Systematic Polar Coding Under Rate Matching Constraints
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Solution Overview
Problem
Systematic polar codes face challenges in practical wireless systems due to rate matching issues that interfere with generating systematic polar codes, particularly when the coded bit length differs from the target codeword length, affecting bit error rate and decoding performance.
Innovation Solution
Implement systematic polar encoding by selecting locations for shortening, puncturing, and bit freezing that satisfy explicit conditions, ensuring systematic encoding, and prioritizing repetition of systematic bits over non-systematic bits to maintain low complexity and improve decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If rate matching operations (puncturing, shortening, repetition) are performed on polar codes to adjust coded bit length to target codeword length, then adaptability to different transmission requirements is improved, but bit error rate performance deteriorates
Solution Approach 1:
The patent applies local quality by making different parts of the codeword have different properties - systematic bits are protected with higher priority during repetition and are frozen at specific locations, while non-systematic bits have different treatment. This localized differentiation ensures that critical information bits maintain higher reliability during rate matching operations.
Solution Approach 2:
The patent performs preliminary action by pre-selecting frozen bit locations and systematic bit positions before rate matching operations. The encoder determines which bits will be frozen and which positions will hold systematic information in advance, ensuring that subsequent puncturing, shortening, or repetition operations do not compromise the integrity of critical information bits.
2Reliability
If systematic polar encoding is implemented with explicit conditions for shortening, puncturing, and bit freezing locations, then decoding performance is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the encoding parameters (frozen bit locations, systematic bit positions, rate matching mode) based on the target codeword length and transmission requirements. The encoder adapts these parameters dynamically while maintaining a structured approach that limits complexity growth, using predefined rules for parameter selection rather than exhaustive optimization.
3Reliability
If systematic bits are prioritized for repetition during rate matching, then bit error rate is improved, but loss of information increases due to selective repetition
Solution Approach 1:
The patent applies self-service by designing a systematic encoding scheme where the encoder automatically identifies and protects critical information bits through freezing and priority repetition without requiring external intervention or complex coordination. The systematic bits serve their own protection needs through the structured encoding process, reducing the need for additional redundancy mechanisms.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. For example, when an output from a systematic polar encoder has a coded bit length N that differs from a target code length E, locations for bit freezing may be selected such that a resulting set of information bit locations (including cyclic redundancy code (CRC) bit locations) satisfy a systematic encoding condition. Furthermore, when the coded bit length N exceeds the target code length E, such that shortening or puncturing is performed to achieve the target code length, locations for shortening or puncturing may be selected to ensure that the set of information bit locations satisfy the systematic encoding condition. In this way, the systematic polar code may include a set of systematic bits at the same locations as the information bits, and the systematic bits do not appear in any untransmitted (for example, punctured or shortened) locations.