Polar Code Puncturing Control for Reliable NAND Memory Encoding

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Solution Overview

Problem

Polar code encoding in nonvolatile memory devices faces challenges in maintaining reliability due to the inherent difficulty in applying puncturing, which results in loss of information word bits and reduced system reliability.

Innovation Solution

The proposed solution involves an operating method for a controller that selects bits for puncturing in a polar encoded code word, refreezes input word bits to overlap with incapable bits, and adjusts the generation matrix calculation to optimize bit error rates, ensuring that frozen bits overlap with incapable bits to prevent information loss and maintain reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If puncturing is applied to polar code encoding to support variable length code words, then adaptability is improved, but information loss occurs and reliability deteriorates

Engineering Contradiction:

Improvevariable length code word supportVSAvoidsystem reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by identifying incapable bits before puncturing occurs and pre-freezing them in the input word. This advance preparation ensures that when puncturing removes code word bits, the corresponding information is already protected through freezing, preventing information loss and maintaining reliability while supporting variable length code words.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary mechanism by using the generation matrix structure to identify incapable bits that serve as a bridge between punctured code word bits and input word bits. This intermediary identification allows the system to determine which input bits correspond to punctured output bits and freeze them accordingly, resolving the contradiction between puncturing and reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If puncturing is applied to reduce code word length, then productivity is improved, but information loss occurs and reliability deteriorates

Engineering Contradiction:

Improveencoding efficiencyVSAvoidinformation word bit loss

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies the taking out principle by selectively removing only the redundant punctured code word bits while preserving the essential information through freezing of incapable bits. This extraction approach allows productivity improvement through puncturing while preventing information loss by removing only the redundant portions that do not contain critical information.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If frozen bits are repositioned to overlap with incapable bits, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvepolar code encoding reliabilityVSAvoidcontroller complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by using the generation matrix structure itself to identify incapable bits and determine the freezing pattern. The generation matrix inherently contains the information needed to identify which input bits correspond to punctured code word bits, allowing the system to automatically determine the refreezing pattern without requiring external complexity, thus improving reliability while minimizing device complexity.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS9239778B2Controllers that generate output bits for storage in non-volatile memory devices by puncturing code word bits and methods for operating the same

Publication Date: 2016.01.19 SAMSUNG ELECTRONICS CO LTD

AI summary

An operating method of a controller includes selecting bits of code word to be punctured; detecting locations of incapable bits of an input word based on locations of the bits to be punctured and a structure of a generation matrix calculation unit; refreezing the input word such that frozen bits and incapable bits of the input word overlap; generating input word bits by replacing information word bits with frozen bits based on the refreezing result; generating the code word by performing generation matrix calculation on the input word bits; generating output bits by puncturing the code word based on locations of the bits to be punctured; and transmitting the output bits to a nonvolatile memory device.