Polar Code Puncturing Choice Across SNR and Coding Rates

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Solution Overview

Problem

Current polar code implementations face limitations in flexibility regarding codeword length, as they typically require lengths to be a power of 2, and existing puncturing schemes for variable block lengths are inefficient, with unknown-bit and known-bit puncturing schemes performing better under different conditions based on coding rates and signal-to-noise ratios.

Innovation Solution

A method is introduced that compares the performance of unknown-bit and known-bit puncturing schemes by calculating log likelihood ratios (LLR) for both schemes and selects the better performing one to generate a punctured codeword of variable length, allowing for improved adaptability and performance across different communication conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If polar codes use fixed power-of-2 block lengths, then decoding complexity is reduced and performance is optimized, but adaptability to variable message lengths is lost

Engineering Contradiction:

Improveadaptability to variable message lengthsVSAvoiddecoding complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The polar code block is segmented into information bits and frozen bits, with the ability to vary the number of information bits based on message length requirements while maintaining the power-of-2 total block structure, thus achieving adaptability without increasing fundamental decoding complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The code parameters (number of information bits k, block length n) are made dynamic and configurable rather than fixed, allowing the system to adapt to different message lengths by adjusting the information-to-frozen bit ratio while maintaining optimized decoding performance

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If puncturing is applied to achieve variable block lengths, then adaptability is improved, but performance degrades under certain coding rates and SNR conditions

Engineering Contradiction:

Improveflexibility in codeword lengthVSAvoiddecoding performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The puncturing pattern parameters are optimized and adjusted based on coding rate and channel conditions. Different puncturing patterns are selected or designed for different operating conditions to maintain performance while achieving the desired variable block length flexibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The puncturing scheme is made adaptive, where the puncturing pattern and degree of puncturing are dynamically selected based on the coding rate and signal-to-noise ratio conditions, ensuring optimal performance across different operating scenarios

Inventive Principle:

Principle #15Dynamics

3Reliability

If unknown-bit puncturing scheme is used, then performance improves at certain coding rates, but performance degrades at other coding rates and SNR conditions

Engineering Contradiction:

Improvedecoding performance at specific coding ratesVSAvoidperformance consistency across coding rates

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The puncturing scheme parameters (treating punctured bits as known or unknown) are changed based on operating conditions. The system selects between known-bit and unknown-bit puncturing approaches depending on the coding rate and SNR, ensuring consistent performance across different scenarios

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The puncturing approach is made dynamic, switching between treating punctured bits as known or unknown based on real-time assessment of coding rate and channel conditions, thereby achieving both reliability and adaptability

Inventive Principle:

Principle #15Dynamics

4Reliability

If known-bit puncturing scheme is used, then performance improves at certain SNR conditions, but performance degrades at other conditions

Engineering Contradiction:

Improvedecoding performance at specific SNR conditionsVSAvoidperformance consistency across SNR conditions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The puncturing scheme parameters are adjusted based on SNR conditions. The system dynamically selects between known-bit and unknown-bit puncturing treatments depending on the signal-to-noise ratio, ensuring reliable performance across varying channel quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The puncturing approach adapts dynamically to channel conditions, switching between known-bit and unknown-bit treatments based on real-time SNR assessment, thereby achieving both reliability and versatility across different operating conditions

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10749633B2Generation of polar codes with a variable block length utilizing

Publication Date: 2020.08.18 QUALCOMM INC

AI summary

Polar codes may be generated with a variable block length utilizing puncturing. Some puncturing schemes consider punctured bits as unknown bits, and set the log likelihood ratio (LLR) for those bits to zero; while other puncturing schemes consider punctured bits as known bits, and set the LLR for those bits to infinity. Each of these puncturing schemes has been observed to provide benefits over the other under different circumstances, especially corresponding to different coding rates or different signal to noise ratio (SNR). According to aspects of the present disclosure, both puncturing schemes are compared, and the puncturing scheme resulting in the better performance is utilized for transmission.