clc
clear
sr=256000; % symbol rate
mod=2; % modulation pattern 1=bpsk , 2=qpsk , 4=16QAM , 6=64QAM
br=mod*sr; % bit rate
ebn0=linspace(0,8,20); % Eb/N0 ranges from 0 to a value
symbnum=1000; % number of symbol in each loop
nloop=400 ;
sample=8; % oversample rate is 8;
delay=5; % sqrt filter delay
ber=zeros(1,length(ebn0));
err=zeros(1,length(ebn0));
hn_sqrt=rcosine(1,sample,'sqrt',0.5,delay); % use square root roll cos filter to generate a pulse, affect 5 symbols
syncpoint=2*delay*sample+1;
for ebii=1:1:length(ebn0)
en=10^(ebn0(ebii)/10); % convert db unit to linear unit
sigma=1/sqrt(2*mod*en); % deviation of noise
for ii=1:1:nloop
data=round(rand(1,symbnum*mod)); % number of bits
[i_mod,q_mod]=modulation(data,symbnum,mod); % modulation, constellation mapping
[i_oversam,q_oversam]=oversample(i_mod,q_mod,symbnum,sample); % oversample rate is 8
i_pulse=conv(i_oversam,hn_sqrt); % constellation pass a sqrt fir filter
q_pulse=conv(q_oversam,hn_sqrt);
[i_rec,q_rec]=awgn(i_pulse,q_pulse,sigma); % through a AWGN channel
i_match=conv(i_rec,hn_sqrt);
q_match=conv(q_rec,hn_sqrt);
i_sync=i_match(syncpoint:sample:length(i_match)-syncpoint); % synchronize the signal after the match filter
q_sync=q_match(syncpoint:sample:length(q_match)-syncpoint);
demod=demodulation(i_sync,q_sync,mod);
err(ebii)=err(ebii)+sum(demod~=data);
end
end
ber=err/symbnum/mod/nloop;
semilogy(ebn0,ber);
grid on;
