Forward Error Control Fec
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(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 errors in data transmission over unreliable or forward error correction example noisy communication channels. The central idea is the sender encodes the message in forward error correction tutorial a redundant way by using an error-correcting code (ECC). The American mathematician Richard Hamming pioneered this field in the forward error correction ppt 1940s and invented the first error-correcting code in 1950: the Hamming (7,4) code.[2] The redundancy allows the receiver to detect a limited number of errors that may occur anywhere in the message, forward error correction pdf 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 where retransmissions are costly or impossible, such as one-way communication links and when transmitting to multiple receivers in multicast. FEC information
Backward Error Correction
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 FEC code, so different forward error correcting codes are suitable for different conditions. Contents 1 How it works 2 Averaging noise to reduce errors 3 Types of FEC 4 Concatenated FEC codes for improved performance 5 Low-density parity-check (LDPC) 6 Turbo codes
Day Digital Footprint A digital footprint is a unique data trace of a user’s activities, actions, communications or transactions in digital media. This data trace can be
Forward Error Correction 3/4
left on the internet, computers, mobile devices or other mediums. A digital forward error correction rate footprint can be used to track the user's activities and devices. A user can leave digital footprint either forward error correction in data communication actively or... Read more Newest Terms Digital Multimeter Digital Pen Digital Filter Burn-In Digital Control Data Link Data Key Cross-Browser CableCARD Capture View All... Top Categories Communication Data Development https://en.wikipedia.org/wiki/Forward_error_correction Enterprise Hardware Internet IT Business Networking Security Software View Tag Cloud... Cloud Computing The Cloud: The Ultimate Tool for Big Data Success The New Efficiency of Cloud Analytics Education Must Turn to the Cloud More Recent Content in Cloud Computing Is the Cloud Ready for the Enterprise? The Innovative Disruption of the Cloud How the Cloud is Changing the Work https://www.techopedia.com/definition/824/forward-error-correction-fec Landscape View All... Cloud Computing Home Virtualization Buzzwords and Jargon Software-as-a-Service (SaaS) Distributed Computing Data Centers Open Source Big Data Amazon Redshift Blob Storage Cloud Archive Cloud Communications Insights as a Service Virtual Desktop Infrastructure Cloud Industry Cloud Cloud Sprawl Global File System Managed Cloud Security The Cyber War Against Terrorism Channeling the Human Element: Policy, Procedure and Process The Persistence of Digital Rights Management More Recent Content in Security The Chip in the Card: EMV Chip Promises Increased Security for Payments Your IT’s Risks are Hiding - Can You Spot Them? Managing Cloud Sprawl in Your Organization View All... Security Home Hacking Data Centers Forensics Legal Viruses Software Data Key Vendor Patch Active Directory Logging Native Audit Active Directory Security Identity Life Cycle Cross-Platform Endpoint Management User De-Provisioning Clickjacking Bullet Camera Big Data Cognitive Computing - The Next Era of Computing? Protecting Your Brand Value with Big Data How Big Data Can Drive Smart Customer Service More Recent Content in Big Data Living on the Edge: The 5 Key Benefits of Edge Analytics The Cloud: The Ultim
Forward Error Correction (FEC) Source: David R. Goff. Fiber Optic Video Transmission, 1st ed. Focal Press: Woburn, Massachusetts, 2003 and other private writings. Technology Basics Forward Error Correction (FEC) is a technique that has been used for a number of years http://www.olson-technology.com/mr_fiber/FEC.htm in submarine fiber optic systems. It is a technique that allows for near perfect data transmission http://www.tech-faq.com/forward-error-correction-fec.html accuracy even when faced with a noisy transmission channel. A number of FEC algorithms are being used including Hamming code, Reed-Solomon code and Bose-Chandhuri-Hocquenghem code. By way of example, consider the operation of your cell phone when you're about to have your signal fade away. Let's say you wanted to tell the person on the other end of the call a sequence of numbers. There forward error are several techniques that could be used to improve accuracy; For instance, assume the list of numbers that you wish to transmit might be 7, 3, 8, 10, 12, and 21. One method would be to repeat the list of numbers two times and have the person at the receive end write down each list and compare them, If they match, the data transmission is probably OK. The drawback is that, since you have to send all data two times, forward error correction the throughput of the system is cut in half and if the lists don't match, you will have no idea which one is correct. Using this most basic method, to ensure that you could verify good transmission and correct some errors, you'd have to send the list three times and verify that two out of the three transmissions matched for each number. A second method might be to first announce that you will be sending six numbers, then send the six numbers followed by the total of the six numbers. The transmission sequence would then be 6, 7, 3, 8, 10, 12, 21, and 61. The person at the receive end would look at the first number and then ensure that the correct number of additional numbers is received and then verify that the number at the end of the sequence that is the sum of the transmitted numbers. This method only requires less additional data to be sent. If any number is received wrong or missed, then the check sum number at the end of the transmission will not match the sum of the transmitted numbers. The methods shown are good examples of error detecting codes. They allow you to determine if the transmission was accurate, but they don't allow you to correct the errors. Note: The term "Forward" in FEC implies that the error correction is accomplished by some information that is sent along with the data transmission.
need for retransmission. How Forward Error Correction Works FEC works by adding “check bits” to the outgoing data stream. Adding more check bits reduces the amount of available bandwidth by increasing the overall block size of the outgoing data, but also enables the receiver to correct for more errors without receiving any additional transmitted data. This dynamic makes FEC ideal when bandwidth is plentiful, but retransmission is costly or impossible. The “check bits,” or redundant bits, that the sender adds to the data stream are coded into the data in a very specific way, which allows for efficient error correction by the receiving device. Many different types of FEC coding have been developed. A simplistic example would be a triple redundancy code, also known as (3,1) repetition code, where each bit of data is simply transmitted 3 times. The results of each triplet are averaged together to account for noise in the transmission, and a corrected result is decided on. Other more advanced coding systems that are in use today include Reed-Solomon coding, a customizable coding scheme that is often used in DVB. Applications of Forward Error Correction Reed-Solomon coding is notable for its use in CD, DVD, and hard disk drives. Although these drives are not transmitting data in the traditional sense, FEC coding allows for error correction on bits that become corrupted through damage to the physical medium of the drive. Many types of multicast transmissions also make use of FEC. Forward Error Correction is particularly well suited for satellite transmissions, both for consumer and space exploration applications, where bandwidth is reasonable but latency is significant. Forward Error Correction vs. Backward Error Correction Forward Error Correction protocols impose a greater bandwidth overhead than backward error correction protocols, but are able to recover from errors more quickly and with significantly fewer retransmissions. Forward Error Correction also places a higher computational demand on the receiving device because the redundant information in the transmission must be interpreted according to a predetermined algorithm. Overall, Forward Error Correction is more suitable for single, long-distance, and relatively high-noise transmissions, rather than situations where smaller batches of information can be sent repeatedly and easily. In these cases, Backward Error Correction is much more likely to