16QAM_星形和矩形星座圖調制解調MATLAB代碼

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(shù)fd=250*106; %碼元速率250Mfs=2500*106; %濾波器采樣率fc=2500*106; %載波頻率2.5Gf=10000*106; %對載波采樣data_len=200000; %數(shù)據(jù)長度sym_len=data_len/4; %碼元序列長度M_QAM=16;%QAM數(shù)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echo off;rec_qam16=QamMod(bit_tx,1

2、6); %方形16QAM調制star_qam16=SrarQamMod(bit_tx); %星形16QAM調制base_rec=base_shape(fd,fs,f,rec_qam16); %基帶成型濾波 base_star=base_shape(fd,fs,f,star_qam16); %基帶成型濾波 for i=1:length(SNR) %信噪比從1dB到12dB計算誤碼率 SNR_=i %方形映射16QAM rf_rec_qam16=CarrierMod(fc,f,base_rec); %載波調制 rf_rec_qam16_n=awgn(rf_rec_qam16,SNR(i),meas

3、ured); %加噪聲 rec_qam16_rx base_rec_rx=CarrierDemod(fd,fs,fc,f,rf_rec_qam16_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16QAM rf_star_qam16=CarrierMod(fc,f,base_sta

4、r); %載波調制 rf_star_qam16_n=awgn(rf_star_qam16,SNR(i),measured); %加噪聲 star_qam16_rx base_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; %scatterplo

5、t(star_qam16_rx); end% 理論誤碼率計算SNRtheo=0:0.1:length(SNR);for i=1:length(SNRtheo) SNRdec=10.(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(fā)送端波形figure;stem(n,bit_tx(n); title(發(fā)送序列); %發(fā)送序列figure(Name,發(fā)送端基帶信號);subplot(411);plot(t,real(base_rec(t); title(方形

6、映射-Q路);subplot(412);plot(t,imag(base_rec(t); title(方形映射-I路);subplot(413);plot(t,real(base_star(t); title(星形映射-Q路);subplot(414);plot(t,imag(base_star(t); 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)

7、;subplot(411);plot(t,real(base_rec_rx(t); title(方形映射-Q路);subplot(412);plot(t,imag(base_rec_rx(t); title(方形映射-I路);subplot(413);plot(t,real(base_star_rx(t); title(星形映射-Q路);subplot(414);plot(t,imag(base_star_rx(t); title(星形映射-I路);%基帶眼圖N1=20000;Tn=f/fd;eye_rex=base_rec(1:N1);eyediagram(eye_rex,Tn*4,Tn);

8、 title(方形基帶眼圖);eye_star=base_star(1:N1);eyediagram(eye_star,Tn*4,Tn); 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);for i=3:3:12 subplot(2,2,i/3); plot(real(qam16_data_rec(i,:),imag(qam16_data_rec(i,:),.); xmax=5;axis(-xmax xmax -xmax xmax) title(Snr=,num2str(SNR

9、(i), dB); endfigure(Name,星形16QAM接收端星座圖);for i=3:3:12 subplot(2,2,i/3); plot(real(qam16_data_star(i,:),imag(qam16_data_star(i,:),.); xmax=3;axis(-xmax xmax -xmax xmax) grid on; 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_qam

10、16);% hold on;semilogy(SNR,perr_qam16_rec,*);hold on;semilogy(SNR,perr_qam16_star,o);xlabel(SNR in dB);ylabel(Prb of Err);legend(方形16QAM,星形16QAM);title(16QAM誤碼性能對比);%-% 基帶成型function base_info=base_shape(fd,fs,f,seq_16QAM)%平方根升余弦濾波器,滾降系數(shù)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_16Q

11、AM);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=conv(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function data_rx base_rx=CarrierDemod(fd,fs,fc,

12、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*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(0 rc_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

13、_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=(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function transmit=CarrierMod(fc,f,bas

14、e)%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_freq_Q+high_freq_I;%-% QAM解調程序，將MQAM碼元還原為二進制數(shù)據(jù)% 入口參數(shù)：data_QAM：QAM碼元數(shù)據(jù)% M_QAM:MQAM中M的大小% 出口參數(shù)：二進制數(shù)據(jù)比特流%-function data_out=QamDemod(data_QAM,M_QAM)k=log2(M_QAM);%每個M進制碼元的bit數(shù)da

15、ta_len=length(data_QAM);%碼元長度%-%QAM信號放縮至與發(fā)送端相同比例data_temp=data_QAM(find(real(data_QAM0);aver=mean(real(data_temp);data_Qam_temp=data_QAM/aver*(2(k/2-1);%-%平移到第一象限data_Qam_temp2=(data_Qam_temp+(2(k/2)-1)*(1+j)/2;%-%將實部虛部分別映射為二進制數(shù)據(jù)%實部data_real=round(real(data_Qam_temp2);%實部判決data_real(find(data_real(2(k/2)-1)=2(k/2)-1;%大于2(k/2)-1的數(shù)據(jù)判定為2(k/2)-1data_real(find(data_real(2(k/2)-1)=2(k/2)-1;%大于2(k/2)-1的數(shù)據(jù)判定為2(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;