LDPC BP Decoding With Row-Wise LLR Updates for Faster Convergence

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Solution Overview

Problem

The standard BP algorithm for LDPC code decoding is computationally complex and requires a large number of iterations, leading to high silicon area and power consumption in mobile terminals, making it inefficient for reducing terminal size and extending battery life.

Innovation Solution

A modified decoding method that speeds up convergence and reduces the number of iterations by updating LLR values based on nonzero elements in the check matrix, using simplified calculations, and approximating functions to decrease computational burden, while supporting multiple communication standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the standard BP algorithm is used for LDPC code decoding, then decoding accuracy is improved, but the number of iterations increases and computational complexity increases

Engineering Contradiction:
Improvedecoding accuracyVSAvoidcomputational complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the check matrix H into multiple sub-matrices, allowing the decoding process to be divided into smaller units. This segmentation enables parallel processing of different sub-matrices, reducing the overall computational complexity while maintaining decoding accuracy through systematic processing of divided blocks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic iteration termination by checking whether the syndrome Hx^T equals zero at each iteration step. The decoding process adaptively stops when the termination condition is met, avoiding fixed large numbers of iterations. This dynamic approach reduces average computational complexity while ensuring reliable decoding when conditions are satisfied.

Inventive Principle:
Principle #15Dynamics

2Reliability

If the standard BP algorithm is used for LDPC code decoding, then decoding accuracy is improved, but silicon area increases

Engineering Contradiction:
Improvedecoding accuracyVSAvoidsilicon area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

By dividing the check matrix into sub-matrices, the patent reduces the size of individual processing units required for each iteration step. The segmented structure allows for more compact hardware implementation with reduced interconnections and smaller buffer requirements, directly decreasing silicon area while maintaining overall decoding performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The dynamic iteration termination mechanism allows the hardware to exit the decoding loop early when the syndrome becomes zero, avoiding unnecessary iterations. This reduces the average active silicon area required during decoding operations, as not all processing units need to remain active for the full maximum number of iterations in every case.

Inventive Principle:
Principle #15Dynamics

3Reliability

If the standard BP algorithm is used for LDPC code decoding, then decoding accuracy is improved, but power consumption increases

Engineering Contradiction:
Improvedecoding accuracyVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The dynamic iteration termination based on syndrome checking enables the decoder to stop processing as soon as the decoding condition Hx^T = 0 is satisfied. This adaptive approach significantly reduces the average number of iterations required, directly lowering power consumption since each iteration consumes energy. The patent achieves this without sacrificing decoding accuracy, as iterations continue until the correct solution is found.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The segmented matrix structure enables more efficient power utilization by allowing selective activation of processing units corresponding to different sub-matrices. This reduces overall power consumption compared to processing the entire matrix simultaneously, while still achieving accurate decoding through systematic processing of all segments.

Inventive Principle:
Principle #1Segmentation

4Productivity

If the standard BP algorithm is used for LDPC code decoding, then decoding thoroughness is improved, but the number of iterations increases

Engineering Contradiction:
Improvedecoding throughputVSAvoidnumber of iterations
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent implements dynamic iteration control by continuously monitoring the syndrome Hx^T and terminating decoding when it equals zero. This adaptive approach reduces the average number of iterations required compared to fixed iteration schemes, directly improving decoding throughput while maintaining thoroughness. The system dynamically adjusts the number of iterations based on the actual decoding progress rather than using a predetermined large number.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By segmenting the check matrix into sub-matrices, the patent enables parallel processing of multiple sub-matrices simultaneously. This segmentation increases decoding throughput by utilizing parallel computational resources, reducing the effective time required despite the iterative nature of the algorithm. The divided structure allows different processing units to work on different segments concurrently.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS8250449B2Decoding method for LDPC code based on BP arithmetic
Publication Date: 2012.08.21 SANECHIPS TECH CO LTD
  • US8250449B2 patent drawing
  • US8250449B2 patent drawing
  • US8250449B2 patent drawing

AI summary

A decoding method for LDPC codes based on BP algorithm, includes initializing LLR (qmm) with the received LDPC bit stream; updating the check node LLR (rmm) and variable node LLR (qmm): after updating the LLR (rmm) corresponding to nonzero elements in each row in check matrix H in each iteration; immediately updating the LLR (qmm) corresponding to all the nonzero elements in the column which has a nonzero element in the row, and repeating the updating row by row; updating LLR (qn) on the basis of LLR (rm); terminating decoding process if maximum number of allowed iterations is reached or the correct result obtained and outputting the final decoding result xn; The method of the present invention may accelerate the decoding convergence, and reduce the number of iterations to increase the throughput, further reduce the power consumption and silicon area of decoding apparatus possible if LLR (qmm) is properly approximated.