Hello Tom, Thank you for your answer.
I dont see how using the viterbi decoder from gr-fec would fix my problem. I would still need the viterbi decoder to work on K=5 to be able to integrate it with gr-ieee802-11, it is the same situation i am now with the decoder i linked. My question is first if there is a highly optimized decoder at least for 1/2 K=5, or in case it does not exist, if it is possible for me to modify an existing implementation. I repeat, i am a novice in the field of convolutional decoding. Thanks 2016-01-28 20:05 GMT-03:00 Tom Rondeau <[email protected]>: > On Thu, Jan 28, 2016 at 11:13 PM, Gonzalo Arcos <[email protected]> > wrote: > >> The dvbt project im talking about is: >> https://github.com/gnuradio/gnuradio/tree/master/gr-dtv/lib/dvbt >> >> And the gr-ieee-80211 project is: >> https://github.com/bastibl/gr-ieee802-11 >> >> thanks in advance >> > > > We have a highly optimized Viterbi decoder for K=7, rate 1/2 in gr-fec, > which is done mostly in a VOLK kernel. Those parameters (R=1/2, K=7) are > fixed, but the polynomials can be set externally. > > Tom > > > > >> 2016-01-28 19:11 GMT-03:00 Gonzalo Arcos <[email protected]>: >> >>> I am trying to optimize the current performance of gr-iee802-11. Ive >>> done some profiling and came to the conclusion that there is a lot of work >>> being put in decoding the convolutional code at the receiver. >>> >>> I have done some research, and found out that there exists a viterbi >>> decoder that was developed for the digital tv branch, that supposedly >>> outperforms IT++ by a factor of 9x!, IT++ being the library that >>> gr-iee802-11 uses to decode the convolution. >>> >>> When trying to adapt this decoder to gr-iee802-11 ive found some >>> hassles. First, the constraint length for the viterbi decoder in dvbt is K >>> = 7, while in gr-ieee802-11 uses a constraint length of K=5. >>> In addition, the generator polynomials also differ. >>> >>> I would appreciate if someone could help me here, i am a beginner in the >>> matter of convolutional codes, i would like if someone could asses me if it >>> is possible to adapt this viterbi decoder to gr-iee802-11 at all, and in >>> case it is indeed possible, if it is very complex task for a non expert on >>> the matter. >>> >>> The source file d_viterbi.c has a comment that says: >>> That changing the polynomials would need me to "regenerate the BUTTERFLY >>> macro calls in viterbi()" I am not certain about what should the new >>> parameters be for the polinomials 0133 0171. >>> https://github.com/gnuradio/gnuradio/tree/master/gr-dtv/lib/dvbt >>> >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >> >> >
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