LDPC Codeword CRC Segmentation for Short-Payload Reliability

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Solution Overview

Problem

In wireless communication systems, Low Density Parity Check Code (LDPCC) encoding lacks reliable parity checks for short codewords, leading to residual false alarm events, while appending a Cyclic Redundancy Check (CRC) to LDPCC codewords increases data transmission overhead, especially for payloads with a small number of bits.

Innovation Solution

A unified code block segmentation method is introduced, where a CRC is generated at the code block level for LDPCC codewords, similar to Turbo Code (TC) encoding, to provide decoding error protection without significantly increasing overhead, even for short payloads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a CRC is appended to each LDPCC codeword for decoding error protection, then reliability is improved, but overhead increases significantly

Engineering Contradiction:

Improvedecoding error protectionVSAvoiddata transmission overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The payload is segmented into multiple code blocks, and a single CRC is generated for the entire set of code blocks rather than appending separate CRCs to each individual codeword. This segmentation approach maintains error protection capability while reducing the total number of CRC bits transmitted, thereby resolving the contradiction between reliability and overhead.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If LDPCC encoding is used to reduce decoding complexity, then ease of operation is improved, but reliability deteriorates for short codewords due to insufficient parity checks

Engineering Contradiction:

Improvedecoding complexityVSAvoidparity check reliability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

Multiple code blocks containing short LDPCC codewords are merged into a unified code block structure, allowing a single CRC to provide cross-block error detection. This merging enables the simple LDPCC encoding to achieve reliable error protection by combining multiple codewords under a unified CRC framework, resolving the contradiction between decoding complexity and reliability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10855315B2Techniques to provide a cyclic redundancy check for low density parity check code codewords

Publication Date: 2020.12.01 QUALCOMM INC

AI summary

Techniques are described for wireless communication. One method includes segmenting a payload into a plurality of code blocks; generating, for each code block, a cyclic redundancy check (CRC); encoding each code block and associated CRC in one or more codewords of a plurality of codewords; and transmitting the codewords. The encoding is based at least in part on a low density parity check code (LDPCC) encoding type. Another method includes receiving a plurality of codewords associated with a payload encoded using a LDPCC encoding type; decoding a set of the codewords associated with the first payload and a CRC; and transmitting one of an acknowledgement (ACK) or a non-acknowledgement (NAK) for the set of the codewords.