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%%16QAM%%等效基带调制clc;clearall;closeall;%%关闭所有窗口，比如之前画的图nsymbol=10000;%%每种信噪比下符号数的发送符号数，10^6个数errornumber=zeros(1,10);errorratio=zeros(1,10);data=randi([0,1],1,4*nsymbol);%%产生1行，4*nsymbol列均匀分布的随机数data_mod1=zeros(1,nsymbol);%%各参量初始化data_mod2=zeros(1,nsymbol);data_demod1=zeros(1,nsymbol);data_demod2=zeros(1,nsymbol);data_demod3=zeros(1,nsymbol);data_demod4=zeros(1,nsymbol);s_receive1=zeros(1,nsymbol);s_receive2=zeros(1,nsymbol);fori=1:nsymbol%%格雷码调制到星座图的映射ifdata(4*i-3)==0&&data(4*i-2)==0data_mod1(i)=3;ifdata(4*i-1)==0&&data(4*i)==0data_mod2(i)=3;elseifdata(4*i-1)==0&&data(4*i)==1data_mod2(i)=1;elseifdata(4*i-1)==1&&data(4*i)==1data_mod2(i)=-1;elseifdata(4*i-1)==1&&data(4*i)==0data_mod2(i)=-3;endelseifdata(4*i-3)==0&&data(4*i-2)==1data_mod1(i)=1;ifdata(4*i-1)==0&&data(4*i)==0data_mod2(i)=3;elseifdata(4*i-1)==0&&data(4*i)==1data_mod2(i)=1;elseifdata(4*i-1)==1&&data(4*i)==1data_mod2(i)=-1;elseifdata(4*i-1)==1&&data(4*i)==0data_mod2(i)=-3;endelseifdata(4*i-3)==1&&data(4*i-2)==1data_mod1(i)=-1;ifdata(4*i-1)==0&&data(4*i)==0data_mod2(i)=3;elseifdata(4*i-1)==0&&data(4*i)==1data_mod2(i)=1;elseifdata(4*i-1)==1&&data(4*i)==1data_mod2(i)=-1;elseifdata(4*i-1)==1&&data(4*i)==0data_mod2(i)=-3;endelseifdata(4*i-3)==1&&data(4*i-2)==0data_mod1(i)=-3;ifdata(4*i-1)==0&&data(4*i)==0data_mod2(i)=3;elseifdata(4*i-1)==0&&data(4*i)==1data_mod2(i)=1;elseifdata(4*i-1)==1&&data(4*i)==1data_mod2(i)=-1;elseifdata(4*i-1)==1&&data(4*i)==0data_mod2(i)=-3;endendendSNR_dB=1:10;%%%信噪比dB形式SNR=10.^(SNR_dB/10);%%信噪比转化为线性值forloop=1:10sigma=sqrt(5/SNR(loop));s_receive1=data_mod1+sigma*randn(1,length(data_mod1));s_receive2=data_mod2+sigma*randn(1,length(data_mod2));%%??fork=1:nsymbolifs_receive1(k)2data_demod1(k)=0;data_demod2(k)=0;ifs_receive2(k)2data_demod3(k)=0;data_demod4(k)=0;elseifs_receive2(k)0&&s_receive2(k)2data_demod3(k)=0;data_demod4(k)=1;elseifs_receive2(k)-2&&s_receive2(k)0data_demod3(k)=1;data_demod4(k)=1;elseifs_receive2(k)-2data_demod3(k)=1;data_demod4(k)=0;endelseifs_receive1(k)0&&s_receive1(k)2data_demod1(k)=0;data_demod2(k)=1;ifs_receive2(k)2data_demod3(k)=0;data_demod4(k)=0;elseifs_receive2(k)0&&s_receive2(k)2data_demod3(k)=0;data_demod4(k)=1;elseifs_receive2(k)-2&&s_receive2(k)0data_demod3(k)=1;data_demod4(k)=1;elseifs_receive2(k)-2data_demod3(k)=1;data_demod4(k)=0;endelseifs_receive1(k)0&&s_receive1(k)-2data_demod1(k)=1;data_demod2(k)=1;ifs_receive2(k)2data_demod3(k)=0;data_demod4(k)=0;elseifs_receive2(k)0&&s_receive2(k)2data_demod3(k)=0;data_demod4(k)=1;elseifs_receive2(k)-2&&s_receive2(k)0data_demod3(k)=1;data_demod4(k)=1;elseifs_receive2(k)-2data_demod3(k)=1;data_demod4(k)=0;endelseifs_receive1(k)-2data_demod1(k)=1;data_demod2(k)=0;ifs_receive2(k)2data_demod3(k)=0;data_demod4(k)=0;elseifs_receive2(k)0&&s_receive2(k)2data_demod3(k)=0;data_demod4(k)=1;elseifs_receive2(k)-2&&s_receive2(k)0data_demod3(k)=1;data_demod4(k)=1;elseifs_receive2(k)-2data_demod3(k)=1;data_demod4(k)=0;endendif(data_demod1(k)~=data(k*4-3))||(data_demod2(k)~=data(k*4-2))||(data_demod3(k)~=data(k*4-1))||(data_demod4(k)~=data(k*4))errornumber(loop)=errornumber(loop)+1;endenderrorratio(loop)=errornumber(loop)/nsymbol;endt=0.75*erfc(sqrt(3*SNR/30));ser_theory=1-(1-t).^2;%理论误码率，注意Q函数和误差函数的对应关系semilogy(SNR_dB,errorratio,'-k*',SNR_dB,ser_theory,'-ro');title('16QAM信号在AWGN信道下的性能（格雷码）');xlabel('信噪比/dB');ylabel('误码率');legend('误码率','理论误码率');gridon;%%坐标线