(完整word版)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clc clear%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_len=200000;sym_len=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,% bit_tx=randint(1,data_len);% 产生随机序列 echo off;%方形16QAM 调制% 星形 16QAM 调制

2、%基带成型滤波% 基带成型滤波% 信噪比从1dB 到 12dB 计算误码率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);for i=1:length(SNR)SNR=i%方形映射16QAMrf_rec_qam16=CarrierMod(fc,f,base_rec);%载波调制rf_rec_qam16_n=awgn(rf_rec_qam16,SNR(i),measure

3、d);%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num_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);%载波调制r

4、f_star_qam16_n=awgn(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;%scatterplot(star_qam16_rx);

5、end% 理论误码率计算SNRtheo=0:0.1:length(SNR);for i=1:length(SNRtheo)SNRdec=10.A(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);plot(t,real(base_rec(t); title( 方形映射-Q 路 );subplot(

6、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, 接收端基带信号);subp

7、lot(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_rx(t);%基带眼图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,T

8、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(12,:);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(Snr=,num2str(SNR(

9、i), dB);endfigure(Name, 星形 16QAM 接收端星座图);for i=3:3:12subplot(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(Snr=,num2str(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_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 误码性能对比);% 基带成型function base_info=base_shape(fd,fs,f,seq_16QAM)%平方根升余弦滤波器,滚降系数0.5，延迟3 个采样点flt=rcosine(fd,fs,sqrt,0.5);%I 路和 Q 路seq_Q=real(s

11、eq_16QAM);seq_I=imag(seq_16QAM);%增采样R=fs/fd;up_seq_Q=upsample(seq_Q,R);up_seq_I=upsample(seq_I,R);%升余弦调制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;% 载波解调function data_rx base_rx=CarrierDemod(fd,fs

12、,fc,f,receive)% 分两路乘正交高频载波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);%减采样后根升余弦匹配滤波，注意对齐采样点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);b

13、ase_rx=low_Q_rcos(1:length(low_I_rcos)+j*low_I_rcos;%两次根升余弦滤波延迟，定位初始信号位置%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);%类型转换data_rx=rc_Q_seq+j*rc_I_seq;% 载波调制function transmit=CarrierMod(fc,f,bas

14、e)%载波调制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 解调程序，将MQAM 码元还原为二进制数据%入口参数：data_QAM ： 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%function data_out=QamDemod(data_QAM,M_QAM)k=log2(M_QAM);% 每个 M 进制码元的b

15、it 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(find(real(data_QAM0);aver=mean(real(data_temp);data_Qam_temp=data_QAM/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;%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)-1 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_imag(find(data_imag2)=2;% 幅度大于2 的判定为2am(find(am1.5)=1;% 幅度大于2 的判定为2%相位判定ang=angle(qam_rev)/pi*180;% 将 -180 度到 0