function [dscdma_closed_ber]=dscdma_closed_looptest(snr_in_dB)

%******************** Preparation part **********************

sr=256000.0; % Symbol rate
ml=1;        % Number of modulation levels
br=sr.*ml;   % Bit rate (=symbol rate in this case)
nd = 1;
N=nd;% Number of symbols that simulates in each loop
ebn0=snr_in_dB;     % Eb/N0(db)
IPOINT=8;    % Number of oversamples

%******************* Filter initialization ********************

irfn=21;     % Number of filter taps          
alfs=0.5;    % Rolloff factor
[xh] = hrollfcoef(irfn,IPOINT,sr,alfs,1);   %Transmitter filter coefficients 
[xh2] = hrollfcoef(irfn,IPOINT,sr,alfs,0);  %Receiver filter coefficients 

m=31;    %擴(kuò)頻碼的碼片數(shù)目


%********************** Spreading code initialization **********************

user  = 1;                                                          % number of users
seq   = 1;                                                          % 1:M-sequence  2:Gold  3:Orthogonal Gold
stage = 5;                                                          % number of stages
ptap1 = [1 3];                                                      % position of taps for 1st
ptap2 = [2 3];                                                      % position of taps for 2nd
regi1 = [1 1 1 1 1];                                                    % initial value of register for 1st
regi2 = [1 1 1 1 1];                                                    % initial value of register for 2nd

%******************** Generation of the spreading code *********************

switch seq
case 1                                                              % M-sequence
    code = mseq(stage,ptap1,regi1,user);
case 2                                                              % Gold sequence
    m1   = mseq(stage,ptap1,regi1);
    m2   = mseq(stage,ptap2,regi2);
    code = goldseq(m1,m2,user);
case 3                                                              % Orthogonal Gold sequence
    m1   = mseq(stage,ptap1,regi1);
    m2   = mseq(stage,ptap2,regi2);
    code = [goldseq(m1,m2,user),zeros(user,1)];
end
code = code * 2 - 1;
code=code';
clen = length(code);

%**************************** START CALCULATION ****************************

nloop = 50000;                                                       % simulation number of times
noe   = 0;
nod   = 0;

for iii=1:nloop
    
%****************************** Transmitter ********************************
    data0=rand(1,nd*ml) > 0.5;
    
%******************** 第一路 BPSK 調(diào)制 ***********************  

      data=data0.*2-1; %————————測(cè)試點(diǎn)————————

%data1=spread(data,code(:,1)) %第一路天線需要發(fā)射的信號(hào)————————測(cè)試點(diǎn)16  nd=2
h=randn(1,2)+randn(1,2)*j;
w1=conj(h(1,1))/sqrt((abs(h(1,1)))^2+(abs(h(1,2)))^2);
w2=conj(h(1,2))/sqrt((abs(h(1,1)))^2+(abs(h(1,2)))^2);
data_1=data*code(:,1);
data_1=data_1*w1;

%[data2] = oversamp( data1, N*m , IPOINT)                 %128  -1,0,1
%[data3] = conv(data2,xh) % conv: built in function--------測(cè)試點(diǎn)  295

%******************** 第二路 BPSK 調(diào)制 ********************
%********************擴(kuò)展原始碼元以實(shí)現(xiàn)擴(kuò)頻序列*************

%data2=spread(data,code(:,2))
data_2=data*code(:,1)*w2;            %第二路天線需要發(fā)射的信號(hào)————————測(cè)試點(diǎn)16
%[data_2] = oversamp( data_1, N*m , IPOINT)                 %128  -1,0,1
%[data_3] = conv(data_2,xh) % conv: built in function--------測(cè)試點(diǎn)  295


%******************產(chǎn)生空間路徑衰落系數(shù)矩陣*******************
%******************產(chǎn)生空間路徑衰落系數(shù)矩陣*******************
%Nr=1;
%Nt=2;
%t=1;
%h=mimo_channel(Nr,Nt,t);  %********2 x 1 天線********
%receiver1=1/sqrt(2)*(h(1,1)*data1+h(1,2)*data_1);  %------16復(fù)數(shù)

receiver1=h(1,1)*data_1+h(1,2)*data_2;

%****************** Attenuation Calculation *****************
	
    spow=sum(data_1.*data_1)/nd;%————————————————————————？？？？
	attn=0.5*spow*sr/br*10.^(-ebn0/10);
	attn=sqrt(attn);
  

%************ Add White Gaussian Noise (AWGN) ***************
	
    inoise=(randn(1,length(data_1)).*attn)';  % randn: built in function
	data4=receiver1+inoise;        %-------16復(fù)數(shù)
	%data5=conv(data4,xh2)  % conv: built in function  ---------462復(fù)數(shù)

	%sampl=irfn*IPOINT+1;
	%data6 = data5(sampl:8:8*nd+sampl-1)  %-------2個(gè)復(fù)數(shù) 
    
    
 %****************************解擴(kuò)信號(hào)************************
           
           data_7=code(:,1)'*data4;       
    
   
%******************** BPSK Demodulation *********************

                 demodata=data_7> 0;
    
%******************** Bit Error Rate (BER) ******************
	
    % count number of instantaneous errors
    noe2=sum(abs(data0-demodata));  % sum: built in function
	
    % count number of instantaneous transmitted data
    nod2=length(data);  % length: built in function
	
    noe=noe+noe2;
	nod=nod+nod2;

	%fprintf('%d\t%e\n',iii,noe2/nod2)
end % for iii=1:nloop    

%********************** Output result ***************************

dscdma_closed_ber = noe/nod;
fprintf('%d\t%d\t%d\t%e\n',snr_in_dB,noe,nod,noe/nod);


%******************** end of file ***************************