Tapered Variable Node Memory for Multi-Rate LDPC Decoding

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Solution Overview

Problem

Existing data storage systems using Low Density Parity Check (LDPC) error correction coding face challenges in efficiently managing memory resources across varying code rates, leading to either inadequate protection or wasteful storage space, as different code rates require different encoder/decoder designs and memory allocations.

Innovation Solution

A system and method that includes a decoder with variable node memories and a processor to determine circulant size and number based on the code rate, allocating memory proportionally to store confidence values, with memory capacities tapering according to the position of variable nodes, optimizing memory usage across multiple code rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If more redundancy (lower code rate) is added to improve error correction performance, then reliability improves, but storage space is wasted

Engineering Contradiction:
Improveerror correction performanceVSAvoidstorage space
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The decoder dynamically configures the number of variable node memories and their memory capacities based on the detected code rate. This allows the system to adapt memory resources to the actual error correction needs, using more memory for lower code rates (higher redundancy) and less memory for higher code rates, thereby resolving the contradiction between reliability and storage space efficiency

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of the memory subsystem by adjusting the number of active variable node memories and their capacity allocations according to the code rate. This parameter adaptation enables optimal balance between error correction performance and memory resource utilization for different coding scenarios

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If different encoder/decoder designs are implemented for different code rates, then adaptability improves, but device complexity increases

Engineering Contradiction:
Improvesupport for multiple code ratesVSAvoiddecoder design complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single unified decoder design is created that can handle multiple code rates through dynamic configuration of variable node memories. The decoder uses a message buffer and processor that operate universally across different code rates, eliminating the need for separate encoder/decoder designs for each code rate while maintaining full adaptability

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The decoder incorporates dynamic configuration capabilities where the number and capacity of variable node memories are adjusted based on the code rate being used. This dynamic adaptation allows one decoder design to serve multiple code rates, reducing device complexity while maintaining versatility

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If fixed memory capacity is allocated to variable node memories, then ease of manufacture improves, but memory efficiency deteriorates across varying code rates

Engineering Contradiction:
Improvememory allocation simplicityVSAvoidmemory efficiency
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

The system transitions from fixed memory capacity allocation to dynamic capacity allocation based on code rate. The processor determines the appropriate memory capacity for each variable node memory based on the detected code rate, allowing efficient memory utilization across different coding scenarios while maintaining manufacturing feasibility through standardized memory components

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS10289348B2Tapered variable node memory
Publication Date: 2019.05.14 SANDISK TECHNOLOGIES LLC
  • US10289348B2 patent drawing
  • US10289348B2 patent drawing
  • US10289348B2 patent drawing

AI summary

The subject technology provides a decoding solution that conserves variable node memory in Low Density Parity Check decoding operations, while supporting multiple choices of code rates. A decoder includes a plurality of variable node memories, with each of the variable node memories having a predetermined memory capacity based on a position of a respective variable node associated with the variable node memory relative to a first variable node in a series of variable nodes. The code rate determines how many of the variable node memories are used, and the size of the data stored in each memory. The capacity of the memories is predetermined so that, as the code rate and number of memories utilized by the decoder increases or decreases, utilization of the memory capacity of each variable node memory is maximized.