16QAM_星形和形星座图调制解调MATLAB代码

%% ------------------------------------------------------------% 软件无线电课程设计%% 方形、星形16QAM调制解调仿真%%%------------------------------------------------------------%%主程序clcclear%% 定义参数fd=250*10^6; %码元速率250Mfs=2500*10^6; %滤波器采样率fc=2500*10^6; %载波频率2.5Gf=10000*10^6; %对载波采样data_len=200000; %数据长度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;rec_qam16=QamMod(bit_tx,16); %方形16QAM调制star_qam16=SrarQamMod(bit_tx); %星形16QAM调制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:length(SNR) %信噪比从1dB到12dB计算误码率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),'measured'); %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rf_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);end%% 理论误码率计算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(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');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');%基带眼图N1=20000;Tn=f/fd;eye_rex=base_rec(1:N1);eyediagram(eye_rex,Tn*4,Tn); title('方形基带眼图');eye_star=base_star(1:N1);eyediagram(eye_star,Tn*4,Tn); 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(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_qam16);% 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(seq_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,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);base_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,base)%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(find(real(data_QAM>0)));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;%----------------------------------------------------------------------%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>(2^(k/2)-1)))=2^(k/2)-1;%大于2^(k/2)-1的数据判定为2^(k/2)-1 data_real(find(data_real<0))=0;%小于0的数据判为0bit_real=abs(dec2bin(data_real))-'0';%虚部data_imag=round(imag(data_Qam_temp2));%虚部判决data_imag(find(data_imag>(2^(k/2)-1)))=2^(k/2)-1;%大于2^(k/2)-1的数据判定为2^(k/2)-1 data_imag(find(data_imag<0))=0;%小于0的数据判为0bit_imag=abs(dec2bin(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_len*k);%-------------------------------------------------------------------------------------------------------------%% QAM调制程序，实现二进制到MQam调制% 入口参数：binary：二进制数据% M_QAM:MQAM中M的大小% 返回参数：MQAM码元%------------------------------------------------------------------------function data_M = QamMod(binary,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=num2str(binary_rec(:,1:k/2));data_m_real=bin2dec(data_str1);%计算虚部data_str2=num2str(binary_rec(:,k/2+1:k));data_m_imag=bin2dec(data_str2);%实部虚部映射到MQamdata_M=((data_m_real*2-2^(k/2)+1)+j*(data_m_imag*2-2^(k/2)+1)).';%---------------------------------------------------------------------------------%% 星形16QAM映射function data_m16 = SrarQamMod(binary)%binary=randint(1,100);%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=num2str(binary_rec);data_dec=bin2dec(data_str);data_mm16=(floor(data_dec/8)+1).*exp(j*45/180*pi*mod(data_dec,8));data_m16=reshape(data_mm16,1,data_len/4);%------------------------------------------------------------------------------%% 星形16QAM解调function data_bit = StarQamDemod(qam_rev)%qam_rev=xing_qam16_noise(1:10);am=abs(qam_rev);%幅度判定am(find(am>2))=2;%幅度大于2的判定为2am(find(am<1.5))=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度变为180度到360度ang(find(ang<0))=ang(find(ang<0))+360;ang_n=round(ang/45);ang_n(find(ang_n>7))=0;data_dec=8*(round(am)-1)+ang_n;%data_dec(find(data_dec>15))=15;%大于15的判定为15%data_dec(find(data_dec<0))=0;%小于0的判定为0data_bit_rec=dec2bin(data_dec);data_bit=reshape(data_bit_rec',1,length(qam_rev)*4)-'0';。