PBCH Polar Rate Matching for Variable SSB Bandwidths
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Solution Overview
Problem
Conventional wireless communication systems degrade the effectiveness of polar codes by performing resource-block-level puncturing on the PBCH, leading to increased block error rate (BLER) and coverage loss, particularly in reduced capability (RedCap) devices with varied SSB bandwidths.
Innovation Solution
Implement bit-level rate matching and channel interleaving techniques that align with the polar reliability sequence, ensuring frozen bits are preferentially removed and reliable bits are preserved during puncturing, and reorder polar codeword bits to minimize impact on decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If resource-block-level puncturing is performed on PBCH, then device complexity is reduced, but BLER performance deteriorates and cell coverage is lost
Solution Approach 1:
The patent segments the rate matching process from coarse resource-block level to fine bit-level, allowing precise control over which bits are punctured. This segmentation enables alignment with polar reliability sequences to preserve reliable bits while removing only frozen bits, thereby maintaining BLER performance without excessive complexity
Solution Approach 2:
The patent applies local quality by differentiating the treatment of different bits within the polar code based on their reliability characteristics. Bits are selectively processed according to their position in the polar reliability sequence, with frozen bits being punctured and reliable bits being preserved, optimizing performance for each bit's specific role
2Adaptability or versatility
If conventional puncturing is used for RedCap devices with varied SSB bandwidths, then adaptability is improved, but BLER performance deteriorates
Solution Approach 1:
The patent implements dynamic rate matching that adapts to different SSB bandwidth configurations (5 MHz and 3 MHz) by selecting appropriate rate matching patterns. The system dynamically adjusts the puncturing strategy based on the actual bandwidth, maintaining optimal BLER performance across varied operational conditions
Solution Approach 2:
The patent changes key parameters including the rate matching pattern selection, the number of frozen bits, and the puncturing positions based on SSB bandwidth. By adjusting these parameters dynamically, the system maintains adaptability to different bandwidth configurations while preserving decoding reliability through aligned puncturing with polar reliability sequences
3Reliability
If bit-level rate matching is implemented, then BLER performance is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple rate matching patterns that are prepared in advance for different SSB bandwidth configurations. These patterns are selected based on the actual bandwidth before executing the puncturing operation, avoiding the need for complex real-time calculations while maintaining optimal performance
Solution Approach 2:
The patent uses copying by replicating the polar reliability sequence structure and using it as a template for determining which bits to puncture. The reliability sequence serves as a copy reference that guides the bit-level selection process, simplifying the implementation by leveraging the existing code structure rather than requiring entirely new complex algorithms
Data Source
AI summary
Various aspects of the present disclosure relate to techniques for rate matching adaptation for polar-coded physical broadcast channel (PBCH). A network equipment is configured to encode a PBCH payload to generate a polar codeword according to a polar reliability sequence, select, based on a synchronization signal block (SSB) bandwidth, a rate matching pattern from a plurality of predefined rate matching patterns, perform bit-level rate matching on the polar codeword in accordance with the selected rate matching pattern, and map quadrature phase-shift keying (QPSK) symbols corresponding to the rate-matched polar codeword to resource elements of an SSB resource grid for transmission.