matlab_LDPC_编码译码_BPSK调制_误码率_低密度奇偶校验

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % 实现功能: % 0. 生成Gallager生成矩阵 % 1. bpsk调制，经过高斯白噪声信道 % 2. 采用对数域的和积译码算法 % 3. 计算BER %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %生成生成Gallager矩阵 clear all close all clc tic miu=3;wr=4;wc=3; % 矩阵H的尺寸为：[miu*wc,miu*wr]，行数：miu*wc，列数：miu*wr，这里的H为[9 18]矩阵 [H,rows,cols] = Gallager_gen_LDPC(miu,wr,wc); % 调用函数Gallager_gen_LDPC生成Gallager生成矩阵 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% [rows,cols]=size(H); %矩阵行与列的大小 n=cols; k=n-rows; %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %初始化 dB=[0:5]; % 定义信噪比的范围单位为dB SNRpbit=10.^(dB/10); % Eb/No conversion from dB to decimal将dB的单位变成十进制的 N0 = 1./SNRpbit; % Eb=1 求出噪声的单边功率谱密度，单边功率谱密度告诉我们在信号的1赫兹带宽中加入的噪声的功率 R = k/n; % 码率 iteration = 50; % 设置最大迭代次数 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% N = round(10^3/n); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% BER=zeros(1,length(dB)); % array for Channel Error Rate %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Errors=zeros(1,length(N*n)); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% for z=1:length(dB) %对每个信噪比进行仿真 %%%%%%%%%%%%%%% BPSK调制 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% for m=1:N v = round(rand(1,k)); [G,valid,t]=H2G(H); % 由校验矩阵生成生成矩阵 u=mod(v*G,2);% 由生成矩阵生成码字 tx_waveform=bpsk(u); % 调用BPSK函数，经过BPSK调制为全-1 sigma=sqrt(N0(z)/2); % 因为N0＝2*sigma^2 rx_waveform=tx_waveform + sigma*randn(1,length(tx_waveform)); % rx_waveform为接收到的波形，产生一个服从N(0,1)分布的量，然后用它乘上sigma就表示服从N（0，sigma^2）分布 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %译码 vhat = decodeLogDomain(rx_waveform, H, sigma, iteration); %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %计算BER Errors(n*(m-1)+find(u~=vhat))=1; %将译出的码字与传输的码字比较，将对应不相等的位 end BER(z)=sum(Errors)/(N*n); %计算比特错误率 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% semilogy(dB,BER,'-o'); %画图 title('Bit Error Rate'); ylabel('BER'); xlabel('Eb/No (dB)'); grid on; toc %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%