clear;clc;%close all; 
timeofprog=cputime; 
K=1;%用戶數 
Lc=31;%擴頻碼長度 
T=1;Tc=T/Lc;%信號比特和擴頻碼周期 
code_type=2;%0=隨機 1=hadamard碼 2=Gold碼 
code_seed=rand('state'); 
codes=cdma_codes(K,0,code_type,Lc,code_seed); 
Q=10;%矩形碼片成型濾波器抽樣因子 
Mpmax=5;%最大多徑數 
Mps=Mpmax*ones(K,1);%每個用戶的多徑數 
 
%隨機產生的時延，每條路徑可分離 
while(1) 
    TausOri=rand(K,Mpmax)*Lc; 
    TausOri=sort(TausOri,2); 
    Tausdelta=TausOri(:,2:Mpmax)-TausOri(:,1:Mpmax-1); 
    TuasSTD=sum(sum(Tausdelta>ones(K,Mpmax-1),1),2); 
    if TuasSTD==K*(Mpmax-1) 
        break 
    end 
end 
Taus=floor(TausOri*Q)/Q; 
TausSam=Taus*Q;%將時延轉換為相應的抽樣數 
 
%仿真數據存儲 
filename='CDMARakedatapp.m'; 
fid=fopen(filename,'a+'); 
fprintf(fid,'%s','???SimuPara:'); 
SimuPara=[Lc,Taus]; 
for dataID=1:length(SimuPara) 
    fprintf(fid,'%f',SimuPara(dataID)); 
end 
fprintf(fid,'\n'); 
fclose(fid); 
 
%設置信噪比SNRdBs 
SNRdBs=-10:0; 
nSNRdBs=length(SNRdBs); 
for SNRID=1:nSNRdBs 
    SNRdB=SNRdBs(SNRID); 
    %AWGN方差的產生 
    N=10;%N???????????????????????????????? 
    N0=1/(10^(SNRdB/10))-(K*Mps(K)-1)*1/(3*N); 
    %AWGN的單邊功率譜密度 
    Bandwidth=Tc/2;%匹配濾波器等效帶寬 
    sigma2=N0*Bandwidth/2;%經過匹配濾波器后AWGN的方差 
    sigma=sqrt(sigma2); 
    nbitsAll=0;%發送總比特數 
    nerrorbits=zeros(Mps(1),1);%錯誤比特數 
    times=0;%循環次數 
    while(1) 
        N=1000;%一次發送的比特數 
        bits=2*rem(unidrnd(2,K,N),2)-1;%BPSK信號 
        Signal=zeros(1,(N+1)*Lc*Q);%不包括AWGN 
        for k=1:K 
            bitsChip=kron(bits(k,:),codes(k,:));%bits-->chips 
            ChipsSam=kron(bitsChip,ones(1,Q));%chips-->samples 
            for pathID=1:Mps(k) 
                Fadings(pathID,:)=kron(raylrnd(1/sqrt(2),1,N),ones(1,Lc*Q));%產生瑞利衰落振幅 
                TauSam=round(TausSam(k,pathID)); 
                Signal(TauSam+1:TauSam+N*Lc*Q)=Signal(TauSam+1:TauSam+N*Lc*Q)+Fadings(pathID,:).*ChipsSam; 
            end 
        end 
        %第一個用戶的rake接收 
        %假設時延已經準確估計 
        TausSamEst=TausSam; 
        Rakebranch=zeros(Mps(1),N); 
        for pathID=1:Mps(1) 
            TauSam=round(TausSamEst(1,pathID)); 
            RakeChipMF=1/2*sum(reshape(Signal(TauSam+1:TauSam+N*Lc*Q),Q,N*Lc),1)*(Tc/Q);%解調后的信號（振幅為解調前的1/2）再經過匹配濾波器 
            Noise=sigma*randn(1,N*Lc); 
            RakeChipMF=RakeChipMF+Noise;%加上噪聲 
            Rakebranch(pathID,:)=codes(1,:)*reshape(RakeChipMF,Lc,N)*Tc;%解擴 
        end 
        %最大比值合并 
        Rakebranchpower=Rakebranch.^2; 
        for pathID=1:Mps(K) 
            power=sum(Rakebranchpower(1:pathID,:),1); 
            for temp=1:pathID 
                MRCPara(temp,:)=Rakebranchpower(temp,:)./power;%每條路徑的最大比值合并系數 
            end 
            orderID=pathID; 
            RakeMRC(orderID,:)=sum(MRCPara(1:pathID,:).*Rakebranch(1:pathID,:),1); 
        end 
        %誤碼率計算 
        RakeRcvSign=sign(RakeMRC); 
        nbitsAll=nbitsAll+N; 
        nerrorbits=nerrorbits+sum(abs(sign(RakeRcvSign-kron(bits(1,:),ones(Mps(K),1)))),2); 
        BER=nerrorbits/nbitsAll; 
        [SNRdB,nbitsAll,nerrorbits'] 
        %輸出數據存儲 
        fid=fopen(filename,'a+'); 
        outdata=[SNRdB,nbitsAll,nerrorbits',BER']; 
        for dataID=1:length(outdata) 
            fprintf(fid,'%f',outdata(dataID)); 
        end 
        fprintf(fid,'\n'); 
        fclose(fid); 
        times=times+1; 
        %跳出WHILE循環的條件 
        if nerrorbits(Mps(1))>=100|times>=10 
            break 
        end 
    end 
end 
timeofprog=cputime-timeofprog 
display('Program exit!!!');