基于MATLAB的(7,4)汉明码的QPSK在AWGN信道下的编译仿真.zip

clear all N = 100000; %信息比特的行数 M = 4; %QPSK调制 n = 7; %Hamming码组长度n=2^m-1 m = 3; %监督位长度 graycode = [0 1 3 2]; msg = randi([0,1],N,n-m); %产生比特数据 msg1 = reshape(msg.',log2(M),N*(n-m)/log2(M)).'; msg1_de = bi2de(msg1,'left-msb'); %消息比特转换为10进制形式 msg1 = graycode(msg1_de+1); %Gray编码 msg1 = pskmod(msg1,M); %QPSK调制 Eb1 = norm(msg1).^2/(N*(n-m)); %计算比特能量 msg2 = encode(msg,n,n-m); %Hamming编码 msg2 = reshape(msg2.',log2(M),N*n/log2(M)).'; msg2_de = bi2de(msg2,'left-msb'); %消息比特转换为10进制形式 msg2 = graycode(msg2_de+1); %Gray编码 msg2 = pskmod(msg2,M); %QPSK调制 Eb2 = norm(msg2).^2/(N*(n-m)); %计算比特能量 EbN0 = 0:2:20; %信噪比 EbN0_lin = 10.^(EbN0/10); %信噪比的线性值 for index=1:length(EbN0_lin) index sigma1 = sqrt(Eb1/(2*EbN0_lin(index))); %未编码的噪声标准差 rx1 = msg1+sigma1*(randn(1,length(msg1))+j*randn(1,length(msg1))); %加入高斯白噪声 y1 = pskdemod(rx1,M); %未编码QPSK解调 y1_de = graycode(y1+1); %未编码的Gray逆映射 [err ber1(index)] = biterr(msg1_de.',y1_de,log2(M)); %未编码的误比特率 sigma2 = sqrt(Eb2/(2*EbN0_lin(index))); %编码的噪声标准差 rx2 = msg2+sigma2*(randn(1,length(msg2))+j*randn(1,length(msg2))); %加入高斯白噪声 y2 = pskdemod(rx2,M); %编码QPSK解调 y2 = graycode(y2+1); %编码的Gray逆映射 y2 = de2bi(y2,'left-msb'); %转换为二进制形式 y2 = reshape(y2.',n,N).'; y2 = decode(y2,n,n-m); %译码 [err ber2(index)] = biterr(msg,y2); %未编码的误比特率 end semilogy(EbN0,ber1,'-ko',EbN0,ber2,'-k*'); legend("未编码","Hamming(7,4)编码"); title("未编码和Hamming(7,4)编码的QPSK在AWGN信道下的性能") xlabel("Eb/N0");ylabel("误比特率"); %结果分界原因是编码增益开始小于信噪比带来的影响