function BPSKerr_rate=berplot
close all;
clear all;
clc

SNRindb=-10:40;
for i=1:length(SNRindb)
smerr_prb(i)=BPSK(SNRindb(i)); 

end

semilogy(SNRindb,smerr_prb);
xlabel('SNR(dB)');
ylabel('BER');
legend(' simulated result');

%子函數
function[p]=BPSK(SNRdb)

N=5000;
E=1; 
SNR=10^(SNRdb/10); 
sgma=E/sqrt(SNR); 
for i=1:N
a=rand;
if(a<0.5)
trans(i)=-1;
else
trans(i)=1;
end
end

numofber=0;
totolnumber=0;
while numofber<1
totolnumber=totolnumber+1;
for i=1:N
H1=normrnd(0,sqrt(0.5))+j*normrnd(0,sqrt(0.5));
H2=normrnd(0,sqrt(0.5))+j*normrnd(0,sqrt(0.5));
H=[H1;H2];
y1=H(1)*trans(i)+(normrnd(0,sgma)+j*normrnd(0,sgma));
y2=H(2)*trans(i)+(normrnd(0,sgma)+j*normrnd(0,sgma));
y=[y1;y2];
s=H'*y;
decis=sign(real(s));
if (decis~=trans(i))
numofber=numofber+1;

end

end
end
p=numofber/(N*totolnumber);