Forward error correction

FECchannel codingerror correcting codesInterleavingcodingECCerror correction codesinterleavederror correction codingforward error correcting
In 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.wikipedia
275 Related Articles

Information theory

information-theoreticinformation theoristinformation
In 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.
Important sub-fields of information theory include source coding, channel coding, algorithmic complexity theory, algorithmic information theory, information-theoretic security, Grey system theory and measures of information.

Error detection and correction

error correctionerror detectionerror-correction
In 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.
Forward error correction (FEC) is a process of adding redundant data such as an error-correcting code (ECC) to a message so that it can be recovered by a receiver even when a number of errors (up to the capability of the code being used) were introduced, either during the process of transmission, or on storage.

Data transmission

data transferdigital communicationsdigital communication
In 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.

Telecommunication

telecommunicationscommunicationstelecom
In 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.
Using forward error correction a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.

Error correction code

error-correcting codeerror correcting codeECC
The central idea is the sender encodes the message in a redundant way, most often by using an error-correcting code (ECC).
Most forward error correction codes correct only bit-flips, but not bit-insertions or bit-deletions.

Return channel

return linkBack-channelreverse channel
FEC gives the receiver the ability to correct errors without needing a reverse channel to request re-transmission of data, but at the cost of a fixed, higher forward channel bandwidth.
Even when the return and forward channels use the same medium, their differences often dictate the use of very different data modulation and coding techniques.

Modem

modemsdial-up modem56k modem
FEC information is usually added to mass storage (magnetic, optical and solid state/flash based) devices to enable recovery of corrupted data, is widely used in modems, is used on systems where the primary memory is ECC memory and in broadcast situations, where the receiver does not have capabilities to request retransmission or doing so would induce significant latency.
In 1980, Gottfried Ungerboeck from IBM Zurich Research Laboratory applied channel coding techniques to search for new ways to increase the speed of modems.

Bit error rate

bit errorbit error ratiobit-error rate
Many FEC coders can also generate a bit-error rate (BER) signal which can be used as feedback to fine-tune the analog receiving electronics.
The BER may be improved by choosing a strong signal strength (unless this causes cross-talk and more bit errors), by choosing a slow and robust modulation scheme or line coding scheme, and by applying channel coding schemes such as redundant forward error correction codes.

ECC memory

ECCECC RAMerror-correcting code memory
FEC information is usually added to mass storage (magnetic, optical and solid state/flash based) devices to enable recovery of corrupted data, is widely used in modems, is used on systems where the primary memory is ECC memory and in broadcast situations, where the receiver does not have capabilities to request retransmission or doing so would induce significant latency.
Interleaving allows for distribution of the effect of a single cosmic ray, potentially upsetting multiple physically neighboring bits across multiple words by associating neighboring bits to different words.

Soft-decision decoder

Soft-decision decodingsoft-decisionhard-decoded
The Viterbi decoder implements a soft-decision algorithm to demodulate digital data from an analog signal corrupted by noise.
Whereas a hard-decision decoder operates on data that take on a fixed set of possible values (typically 0 or 1 in a binary code), the inputs to a soft-decision decoder may take on a whole range of values in-between.

Coding theory

algebraic coding theorycodingchannel code
In 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.

Communication channel

channelchannelscommunications channel
In 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.

Redundancy (information theory)

redundancyredundantdata redundancy
The central idea is the sender encodes the message in a redundant way, most often by using an error-correcting code (ECC).

Multicast

multicastinggroup addressingInteractive Multicast
FEC is therefore applied in situations where re-transmissions are costly or impossible, such as one-way communication links and when transmitting to multiple receivers in multicast.

Uranus

Uranian34 TauriMagnetosphere of Uranus
For example, in the case of a satellite orbiting around Uranus, a re-transmission because of decoding errors can create a delay of 5 hours.

Mass storage

mass storage devicemass-storageBacking store
FEC information is usually added to mass storage (magnetic, optical and solid state/flash based) devices to enable recovery of corrupted data, is widely used in modems, is used on systems where the primary memory is ECC memory and in broadcast situations, where the receiver does not have capabilities to request retransmission or doing so would induce significant latency.

Analog-to-digital converter

ADCanalog to digital converteranalog-to-digital conversion
For the latter, FEC is an integral part of the initial analog-to-digital conversion in the receiver.

Viterbi decoder

ViterbiViterbi decodingViterbi-decoded
The Viterbi decoder implements a soft-decision algorithm to demodulate digital data from an analog signal corrupted by noise.

Noisy-channel coding theorem

Shannon limitnoisy channelShannon's theorem
The noisy-channel coding theorem of Claude Shannon answers the question of how much bandwidth is left for data communication while using the most efficient code that turns the decoding error probability to zero.

Polar code (coding theory)

polar codespolar codepolar coding
However, after years of research, some advanced FEC systems like polar code come very close to the theoretical maximum.

Convolutional code

convolutional codingtrellis diagramConvolutional
In telecommunication, a convolutional code is a type of error-correcting code that generates parity symbols via the sliding application of a boolean polynomial function to a data stream.

Turbo code

turbo codesTurbo codingTurbo
In information theory, turbo codes (originally in French Turbocodes) are a class of high-performance forward error correction (FEC) codes developed around 1990–91, but first published in 1993.

Hybrid automatic repeat request

Hybrid ARQhybrid automatic repeat-requestHARQ
Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error-correcting coding and ARQ error-control.

DVB-T2

T2DVB T2DVB-T2 (where available)
This system transmits compressed digital audio, video, and other data in "physical layer pipes" (PLPs), using OFDM modulation with concatenated channel coding and interleaving.

Data compression

compressionvideo compressioncompressed
Source coding should not be confused with channel coding, for error detection and correction or line coding, the means for mapping data onto a signal.