mod_demod.rar_MOD_QPSK RRC_QPSK匹配滤波_RRC滤波_匹配滤波器

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;