ds-cdma.asv

此程序为DS-CDMA链路中加入基于子空间的PASTd多用户检测方法。系统中采用m序列阔频

% Program 5-6
%
% Simulation program to realize DS-CDMA system
%
% dscdma.m
%
% Programmed by yixiongshu,2006.8.9
clear all;
clc;

%----------------------preparation part -----------------------------
sr=256000.0;                            % symboll rate
ml=2;                                       % number of modulation levels
br=sr*ml;  % bit rate
nd=100;    % number of symbol
ebno=8;    % Ebno

%-----------------------------------------------Filter initialization-----------------
irfn=21;
IPOINT=8;
alfs=0.5;
[xh]=hrollfcoef(irfn,IPOINT,sr,alfs,1);       % Transmitting Filter
[xh2]=hrollfcoef(irfn,IPOINT,sr,alfs,0);      % Received Filter

%------------------------------ Spreading code initialization--------------------
user=1;   % number of users
seq=1;  % 1:m-sequence     2:Gold    3:orthogonal Gold
stage=3;
ptap1=[1 3];
ptap2=[2 3];
regi1=[1 1 1];
regi2=[1 1 1];

% ----------------------------- Generation of the spreading code --------
switch seq
    case 1
        code=mseq(stage,ptap1,regi1,user);
    case 2
        m1=mseq(stage,ptap1,regi1);
        m2=mseq(stage,ptap2,regi2);
        code=goldseq(m1,m2,user);
    case 3
        m1=mseq(stage,ptap1,regi1);
        m2=mseq(stage,ptap2,regi2);
        code=[goldseq(m1,m2,user),zeros(user,1)];
end
code=code*2-1;
clen=length(code);

% ---------------------------------- Fading initialization ---------------
rfade=0;   % Rayleigh fading  0:nothing  1:consider
itau=[0,8];   % delay time
dlvl1=[0.0,40.0];  % attenuation level
n0=[6,7];
th1=[0.0,0.0];
itnd1=[3001,4004];
now1=2;
tstp=1/sr/IPOINT/clen;  % time resolution
fd=160;
flat=1;
itnde1=nd*IPOINT*clen*30;

% ----------------------------- Start calculation -------------
nloop=1000;
noe=0;
nod=0;

for ii=1:nloop
    
    % -------------------------- Transmitter ---------------------
    data=rand(user,nd*ml)>0.5;
    [ich,qch]=qpskmod(data,user,nd,ml);
    
    [ich1,qch1]=spread(ich,qch,code);
    
    [ich2,qch2]=compoversamp2(ich1,qch1,IPOINT);
    [ich3,qch3]=compconv2(ich2,qch2,xh);
    
    if user==1
        ich4=ich3;
        qch4=qch3;
    else
        ich4=sum(ich3);
        qch4=sum(qch3);
    end

 % -------------------------- Fading channel -------------------
 if rfade==0
     ich5=ich4;
     qch5=qch4;
 else
     [ich5,qch5]=sefade(ich4,qch4,itau,dlvl1,th1,n0,itnd1,...
         now1,length(ich4),tstp,fd,flat);
     itnd1=itnd1+itnde1;
 end
 
 % ---------------------------------- Receiver  -----------------------------
 spow=sum(rot90(ich3.^2+qch3.^2))/nd;
 attn=sqrt(0.5*spow*sr/br*10^(-ebno/10));
 
 [ich6,qch6]=comb2(ich5,qch5,attn);
 
 [ich7,qch7]=compconv2(ich6,qch6,xh2); % filter
 
 samp1=irfn*IPOINT+1;
 ich8=ich7(:,samp1:IPOINT:IPOINT*nd*clen+samp1-1);
 qch8=qch7(:,samp1:IPOINT:IPOINT*nd*clen+samp1-1);
 
 [ich9 qch9]=despread(ich8,qch8,code);
 
 demodata=qpskdemod(ich9,qch9,user,nd,ml);   % QPSK demodulation
 
 %--------------------- BER -----------------------------
 noe2=sum(sum(abs(data-demodata)));
 nod2=user*nd*ml;
 noe=noe+noe2;
 nod=nod+nod2;
 
%  fprintf('%d\t%e\n',ii,noe2/nod2);
end

% ------------------------------Data file --------------------------

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

fid=fopen('BER.mat','a');
fprintf(fid,'%d\t%d\t%d\t%e\n',ebno,noe,nod,ber);

fclose(fid);

% --------------------------- end of file ----------------------

 



% qpskdemod.m
function [demodata]=qpskdemod(idata,qdata,para,nd,ml)

demodata=zeros(para,ml*nd);
demodata((1:para),(1:ml:ml*nd-1))=idata((1:para),(1:nd))>=0;
demodata((1:para),(2:ml:ml*nd))=qdata((1:para),(1:nd))>=0;

 

% qpskmod.m
function [iout,qout]=qpskmod(paradata,para,nd,ml)
m2=ml./2;
paradata2=paradata.*2-1;
count2=0;

for jj=1:nd
    isi=zeros(para,1);
    isq=zeros(para,1);
    for ii=1:m2
        isi=isi+2.^(m2-ii).*paradata2((1:para),ii+count2);
        isq=isq+2.^(m2-ii).*paradata2((1:para),m2+ii+count2);
    end
    iout((1:para),jj)=isi;
    qout((1:para),jj)=isq;
    count2=count2+ml;
end

 

% sefade.m
%
% This function generates frequency selecting fading
%
function [iout,qout,ramp,rcos,rsin]=sefade(idata,qdata,itau,...
    dlvl,th,n0,itn,n1,nsamp,tstp,fd,flat)

%************************ variables *****************************
% idata input Ich data
% qdata input  Qch data
% iout output Ich data
% qout output Qch data
% ramp : Amplitude contaminated by fading
% rcos : Cosine value contaminated by fading
% rsin : Sine value contaminated by fading
% itau : Delay time for each multipath fading
% dlvl : Attenuation level for each multipath fading
% th   : Initialized phase for each multipath fading
% n0   : Number of waves in order to generate each multipath fading
% itn  : Fading counter for each multipath fading
% n1   : Number of summation for direct and delayed waves
% nsamp: Total number of symbols 
% tstp : Minimum time resolution
% fd   : Maximum doppler frequency
% flat : flat fading or not

iout=zeros(1,nsamp);
qout=zeros(1,nsamp);

total_attn=sum(10.^(-1.0.*dlvl./10.0));
for k=1:n1
    atts=10.^(-0.05.*dlvl(k));
    if dlvl(k)==40.0
        atts=0.0;
    end
    theta=th(k).*pi./180.0;
    [itmp,qtmp]=delay(idata,qdata,nsamp,itau(k));
    [itmp3,qtmp3,ramp,rcos,rsin]=fade(itmp,qtmp,...
        nsamp,tstp,fd,n0(k),itn(k),flat);
    iout=iout+atts.*itmp3./sqrt(total_attn);
    qout=qout+atts.*qtmp3./sqrt(total_attn);
end

 

% Program 5-3
% shift.m
%
% Shift the contents of the register
%
% Programmed by yixiongshu,2006.8.9
function [outregi]=shift(inregi,shiftr,shiftu)
%
% inregi : Vector or matrix
% shiftr :  The amount of shift to the right.
% shiftu : The amount of shift to the top.
% outregi: Register output 

% ----------------------------------------------------
[h,v]=size(inregi);
outregi=inregi;
shiftr=rem(shiftr,v);
shiftu=rem(shiftu,h);
if shiftr>0
    outregi(:,1:shiftr)=inregi(:,v-shiftr+1:v);
    outregi(:,1+shiftr:v)=inregi(:,1:v-shiftr);
elseif shiftr<0
    outregi(:,1:v+shiftr)=inregi(:,1-shiftr:v);
    outregi(:,v+shiftr+1:v)=inregi(:,1:-shiftr);
end

inregi=outregi;

if shiftu>0
    outregi(1:h-shiftu,:)=inregi(1+shiftu:h,:);
    outregi(h-shiftu+1:h,:)=inregi(1:shiftu,:);
elseif shiftu<0
    outregi(1:-shiftu,:)=inregi(h+shiftu+1:h,:);
    outregi(1-shiftu:h,:)=inregi(1:h+shiftu,:);
end

% end of file.

 

% Program 5-7
% spread.m
%
% Data spread function
%
% programmed by yixongshu,2006.8.9
function [iout,qout]=spread(idata,qdata,code1);
%
% code1: spread code sequence
%
switch nargin
    case{0,1}
        error('lack of input argument');
    case 2
        code1=qdata;
        qdata=idata;
end
[hn,vn]=size(idata);
[hc,vc]=size(code1);

if hn>hc
    error('lack of spread code sequences');
end

iout=zeros(hn,vn*vc);
qout=zeros(hn,vn*vc);

for ii=1:hn                       % spread the information correctly.
    iout(ii,:)=reshape(rot90(code1(ii,:),3)...
        *idata(ii,:),1,vn*vc);
    qout(ii,:)=reshape(rot90(code1(ii,:),3)...
        *qdata(ii,:),1,vn*vc);
end

% end of file.