LDPC Rate Matching with Systematic Bit Puncturing

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Solution Overview

Problem

Existing LDPC codes require efficient rate matching methods for varying block lengths and code rates, particularly in systems like 802.11n, where puncturing, shortening, and repetition are not clearly defined, especially for codes that puncture systematic bits by design.

Innovation Solution

A method involving circular buffer-based rate matching is employed, where systematic bits are punctured, and dummy bits are added or omitted to achieve desired code sizes, with redundancy versions defined for retransmissions, maintaining weight distribution and enabling flexible code rate adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate procedures for shortening, puncturing, and repetition are used, then code flexibility is improved, but device complexity increases

Engineering Contradiction:

Improvecode flexibilityVSAvoidprocedure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines shortening, puncturing, and repetition operations into a single circular buffer-based rate matching procedure. The encoder writes codeword bits to a circular buffer and reads them out with wrapping, achieving all three operations through one unified mechanism rather than separate procedures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The circular buffer structure serves multiple functions simultaneously: it enables shortening by controlling write positions, enables puncturing by controlling read positions, and enables repetition through wrapping behavior. This single structure replaces multiple specialized procedures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Productivity

If circular buffer-based rate matching with systematic bit puncturing is used, then procedure efficiency is improved, but decoding performance may worsen

Engineering Contradiction:

Improverate matching efficiencyVSAvoiddecoding performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies different treatments to different parts of the codeword: systematic bits are punctured (not written to or read from the buffer) while parity bits are fully processed. This local differentiation optimizes the balance between efficiency and performance by protecting the more critical parity information.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the code rate by controlling the number of information bits k and coded bits ntx through the circular buffer operations. By adjusting these parameters and the buffer read/write positions, the system achieves flexible rate matching while maintaining decoding performance through careful selection of which bits to puncture.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12562756B2Rate matching methods for LDPC codes

Publication Date: 2026.02.24 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method of producing a set of coded bits from a set of information bits for transmission between a first node and a second node in a wireless communications system, the method comprises generating a codeword vector by encoding the set of information bits with a low-density parity-check code, wherein the codeword vector is composed of systematic bits and parity bits. The method comprises performing circular buffer-based rate matching on the generated codeword vector to produce the coded bits for transmission, wherein the circular buffer-based rate matching comprises puncturing a first plurality of systematic bits.