selina4.asv

认知无线电系统中多载波信号带外干扰的抑制

%实验一
%余弦信号的傅立叶变换
global dt df N t f T %全局变量
close all
N=2^15;      %采样点数
% L=64;			%每码元的采样点数
% M=N/L;			%码元数
M=2^8;%码元数
dt=0.01;    %时域采样间隔
df=1/(N*dt);%频域采样间隔
T=N*dt;     %截短时间
Bs=N*df/2;  %系统带宽
t=linspace(-T/2,T/2,N);
f=linspace(-Bs,Bs,N);

fl=3.1;
fh=10.6;
B1=(fh-fl)/M;


for loop1=1:10
    Eb_N0(loop1)=(loop1-1); %分贝值变为真值
    eb_n0(loop1)=10^(Eb_N0(loop1)/10);
    Eb=1;
    n0=Eb/eb_n0(loop1);   	%信道噪声谱密度
    sita=n0*B1*M;

    n_err=0;
    s=zeros(1,N);
    rk=zeros(1,N);
    S=zeros(1,N);
    aa=zeros(1,M);
    Ebn=1/M;
    A=sqrt(2*Ebn);
    for loop2=1:3
        a=round(rand(1,M));
        n_ch=sqrt(sita)*randn(size(t));


        for k=1:M
            f0=fl+(k-0.5)*B1;
            sn=(2*a(k)-1)*A*cos(2*pi*f0*t);
            s=sn+s;
        end
        S=abs(t2f(s));
        s=s+n_ch;
        R=t2f(s);

        for k=1:M
            f0=fl+(k-0.5)*B1;
            rn=cos(2*pi*f0*t);
            rk=rk+rn;
        end
        Rk=t2f(rk);
        for k=1:M
            x=angle(R(N/2+round((fl+(k-0.5)*B1)/df)+1))-angle(Rk(N/2+round((fl+(k-0.5)*B1)/df)+1));
            aa(k)=abs(sign(round(x)))*-1+1;
        end

        n_err=n_err+length(find(aa~=a)) ;
    end
    Pe(loop1)=n_err/(M*loop2);

end
Pe





figure(1)
set(1,'position',[10,50,300,200])%设定窗口位置及大小
figure(2)
set(2,'position',[350,50,300,200]);%设定窗口位置及大小
figure(3)
set(3,'position',[350,50,300,200]);%设定窗口位置及大小
figure(1)
plot(f,S,'g')
grid;
axis([-fh,fh,min(S),max(S)]);
xlabel('f(kHZ)');
ylabel('S(f)(V/kHZ)');
figure(2)
plot(t,s,'b')
grid
axis([-T/2,T/2,min(s),max(s)]);
xlabel(('t(ms)'));
ylabel('s(t)(V)');

figure(3)
semilogy(Eb_N0,Pe,'g');
axis([0,9,1e-2,1])
xlabel('Eb/N0')
ylabel('Pe')