Soft-in soft-out decoder: Difference between revisions

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{{more citations needed|date=March 2010}}

A soft-in soft-out decoder is used by certain error correcting codes to correct errors. The decoder calculates the most probable value for the data and successive passes through the decoder gradually get closer to the original error free data. Soft refers to the fact that both the input and the output are probablistic.

A '''soft-in soft-out decoder''' ('''SISO decoder''') is a type of [[soft-decision decoder]] used with [[error correcting code]]s.<ref name="NeubauerFreudenberger2007">{{cite book|author1=Andre Neubauer|author2=Jurgen Freudenberger|author3=Volker Kuhn|title=Coding Theory.: Algorithms, Architectures and Applications|url=https://books.google.com/books?id=j5zNVqjY0uYC&q=Soft-in+soft-out+decoder|date=22 October 2007|publisher=John Wiley & Sons|isbn=978-0-470-51982-0}}</ref> "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]] 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]]s, or to modify the input to a further decoding iteration such as in the decoding of [[turbo code]]s.

Examples include the [[BCJR algorithm]] and the [[soft output Viterbi algorithm]].

== See also ==

* [[Decoding methods]]

* [[Error detection and correction]]

* [[Forward error correction]]

* [[Multidimensional parity-check code]]

==References==

{{Reflist}}

[[Category:Error detection and correction]]