Article · Wikipedia archive · Last revised Jun 10, 2026

Soft-in soft-out decoder

A soft-in soft-out decoder is a type of soft-decision decoder used with error correcting codes. "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 codes, or to modify the input to a further decoding iteration such as in the decoding of turbo codes.

Last revised
Jun 10, 2026
Read time
≈ 1 min
Length
142 w
Citations
1
Source
Wikipedia ↗

A soft-in soft-out decoder (SISO decoder) is a type of soft-decision decoder used with error correcting codes.1 "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 codes, 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

See also

References

References

  1. Andre Neubauer; Jurgen Freudenberger; Volker Kuhn (22 October 2007). Coding Theory.: Algorithms, Architectures and Applications. John Wiley & Sons. ISBN 978-0-470-51982-0.