xiaobokangganrao.m

扩频通信中小波包变换的抗干扰性能的分析

clear;
Lc=64;
w0=0.3142;
A=100;
SNRindB=0:2:20;
for k=1:length(SNRindB);
snr=10^(SNRindB(k)/10);
sgma=1;
Eb=2*sgma^2*snr;
E_chip=Eb/Lc;
N=10000;
num_of_err=0;
RECSIG=zeros(1,640000);
for i=1:N
    temp=rand;
    if(temp)<0.5,data=-1;
    else data=1;
    end;
    DATA(i)=data;
    for j=1:Lc
        repeated_data(j)=data;
    end;
    for j=1:Lc
        temp=rand;
        if(temp<0.5) pn_seq(j)=-1;
        else pn_seq(j)=1;
        end;
    end;
    PN_SEQ(1,(Lc*i-Lc+1):Lc*i)=pn_seq;
    trans_sig=sqrt(E_chip)*repeated_data.*pn_seq;
    noise=sgma*randn(1,Lc);
    n=(i-1)*Lc+1:i*Lc;
    interference=A*sin(w0*n);
    rec_sig=trans_sig+noise+interference;
    RECSIG(1,(Lc*i-Lc+1):Lc*i)=rec_sig;
end;
wpt=wpdec(RECSIG,5,'db2');
for m=1:62;
    cfs=wpcoef(wpt,m);
    d(m)=var(cfs);
end;
D=min(d);
[terNI] = get(wpt,'terNI');
m1=terNI{1};
t=terNI{2};
for j=1:32;
    m2(1,(20002*j-20001):20002*j)=t(1,(20002*j-20001):20002*j)*D/d(j+30);
end;
wpt=set(wpt,'terNI',{m1,m2});
X=wprec(wpt);
for l=1:N;
    temp=X(1,(l*Lc-Lc+1):l*Lc).*PN_SEQ(1,(Lc*l-Lc+1):Lc*l);
    decision_variable=sum(temp);
    if(decision_variable<0) decision=-1;
    else decision=1;
    end;
    if(decision~=DATA(l))
        num_of_err=num_of_err+1;
    end;
end;
p(k)=num_of_err/N;
end;
semilogy(SNRindB,p,'r-');