Talk:Forward error correction

message: I have heard that some methods for FEC are covered by software patents. Does anyone know if this is (still) the case? If so, it should probably be mentioned in the article. Haakon 13:06, 17 Jan 2005 (UTC)
thread_title:  Software patents 

message: From the article:
The original information may or may not appear in the encoded output; codes that include the unmodified input in the output are systematic, while those that do not are nonsystematic.. 
Ehm, if the original information did not appear in the encoded output, then what sense should such an encoded output make? We couldn't reconstruct the original information back from the encoded output... or do you mean "the original information may not appear in plain text in the encoded output"?
: Yes, exactly -- the original sequence of bits always occurs in the output of a systematic encoder, but the original sequence of bits almost never occurs in the output of a nonsystematic decoder (although, of course, the information can still be extracted). Please improve the article to make this easier to understand. --75.37.227.177 07:31, 16 July 2007 (UTC)
replies: text: Think you mean that the original sequence of bits almost never occurs in the output of a nonsystematic _encoder_.  The job of the decoder is to extract the original information, perhaps correct it, and flag whether (uncorrectable) errors have occurred.  — Preceding unsigned comment added by 139.95.251.21 (talk) 21:58, 14 September 2011 (UTC)
thread_title:  Weird 

message: From the article:
Nearly all block codes apply the algebraic properties of.
The algebraic properties of what?
[Turbo Codes] perform to within a fraction of a decibel of the Shannon limit.
Does that mean it is even below the Shannon limit ("just a fraction of the Shannon limit"), or very close to it, but still above it?
:-no, it approaches the Shannon limit but can not surpass it (very close to it, but still above it) 16:28, 7 January 2006 (UTC)
thread_title:  Incomplete text 

message: What is so "forward" on the "forward error correction" codes?
Thanks for your help, --Abdull 05:29, 16 October 2005 (UTC)
replies: text: In this context, forward refers to when you can start performing the error correction: you can correct bits "going forward  from here". Some error correction algorithms require te entire message to be received in order for the ECC algorithm to be applied to it. FEC algorithms generally allow you to fix errors as the message comes in, bit by bit, rather than analysiing the entire message. A general ECC algorithm may require looking at "future" bits, yet to be received, as well as "past" bits, to correct the current bit. The Viterbi algorithm is famous in that it took a particularly strong form of ECC, and got rid of the part that depended on future, as-yet-unrecieved bits. linas 17:40, 26 May 2006 (UTC)
thread_title: What is forward?

message: * I vote Do not merge - the article on touches upon Forward Error Correction and its applications, and can be expanded considerably.  Rather than mergeing into a general Error detection and correction article, I believe it is correct to split this topic out.  When treated properly, this article alone will generate several sub-articles. WLD 20:26, 5 February 2006 (UTC)
thread_title:  Merge? 

message: The article says:
The most recent (early 1990s) development in error correction is turbo coding,
Have their been any other major developments since that or are their likely to be any more in the future?
--Timmywimmy 02:59, 13 July 2006 (UTC)
thread_title:  Most recent development? 

message: The edit dated 29 July 2006 added the following citation:
*
While I find this article very interesting, I don't see a clear connection to FORWARD error correction. Am I missing something? Ged Davies 17:37, 28 February 2007 (UTC)
thread_title:  Relevance of reference 

message: What is FEQ?
Clicking on FEQ doesn't tell me, because FEQ currently redirects to forward error correction, which never mentions "FEQ".
--75.37.227.177 07:31, 16 July 2007 (UTC)
replies: text: FEQ isn't an abbreviation that matches anything to FEC that I know of or can find a reference to.  I just proposed FEQ for deletion. Danoelke (talk) 15:46, 27 February 2008 (UTC)
replies: text:  The section on Averaging noise to reduce errors still uses the term FEQ without explanation. Should each instance of FEQ be replaced with FEC? 83.104.249.240 (talk) 20:26, 13 November 2008 (UTC)
thread_title:  FEQ vs. FEC 

message: This article needs a simple layman's terms explanation.  I wrote the following based on how I understand error correction to work, but I'm far from an expert.  So I'm gonna post my proposed article text here and let someone else post it once an expert confirms the validity.
----
Error correction works sort of like a game of sudoku.  If a single number is missing from any random location on nearly complete sudoku board, then any one of the relational number rules of sudoku provide all the extra information you need to correctly fill in that particular missing number box back to its intended value.  However, as more and more numbers are missing you need to know more and more different sudoku rules in order to recreate the missing numbers.  
So the original data to be kept corrected of errors is like the numbers you start with on an incomplete sudoku board, and the additional error correction parity files you use to correct errors in your data back to the original set are like the rules you use on a sudoku board to fill in the missing number squares back to their intended values.  
If too many squares on your sudoku board are missing (i.e. there are too many errors in your data) then the rules of sudoku don't give you enough information to fill in the missing numbers (i.e. the parity files don't contain enough extra information to recreate the errors in your data).  But if you knew additional sudoku rules (i.e. had more parity files) then you could recreate the correct set of numbers on your sudoku board (i.e. you could recreate the correct data in the portions which contain errors).
---
If that is approximately correct, then please add this text to the article!  =)  —Preceding unsigned comment added by 67.101.31.49 (talk) 08:40, 19 September 2007 (UTC)
thread_title:  Simplified Layman's terms explanation 

message: I think the whole article requires a rewrite.
-Muthu  —Preceding unsigned comment added by 129.107.27.193 (talk) 19:15, 30 September 2007 (UTC)
thread_title:  Rewrite 

message: The acronym FEC is usually accompanied by a pair of numbers denoting a fraction or ratio. Shouldn't this be explained in the article? 83.104.249.240 (talk) 20:32, 13 November 2008 (UTC)
thread_title:  2/3 FEC and 3/4 FEC 

message: Recently, a list of codes was moved from the "error detection and correction" article to the "forward error correction" article.
While I think this edit improved both articles, I think Wikipedia:WikiProject Laundromat and Wikipedia:Embedded list seems to discourage such lists, and I'm thinking about deleting that list entirely.
Is there any good reason to manually maintain that list in this article, instead of using the automatically-updated category mechanism -- similar to :Category:Checksum algorithms?
Is the list at :Category:Error detection and correction adequate for our readers, or should we use a more specific category for that list?
--68.0.124.33 (talk) 16:45, 25 January 2010 (UTC)
replies: text: The list was moved here temporarily, as the article needs a rewrite anyway. However, do not just delete the list, but rather move it to a list article like "List of forward error correction codes". Also, an appropriate category would be "Forward error correction codes", and be defined as a sub-category of "Forward error correction", which itself is a sub-category of :Category:Error detection and correction. Category "Forward error correction" would include all the theoretical background articles on the topic. I would be glad if you could do these changes, and provide a link to the list article in the "See also" section. Nageh (talk) 22:23, 25 January 2010 (UTC)

text: Also, all the articles referenced in the list should be moved to the new category from :Category:Error detection and correction. Nageh (talk) 22:26, 25 January 2010 (UTC)
thread_title:  list of error-correcting codes 

message: Let's get this straight.
One interleaving example cites "aaaa, eeee, ffff, gggg" as codewords. i.e. a codeword is represented as four consecutive letters.
Another example cites "cddd" as a codeword. i.e. the codeword is inexplicably made of different letters. Apparently this is "correct".
Since "codeword" seems to be randomly defined, there needs to be an explanation of these examples, otherwise it makes no sense.
What's the significance of groups of four letters if you can just make up whatever boundaries you like? If the letter boundaries aren't codeword boundaries, then what are they?
Ghiraddje 17:59, 7 May 2014 (UTC)
replies: text: Yeah, I read it that way too. I've changed it again, with elaboration in the text. —Quondum 22:05, 7 May 2014 (UTC)
thread_title:  Codeword confusion 

message: I suggest merging channel code into forward error correction.
The Wikipedians who wrote coding theory, forward error correction, and channel coding already seem to think that channel code is a synonym for "forward error correction code".
Perhaps the difference, if any, can be summarized in a couple of paragraphs in the merged article.
--DavidCary (talk) 07:52, 31 January 2015 (UTC)
replies: text:  KvnG, my understanding is that automatic repeat request is *not* a channel code. The first reference in the coding theory ( Irvine and Harle 2002 ), if I'm reading page 4 correctly, defines "channel code" in a way that excludes automatic repeat request. What are the next steps towards solving the larger problem? --DavidCary (talk) 13:26, 20 August 2019 (UTC)
thread_title:  Merge? 

message: There is discussion in a newsgroup about fire codes using in disks such as the IBM 3330 and DEC RP06.  It seems to be a form of FEC that is easier to process than some more modern ones. (That is, using late 1960's technology.)  I don't see anything here about it, though. Does it have a different name? Gah4 (talk) 00:26, 29 July 2015 (UTC)
thread_title:  Fire codes 

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thread_title:  External links modified 

message: The title "forward error correction" is a process that may use an ECC - most of the article is about ECC.  Also the article uses the accroymn FEC where it really means ECC, or at best FECC, the latter not being in the IEEE dictionary and far less in use per a Google search (not necessarily a reliable source).  Also note that the term ECC goes back to Hamming 1950 and Shannon 1948 discusses the correction of errors without once using the term "forward."  I don't know when and where the term FEC comes from, I suspect telcom but earliest cite I can find is 1972.  So it seems we have two subjects, ECC and FEC, mixed up in one article with the preponderance of the article devoted to ECC. I suggest the simplest fix is to split the articles into an ECC article and an FEC article with the latter being relatively short, almost a dictionary entry.  If nothing else all the FECs that really mean ECC need to be changed.  Tom94022 (talk) 17:06, 2 April 2018 (UTC)
replies: text: If ECC and FEC are different enough to be "two subjects", could someone please write a sentence or two clearly explaining the difference between them? Tom94022? Thank you. --DavidCary (talk) 13:26, 20 August 2019 (UTC)
replies: text: Above there is discussion about VoIP, sending each packet twice.  It seems to me that is FEC without ECC. (Or, sending duplicate packets is a degenerate case of ECC, with no actual coding.)  I think that means that separate article are fine, but we should be careful as to what goes where.  FEC should maximize the idea of the forward part (mostly not requiring requests or waiting for retransmission) and minimize the ECC part.  If that makes FEC too small, though that doesn't seem so likely, then consider a merge.  Is there a suggested minimum for article size?  Gah4 (talk) 06:52, 24 August 2019 (UTC)
thread_title:  Misleading title - split the article 

message: The article includes the following example of a ECC benefit: "Long-latency connections also benefit; in the case of a satellite orbiting Uranus, retransmission due to errors can create a delay of five hours".  Please correct me if I'm wrong, but pretty sure there are currently no (nor have there ever been) man-made, transmitting satellites around Uranus.  What an odd example, why not cite Juno orbiting Jupiter, or the MRO orbiting Mars? Jsinnreich (talk) 02:29, 10 December 2023 (UTC)
thread_title:  Satellites around Uranus?