Polar Code Rate Matching With Unified Puncturing and Shortening
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Solution Overview
Problem
Polar codes face limitations in achieving flexible code lengths and efficient rate matching, as their original construction only allows code lengths that are powers of two, and existing rate matching techniques are complex and inefficient.
Innovation Solution
A method for polar code rate matching that determines whether to puncture or shorten a mother polar code based on the code rate and reliability of synthesized channels, using a predetermined index list to select positions for information bits and perform operations like puncturing, shortening, or repetition to match the desired code length, while maintaining channel polarization effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polar codes use original construction with power-of-two code lengths, then encoding structure is simple and regular, but code length flexibility is limited
Solution Approach 1:
The patent segments the mother polar code into multiple parts through puncturing (removing specific code bits) or shortening (setting specific code bits to fixed values). This allows the code length to be flexibly adjusted from the original power-of-two length to any desired length while maintaining the underlying structured encoding framework.
Solution Approach 2:
The patent introduces dynamic rate matching mechanisms where the encoder can adaptively select between puncturing and shortening modes based on channel conditions and target code rates. The rate matching configuration is dynamically adjustable to achieve different code lengths and rates while maintaining optimal performance.
2Adaptability or versatility
If polar codes implement rate matching to achieve arbitrary code lengths, then code length flexibility improves, but encoding complexity increases
Solution Approach 1:
The patent performs preliminary rate matching configuration by pre-determining which code bit positions to puncture or shorten based on the target code length and rate. This preliminary setup allows the encoder to efficiently achieve the desired code length without complex real-time calculations during encoding, reducing operational complexity.
Solution Approach 2:
The patent changes key parameters such as the puncturing pattern, shortening positions, and rate matching configuration to achieve different code lengths and rates. By systematically varying these parameters, the system can adapt to different transmission requirements while maintaining a unified encoding framework.
3Reliability
If polar codes select information bit positions based on channel reliability, then coding performance improves, but selection complexity increases
Solution Approach 1:
The patent applies local quality optimization by selecting specific input bit positions corresponding to the most reliable synthesized channels for information bit placement. Each position is evaluated based on its local channel reliability characteristics, ensuring that information bits are placed in the most favorable positions while frozen bits occupy less reliable positions.
Solution Approach 2:
The patent uses parameter changes in the form of pre-computed reliability metrics and index lists that rank input bit positions according to channel reliability. These parameters are derived offline or through simplified calculations, allowing efficient selection of information bit positions without complex real-time optimization.
Data Source
AI summary
Aspects of the disclosure provide polar code rate matching methods. A first method can include determining whether to puncture or shorten a mother polar code according to a mother code rate and/or a rate matched code rate, and selecting K positions in the sequence of N input bits for input of K information bits to a polar encoder according to an offline prepared index list ordered according to the reliabilities of respective synthesized channels. Frozen input bits caused by puncturing or shortening are skipped during the selection. A second method includes generating a mother polar code, rearranging code bits of the mother polar code to form a rearranged sequence that can be stored in a circular buffer, and performing, in a unified way, one of puncturing, shortening, or repetition on the rearranged sequence to obtain a rate matched code.