Joint compression of multiple types of soft metrics in soft decoders

Abstract

The decoder decodes a codeword of an ECC in a sequence of decoding steps. In a given decoding step, the decoder attempts decoding a respective subset of bits of the codeword by: (a) receiving a combination of (i) channel soft metrics and (ii) intermediate soft metrics that have gone through one or more previous decoding steps, for the bits in the subset, (b) attempting to decode the subset by processing the channel soft metrics and the intermediate soft metrics, and (c) updating one or more of the intermediate soft metrics. The compressor converts at least some of the intermediate LLRs belonging to a subset into a joint compressed representation. The decompressor decompresses the joint compressed representation to produce decompressed intermediate soft metrics, and provides the decompressed intermediate soft metrics for use in subsequent decoding steps.

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