matlab-(含教程)基于matlab的QPSK调制解调通信系统性能仿真,输出误码率,星座图等

clear; %%%%%%%%%%%%%%%%%%%%% %%% 初始化参数 %%%%%%%%%%%%%%%%%%%%% T=1; % 基带信号宽度，也就是频率 fc=10/T; % 载波频率 ml=2; % 调制信号类型的一个标志位（选取2的原因见23行） nb=100; % 传输的比特数 delta_T=T/200; % 采样间隔 fs=1/delta_T; % 采样频率 SNR=0; % 信噪比 t=0:delta_T:nb*T-delta_T; % 限定t的取值范围 N=length(t); % 采样数 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%% 调制部分 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 基带信号的产生 data=randn(1,nb)>0.5; % 调用一个随机函数（0 or 1），输出到一个1*100的矩阵 datanrz=data.*2-1; % 变成极性码 data1=zeros(1,nb/delta_T); % 创建一个1*nb/delta_T的零矩阵 for q=1:nb data1((q-1)/delta_T+1:q/delta_T)=datanrz(q); % 将极性码变成对应的波形信号 end % 将基带信号变换成对应波形信号 data0=zeros(1,nb/delta_T); % 创建一个1*nb/delta_T的零矩阵 for q=1:nb data0((q-1)/delta_T+1:q/delta_T)=data(q); % 将极性码变成对应的波形信号 end % 发射的信号 data2=abs(fft(data1)); % 串并转换，将奇偶位数据分开 idata=datanrz(1:ml:(nb-1)); % 将奇偶位分开，因此间隔m1为2 qdata=datanrz(2:ml:nb); % QPSK信号的调制 ich=zeros(1,nb/delta_T/2); % 创建一个1*nb/delta_T/2的零矩阵，以便后面存放奇偶位数据 for i=1:nb/2 ich((i-1)/delta_T+1:i/delta_T)=idata(i); end for ii=1:N/2 a(ii)=sqrt(2/T)*cos(2*pi*fc*t(ii)); end idata1=ich.*a; % 奇数位数据与余弦函数相乘，得到一路的调制信号 qch=zeros(1,nb/2/delta_T); for j1=1:nb/2 qch((j1-1)/delta_T+1:j1/delta_T)=qdata(j1); end for jj=1:N/2 b(jj)=sqrt(2/T)*sin(2*pi*fc*t(jj)); end qdata1=qch.*b; % 偶数位数据与余弦函数相乘，得到另一路的调制信号 s=idata1+qdata1; % 将奇偶位数据合并，s即为QPSK调制信号 ss=abs(fft(s)); % 快速傅里叶变换得到频谱 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%% 瑞利衰落信道和高斯信道 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 瑞利衰落信道 ray_ich=raylrnd(0.8,1,nb/2/delta_T); ray_qch=raylrnd(0.8,1,nb/2/delta_T); Ray_idata=idata1.*ray_ich; Ray_qdata=qdata1.*ray_qch; Ray_s=Ray_idata+Ray_qdata; %%%%%%%%%%%%%%%%%%%%%%%%%% % 高斯信道 s1=awgn(s,SNR); % 通过高斯信道之后的信号 s11=abs(fft(s1)); % 快速傅里叶变换得到频谱 s111=s1-s; % 高斯噪声曲线 %%%%%%%%%%%%%%%%%%%%%%%%%% Awgn_s=awgn(Ray_s,SNR); % 通过高斯信道再通过瑞利衰落信道 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%% QPSK 解调部分 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 解调部分（高斯信道） idata2=s1.*a; % 这里面其实隐藏了一个串并转换的过程 qdata2=s1.*b; % 对应的信号与正余弦信号相乘 idata3=zeros(1,nb/2); % 建立1*nb数组，以存放解调之后的信号 qdata3=zeros(1,nb/2); % 抽样判决的过程，与0作比较，data>=0,则置1，否则置0 for n=1:nb/2 % A1(n)=sum(idata2((n-1)/delta_T+1:n/delta_T)); if sum(idata2((n-1)/delta_T+1:n/delta_T))>=0 idata3(n)=1; else idata3(n)=0; end % A2(n)=sum(qdata2((n-1)/delta_T+1:n/delta_T)); if sum(qdata2((n-1)/delta_T+1:n/delta_T))>=0 qdata3(n)=1; else qdata3(n)=0; end end % 为了显示星座图,将信号进行处理 idata4=zeros(1,nb/2); qdata4=zeros(1,nb/2); for n=1:nb/2 Awgn_ichsum(n)=sum(idata2((n-1)/delta_T+1:n/delta_T))*delta_T; if Awgn_ichsum(n)>=0 idata4(n)=1; else idata4(n)=0; end Awgn_qchsum(n)=sum(qdata2((n-1)/delta_T+1:n/delta_T))*delta_T; if Awgn_qchsum(n)>=0 qdata4(n)=1; else qdata4(n)=0; end end % 将判决之后的数据存放进数组 demodata=zeros(1,nb); demodata(1:ml:(nb-1))=idata3; % 存放奇数位 demodata(2:ml:nb)=qdata3; % 存放偶数位 %为了显示，将它变成波形信号（即传输一个1代表单位宽度的高电平） demodata1=zeros(1,nb/delta_T); % 创建一个1*nb/delta_T的零矩阵 for q=1:nb demodata1((q-1)/delta_T+1:q/delta_T)=demodata(q); % 将极性码变成对应的波形信号 end % 累计误码数 % abs(demodata-data)求接收端和发射端 % 数据差的绝对值，累计之后就是误码个数 Awgn_num_BER=sum(abs(demodata-data)) %%%%%%%%%%%%%%%%%%% % 解调部分（瑞利+高斯） Ray_idata2=Ray_s.*a; % 这里面其实隐藏了一个串并转换的过程 Ray_qdata2=Ray_s.*b; % 对应的信号与正余弦信号相乘 % Ray_idata3=zeros(1,nb/2); % 建立1*nb数组，以存放解调之后的信号 % Ray_qdata3=zeros(1,nb/2); % 抽样判决的过程，与0作比较，data>=0,则置1，否则置0 % for n=1:nb/2 % if Ray_sum(Ray_idata2((n-1)/delta_T+1:n/delta_T))>=0 % Ray_idata3(n)=1; % else Ray_idata3(n)=0; % end % if Ray_sum(Ray_qdata2((n-1)/delta_T+1:n/delta_T))>=0 % Ray_qdata3(n)=1; % else Ray_qdata3(n)=0; % end % end % 为了显示星座图,将信号进行处理 Ray_idata4=zeros(1,nb/2); Ray_qdata4=zeros(1,nb/2); for n=1:nb/2 Ray_ichsum(n)=sum(idata2((n-1)/delta_T+1:n/delta_T))*delta_T; if Ray_ichsum(n)>=0 Ray_idata4(n)=1; else Ray_idata4(n)=0; end Ray_qchsum(n)=sum(qdata2((n-1)/delta_T+1:n/delta_T))*delta_T; if Ray_qchsum(n)>=0 Ray_qdata4(n)=1; else Ray_qdata4(n)=0; end end % 将判决之后的数据存放进数组 Ray_demodata=zeros(1,nb); Ray_demodata(1:ml:(nb-1))=Ray_idata4; % 存放奇数位 Ray_demodata(2:ml:nb)=Ray_qdata4; % 存放偶数位 %为了显示，将它变成波形信号（即传输一个1代表单位宽度的高电平） Ray_demodata1=zeros(1,nb/delta_T); % 创建一个1*nb/delta_T的零矩阵 for q=1:nb Ray_demodata1((q-1)/delta_T+1:q/delta_T)=Ray_demodata(q); % 将极性码变成对应的波形信号 end % 累计误码数 % abs(demodata-data)求接收端和发射端 % 数据差的绝对值，累计之后就是误码个数 Ray_num_BER=sum(abs(Ray_demodata-data)) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %% 误码率计算 %% 调用了cm_sm32();和cm_sm33(）函数 %%声明： 函数声明在另外俩个M文件中 %%作用： cm_sm32()用于瑞利信道误码率的计算 %% cm_sm33()用于高斯信道误码率的计算 %% ecoh on/off 作用在于决定是否显示指令内容 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SNRindB1=0:1:6; SNRindB2=0:0.1:6; % 瑞利衰落信道 for i=1:length(SNRindB1), [pb,ps]=cm_sm32(SNRindB1(i)); % 比特误码率 smld_bit_ray_err_prb(i)=pb; smld_symbol_ray_err_prb(i)=ps; disp([ps,pb]); echo off; end; % 高斯信道 echo on; for i=1:length(SNRindB1), [pb1,ps1]=cm_sm32(SNRindB1(i)); smld_bit_awgn_err_prb(i)=pb1; smld_symbol_awgn_err_prb(i)=ps1; disp([ps1,pb1]); echo off; end; % 理论曲线 echo on; for i=1:length(SNRindB2), SNR=exp(SNRindB2(i)*log(10)/10); % 信噪比 theo_err_awgn_prb(i)=0.5*erfc(sqrt(SNR)); % 高斯噪声理论误码率 theo_err_ray_prb(i)=0.5*(1-1/sqrt(1+1/SNR)); % 瑞利衰落信道理论误码率 echo o