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1. Top results related to forward error correction algorithm

   • Forward Error Correction in Computer Networks

     1. Using Hamming Distance :

     2. Using XOR :

     3. Chunk Interleaving :

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   • Forward error correction in .NET

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     Answered Sep 17, 2010 · 3 votes

     If you have free C++ libraries why don't you try to build CLI wrapper around them?

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   • Error detection and error correction algorithm

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     Answered Sep 06, 2011 · 1 votes

     Here is an attempt with some ideas pinched from http://en.wikipedia.org/wiki/Frame_Relay.

     Start off each 64-bit chunk with a fixed header of 01110. Where you have more header info (e.g. sequence number or alternating bit flag, checksum...) you can probably arrange that the bit-pattern 01110 never appears. For arbitrary data, replace any occurrence of 0111 with 01111 - meaning that the effective data rate now depends on the underlying data. Have the provider of data to this layer make sure the data is pretty much random, e.g. by applying a http://en.wikipedia.org/wiki/Randomizer. I think your total data loss here is about 6 bits, which fits with the 6 bits necessary to describe a shift of 0..63.

     In the receiver, look for 01110 to mark the true start of the chunk. If you do not see exactly one such pattern, you know that the chunk has been garbled. I think it takes at least a two-bit error to both destroy an existing 01110 and produce a fake one.

     Garbles that cause chunk misalignment don't look like typical bit garbles, so CRC error rate calculations won't apply out of the box. I would include a non-CRC checksum in each chunk - perhaps a check calculated mod 31 or mod 961 so as to avoid the forbidden 5-bit pattern 01110, although depending on what abuts this you may need to be more restrictive. The chance of an error not being detected would then be about 1 in 31 or 1 in 961, with no particular guarantee about all single errors, unlike polynomial CRC.

     I don't think you have enough space to do per-chunk error correction sensibly, but you could include N error correction chunks after every M ordinary chunks, using e.g. SECDED applied down the columns. You might have e.g. 57 data-bearing chunks and then 6 error correction chunks, treating each payload bit position as bearing 57 data bits and then 6 checksum bits. This should work well if errors tend to corrupt all or none of a single chunk e.g. by causing chunk realignment to fail.

     after comment -

     EDIT

     OK, with one continuously transmitting message you have less bandwidth but relatively more cpu. Two things come to mind:

     1) Given any sort of checksum or other constraint on the message you can achieve some limited error correction by e.g. considering all single bit errors, flipping a bit of the received message, and seeing if the checksum now works.

     2) A message can be checked to see if complies with the bit-stuffing scheme suggested above by looking at only a 5-bit window passed over the message. I think this holds true even if you need to tweak it to work properly at the wraparound. This means that a message can be checked by a BDD of tractable size (Knuth 4A section 7.1.4). This means that you can count the number of 64-bit messages that comply with the bit-stuffing scheme and convert efficiently between message number and message (same section). So you can use this scheme without underlying randomisation or worst-case assumptions about the data to be sent, by just regarding it as an encoding of a number in the range 0..N (where N is to be computed via BDDs) and a 64-bit message. In fact, less elegantly, I think you could use dynamic programming with a 5-bit state instead of BDDs.

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   • When is forward error correction a good idea for packets?

     Top Answer

     Answered Feb 12, 2009 · 5 votes

     I think it's useful for some applications like Voice (VoIP), where you want to avoid errors, and where you never want stop (to retransmit a NAKed packet) and wait (until it's retransmitted).

     So it might be implemented on top of the Real-time Transport Protocol flavour of UDP.

     Wouldn't it be terrible for latency?

     Are you asking whether forward error correction increases end-to-end delay? If so, I think the answer is "no", but it does increase the needed bandwidth.

     I believe you always already need some latency, to avoid jitter; so for example, you might say "let's delay the whole voice channel by 200 msec, so any/every packet can take from 0 to 200 msec to cross the internet, and be reassembled and sent through the D-to-A converter at the other end."

     Given those numbers, then having no forward error correction might mean that, in each 200 msec period, you send 10 packets each containing 20 msec of data ... and if one is lost, then that's a gap (a glitch) at the other end.

     Whereas, having some forward error correction might mean that, in each 200 msec period, you still send 10 packets ... each packet contains 20 msec of data, plus 10 msec of data that's already been transmitted in another packet (or, maybe you send 30 packets instead of 20). Then, if any single packet is lost, the data which it carried was delivered redundently (half in each of two other packets), which avoids any glitch in the decoded output.

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   • forward backward algorithm pseudocode clarification

     Top Answer

     Answered Feb 09, 2017 · 0 votes

     This might be a little late. The goal of this algorithm is to inference on data given the model. By this calculation you are calculating the posterior probability of P(x_i|o_i) which can help finding out the next step in the test procedure.

     Hope that has helped.

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2. en.wikipedia.org › wiki › Error_correction_codeError correction code - Wikipedia

   en.wikipedia.org › wiki › Error_correction_code

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   In computing, telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels.

3. www.geeksforgeeks.org › forward-error-correctionForward Error Correction in Computer Networks - GeeksforGeeks

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   Jun 4, 2020 · Last Updated : 04 Jun, 2020. Forward Error Correction (FEC) is a technique used to minimize errors in data transmission over communication channels.

4. People also ask

   What does forward error correction mean?

   • Forward error correction (FEC) is a digital signal processing technique used to enhance data reliability. It does this by introducing redundant data, called error correcting code, prior to data transmission or storage.

   Forward Error Correction - Techopedia

   www.techopedia.com/definition/824/forward-error-correction-fec

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   What is forward error correction (FEC)?

   • In computing, telecommunication, information theory, and coding theory, forward error correction ( FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels .

   Error correction code - Wikipedia

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   What is forward error coding?

   • It is a method adopted to obtain error control in data transmission where the transmitter sends redundant data. Only a portion of the data without apparent errors is recognized by the receiver. This allows broadcasting data to be sent to multiple destinations from a single source. Forward error coding is also known as channel coding.

   Forward Error Correction - Techopedia

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   What is error correcting code (FEC)?

   • It does this by introducing redundant data, called error correcting code, prior to data transmission or storage. FEC provides the receiver with the ability to correct errors without a reverse channel to request the retransmission of data. The first FEC code, called a Hamming code, was introduced in the early 1950s.

   Forward Error Correction - Techopedia

   www.techopedia.com/definition/824/forward-error-correction-fec

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5. en.wikipedia.org › wiki › Reed–Solomon_errorReed–Solomon error correction - Wikipedia

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   Reed–Solomon codes are also used in xDSL systems and CCSDS's Space Communications Protocol Specifications as a form of forward error correction. Space transmission Deep-space concatenated coding system. Notation: RS(255, 223) + CC ("constraint length" = 7, code rate = 1/2).

6. simple.wikipedia.org › wiki › Forward_error_correctionForward error correction - Simple English Wikipedia, the free ...

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   How it works. Forward error correction. In telecommunications Forward error correction (FEC) is a special code for error detection and correction. The sender adds parts of the data again. This is called redundancy. The receiver is then able to detect certain errors that came from sending data.

7. www.sciencedirect.com › forward-error-correctionForward Error-Correction - an overview | ScienceDirect Topics

   www.sciencedirect.com › forward-error-correction

   Forward error correction works by adding redundant bits to a bitstream to help the decoder detect and correct some transmission errors without the need for retransmission. The name forward stems from the fact that the flow of data is always in the forward direction (i.e., from encoder to decoder).

8. www.edn.com › defining-a-forward-error-correctionDefining a forward error correction algorithm - EDN

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   Mar 26, 2007 · Pro-MPEG FEC (forward error correction) is a two-dimensional XOR algorithm with several possibilities determining the size of the data matrix. The FEC dictates that there be a minimum of at least one column and at least four rows, and a maximum of no more than 20 columns and and no more than 20 rows.

9. www.techopedia.com › forward-error-correction-fecWhat is Forward Error Correction (FEC)? - Definition from ...

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   Jan 4, 2017 · Forward error correction (FEC) is a digital signal processing technique used to enhance data reliability. It does this by introducing redundant data, called error correcting code, prior to data transmission or storage. FEC provides the receiver with the ability to correct errors without a reverse channel to request the retransmission of data.