Matlab implementation of CTC in WiMax

[rmreddy]

hello everyone,
i have implemented conventional convolutional codes in my wimax project.
now i am suppose to add convolutional Turbo codes as our further enhancement ..

so can anyone supply me with good study material or matlab implementation of CTC encoders ..
its very urgent ...

waiting ...

thanks in advance ..

 

[rmreddy]

Re: CTC in WiMax

hello,
can anyone suggest me some thing ....

 

[mar-cas1]

Re: CTC in WiMax

If you have implemented convolutional codes you should first try to make a recursive encoder which is very easy (feed back one of the modulo 2 adders). Codes (3, [5 7]) can be a good start. Then you have to concatenate it in parallel with another encoder. Parallel concatenation can be done by feeding the other encoder with the same imput as for the fist one. The trick in turbo codes is to interleave the imput of the second encoder. Finally you make the encoder systematic by having an output the same as the imput. you get three outputs for a rate 1/3 turbo code. Punturing could be use to increase the code rate.
For the decoding process you need to start working on the MAP algorithm and the concept of soft imput soft output decoders. You can also have a look to the soft output viterbi algorithm. The decoding process also concatenates the decoders through the interleaver. The output of the second decoder is feeded to the fisrt encoder and then you make it iterate. This is the turbo concept.

 

[yasiranwar86]

CTC in WiMax

can u give c code of viterbi decodere or any link related to it