In information theory and coding error control is divided in two main categories: Information theory is a branch of the mathematical theory of probability and mathematical statistics that quantifies the concept of information. ... The term coding has the following meanings: In communications systems, the altering of the characteristics of a signal to make the signal more suitable for an intended application, such as optimizing the signal for transmission, improving transmission quality and fidelity, modifying the signal spectrum, increasing the information content, providing error...

Error Detection Redundancy allows a receiver to check whether received data has been corrupted during transmission. He can for example request a retransmission. In information theory and coding, an error-detecting code is a code in which each data signal conforms to specific rules of construction so that departures from this construction in the received signal can generally be automatically detected. ...

Error Correction This type of error control allows a receiver to reconstruct the original information when it has been corrupted during transmission. This is especially useful when there is only one-way communication. In information theory and coding, an error-correcting code or ECC is a code in which each data signal conforms to specific rules of construction so that departures from this construction in the received signal can generally be automatically detected and corrected. ...

Examples

One of the roles of the Data Link Layer Protocol is to detect errors on a receiving side. Parity, checksum, Cyclic redundancy check (CRC), Vertical redundancy check, Horizontal redundancy check and Rectangular redundancy check are examples of varieties of error-checking mechanisms. The data link layer is level two of the seven-level OSI model. ... Parity is a concept of equality of status or functional equivalence. ... A checksum is a form of redundancy check, a very simple measure for protecting the integrity of data by detecting errors in data that is sent through space (telecommunications) or time (storage). ... A cyclic redundancy check (CRC) is a type of hash function used to produce a checksum, which is a small number of bits, from a large block of data, such as a packet of network traffic or a block of a computer file, in order to detect errors in transmission... In telecommunication, a transverse redundancy check (TRC) or vertical redundancy check is a redundancy check for synchronized parallel bit streams, (a) that is based on the formation of a block check following preset rules, (b) in which the check-formation rule applied to blocks is also applied to characters, and... In telecommunication, a longitudinal redundancy check (LRC) or horizontal redundancy check is a form of redundancy check based on the formation of a block check following preset rules. ...

There are 2 ways to correct found errors: Forward error correction and Automatic repeat request (ARQ). The first one is practical in cases where the communication channel is remarkably long - with long dramatic delay - and is prone to errors. In this case, it is not practical to send retransmission requests. Instead, sets of redundant information is sent with the data, so that correction can be done on the fly. ARQ is an interactive way of correcting errors by bouncing back and forth between a sender and a receiver until accuracy is ensured. In telecommunication, forward error correction (FEC) is a system of error control for data transmission wherein the receiving device has the capability to detect and correct fewer than a predetermined number or fraction of bits or symbols corrupted by transmission errors. ... ARQ is an acronym for: Automatic Repeat-reQuest. ...

See also

• Reed-Solomon error correction
• Hamming code