卷积码译码

%[2,1,2]递归卷积码,维特比译码 clear; %---------------------码序列--------------------------- m = [randint(1,10000,[0,1]),zeros(1,2)]; %------------------------------------------------------ A=1;sigma=0.32; %---------------------编码----------------------------- C = convolution_212_DG(m); C = (C == 1) - ( C == 0); %双极性码,0对应-1 C2 = A*C + randn(1,length(C))*sigma; %加噪 C2 = (C2 >= 0) - (C2 <0); error_1=sum(C2~=C); %------------------------------------------------------ %--------------------维特比译码------------------------- for i = 1:length(m)+1 %初始化 for j = 1:4 state{i,j}.st_last_num = 0; state{i,j}.dis = 0; end end for i = 2:length(m)+1 temp = [C2((i-1)*2-1),C2((i-1)*2)]; for j=1:4 switch j case 1 dis_1 = abs(sum([-1 -1] ~= temp)) + state{i-1,1}.dis; dis_2 = abs(sum([1 1] ~= temp)) + state{i-1,2}.dis; if dis_1 < dis_2 state{i,j}.st_last_num = 0; state{i,j}.dis = dis_1; else state{i,j}.st_last_num = 1; state{i,j}.dis = dis_2; end case 2 dis_1 = abs(sum([1 -1] ~= temp)) + state{i-1,3}.dis; dis_2 = abs(sum([-1 1] ~= temp)) + state{i-1,4}.dis; if dis_1 < dis_2 state{i,j}.st_last_num = 2; state{i,j}.dis = dis_1; else state{i,j}.st_last_num = 3; state{i,j}.dis = dis_2; end case 3 dis_1 = abs(sum([-1 -1] ~= temp)) + state{i-1,2}.dis; dis_2 = abs(sum([1 1] ~= temp)) + state{i-1,1}.dis; if dis_1 < dis_2 state{i,j}.st_last_num = 1; state{i,j}.dis = dis_1; else state{i,j}.st_last_num = 0; state{i,j}.dis = dis_2; end case 4 dis_1 = abs(sum([1 -1] ~= temp)) + state{i-1,4}.dis; dis_2 = abs(sum([-1 1] ~= temp)) + state{i-1,3}.dis; if dis_1 < dis_2 state{i,j}.st_last_num = 3; state{i,j}.dis = dis_1; else state{i,j}.st_last_num = 2; state{i,j}.dis = dis_2; end end end end ord = zeros(1,length(m)+1); %状态变化 j=1; for i=length(m)+1:-1:2 ord(i-1) = state{i,j}.st_last_num; j = state{i,j}.st_last_num + 1; end for i= 2:length(m)+1 %译码 if ord(i-1)==0 && ord(i)==0 M(i-1)=0; end if ord(i-1)==0 && ord(i)==2 M(i-1)=1; end if ord(i-1)==1 && ord(i)==2 M(i-1)=0; end if ord(i-1)==1 && ord(i)==0 M(i-1)=1; end if ord(i-1)==2 && ord(i)==1 M(i-1)=1; end if ord(i-1)==2 && ord(i)==3 M(i-1)=0; end if ord(i-1)==3 && ord(i)==3 M(i-1)=1; end if ord(i-1)==3 && ord(i)==1 M(i-1)=0; end end error = sum(M~=m); %误码率