Polar CRC Bit Selection for Lower Frame Error Rates
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Solution Overview
Problem
Existing methods for encoding polar codes concatenated with CRC codes do not achieve optimal performance, especially when the CRC code length is relatively short, leading to suboptimal frame error rates.
Innovation Solution
The proposed method involves selecting a subset of input bits for CRC encoding based on row weights and reliability of polarized subchannels, and then performing polar encoding on both the CRC-coded bits and the remaining input bits to improve the performance of the polar code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CRC concatenation methods are used for polar codes, then the encoding process is simple, but the frame error rate performance is suboptimal, especially when the CRC code length is short
Solution Approach 1:
The patent applies local quality by differentiating the treatment of information bits based on their reliability characteristics. Specifically, the method identifies and separates information bits into different groups based on the reliability of their corresponding polarized subchannels, then applies CRC encoding selectively to specific groups. This localized approach optimizes error detection for the most vulnerable bits without unnecessarily complicating the encoding of all bits, thereby improving frame error rate performance while controlling encoding complexity.
Solution Approach 2:
The patent employs parameter changes by dynamically adjusting which information bits are selected for CRC encoding based on reliability metrics of polarized subchannels. The method changes the parameter of bit selection criteria from a fixed conventional approach to a dynamic reliability-based approach. This allows the system to adapt the CRC encoding configuration to channel conditions, improving reliability performance without requiring a complete redesign of the encoding structure.
2Reliability
If all information bits are encoded with CRC, then error detection capability is maximized, but the computational complexity and overhead increase significantly
Solution Approach 1:
The patent applies the taking out principle by extracting only the most critical information bits for CRC encoding. Instead of applying CRC to all information bits, the method identifies and extracts the subset of bits corresponding to unreliable polarized subchannels. This extraction approach maintains essential error detection capability for the most vulnerable bits while removing unnecessary CRC overhead and computational complexity associated with encoding all bits, thus resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent implements partial action by applying CRC encoding to only a portion of information bits rather than all bits. The method determines an appropriate subset of information bits based on reliability criteria, applying CRC selectively to this partial set. This partial application provides sufficient error detection capability for the most critical bits without the excessive computational burden of processing all bits, achieving an optimal balance between reliability improvement and complexity control.
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4(a)
AI summary
This application provides a method and an apparatus for encoding a polar code concatenated with a CRC. In the method, a bit sequence whose length is K is obtained at a transmit end. M bits are selected from K bits in the sequence to perform CRC encoding. The M bits are determined based on reliability of K polarized subchannels on which the K bits are placed or row weights of K rows, in a first matrix, corresponding to the K polarized subchannels on which the K bits are placed, or the M bits are determined based on reliability of K polarized subchannels on which the K bits are placed and row weights of K rows, in the first matrix, corresponding to the K polarized subchannels on which the K bits are placed. The first matrix is an encoding matrix of polar encoding. Polar encoding is performed on the K bits and obtained CRC check bits. An encoded codeword is output. A simulation result shows that the method can be used to effectively reduce a frame error rate and obtain a performance gain compared with a conventional method for a polar code concatenated with a CRC having a same length.