??
pi=3.1415926;
fc=5;
N=2^8;
L=8;
M=N/L;
Rb=2;
Tb=1/Rb;
dt=Tb/L;
df=1/（dt*N）;
T=N*dt;
B=N*df/2;
t=[-T/2+dt/2:dt:T/2];
f=[-B+df/2:df:B];
EP=zeros（size（f））;
EPg=zeros（size（f））;
for?ii=1:10;
???for?j=1:50;
???????b=sign（randn（1M））;
???????for?i=1:L
???????????s（i+[0:M-1]*L）=b;
???????end
%????????P=t.*f（s）;
???????P=P.*conj（P）/T;?
???????EP=（EP*（j-1）+P）/j;?
???end?

Ps=10*log10（EP+eps）;?
Bb=Tb/0.3;?
alpha=sqrt（logm（2）/2/Bb^2）;
H=exp（-alpha^2*f.^2）;?
a（1）=b（1）;?
for?i=M:-1:2?
????a（i）=b（i）*b（i-1）;
end
for?i=1:L
????sa（i+[0:M-1]*L）=a;
end
send=real（f2t（t2f（s）.*H））;
It=zeros（size（t））;
for?k=0:2*L:N-1;
????kk=1:2:2*L;
????kkk=1:L;
????It（k+kk）=send（k+kkk+L）;
????It（k+kk+1）=send（k+kkk+L）;?
end?
for?k=N:-1:L+1
????It（k）=It（k-L）;
end
Qt=zeros（si