Timeline for Error correcting codes obtained as superposition of two codes e.g. CRC+Convolutional
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 24, 2012 at 7:26 | vote | accept | Alexander Chervov | ||
| Jul 10, 2012 at 10:22 | comment | added | Jyrki Lahtonen | That polynomial generates a massively shortened Hamming code with minimum distance 4. For hard decision a look-up table of syndromes would do for a code this short (can correct just one error). A list variant of Viterbi may be better, because you can base the final decision on soft metric. A simulation will tell more. | |
| Jul 10, 2012 at 10:00 | comment | added | Alexander Chervov | The code is fixed by standard, I can change nothing except decoder. Such things used in GSM, LTE etc. There are papers which propose to use list-Viterbi, probably it is the best way... | |
| Jul 10, 2012 at 9:34 | comment | added | Jyrki Lahtonen | Are you stuck with that CRC-polynomial? Is that really the recommended CRC for short data segments like this? As you are planning on using the CRC-bits, at least partly, for error-correction as well, a case can be made for using a generator polynomial of a suitable cyclic code. But in either case, I don't see an efficient way of using soft inputs, and would just use a hard decision decoder on the output of plain Viterbi (cannot use SOVA). The trellis representations of mid-rate codes such as this have a tendency to blow up on your face in terms of complexity. | |
| Jul 10, 2012 at 9:17 | comment | added | Jyrki Lahtonen | IOW="In other words". | |
| Jul 10, 2012 at 8:37 | comment | added | Alexander Chervov | What is "IOW" ? | |
| Jul 10, 2012 at 8:36 | comment | added | Alexander Chervov | @Jyrki Lahtonen Thank you very much ! Let me think. Well, actually my CRC is not so simple - it is 24dat+16CRC given by g= x^16+x^12+x^5+1, can something be done in this case ? PS I wrote this comment before yours comment appeared :) | |
| Jul 10, 2012 at 8:33 | comment | added | Jyrki Lahtonen | If you use a more complicated CRC (not just a single parity bit), then decoding may become quite complex. An appealing solution then would be to use, instead of a standarda CRC, a suitable error-correcting block code, like a BCH-code. The BCH-code will then correct a couple of residual bit errors (if any), and decoding failure will give a very satisfactory certificate about the correctness of the data. IOW the BCH-code would act as both an error-correcting code and as an error-detecting code. | |
| Jul 10, 2012 at 8:30 | history | edited | Jyrki Lahtonen | CC BY-SA 3.0 |
added 487 characters in body
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| Jul 10, 2012 at 8:22 | history | answered | Jyrki Lahtonen | CC BY-SA 3.0 |