dscdma_no_diversity.m

CDMA系统中开环发射分集系统的仿真和实现

% Simulation program to realize DS-CDMA system
%
%
function [dscdma_no_diversity_ber]=dscdma_no_diversity(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
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;    %扩频码的码片数目


%********************** 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 = 10000;                                                       % simulation number of times
noe   = 0;
nod   = 0;

for iii=1:nloop
    
%****************************** Transmitter ********************************
    %data0 = rand(1,nd*ml) > 0.5;
    data0 = randint;
    %data=data0.*2-1; %————————测试点————————
     data=pskmod(data0,2);
    %data1=(spread(data,code(1,:)))'
  
    data1=data*code;
    
    

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


%******************产生空间路径衰落系数矩阵*******************
%******************产生空间路径衰落系数矩阵*******************
%Nr=1;
%Nt=2;
%t=1;
%h=mimo_channel(Nr,Nt,t);  %********2 x 1 天线********
%receiver1=1/sqrt(2)*(h(1,1)*data1+h(1,2)*data_1);  %------16复数
h=randn(1,1)+randn(1,1)*j;
receiver1=h*data1;

%****************** Attenuation Calculation *****************
	
    spow=sum(data1.*data1)/nd;
	attn=0.5*spow*sr/br*10.^(-ebn0/10);
	attn=sqrt(attn);
  

%************ Add White Gaussian Noise (AWGN) ***************
	
    inoise=(randn(1,length(data1)).*attn)' ; % randn: built in function
	data4=receiver1+inoise; 
	%data5=conv(data4,xh2)  % conv: built in function  ---------462复数

	%sampl=irfn*IPOINT+1;
	%data6 = data5(sampl:8:8*nd+sampl-1)  %-------2个复数 
    
    
 %****************************解扩信号************************
           
           data_7=code'*data4;            %;
           %data7=despread(data4,code(1,:))    %---------2复数
           %data8=despread(data4,code(2,:))    %-----同上
           %data9=conj(h(1,1))*data7+conj(h(1,2))*data8       %--------2复数
           %data_9=1/sqrt(2)*((abs(h(1,1)))^2+(abs(h(1,2)))^2)*data+(conj(h(1,1))*code(1,:)+conj(h(1,2))*code(2,:))*inoise'
    
   
%******************** BPSK Demodulation *********************

                 demodata=pskdemod(data_7,2);
    
%******************** 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_no_diversity_ber = noe/nod;
fprintf('%d\t%d\t%d\t%e\n',snr_in_dB,noe,nod,noe/nod);


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