16qam星形和矩形星座圖調(diào)制解調(diào)matlab代碼

1、% -% 軟件無線電課程設(shè)計% 方形、星形16qam調(diào)制解調(diào)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(chǎn)生隨機序列echo off;rec_qam16=qammod(bit_tx,16

2、); %方形16qam調(diào)制star_qam16=srarqammod(bit_tx); %星形16qam調(diào)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(diào)制 rf_rec_qam16_n=awgn(rf_rec_qam16,snr(i),measu

3、red); %加噪聲 rec_qam16_rx base_rec_rx=carrierdemod(fd,fs,fc,f,rf_rec_qam16_n); %載波解調(diào) bit_rec_rx=qamdemod(rec_qam16_rx,16); %mqam解調(diào) 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_star

4、); %載波調(diào)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(diào) bit_star_rx=starqamdemod(star_qam16_rx); %mqam解調(diào) num_qam16,perr_qam16_star(i)=biterr(bit_tx,bit_star_rx);%誤碼率 qam16_data_star(i,:)=star_qam16_rx; %scatterplot

5、(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(方形映

6、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_qam1

10、6);% 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_16qa

11、m);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(diào)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(diào)function data_rx base_rx=carrierdemod(fd,fs,fc,f

12、,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(zhuǎn)換data_rx=rc_q_seq+j*rc_i_seq;%-% 載波調(diào)制function transmit=carriermod(fc,f,base

14、)%載波調(diào)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(diào)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)dat

15、a_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