pta.m

正交频分复用基于IEEE802.11a的PTA跟踪法

function pta(in,offset)
a1=AWAG_channel_backup(in,25,offset);
length1=length(a1);
a2=a1(193:length1);
length2=fix((length(a2)-128)/80);
a3(1:64)=b_fft(a2(1:64));
a3(65:128)=b_fft(a2(65:128));
for i=1:length2
    a3(128+(i-1)*64+1:128+(i-1)*64+64)=b_fft(a2((i-1)*80+1+128+16:(i-1)*80+80+128));
end
Bl=0.00008;
kesai=0.707;
k=1;
C1=(4*kesai*Bl/(kesai+0.25/kesai));
C2=((2*Bl/(kesai+0.25/kesai))^2);
e1(1:length2+1)=0;
e2(1:length2+1)=0;
e3=0;
sum_angle(1:length2+1)=0;

for i=3:length2;
    e3=0;
    for n=1:64
        e3=mod(i*e2(i-1)+e3,2*pi);
        a3((i)*64+n)=(a3((i)*64+n)*(exp(-j*((e3)))));
    end
    R1(i)=(a3((i)*64+12))*(conj(a3((i-1)*64+12)));
    R2(i)=(a3((i)*64+26))*(conj(a3((i-1)*64+26)));
    R3(i)=(a3((i)*64+40))*(conj(a3((i-1)*64+40)));
    R4(i)=(a3((i)*64+54))*(conj(a3((i-1)*64+54)));
    sum_angle(i)=(((imag(R1(i))+imag(R2(i))+imag(R3(i))+imag(R4(i)))))+ sum_angle(i-1);
    e3(i)=(C2*sum_angle(i));%这个值很小可以忽略不计
    
   e1(i)=(C1+C2)*sum_angle(i)-C1*sum_angle(i-1)+e1(i-1);
   e2(i)=(e1(i))+e2(i-1);
end
plot(e2/(2*pi));
xlabel('OFDM符号数');
ylabel('频率误差');