mrrc_1xnr.m

基于MIMO通信系统中的各种空时编译码算法

% BPSK modulation, 1 X Nr antenna array
% Maximal Ratio Receive Combining(MRRC)
% MRRC_1XNr.m
clear all;
%% initialztion
maxEbNo=18;
stepEbNo=3;
Nr=2; % Modify here!
M=2;% M-QAM,can't be modified
data_length=100000;% there are data_length*Nt bits at all

EbNo=(0:stepEbNo:maxEbNo);
BER=zeros(size(EbNo));
fr_length=data_length/(log2(M));
h=waitbar(0,'Percentage Completed');
set(h,'name','MRRC 1XNr...');
step_wb=100/(maxEbNo/stepEbNo);
wb=0;
%% QAM modulation
data=randint(data_length,1);
X=qammod(data,M); %M-QAM
constellation=qammod((0:M-1),M);
%% channel 
H=(randn(fr_length,Nr)+j*randn(fr_length,Nr))/sqrt(2);
Habs=sum(abs(H).^2,2);
%% received signal per receiver antenna 
SNR=EbNo;
r=[];
for ii=1:length(SNR)
    for n=1:Nr 
        r(:,n)=sum(H(:,n).*X,2) +  sqrt(0.5/(10^(SNR(ii)/10)))*(randn(fr_length,1)+j*randn(fr_length,1));
    end
    % MRRC
    z=r.*conj(H);
    Xe=sum(z,2); % estimation of X
    % Maximum Likelihood Decision    
    for m=1:M
        d(:,m)=(sum(Habs,2)-1)*abs(constellation(m))^2  +  abs(Xe-constellation(m)).^2;
    end
    [Xd,index]=min(d,[],2);
    Xd=constellation(index).';
    % QAM demodulation
    Xd_bit=qamdemod(Xd,M);
    [errnum,BER(ii)]=biterr(data,Xd_bit);
     %update the waitbar
    str_bar=[num2str(wb) '% Completed'];
    waitbar(wb/100,h,str_bar);
    wb=wb+step_wb;
end
close(h);
semilogy(EbNo,BER,'r-o');
%legend('1XNr MRRC');
xlabel('EbNo');
ylabel('Bit Error Rate');
grid on;