Polar Code CRC Bit Placement for Finite-Length Decoding Latency
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Solution Overview
Problem
Polar codes face challenges with finite-length performance and high decoder latency due to serial decoding and energy expenditure on CRC encoding, especially for short-to-medium block lengths, which affects decoding efficiency in wireless communication systems.
Innovation Solution
The strategic placement of CRC bits within a polar code codeword using a multi-dimensional interpretation, where error correction codes are selectively inserted at specific locations based on criteria to improve decoding latency and performance, and further encoding using non-polar codes to enhance error-exponents and reduce complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRC bits are placed in regular intervals in a data stream to be encoded by a Polar code, then error correction performance is improved, but decoding latency increases due to serial decoding
Solution Approach 1:
The patent segments the CRC verification process into multiple distributed verification points throughout the decoding chain. Instead of a single serial CRC check at the end, multiple CRC bits are inserted at different positions in the codeword, enabling parallel verification of different segments of the decoded data. This segmentation allows the decoder to verify error correction performance at multiple points simultaneously, reducing overall decoding latency while maintaining reliability.
Solution Approach 2:
The patent transitions from a one-dimensional serial decoding approach to a multi-dimensional decoding structure by inserting CRC bits at multiple positions in the codeword. This creates a two-dimensional verification structure where both spatial distribution of CRC bits and temporal processing can occur in parallel. The multi-dimensional interpretation of Polar codes allows simultaneous processing of multiple codeword segments, reducing the serial bottleneck while maintaining error correction performance.
2Device complexity
If standard Polar coding is used for short-to-medium block lengths, then implementation complexity is reduced, but error correction performance deteriorates
Solution Approach 1:
The patent creates a composite coding structure by combining Polar codes with distributed CRC bits inserted at multiple positions. This composite approach integrates the simplicity of Polar coding with the enhanced error correction capabilities of distributed CRC verification. The resulting structure maintains the low implementation complexity of Polar codes while adding the performance benefits of multiple CRC checks, effectively creating a hybrid coding scheme that achieves both goals.
Solution Approach 2:
The patent applies local quality enhancement by strategically placing CRC bits at specific positions within the codeword based on reliability criteria. Different segments of the codeword receive CRC protection based on their individual error susceptibility, with higher reliability segments receiving CRC bits at optimized positions. This localized approach enhances error correction performance where needed most while maintaining overall implementation simplicity.
3Reliability
If multiple CRC bits are inserted at different locations to improve error correction, then energy expenditure on CRC encoding increases
Solution Approach 1:
The patent applies partial action by inserting CRC bits at only the most critical positions in the codeword rather than uniformly distributing them throughout. The selection of CRC insertion positions is based on reliability criteria that identify where error correction is most needed. This partial approach achieves effective error correction performance while minimizing the total number of CRC bits required, thereby reducing the energy expenditure on CRC encoding operations.
Data Source
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AI summary
Certain aspects of the present disclosure relate to techniques and apparatus for improving decoding latency and performance of Polar codes. An exemplary method generally includes generating a codeword by encoding information bits, using a multidimensional interpretation of a polar code of length N, determining, based on one or more criteria, a plurality of locations within the codeword to insert error correction codes generating the error correction codes based on corresponding portions of the information bits, inserting the error correction codes at the determined plurality of locations, and transmitting the codeword. Other aspects, embodiments, and features are also claimed and described.