ieee802_16_ctc.m

国外大学的同志作出来的好程序

function [sys_bits, ctc_codedbits, zp_info_bits]=ieee802_16_ctc(info_bits, interleaver_type);
%implement the convolutional
%turbo encoder in IEEE 802.16-SCa standard (page 368)
%with some modifications:
%for long information blocks: make it into blocks of 256*8 bit length.
%
%
%Aijun Song
byte=8;
nibble=4;

if nargin<1 | nargin>3
    disp('[ieee802_16_ctc]Number of input not supported.')
    return;
end

num_infobits=length(info_bits);
%Make N=(num_infobits/2) multiple of 4, but not multiple of 7.
tval=mod(num_infobits, 8);
if tval~=0,
    zp_info_bits=[info_bits; zeros(8-tval, 1)];
    disp('[ieee802_16_ctc]Warning: source infobits has been padded(for multiple-8).');
else
    zp_info_bits=info_bits;
end
tval=mod(num_infobits, 14);
if tval==0,
    zp_info_bits=[info_bits; zeros(8, 1)];
    disp('[ieee802_16_ctc]Warning: source infobits has been padded(for not multiple-7).');
else
    zp_info_bits=info_bits;
end

%if the length is less than 32 byte, ctc is not suitable.
%specified in 802-16 standard.
num_infobits=length(zp_info_bits);
if num_infobits<32*byte,
    disp('[ieee802_16_ctc]The number of source bits is less than 32 byte.');
    output=[]; zp_info_bits=[];
    return;
end

if nargin==1 & num_infobits<256*byte
    interleaver_type='arp';
elseif nargin==1 & num_infobits>256*byte
    interleaver_type='random';
end
if isempty(interleaver_type) & num_infobits<256*byte
    interleaver_type='arp';
elseif isempty(interleaver_type) & num_infobits>256*byte
    interleaver_type='random';
end

%choose a number for random interleaver state.
if strcmp(lower(interleaver_type), 'random'),
    interleaver_state=99828;
end


%for large block, trim it into 256*byte*nF
if num_infobits>512*byte & strcmp(lower(interleaver_type), 'arp'),
    nF= floor(num_infobits/(256*byte));
    if nF*256*byte~=length(zp_info_bits),
        disp('[ieee802_16_ctc]Warning: info bits beyond 512*byte trimmed.');
    end
    zp_info_bits=zp_info_bits(1: nF*256*byte);
    info_bits_mat=zp_info_bits(1: nF*256*byte);
    info_bits_mat=reshape(info_bits_mat, 256*byte, nF);
else
    info_bits_mat=zp_info_bits;
end

trellis=ieee802_16_ctc_trellis;
convenc_type='notailing';
codedbits_mat=[];
for ic=1: size(info_bits_mat, 2),

    %Get infobits
    cinfobits=info_bits_mat(:, ic);

    %encoded by C1 without interleaver
    %Try to code first and find circulation state
    [tval, ES]=trellis_encoder(cinfobits, trellis, 0, convenc_type);

    %get trellis variable compatible with MATLAB
    tt=trellis;
    tt=rmfield(tt,'numTotalInput');
    tt=rmfield(tt,'numTotalOutput');
    [tval2, ES2]=convenc(double(cinfobits), tt, 0);

    if tval~=tval2 | ES~=ES2
        disp('[ieee802_16_ctc]Error: trellis encoding errors spotted by CONVENC.');
    else
        %disp('[ieee802_16_ctc]Trellis encoding has been confirmed right.');
    end

    cs=ieee802_16_ctc_circulations_state(ES, length(cinfobits)/2);
    %encoded by C1 without interleaver but with circulation state
    [coded_bits_c1, currentState]=trellis_encoder(cinfobits, trellis, cs, convenc_type);
    if cs~=currentState
        disp('[ieee802_16_ctc]Errors in circulation state caculation.')
        return;
    end

    [tval2, currentState2]=convenc(double(cinfobits), tt, cs);
    if coded_bits_c1~=tval2 | currentState~=currentState2
        disp('[ieee802_16_ctc]Error: trellis encoding errors spotted by CONVENC.');
    else
        %disp('[ieee802_16_ctc]Trellis encoding has been confirmed right.');
    end

    %encoded by C2 with interleaver
    %Try to code first and find circulation state
    %interleaving
    if strcmp(lower(interleaver_type), 'arp'),
       cint_infobits=ieee802_16_ctc_interleaver(cinfobits);
    elseif strcmp(lower(interleaver_type), 'random'),
       cint_infobits=randintrlv(double(cinfobits), interleaver_state);
    end

    [tval, ES]=trellis_encoder(cint_infobits, trellis, 0, convenc_type);
    cs=ieee802_16_ctc_circulations_state(ES, length(cint_infobits)/2);

    %encoded by C2 with interleaver/circulation state
    [coded_bits_c2, currentState]=trellis_encoder(cint_infobits, trellis, cs, convenc_type);
    if cs~=currentState
        disp('[ieee802_16_ctc]Errors in circulation state caculation.')
        return;
    end
    codedbits_mat=[codedbits_mat; coded_bits_c1 coded_bits_c2];
end

%all the coded bits into two column: first column for C1
%second column for C2.
ctc_codedbits=[codedbits_mat];

sys_bits=zp_info_bits;