Log-MAP based decoding method and decoding device thereof in turbo decoding

Abstract

The invention relates to a method and a device thereof in the technical field of mobile communication technologies, in particular to a Log-MAP based decoding method and a decoding device thereof in turbo decoding. In the invention, in a Log-MAP decoding structure, the realizations of a forward state measurement and recursion structure and a backward state measurement and recursion structure are separated from the realization of an LLR computation structure; in LLR computation, an eight-input Logsum structure is not realized by adopting a two-input Logsum structure any more; the recursion of forward state measurement and the backward state measurement is realized by adopting a Max-Log-Map structure, so that the two-input Logsum structure still maintains a lowest realization complexity, meanwhile, the realization complexity of the eight-input Logsum structure is also reduced; and most importantly, the decoding properties and good properties close to an optimal Log-Map method are also maintained. The invention obtains good balance between the realization complexity and the properties of a decoder.

Description

technical field [0001] The present invention relates to a method and device in the technical field of mobile communication, in particular to a decoding method based on Log-MAP in turbo decoding and a decoding device thereof. Background technique [0002] Since the Turbo code was proposed in 1993, due to its excellent performance close to the Shannon limit, it has been widely used in the field of mobile communication technology, and has been determined to be used in the channel coding and decoding of the third generation mobile communication system and LTE (Long Term Evolution) mobile communication system. One of the options. [0003] At present, the decoding method used by Turbo is mainly MAP (maximum a posteriori, maximum a posteriori probability) type method, which generally performs operations on the logarithmic domain, and converts all multiplication operations into addition and table lookup operations, so it is beneficial to the decoder. The hardware implementation red...

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Problems solved by technology

[0004] Existing technologies realize eight-input Logsum on the basis of two-input Logsum structure. There are two structures for two-input Logsum. The first is that the two-input Logsum structure only takes the maximum value of the two inputs. The method is called the Max-Log-Map two-input Logsum structure. This method reduces the complexity, but also loses the most performance. The second structure is that the two-input Logsum adds a correction amount on the basis of taking the maximum value. Use a lookup table to add the correction amount. There are many ways to calculate the correction amount. This method keeps the performance close to the lossless Log-Map, but the complexity is very high.

[0005] The above two structures combine the forward state metric recursion and the structure of the two-input Logsum in the backward state metric recursion with the structure of the eight-input Logsum in the LLR calculation, so the result is either high complexity, Either the performance is poor, and there is no good compromise between complexity and performance. In actual system implementation, because the complexity of Turbo decoding is very high, Logsum generally adopts the Max-Log-Map two-input Logsum structure. Inevitable loss of performance

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