% BPSK modulation, 1 X Nr antenna array% Maximal Ratio Receive Combining(MRRC)% MRRC_1XNr.mclear all;%% initialztionmaxEbNo=18;stepEbNo=3;Nr=2; % Modify here!M=2;% M-QAM,can't be modifieddata_length=100000;% there are data_length*Nt bits at allEbNo=(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 modulationdata=randint(data_length,1);X=qammod(data,M); %M-QAMconstellation=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;endclose(h);semilogy(EbNo,BER,'r-o');%legend('1XNr MRRC');xlabel('EbNo');ylabel('Bit Error Rate');grid on;