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.
While soft output can be naturally obtained from methods like tensor network decoders, these approaches are computationally expensive, often requiring exponen-tial time. More recently, the concept of the complemen-tary gap (also known as the logical gap) has been in-troduced,enablingtheecientcalculationofsoftout-put [10, 15, 18].
Moving forward, it's essential to keep these visual contexts in mind when discussing Call Soft Output.
The distinguishing feature of soft-output GRAND (SOGRAND) is the provision of an estimate that the correct decoding has not been found, even when providing a single decoding. Per-block SO can be converted into accurate per-bit SO by a weighted sum that includes a term for the SI.
SOFT OUTPUT VITERBI ALGORITHM The Viterbi algorithm (VA) is a widely-used method for maximum likelihood decoding, and its simple implementation makes it an easy choice in most practical applications. One of its shortcomings, however, is its inability to provide soft-decision outputs. Significant performance loss is encountered when con-catenating two VA decoders, as opposed to soft-output ...
The essential element of all iterative processing techniques is some form of a soft-input, soft-output (SISO) module. A detailed description is given of the most common SISO modules, namely the soft-output Viterbi algorithm (SOVA) and several versions of the Bahl, Cocke, Jelinek and Raviv (BCJR) or maximum a posteriori (MAP) algorithm.
Blockwise Soft Output (SO) decoders return beliefs about the veracity of their returned decoding. Following seminal work of Forney in the 1960s, blockwise soft output is normally only available for decoders that pro-offer more than one decoding possibility, i.e. list decoders.
In this letter, a soft-input/soft-output version of the BMA is developed. Additional complexity-reduction techniques are also described.
