rake_3path_max.m

采用matlab对无线信道进行仿真的源程序。

%Rake接收机rake.m
clear all;
close all;
Tc = 1;
N = 128;
gx = '1000010111000101';%g(x) = x^15+x^13+x^9+x^8+x^7+x^5+1
g = bin2dec(gx);
state = 1;
L = 2^13;

EcN0dB = -21:-14;

for  k = 1:length(EcN0dB)
    error(k) = 0;%计数错误比特数
    total(k) = 0;%计数总的传输比特数
    sigma(k) = sqrt(10.^(-EcN0dB(k)/10)/2);
    while(error(k)<100)
        %多径结构
        p1 = sqrt(0.5/2)*(randn(1,L)+j*randn(1,L));
        p2 = sqrt(0.3/2)*(randn(1,L)+j*randn(1,L));
        p3 = sqrt(0.2/2)*(randn(1,L)+j*randn(1,L));
        t1 = 0;
        t2 = 1;
        t3 = 2;
        
        pt = mgen(g,state,L+t3);%调用m序列发生器函数
        pt = 2*pt-1;
        
        %数据产生
        d = sign(randn(1,L/N));%一次64个
        %扩频，先将数据扩展，然后与pt点积
        dd = sigexpand(d,N);
        s = conv(dd,ones(1,N));
        st = s(1:L+t3).*pt(1:L+t3);         %扩频
        
        %经过多径信道，加入噪声
        z = sigma(k)*(randn(1,L)+j*randn(1,L));
        
        rt = st(1:L).*p1 + st(t2+1:L+t2).*p2 + st(t3+1:t3+L).*p3 + z;
        %rake接收
        r1 = rt.*conj(p1).*pt(1:L);
        r2 = rt.*conj(p2).*pt(t2+1:L+t2);
        r3 = rt.*conj(p3).*pt(t3+1:L+t3);
        
        %积分
        r1 = reshape(r1,N,L/N);y1 = sum(r1);
        r2 = reshape(r2,N,L/N);y2 = sum(r2);
        r3 = reshape(r3,N,L/N);y3 = sum(r3);
        %合并
        y = y1 + y2 + y3;%最大比合并
        %判决
        dc = sign(real(y));
        error(k) = error(k) + sum(abs((d-dc))/2);
        total(k) = total(k) + L/N;
        BitErrorRate(k) = error(k)/total(k);
    end
end
semilogy(EcN0dB,BitErrorRate);
grid on;