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Soft output viterbi algorithm method and decoder

A soft output Viterbi, soft output technology, applied in the field of error correction code decoding, can solve problems such as complex update process, and achieve the effect of reducing error probability, reducing implementation complexity, and improving bit error rate performance

Inactive Publication Date: 2012-05-30
TELEFON AB LM ERICSSON (PUBL)
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0032] On the other hand, low-latency SOVA-type algorithms require complex update procedures if the MAP baseline performance is to be fully maintained as explained above

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  • Soft output viterbi algorithm method and decoder
  • Soft output viterbi algorithm method and decoder
  • Soft output viterbi algorithm method and decoder

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Embodiment Construction

[0076] Next, an embodiment of the present invention applying a modified update rule to SOVA will be described. Compared with BR-SOVA, the modified update rule reduces complexity while achieving better BER performance than HR-SOVA.

[0077] According to some embodiments, the modified update rule for updating the reliability value can be expressed as:

[0078] if u k-U (s)≠u k-U (c), then L k-U (s)←min(L k (s), L k-U (s)), and

[0079] if u k-U (s)=u k-U (c), then L k-U (s)←min(L k (s)+Δ k-U (c), L k-U (s)).

[0080] Among them, Δ k-U (c) is u k-U (c) Initial reliability value. Thus, the modified update rule uses the initial reliability value (ie, metric difference) of the concurrent paths instead of the (possibly updated) reliability value as in the Battail rule. Therefore, there is no need to update the reliability value along the concurrent paths, which easily improves the latency and complexity of the algorithm.

[0081] In the Battail rule, suppose to updat...

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Abstract

A method of decoding a block with a Soft Output Viterbi Algorithm (SOVA) using a trellis representation and a sliding window wherein each position of the sliding window has a path determination stage at one end of the sliding window and a symbol decision stage at another end of the sliding window is disclosed. The method comprises determining, for each path determination stage and for each node of the path determination stage, a surviving path (including a surviving path input symbol and a surviving decision stage node) and a concurrent path (including a concurrent path input symbol and a concurrent decision stage node) based on path metrics. A path metric disparity value is calculated and stored for each node. Based on decision criteria, a soft output value of the surviving decision stage node is determined as either of the path metric disparity value of the node of the path determination stage, a function of the path metric disparity value of the node of the path determination stage and the stored path metric disparity value of the concurrent decision stage node, and the stored path metric disparity value of the surviving decision stage node. Corresponding computer program product, decoder and communication apparatus are also disclosed.

Description

technical field [0001] The invention relates to the field of decoding error correcting codes. More specifically, it relates to decoding trellis codes. Background technique [0002] For example, in "Iterative decoding of binary block and convolutional codes" published by J.Hagenauer, E.Offer and L.Papke (see IEEE Trans.Inf.Theory, vol.42, no.2, pp.429-445, Mar.1996) described the principle of iterative decoder in one article. Generally, iterative decoding can be based on soft-input soft-output (SISO) exchange of decorrelated extrinsic information between constituent decoders. [0003] Figure 1A An example implementation of iterative decoding using such an arrangement of constituent SISO decoders 11 and 13 is shown, which may be adapted to decode eg turbo codes using rate 1 / 2 constituent codes. [0004] In this example, received intrinsic soft values ​​representing two code bits (code symbols in the more general case) are input to the first In SISO decoder 11 (decoder 1)....

Claims

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Application Information

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IPC IPC(8): H03M13/41
CPCH03M13/39H03M13/3776H03M13/4184H03M13/41H03M13/6525H03M13/3972H03M13/4153H03M13/4146H03M13/6511H03M13/3707
Inventor 马蒂亚斯·卡穆夫安丽航林维关
Owner TELEFON AB LM ERICSSON (PUBL)