LDPC码编译码matlab代码

function H=peg(length_all,length_info,d) length_check=length_all-length_info; H_info=zeros(length_check,length_info); %% %信息位的编码 record=zeros(1,length_check); i=1; select=randperm(length_check,d(i));%随机选取3个 H_info(select,i)=1; record(select)=record(select)+1; while min(record)==0%第二个输出符号开始,未全覆盖则努力 i=i+1; wheremin=find(record==min(record));%即此时min(record)为0； temporary=ones(1,length_check); f=0; while min(record)==0&&f<d(i)%未全覆盖且第i个信息位的边没加完 f=f+1; fff=randperm(length(wheremin),1); H_info(wheremin(fff),i)=1; %将这个对应G中的位置 置一 record(wheremin(fff))=record(wheremin(fff))+1;%度数+1 temporary(wheremin(fff))=0;%表示被选过了 wheremin=find(record==min(record)); end%全覆盖了，可以开始考虑树了 remain=d(i)-f;%第i个信息位是否添加完 if remain~=0%没玩 aaa=find(temporary==1);%还没用过的校验节点 select_remain=randperm(length(aaa),remain);%此时检验节点度都是1，所以随机 H_info(aaa(select_remain),i)=1; %将这个对应G中的位置 置一 record(aaa(select_remain))=record(aaa(select_remain))+1;%度数+1 end end%现在所有的输入符号的度数都至少是1了，全覆盖，正确无误 then=i+1;%从下一个信息节点开始 %% for i=then:length_info%以后的信息节点 disp(i) select=zeros(1,d(i));%第i个信息节点选了哪些校验节点 wheremin=find(record==min(record)); ff=randperm(length(wheremin),1);%wheremin中第ff个 select(1)=wheremin(ff);%该输出符号的第一条边与度最小的输入符号相连 H_info(select(1),i)=1; record(wheremin(ff))=record(wheremin(ff))+1;%又选了一次，度数+1 temporary=ones(1,length_check); temporary(select(1))=0;%选过了的不能再选 for s=2:d(i)%还要选这么多个校验节点 rember=zeros(5,length_check);%记录树形 H_inof_tree=H_info; heigh=1;%树的高度 out2in=find(H_info(:,i)==1);%与第i个信息节点（根）相连的第一层 N->K H_inof_tree(out2in,i)=0;%拆掉，避免重复 rember(heigh,out2in)=1;%第一层 %必须用while，因为不知道树有多高 choose_record=ones(1,length_check); choose_record(out2in)=0; while 1 G_row=H_inof_tree(out2in,:);%这些行（校验节点）与欲求的信息节点相连,要对每一行查1，即下一层的信息节点 H_inof_tree(out2in,:)=0;%拆掉该输入节点 if length(out2in)==1 in2out=find(G_row==1); else in2out=find(max(G_row)==1); end if isempty(in2out) break; end G__clo=H_inof_tree(:,in2out);%1 2 3 H_inof_tree(:,in2out)=0; G_col=G__clo'; if length(in2out)==1 inter_out2in=find(G_col==1); else inter_out2in=find(max(G_col)==1); end if isempty(inter_out2in) break; end heigh=heigh+1;%都不空，树高度+1 out2in_old=inter_out2in; out2in=inter_out2in;%本来在这里+1 rember(heigh,out2in_old)=1; choose_record(out2in_old)=0; end if max(choose_record)==1%有校验节点不在树里 not_in_tree=find(choose_record==1);%这些节点不在树中 not_in_tree_min=find(record(not_in_tree)==min(record(not_in_tree))); fff=randperm(length(not_in_tree_min),1); select(s)=not_in_tree(not_in_tree_min(fff)); else%校验节点都在树里，在树里找 longest=find(rember(heigh,:)==1); in_tree_min=find(record(longest)==min(record(longest))); fff=randperm(length(in_tree_min),1); select(s)=longest(in_tree_min(fff)); end H_info(select(s),i)=1; record(select(s))=record(select(s))+1; temporary(select(s))=0; end end ss=ones(1,length_check); H_check=diag(ss);%需要是一个三角矩阵，上或者下 for i=1:length_check-1 H_check(i+1,i)=1; end H=[H_info H_check];