Difference Between Forward Error Correction And Backward Error Correction
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re-send information. Backward Error Correction is used in situations where some of the transmitted data has been lost or corrupted during transit and the transmitting device must resend the information in order for the receiving difference between forward error correction and retransmission device to understand the transmission. Backward Error Correction is the opposite of “Forward Error distinguish between forward error correction vs error correction by retransmission Correction”, in which a transmitting device simply sends redundant information to make up for any potential errors. How Backward Error advantages of forward error correction Correction Works Backward Error Correction is dependent on a number of protocols and algorithms, such as parity bits, cyclic redundancy checks, and longitudinal redundancy checks, but relies on the same procedure. As usual, a transmitting forward and backward error correction techniques device will send data to a receiving device. The receiving device will then run checks to ensure that all of the information is present, readable, and makes sense. If the received information does not make sense, is not all there, or cannot be read for any reason, the receiving device will send a request to the transmitting device to resend that data. Applications Backward Error Correction is often used instead
What Is Forward Error Correction
of Forward Error Correction because it requires less bandwidth. However, because Backward Error Correction requires the receiving device to receive a signal before it requests redundant information, it requires more time than Forward Error Correction and may even use more bandwidth for individual transfers due to constant messaging between the two devices. While Forward Error Correction is usually preferred on systems that are prone to errors, such as long-distance communications systems, Backward Error Correction is ideal for systems that rarely have errors or only handle small amounts of data. Follow Us! Rate this article: ★ ★ ★ ★ ★ Backward Error Correction (BEC), 4.67 / 5 (3 votes) You need to enable JavaScript to vote Mail this article Print this article Last updated 11 March, 2016. Related Posts Medium Earth Orbit Medium Earth Orbit (MEO) refers to a satellite which orbits the earth at an altitude ... Satellite Systems The basic types of satellite systems include geostationary (GEO), Low Earth Orbit (LEO), Medium Earth ... Low Earth Orbit Low Earth Orbit (LEO) refers to a satellite which orbits the earth at altitudes between ... Search for: ReferenceSoftware Tutorials Unit Conversion Practice Tests Web Tools Site Index Audio-Video Databases Electronics File Compression File Conversion Gaming Graphics Hardware Internet IT Management Macintosh
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Error Detection And Correction
correction Print this article Print all entries for this topic forward error correction tutorial Cite this article Tools backward error correction A Dictionary of Computing © A Dictionary of forward error correction example Computing 2004, originally published by Oxford University Press 2004. backward error correction (backward correction) Error correction that occurs in a channel through the detection http://www.tech-faq.com/backward-error-correction-bec.html of errors by the receiver: the receiver responds to any errors in a block by requesting the transmitter to retransmit the affected block. Backward correction requires a return channel, by contrast with forward error correction.There are two ways in which the return channel can be used to indicate errors: positive http://www.encyclopedia.com/doc/1O11-backwarderrorcorrection.html acknowledgment and negative acknowledgment. With positive acknowledgment, the receiver returns confirmation of each block received correctly, and the transmitter is prepared to retransmit a block that is not acknowledged within an appropriate time. With negative acknowledgment, the receiver returns a request to retransmit any block received erroneously, and the transmitter is prepared to retransmit such a block (implying that the transmitter retains a copy of every block sent, indefinitely).Since the return channel itself may be prone to errors, and to limit the amount of storage necessary at the transmitter, the positive acknowledgment and retransmission (PAR) technique is generally preferred. See also error-detecting code. Cite this article Pick a style below, and copy the text for your bibliography. MLA Chicago APA "backward error correction." A Dictionary of Computing. . Encyclopedia.com. 9 Oct. 2016
(Discuss) Proposed since January 2015. In telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding[1] is a technique used for controlling https://en.wikipedia.org/wiki/Forward_error_correction errors in data transmission over unreliable or noisy communication channels. The central idea is the sender encodes the message in a redundant way by using an error-correcting code (ECC). The American mathematician Richard Hamming pioneered this field in the 1940s and invented the first error-correcting code in 1950: the Hamming (7,4) code.[2] The redundancy allows the receiver error correction to detect a limited number of errors that may occur anywhere in the message, and often to correct these errors without retransmission. FEC gives the receiver the ability to correct errors without needing a reverse channel to request retransmission of data, but at the cost of a fixed, higher forward channel bandwidth. FEC is therefore applied in situations forward error correction where retransmissions are costly or impossible, such as one-way communication links and when transmitting to multiple receivers in multicast. FEC information is usually added to mass storage devices to enable recovery of corrupted data, and is widely used in modems. FEC processing in a receiver may be applied to a digital bit stream or in the demodulation of a digitally modulated carrier. For the latter, FEC is an integral part of the initial analog-to-digital conversion in the receiver. The Viterbi decoder implements a soft-decision algorithm to demodulate digital data from an analog signal corrupted by noise. 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 noisy-channel coding theorem establishes bounds on the theoretical maximum information transfer rate of a channel with some given noise level. Some advanced FEC systems come very close to the theoretical maximum. The maximum fractions of errors or of missing bits that can be corrected is determined by the design of the FE