16QAM_星形和矩形星座图调制解调MATLAB代码

1、%软件无线电课程设计%方形、星形16QAM调制解调仿真% %主程序clcclear%码元速率250M%滤波器采样率%载波频率2.5G%对载波采样%数据长度%定义参数 fd=250*10A6;fs=2500*10A6; fc=2500*10A6;f=10000*10A6; data_le n=200000;symen=data_len/4; %码元序列长度M_QAM=16;%QAM 数k=log2(M_QAM);SNR=1:12;%白噪声信噪比，%方形16QAM调制%星形16QAM调制bit_tx=randint(1,data_len);% 产生随机序列 echo off;rec_qam16=Q

2、amMod(bit_tx,16); star_qam16=SrarQamMod(bit_tx);base_rec=base_shape(fd,fs,f,rec_qam16); % 基带成型滤波 base_star=base_shape(fd,fs,f,star_qam16); % 基带成型滤波for i=1:le ngth(SNR)SNR_=i%信噪比从1dB到12dB计算误码率%方形映射16QAM rf_rec_qam16=CarrierMod(fc,f,base_rec);% 载波调制rf_rec_qam16_ n=awg n( rf_rec_qam16,SNR(i),'measu

3、red');% 加噪声rec_qam16_rx base_rec_rx=CarrierDemod(fd,fs,fc,f,rf_rec_qam16_ n);% 载波解调bit_rec_rx=QamDemod(rec_qam16_rx,16);%MQAM 解调nu m_qam16,perr_qam16_rec(i)=biterr(bit_tx,bit_rec_rx);%误码率qam16_data_rec(i,:)=rec_qam16_rx;%scatterplot(rec_qam16_rx);%星形映射16QAMrf_star_qam16=CarrierMod(fc,f,base_star

4、);% 载波调制rf_star_qam16_n=awg n(rf_star_qam16,SNR(i),'measured');% 加噪声star_qam16_rx base_star_rx=CarrierDemod(fd,fs,fc,f,rf_star_qam16_n);% 载波解调bit_star_rx=StarQamDemod(star_qam16_rx);%MQAM 解调num _qam16,perr_qam16_star(i)=biterr(bit_tx,bit_star_rx);% 误码率 qam16_data_star(i,:)=star_qam16_rx;%sca

5、tterplot(star_qam16_rx);end%理论误码率计算SNRtheo=0:0.1:le ngth(SNR);for i=1:le ngth(SNRtheo)SNRdec=104(SNRtheo(i)/10); theo_perr_qam16(i)=(3/8)*erfc(sqrt(SNRdec*2/5);end%基带波形N=200;n=1:N;t=1:N*10;%发送端波形figure;stem(n,bit_tx(n);title('发送序列');%发送序列figure('Name','发送端基带信号');subplot(411);

6、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');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('

7、;方形接收序列');subplot(212);stem(n,bit_star_rx(n); title('星形接收序列');figure('Name','接收端基带信号');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); subplot(413); plot(t,real(base_star_rx(t); subplot(414); plot(t,imag(base_star

8、_rx(t);%基带眼图N1=20000;Tn=f/fd;eye_rex=base_rec(1:N1); eyediagram(eye_rex,T n*4,T n); eye_star=base_star(1:N1); eyediagram(eye_star,T n*4,T n);title（'方形映射-I路'）;title（'星形映射-Q路'）;title（'星形映射-I路'）;title（'方形基带眼图'）;title（'星形基带眼图'）;%接收端星座图%scatterplot(qam16_data_rec(1

9、2,:); figure('Name','方形16QAM接收端星座图');for i=3:3:12subplot(2,2,i/3);plot(real(qam16_data_rec(i,:),imag(qam16_data_rec(i,:),'.');xmax=5;axis(-xmax xmax -xmax xmax) title('S nr=', nu m2str(SNR(i),' dB'); end figure('Name','星形16QAM接收端星座图'); for i=3:

10、3:12subplot(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('S nr=', nu m2str(SNR(i),' dB');end %功率谱密度f_plot;%误码率分析%16QAM误码率曲线figure('Name','16QAM 误码性能对比'); % semilogy(SNRtheo,theo_perr_qa

11、m16); % 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误码性能对比');%基带成型function basenfo=base_shape(fd,fs,f,seq_16QAM)%平方根升余弦

12、滤波器，滚降系数0.5,延迟3个采样点flt=rcosi ne(fd,fs,'sqrt',0.5);%I路和Q路seq_Q=real(seq_16QAM);seq_I=imag(seq_16QAM);%增采样R=fs/fd;up_seq_Q=upsample(seq_Q,R); up_seq_l=upsample(seq_l,R);%升余弦调制rcos_Q=c on v(up_seq_Q,flt);rcos_I=c on v(up_seq_I,flt);%提升rcos_Q_up=i nterp(rcos_Q,f/fs);rcos_I_up=i nterp(rcos_l,f/fs

13、);base_ in fo=rcos_Q_up+j*rcos_I_up;%载波解调fun ctio n data_rx base_rx=CarrierDemod(fd,fs,fc,f,receive)%分两路乘正交高频载波rc_le ngth=le ngth(receive);flt=rcosi ne(fd,fs,'sqrt',0.5);t=0:rc_le ngth-1;rc_Q=receive .* sin (2*pi*fc*t/f);rc_I=receive .* cos(2*pi*fc*t/f);%减采样后根升余弦匹配滤波，注意对齐采样点dow n_Q=dow nsamp

14、le(0 rc_Q,f/fs);dow n=dow nsample(rc_l,f/fs); low_Q_rcos=c on v(dow n_Q,flt); low_l_rcos=c on v(dow n,flt);base_rx=low_Q_rcos(1:le ngth(low丄rcos)+j*low丄rcos;%两次根升余弦滤波延迟，定位初始信号位置%delay+1:e nd-delay-1R=fs/fd;delay=3*R*2;%类型转换rc_Q_seq=(dow nsample(low_Q_rcos(delay+1:e nd-delay-1),R); rc_I_seq=(dow nsam

15、ple(low丄rcos(delay+1:e nd-delay-1),R);data_rx=rc_Q_seq+j*rc_I_seq;%载波调制fun ctio n tran smit=CarrierMod(fc,f,base)%载波调制t=0:le ngth(base)-1;high_freq_Q=real(base) .* sin (2*pi*fc*t/f); high_freq_I=imag(base) .* cos(2*pi*fc*t/f);tran smit=high_freq_Q+high_freq_I;%QAM解调程序，将 MQAM码元还原为二进制数据%入口参数：data_QAM

16、: QAM码元数据%M_QAM:MQAM 中M的大小%出口参数：二进制数据比特流%fun ctio n data_out=QamDemod(data_QAM,M_QAM)k=log2(M_QAM);% 每个M进制码元的bit数 data_len=length(data_QAM);% 码元长度%QAM信号放缩至与发送端相同比例data_temp=data_QAM(fi nd(real(data_QAM>0);aver=mea n(real(data_temp); data_Qam_temp=data_QAM/aver*(2A(k/2-1);%平移到第一象限data_Qam_temp2=(d

17、ata_Qam_temp+(2A(k/2)-1)*(1+j)/2;%将实部虚部分别映射为二进制数据%实部data_real=round(real(data_Qam_temp2);% 实部判决data_real(find(data_real>(2A(k/2)-1)=2A(k/2)-1;% 大于 2A(k/2)-1 的数据判定为 2A(k/2)-1data_real(find(data_real<0)=0;% 小于 0 的数据判为 0bit_real=abs(dec2bi n(data_real)-'0：%虚部data_imag=round(imag(data_Qam_temp

18、2);% 虚部判决data_imag(find(data_imag>(2A(k/2)-1)=2A(k/2)-1;% 大于 2A(k/2)-1 的数据判定为 2人(刃2)-1 data_imag(find(data_imag<0)=0;% 小于 0 的数据判为 0bit_imag=abs(dec2b in( data_imag)-'0'%还原为二进制比特流bit_rec=bit_real,bit_imag'data_out=reshape(bit_rec,1,data_le n*k);%QAM调制程序，实现二进制到MQam调制%入口参数：binary :二进制

19、数据%M_QAM:MQAM 中M的大小%返回参数：MQAM码元%fun ctio n data_M = QamMod(bi nary,M_QAM)k=log2(M_QAM);% 每个M进制码元的bit数data_len=length(binary);% 比特长度binary_rec=reshape(binary,k,data_len/k)'% 转化为 data_len/k 行，k 列，的矩阵，以便转化为16进制M进制%计算实部data_str1= nu m2str(b in ary_rec(:,1:k/2);data_m_real=b in 2dec(data_str1);%计算虚部d

20、ata_str2=n um2str(bi nary_rec(:,k/2+1:k);data_m_imag=b in 2dec(data_str2);%实部虚部映射到 MQamdata_M=(data_m_real*2-2A(k/2)+1)+j*(data_mmag*2-2A(k/2)+1).'%星形16QAM映射function data_m16 = SrarQamMod(b in ary)%binary=randint(1,1OO);% 产生随机序列data_len=length(binary);% 比特长度binary_rec=reshape(binary,4,data_len/4)'% 转化为 data_len/4 行，4 列，的矩阵，以便转化为 16进制data_str =nu m2str(b in ary_rec);data_dec=b in 2dec