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1. Top results related to forward error correction (fec)

   • Forward error correction in .NET

     Top Answer

     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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   • Forward Error Correction in Computer Networks

     Forward Error Correction (FEC) is a technique used to minimize errors in data transmission over communication channels. In real-time multimedia transmission, re-transmission of corrupted and lost packets is not useful because it creates an unacceptable delay in reproducing : one needs to wait until the lost or corrupted packet is resent. Thus, there must be some technique which could correct the error or reproduce the packet immediately and give the receiver the ability to correct errors without needing a reverse channel to request re-transmission of data. There are various FEC techniques designed for this purpose.

     These are as follows :

     1. Using Hamming Distance : For error correction, the minimum hamming distance required to correct t errors is:

     For example, if 20 errors are to be corrected then the minimum hamming distance has to be 2*20+1= 41 bits. This means, lots of redundant bits need to be sent with the data. This technique is very rarely used as we have large amount of data to be sent over the networks, and such a high redundancy cannot be afforded most of the time.

     2. Using XOR : The...

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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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   • Error detection and error correction algorithm

     Top Answer

     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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   • Error Correction in Computer Networks

     This article covers in-depth details about Errors in Networking, their types, and methods of Error Correction. By the end of this, you will gain a clear understanding of Error Correction in Computer Networking. So, let us dive deep into Error Correction in Networking.

     Table of Content

     • Introduction
     • Table of Contents
     • What are Errors in Networking?
     • Types of Network Errors
     • Error Identification in Computer Network
     • Error Correction in Computer Networks
     • Conclusion

     Computer Networks play a crucial role in the secured and encrypted transmission of data over the internet. However, the data transfer over a network includes many complex processes that cause some flaws in the data transmission. These flaws are called Errors which can be of different types. Therefore, it is important to correct them for efficient data transmission.

     In this article, we will learn about the different methods of Error Correction in Computer Networks. We will also see the types of errors and methods to identify them. This will resolve all your doubts...

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2. People also ask

   What are forward error correction (FEC) codes?

   • We consider the use of two classes of forward error correction (FEC) codes (concatenated codes with interleaver and LDPC codes) in optical communication systems. Soft iterative decoding is applied to both class of codes.

   Soft Decoding in Optical Systems: Turbo Product Codes vs. LDPC Codes

   link.springer.com/chapter/10.1007/0-387-23136-6_9

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   What is forward error correction (FEC) on VPN overlay networks?

   • This topic shows an SD-WAN with forward error correction (FEC) on VPN overlay networks. FEC is a technique used to control and correct errors in data transmission by sending redundant data across the VPN. It uses six parameters in IPsec phase1/phase1-interface settings:

   Forward error correction on VPN overlay networks | FortiGate / FortiOS

   docs.fortinet.com/document/fortigate/6.4.0/administration-guide/697460/forward-error-correction-on-vpn-overlay-networks

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   How to achieve two bit error correction?

   • To achieve two bit error correction, D=5 is necessary. A code with this property can be constructed from the above (D=3) single bit error corrrecting matrix by extending the matrix (with another single bit error correcting matrix) to give a double bit error correcting check matrix.

   ECE4253 Introduction to BCH Codes - UNB

   www.ece.unb.ca/tervo/ee4253/bch.shtml

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   Why is single bit error correction possible?

   • Single bit error correction is possible because every 3-bit column is unique. For example, the single bit error E (x) = x = (0010000) returns the syndrome 6 from column C and no other single bit error will return this same value. Double-bit error correction is possible because different two-bit errors do not give a unique result.

   ECE4253 Introduction to BCH Codes - UNB

   www.ece.unb.ca/tervo/ee4253/bch.shtml

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3. community.fs.com › encyclopedia › a-fecWhat Is A-FEC? Why Is A-FEC Required? | FS Community

   community.fs.com › encyclopedia › a-fec

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   1 day ago · To address this challenge, A-FEC employs FEC encoding at the transmit end to create redundant packets, alongside the original data, providing backup data. Consequently, even if packet loss occurs during transmission, the receiving end can conduct FEC decoding using the redundant packets, thereby recovering lost packets and implementing forward ...

4. www.geeksforgeeks.org › how-error-correction-is-doneHow Error Correction is Done? - GeeksforGeeks

   www.geeksforgeeks.org › how-error-correction-is-done

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   3 days ago · A Computer Science portal for geeks. It contains well written, well thought and well explained computer science and programming articles, quizzes and practice/competitive programming/company interview Questions.

5. discourse.gstreamer.org › t › add-error-correctionAdd error correction (rtpulpfecenc) results in linking error

   discourse.gstreamer.org › t › add-error-correction

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   2 days ago · I am still new with GStreamer and I am trying to add forward error correction to my pipeline because I have a lot of packet loss on my radio link.

6. Videos

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     2:33

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     Tutorial – Why Use Forward Error Correction (FEC)

     Oct 15, 2019

     11.2K Views

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     8:51

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     Forward Error Correction | Computer Networks | Part 2 | FEC error detection in computer networking

     Apr 6, 2020

     17.9K Views

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     13:28

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     Error Detection and Correction 3: Forward Error Correction

     Jun 7, 2016

     96.2K Views

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7. telcomatraining.com › what-is-pir-partialWhat is PIR Partial Incremental Redundancy

   telcomatraining.com › what-is-pir-partial

   12 hours ago · The technical details of pIPX Producer’s IPX. This innovative framework is designed to empower content…

8. www.ece.unb.ca › tervo › ee4253ECE4253 Introduction to BCH Codes - UNB

   www.ece.unb.ca › tervo › ee4253

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   3 days ago · The check matrix confirms the performance of this code in identifying and correcting two bit errors. While this choice of two rows from the table lead to enhanced code performance, not all row pairs will be as successful, as shown below.

9. www.ece.unb.ca › tervo › ee4253ECE4253 Hamming Code - A Matrix Approach - UNB

   www.ece.unb.ca › tervo › ee4253

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   4 days ago · The Hamming code concepts can be described in matrix form, where a generating matrix (G) creates valid codewords from information bits, and a check matrix (H) computes syndromes for error checking. When a valid codeword is multiplied by the check matrix, the result (syndrome) is zero.

10. mdpi-res.com › d_attachment › electronicsInvestigation of IEEE 802.16e LDPC Code Application in PM ...

    mdpi-res.com › d_attachment › electronics

    6 days ago · strong support of advanced optical technology and forward error correction technology. Forward error correction (FEC) technology has long been used in electrical communica-tion systems. It is the main technology to improve the reliability of digital communication systems and reduce the bit error rate. It has been widely used in deep-space ...