LDPC Codeword CRC Segmentation for Low-Overhead Error Detection

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Solution Overview

Problem

In wireless communication systems, Low Density Parity Check Code (LDPCC) codewords lack reliable error detection due to short parity checks, while appending a Cyclic Redundancy Check (CRC) to LDPCC codewords increases data transmission overhead, especially for high data rate transmissions.

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.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a CRC is appended to each LDPCC codeword, then decoding error detection reliability is improved, but data transmission overhead increases

Engineering Contradiction:

Improvedecoding error detection reliabilityVSAvoiddata 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 individual CRCs for each codeword. This segmentation approach reduces the total number of CRC bits required while maintaining error detection capability across all codewords derived from the segmented code blocks.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple code blocks are combined into a unified structure where a single CRC polynomial is applied to detect errors across all resulting codewords. This merging of error detection function reduces overhead compared to individual CRCs per codeword, while the unified CRC still provides reliable error detection for the entire transmission unit.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If Turbo Code (TC) encoding is used, then hybrid automatic repeat request (HARD) processes and rate matching are supported, but decoding complexity increases

Engineering Contradiction:

Improvesupport for HARQ and rate matchingVSAvoiddecoding complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the encoding parameter from Turbo Code to LDPCC encoding, which has lower decoding complexity. The LDPCC encoding maintains compatibility with HARQ and rate matching processes through appropriate parameter adjustments in the coding scheme, achieving the same adaptability with reduced complexity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the number of TC decoders is increased, then decoding throughput is improved, but device complexity and resource consumption increase

Engineering Contradiction:

Improvedecoding throughputVSAvoidnumber of decoders deployed

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

By changing the encoding type to LDPCC, the decoding complexity per decoder is reduced significantly. This allows achieving the same decoding throughput with fewer decoder instances, or alternatively, provides headroom to increase throughput by adding decoders without proportionally increasing overall system complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11700021B2Techniques to provide a cyclic redundancy check for low density parity check code codewords

Publication Date: 2023.07.11 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.