A soft-in soft-out decoder (SISO decoder) is a type of
soft-decision decoder used with
error correcting code
In computing, 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.
The centra ...
s.
"Soft-in" refers to the fact that the incoming data may take on values other than 0 or 1, in order to indicate reliability. "Soft-out" refers to the fact that each
bit
The bit is the most basic unit of information in computing and digital communication. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented as ...
in the decoded output also takes on a value indicating reliability. Typically, the soft output is used as the soft input to an outer decoder in a system using
concatenated code
In coding theory, concatenated codes form a class of error-correcting codes that are derived by combining an inner code and an outer code. They were conceived in 1966 by Dave Forney as a solution to the problem of finding a code that has both expo ...
s, or to modify the input to a further decoding iteration such as in the decoding of
turbo codes.
Examples include the
BCJR algorithm and the
soft output Viterbi algorithm.
See also
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Decoding methods
In coding theory, decoding is the process of translating received messages into Code word (communication), codewords of a given code. There have been many common methods of mapping messages to codewords. These are often used to recover messages se ...
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Error detection and correction
In information theory and coding theory with applications in computer science and telecommunications, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communi ...
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Forward error correction
In computing, 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.
The centra ...
References
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Error detection and correction