三种差错控制编码在AWGN信道中的性能分析,两种基本差错控制编码,matlab

cycl=20; SNR=0:1:12; msg=randint(1,10000); BER0=zeros(1,length(SNR)); BER1=zeros(1,length(SNR)); BER2=zeros(1,length(SNR)); %------------------------ for n=1:cycl for k=1:length(SNR); modbit0=pskmod(msg,2); y0=awgn(modbit0,SNR(k),'measured'); N=BurstNoise(100,5,length(msg)); y0=N+y0; demmsg0=pskdemod(y0,2); recode0=reshape(demmsg0',1,[]); [num0,rat0]=biterr(recode0,msg); BER0(n,k)=rat0; end end BER0=mean(BER0); %---------------------- trellis=poly2trellis(3,[5,7]); code=convenc(msg,trellis); for n=1:cycl for k=1:length(SNR) modbit1=pskmod(code,2); y1=awgn(modbit1,SNR(k),'measured'); N1=BurstNoise(100,5,length(code)); y1=N1+y1; demmsg1=pskdemod(y1,2); recode1=reshape(demmsg1',1,[]); tblen=5; decoded1=vitdec(recode1,trellis,tblen,'cont','hard'); [num1,rat1]=biterr(double(decoded1(tblen+1:end)),msg(1:end-tblen)); BER1(n,k)=rat1; end end BER1=mean(BER1); %----------------------------- code2=encode(msg,7,4,'hamming'); for n=1:cycl for k=1:length(SNR) modbit2=pskmod(code2,2); y2=awgn(modbit2,SNR(k),'measured'); N2=BurstNoise(100,5,length(code2)); y2=N2+y2; demmsg2=pskdemod(y2,2); recode2=reshape(demmsg2',1,[]); bitdecoded=decode(recode2,7,4,'hamming'); error2=(bitdecoded~=msg); errorbits=sum(error2); BER2(n,k)=errorbits/length(msg); end end BER2=mean(BER2); %------------------------------------------- semilogy(SNR,BER0,'b - o',SNR,BER1,'r - s',SNR,BER2,'k - +'); legend('未编码','卷积编码','汉明编码'); title('突发干扰情况下卷积码编码性能'); xlabel('SNR/dB'); ylabel('BER'); grid on;