LDPC Decoder Bit Flipping With Incremental Threshold Updates

Solution Overview

Problem

Conventional low-density parity-check (LDPC) decoders with bit flipping schemes face slow convergence due to the need to calculate all preliminary syndromes for a complete codeword before determining flipping thresholds, leading to complex computations and inefficient processing.

Innovation Solution

A method and decoder architecture that calculates a flipping function value for a specific data portion using parity check matrix equations and compares it to a threshold based on previous data portions, allowing for immediate flipping decisions without waiting for all syndromes to be calculated, incorporating a barrel shifter, syndrome calculator, inverse barrel shifter, flipping function value calculator, and determining block.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If all preliminary syndromes of all data bits are calculated before determining flipping threshold, then the flipping decision accuracy is improved, but the computational complexity increases and convergence speed decreases

Engineering Contradiction:

Improveflipping decision accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the codeword into multiple data portions and processes them sequentially rather than calculating all syndromes at once. The flipping threshold is updated incrementally as each data portion is processed, allowing early flipping decisions without waiting for complete syndrome calculation of all bits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent calculates flipping thresholds in advance for each data portion before actual flipping decisions are made. By pre-calculating thresholds based on available syndromes and updating them incrementally, the system enables immediate flipping decisions without requiring complete syndrome information.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If all preliminary syndromes of all data bits are calculated before determining flipping threshold, then the flipping decision accuracy is improved, but the convergence speed decreases

Engineering Contradiction:

Improveflipping decision accuracyVSAvoidconvergence speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The patent divides the codeword into multiple data portions and processes them sequentially rather than calculating all syndromes at once. The flipping threshold is updated incrementally as each data portion is processed, allowing early flipping decisions without waiting for complete syndrome calculation of all bits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent maintains continuous processing by calculating syndromes, updating thresholds, and making flipping decisions in an ongoing sequential manner. This continuous action eliminates idle waiting time and accelerates convergence by keeping the decoding process active throughout.

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If flipping threshold is determined based on all preliminary syndromes, then the flipping decision reliability is improved, but the processing time increases

Engineering Contradiction:

Improveflipping decision reliabilityVSAvoidprocessing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent calculates flipping thresholds in advance for each data portion before actual flipping decisions are made. By pre-calculating thresholds based on available syndromes and updating them incrementally, the system enables immediate flipping decisions without requiring complete syndrome information.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses partial syndrome information from previously processed data portions to determine flipping thresholds, rather than waiting for complete syndrome information. This partial action approach provides sufficient reliability for flipping decisions while significantly reducing processing time.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11296725B2Method employed in LDPC decoder and the decoder

Publication Date: 2022.04.05 SILICON MOTION INC

AI summary

A method employed in a low-density parity-check code decoder includes: receiving a specific data portion of a first codeword; calculating a flipping function value of the specific data portion of the first codeword according to the specific data portion by using checking equations of a parity check matrix to calculate checking values of the specific data portion; and determining whether to flip the specific data portion of the first codeword by comparing the flipping function value with a flipping threshold which has been calculated based on a plurality of flipping function values of a plurality of previous data portions earlier than the specific data portion.