K,K); for ii=1:K for jj=1:K R(ii,jj)=sum(goldseq(ii,:).*goldseq(jj,:)); end end R=R/L; %归一化互相关矩阵 I=eye(K,K); M1=I; %传统检测器 M2=inv(R); %解相关检测器 %——产生发送序列—— signal_unspread=randsrc(K,N);%产生K*N矩阵 signal_spread=zeros(K,L*N); %产生K*(L*N)矩阵 %——对发送序列扩频—— for ii=1:K j=1; for i = 1:N for k = j:(j+L-1) signal_spread(ii,k) = signal_unspread(ii,i); end signal_spread(ii,j:(j+L-1)) = signal_spread(ii,j:(j+L-1)).*goldseq(ii,:); j = L*i+1; end end %－－PSK调制Modulation—— %ind2=find(signal_spread==-1); %将扩频后的-1、1序列变为0、1序列 %signal_spread(ind2)=0; %for ii=1:K % mod_signal(ii,:)=pskmod(signal_spread(ii,:),M); %PSK调制 %end; mod_signal(ii,:)=signal_spread(ii,:); xx=zeros(K,L*N); x=zeros(1,L*N); SNR=0:1:10;%信噪比范围 for nn=1:length(SNR) Eb_N0=10^(SNR(nn)/10); %转化为DB值 sigma=sqrt(1/(2*Eb_N0)); %噪声信号方差 %----K个用户通过AWGN信道---- for ii=1:K %xx(ii,:)=awgn(mod_signal(ii,:),SNR(nn),'measured'); xx(ii,:)=awgn(mod_signal(ii,:),SNR(nn)); end %——加高斯白噪声-- for ii=1:K x=x+xx (ii,:); end x=x/sqrt(K); y_undemod=x; M3=inv(R+sigma*I); %MMSE检测器 %——解调—— %y=pskdemod(y_undemod,M); %ind2=find(y==0); %将解扩后的0、1序列变为-1、1序列 %y(ind2)=-1; y=y_undemod; %——解扩—— r=zeros(K,N); for ii=1:K j=1; for iii = 1:N r(ii,iii) = sum(y(j:(j+L-1)).*goldseq(ii,:)); j = L*iii+1; end end bk1=M1*r;signal_rec1=sign(bk1); bk2=M2*r;signal_rec2=sign(bk2); bk3=M3*r;signal_rec3=sign(bk3); MF_PE(nn)=length(find(signal_unspread(goal_user,:)-signal_rec1(goal_user,:))); De_PE(nn)=length(find(signal_unspread(goal_user,:)-signal_rec2(goal_user,:))); MMSE_PE(nn)=length(find(signal_unspread(goal_user,:)-signal_rec3(goal_user,:))); end MF_BER=MF_PE/N; De_BER=De_PE/N; MMSE_BER=MMSE_PE/N; % semilogy(SNR,De_BER,'-k*'); hold on; semilogy(SNR,MF_BER,'-.ro'); hold on; semilogy(SNR,MMSE_BER,'--b+'); grid on; xlabel('SNR/dB'); ylabel('BER'); title('同步系统AWGN下解相关和MMSE多用户检测的误码率性能'); legend('解相关检测','MF','MMSE');