1、%軟件無線電課程設計%方形、星形16QAM調制解調仿真%主程序clcclear%定義參數fd=250*10A6;fs=2500*10A6;恒=2500*10人6;f=10000*10A6;data_len=200000;sym_len=data_len/4;%碼元序列長度%方形映射16QAMrf_rec_qam16=CarrierMod(fc,f,base_rec);%載波調制rf_rec_qam16_n=awgn(rf_rec_qam16,SNR(i),measured);%加噪聲rec_qam16_rxbase_rec_rx=CarrierDemod(fd,fs,fc,f,rf_rec_q

2、am16_n);%載波解調bit_rec_rx=QamDemod(rec_qam16_rx,16);%MQAM解調num_qam16,perr_qam16_rec(i)=biterr(bit_tx,bit_rec_rx);%誤碼率qam16_data_rec(i,:)=rec_qam16_rx;%scatterplot(rec_qam16_rx);%星形映射16QAMrf_star_qam16=CarrierMod(fc,f,base_star);%載波調制rf_star_qam16_n=awgn(rf_star_qam16,SNR(i),measured);%加噪聲%碼元速率250M%濾波器

3、采樣率%載波頻率2.5G%對載波采樣%數據長度M_QAM=16;%QAM數k=log2(M_QAM);SNR=1:12;%白噪聲信噪比，%bit_tx=randint(1,data_len);%產生隨機序列echooff;rec_qam16=QamMod(bit_tx,16);star_qam16=SrarQamMod(bit_tx);base_rec=base_shape(fd,fs,f,rec_qam16);base_star=base_shape(fd,fs,f,star_qam16);fori=1:length(SNR)SNR=i%方形16QAM調制%星形16QAM調制%基帶成型濾波%

4、基帶成型濾波%信噪比從1dB到12dB計算誤碼率star_qam16_rxbase_star_rx=CarrierDemod(fd,fs,fc,f,rf_star_qam16_n);%載波解調bit_star_rx=StarQamDemod(star_qam16_rx);%MQAM解調num_qam16,perr_qam16_star(i)=biterr(bit_tx,bit_star_rx);%誤碼率qam16_data_star(i,:)=star_qam16_rx;%scatterplot(star_qam16_rx);end%理論誤碼率計算SNRtheo=0:0.1:length(SN

5、R);fori=1:length(SNRtheo)SNRdec=10.A(SNRtheo(i)/10);theo_perr_qam16(i)=(3/8)*erfc(sqrt(SNRdec*2/5);end%基帶波形N=200;n=1:N;t=1:N*10;%發送端波形figure;stem(n,bit_tx(n);title(發送序列)；發送序列figure(Name,發送端基帶信號)；subplot(411);plot(t,real(base_rec(t);title(方形映射-Q路);subplot(412);plot(t,imag(base_rec(t);title(方形映射-I路);s

6、ubplot(413);plot(t,real(base_star(t);title(星形映射-Q路,);subplot(414);plot(t,imag(base_star)；title(星形映射-I路,);%接收端波形figure;subplot(211);stem(n,bit_rec_rx(n);title(方形接收序列,);subplot(212);stem(n,bit_star_rx(n);title(星形接收序列,);figure(Name,接收端基帶信號)；subplot(411);plot(t,real(base_rec_rx(t);title(方形映射-Q路,);subplo

7、t(412);plot(t,imag(base_rec_rx(t);subplot(413);plot(t,real(base_star_rx(t);subplot(414);plot(t,imag(base_star_rx(t);%基帶眼圖N1=20000;Tn=f/fd;eye_rex=base_rec(1:N1);eyediagram(eye_rex,Tn*4,Tn);eye_star=base_star(1:N1);eyediagram(eye_star,Tn*4,Tn);title（方形映射-I路）;title（星形映射-Q路）;title（星形映射-I路）;title（方形基帶眼圖

8、）;title（星形基帶眼圖）;%接收端星座圖%scatterplot(qam16_data_rec(12,:);figure(Name,方形16QAM接收端星座圖);fo門=3:3:12subplot(2,2,i/3);plot(real(qam16_data_rec(i,:),imag(qam16_data_rec(i,:),.);xmax=5;axis(-xmaxxmax-xmaxxmax)title(Snr=,num2str(SNR(i),dB);endfigure(Name,星形16QAM接收端星座圖);fori=3:3:12subplot(2,2,i/3);plot(real(qa

9、m16_data_star(i,:),imag(qam16_data_star(i,:),.);xmax=3;axis(-xmaxxmax-xmaxxmax)gridon;title(Snr=,num2str(SNR(i),dB);end%功率譜密度f_plot;%誤碼率分析%16QAM誤碼率曲線figure(Name,16QAM誤碼性能對比);%semilogy(SNRtheo,theo_perr_qam16);%holdon;semilogy(SNR,perr_qam16_rec,*);holdon;semilogy(SNR,perr_qam16_star,o);xlabel(SNRind

10、B);ylabel(PrbofErr);legend(方形16QAM,星形16QAM);title(16QAM誤碼性能對比,);%基帶成型functionbase_info=base_shape(fd,fs,f,seq_16QAM)%平方根升余弦濾波器，滾降系數0.5,延遲3個采樣點flt=rcosine(fd,fs,sqrt,0.5);%I路和Q路seq_Q=real(seq_16QAM);seq_I=imag(seq_16QAM);%增采樣R=fs/fd;up_seq_Q=upsample(seq_Q,R);up_seq_I=upsample(seq_I,R);%升余弦調制rcos_Q=c

11、onv(up_seq_Q,flt);rcos_I=conv(up_seq_I,flt);%提升rcos_Q_up=interp(rcos_Q,f/fs);rcos_I_up=interp(rcos_I,f/fs);base_info=rcos_Q_up+j*rcos_I_up;%載波解調functiondata_rxbase_rx=CarrierDemod(fd,fs,fc,f,receive)%分兩路乘正交高頻載波rc_length=length(receive);flt=rcosine(fd,fs,sqrt,0.5);t=0:rc_length-1;rc_Q=receive.*sin(2*

12、pi*fc*t/f);rc_I=receive.*cos(2*pi*fc*t/f);%減采樣后根升余弦匹配濾波，注意對齊采樣點down_Q=downsample(0rc_Q,f/fs);down_I=downsample(rc_I,f/fs);low_Q_rcos=conv(down_Q,flt);low_I_rcos=conv(down_I,flt);base_rx=low_Q_rcos(1:length(low_I_rcos)+j*low_I_rcos;%兩次根升余弦濾波延遲，定位初始信號位置%delay+1:end-delay-1R=fs/fd;delay=3*R*2;rc_Q_seq=

13、(downsample(low_Q_rcos(delay+1:end-delay-1),R);rc_I_seq=(downsample(low_I_rcos(delay+1:end-delay-1),R);%類型轉換data_rx=rc_Q_seq+j*rc_I_seq;%載波調制functiontransmit=CarrierMod(fc,f,base)%載波調制t=0:length(base)-1;high_freq_Q=real(base).*sin(2*pi*fc*t/f);high_freq_I=imag(base).*cos(2*pi*fc*t/f);transmit=high_f

14、req_Q+high_freq_I;%QAM解調程序，將MQAM碼元還原為二進制數據%人口參數：data_QAM:QAM碼元數據%M_QAM:MQAM中M的大小%出口參數：二進制數據比特流%functiondata_out=QamDemod(data_QAM,M_QAM)k=log2(M_QAM);%每個M進制碼元的bit數data_len=length(data_QAM);%碼元長度%QAM信號放縮至與發送端相同比例data_temp=data_QAM(find(real(data_QAM0);aver=mean(real(data_temp);data_Qam_temp=data_QAM/

15、aver*(2A(k/2-1);%平移到第一象限data_Qam_temp2=(data_Qam_temp+(2A(k/2)-1)*(1+j)/2;%將實部虛部分別映射為二進制數據%實部data_real=round(real(data_Qam_temp2);%實部判決data_real(find(data_real(2A(k/2)-1)=2A(k/2)-1;%大于2A(k/2)-1的數據判定為2A(k/2)-1data_real(find(data_real(2A(k/2)-1)=2A(k/2)-1;%大于2A(k/2)-1的數據判定為2A(k/2)-1data_imag(find(data_imag2)=2;%幅度大于2的判定為2am(find(am1.5)=1;%幅度大于2的判定為2%相位判定ang=angle(qam_rev)/pi*180;%將-18