function?[soft_outex_info]=algorithm_logmap（ingLcpri_infolstatenstatelparoutput）
%turbo?decoder?-logMAP?algorithm
%Input:
%?in???????????--2?by?N?matrix.
%??????????????--row1?information?bitsincluding?terminating?bits
%??????????????--row2?parity?bits
%?g????????????--generator?vectors
%?Lc???????????--channel?reliability?factor?
%?pri_info?????--priori?information.?not?including?terminating?bits
%?lstate???????--last?state
%?nstate???????--next?state
%?lparoutput???--last?parity?output
%Output:
%?soft_out?????--soft?outputnot?including?termianting?bits
%?ex_info??????--external?information?not?including?terminating?bits
%
%?chenxiao?2010.7?SEU?Email:chenxiao20072008@gmail.com

[~L_total]=size（in）;?%?total?number?of?bits
[~K]=size（g）;?
m=K-1;
nstates=2^m;?%?number?of?states?in?the?trellis
infinity=1000;

%?alpha?initialization
alpha（11）=0;?
alpha（12:nstates）=-infinity*ones（1nstates-1）;

%?beta?initialization
%?no?terminate
beta（L_total+11:nstates）=log（1/nstates）;

%?compute?gamma
gamma=zeros（L_totalnstates2）;?%preallocate?for?speed

for?i=1:L_total
????for?st=1:nstates
????????gamma（ist1）=（-1）*pri_info（i）/2+Lc/2*（[-1?lparoutput（1st）]*in（:i））;?%?a?trasition?by?0
????????gamma（ist2）=pri_info（i）/2+Lc/2*（[1?lparoutput（2st）]*in（:i））;?%?a?trasition?by?1
????end
end

%?Trace?forward?compute?alpha
for?i=2:L_total
????for?st=1:nstates
????????alpha（ist）=max（gamma（i-1st1）+alpha（i-1lstate（1st））...
????????????gamma（i-1st2）+alpha（i-1lstate（2st）））+...
????????????log（1+exp（-abs（gamma（i-1st1）+alpha（i-1lstate（1st））-...
????????????gamma（i-1st2）-alpha（i-1lstate（2st）））））;?%?look?up?table?is?better
????end
end

%?Trace?backward?compute?beta
for?i=L_total:-1:2
????for?st=1:nstates
????????beta（ist）=max（gamma（instate（1st）1）+beta（i+1nstate（1st））...
????????????gamma（instate（2st）2）+beta（i+1nstate（2st）））+...
????????????log（1+exp（-abs（gamma（instate（1st）1）+beta（i+1nstate（1st））-...
????????????gamma（instate（2st）2）-beta（i+1nstate（2st）））））;?%?look?up?table?is?better
????end
end

%?Compute?the?soft?output?log-likelihood?ratio?of?symbols?in?the?frame
temp0=zeros（1nstates）;?%preallocate?for?speed
temp1=zeros（1nstates）;?%preallocate?for?speed
soft_out=zeros（1L_total）;?%preallocate?for?speed
for?i=1:L_total
????for?st=1:nstates
????????temp0（st）=gamma（ist1）+alpha（ilstate（1st））+beta（i+1st）;
????????temp1（st）=gamma（ist2）+alpha（ilstate（2st））+beta（i+1st）;
????end
????soft1=max（temp1（2）temp1（1））+log（1+exp（-abs（temp1（2）-temp1（1））））;
????soft0=max（temp0（2）temp0（1））+log（1+exp（-abs（temp0（2）-temp0（1））））;
????for?j=3:nstates
????????soft1=max（temp1（j）soft1）+log（1+exp（-abs（temp1（j）-soft1）））;
????????soft0=max（temp0（j）soft0）+log（1+exp（-abs（temp0（j）-soft0）））;
????end
????soft_out（i）=soft1-soft0;
end
ex_info=soft_out-pri_info-Lc*in（1:）;

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件??????10651??2013-10-29?11:45??Turbo碼在AWGN信道下仿真\log1000-AWGN\1000_1.fig

?????文件??????13180??2013-10-28?14:35??Turbo碼在AWGN信道下仿真\log1000-AWGN\1000_2.fig

?????文件???????6799??2013-10-28?15:12??Turbo碼在AWGN信道下仿真\log1000-AWGN\1000_eg.fig

?????文件???????2830??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1000-AWGN\algorithm_logmap.m

?????文件???????2216??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1000-AWGN\algorithm_maxlogmap.m

?????文件???????6738??2014-03-12?16:26??Turbo碼在AWGN信道下仿真\log1000-AWGN\AWGN.fig

?????文件???????2232??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1000-AWGN\decoder.m

?????文件???????2121??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1000-AWGN\encoder.m

?????文件???????1518??2013-10-25?11:10??Turbo碼在AWGN信道下仿真\log1000-AWGN\gen_trellis.m

?????文件???????2379??2014-03-12?16:02??Turbo碼在AWGN信道下仿真\log1000-AWGN\method_Log1000.m

?????文件????????591??2014-03-12?16:25??Turbo碼在AWGN信道下仿真\log1000-AWGN\method_Log_eg1000.mat

?????文件?????????72??2014-03-12?16:55??Turbo碼在AWGN信道下仿真\log1000-AWGN\新建?文本文檔.txt

?????文件???????2830??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1024_31\algorithm_logmap.m

?????文件???????2216??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1024_31\algorithm_maxlogmap.m

?????文件???????2232??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1024_31\decoder.m

?????文件???????2121??2010-07-17?19:32??Turbo碼在AWGN信道下仿真\log1024_31\encoder.m

?????文件???????1518??2013-10-25?11:10??Turbo碼在AWGN信道下仿真\log1024_31\gen_trellis.m

?????文件???????2343??2013-11-01?10:51??Turbo碼在AWGN信道下仿真\log1024_31\method_Log1024_31.m

?????文件???????8772??2013-10-30?11:10??Turbo碼在AWGN信道下仿真\test\1.fig

?????文件??????15676??2013-10-29?13:23??Turbo碼在AWGN信道下仿真\test\75_1315_3721.fig

?????文件??????13492??2013-10-29?13:30??Turbo碼在AWGN信道下仿真\test\campare.fig

?????文件????????595??2013-10-30?11:04??Turbo碼在AWGN信道下仿真\test\method_Log_eg.mat

?????文件????????593??2013-10-28?15:11??Turbo碼在AWGN信道下仿真\test\method_Log_eg1000.mat

?????文件????????560??2013-10-25?21:35??Turbo碼在AWGN信道下仿真\test\method_Log_eg3721.mat

?????文件????????603??2013-10-25?20:47??Turbo碼在AWGN信道下仿真\test\method_Log_eg75.mat

?????文件????????701??2013-10-30?11:10??Turbo碼在AWGN信道下仿真\test\test3_1.m

?????目錄??????????0??2014-03-12?16:53??Turbo碼在AWGN信道下仿真\log1000-AWGN

?????目錄??????????0??2014-03-12?16:52??Turbo碼在AWGN信道下仿真\log1024_31

?????目錄??????????0??2014-03-12?16:52??Turbo碼在AWGN信道下仿真\test

?????目錄??????????0??2014-03-12?16:52??Turbo碼在AWGN信道下仿真

............此處省略3個文件信息