Polar Code Information Sequences for SCL Decoder Bit Loading
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Solution Overview
Problem
Polar codes' finite-length performance under Successive Cancellation (SC) decoding is not competitive with other modern channel coding schemes like LDPC and Turbo codes, and the existing Polarization Weight (PW) sequence imposes artificial relationships among bit channel reliabilities, which is not optimized for Soft-Output List (SCL) decoders.
Innovation Solution
Numerically optimized information sequences for specific code lengths are presented, accounting for the performance of SCL decoders at different Block Error Rate (BLER) levels, providing better performance compared to the PW sequence by individually optimizing bit channel loading for SCL decoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the Polarization Weight (PW) sequence is used to determine information bit locations, then the coding structure is simple and systematic, but the finite-length performance under SCL decoding is not optimized and remains non-competitive with LDPC and Turbo codes
Solution Approach 1:
The patent changes the parameters of the information sequence by providing different optimized sequences for specific code lengths (N=64, 128, 256, 512) rather than using a single PW sequence for all lengths. This allows the system to achieve better finite-length performance under SCL decoding while maintaining the systematic structure of polar codes, resolving the contradiction between structural simplicity and performance reliability.
2Adaptability or versatility
If the PW sequence is used for all code lengths, then the method is universally applicable and easy to implement, but it imposes artificial relationships among bit channel reliabilities that are not optimized for SCL decoders
Solution Approach 1:
The patent segments the universal PW sequence approach into specific optimized sequences for different code lengths (N=64, 128, 256, 512). Each segmented sequence is independently optimized for its specific code length and SCL decoding performance, eliminating the artificial relationships imposed by the generic PW sequence while maintaining ease of implementation through lookup tables.
3Device complexity
If SC decoding is used for polar codes, then the decoder complexity is low, but the finite-length performance is not competitive with other modern channel coding schemes
Solution Approach 1:
The patent changes the information sequence parameter to be specifically optimized for SCL decoding rather than SC decoding. By providing numerically optimized information sequences for SCL decoders at different BLER levels, the system achieves competitive finite-length performance with modern codes while SCL decoding maintains moderate complexity, resolving the performance- complexity tradeoff.
Data Source
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AI summary
According to some embodiments, a method of operation of a transmit node in a wireless communication system comprises performing polar encoding of a set of K information bits to thereby generate a set of polar-encoded information bits. The K information bits are mapped to the first K bit locations in an information sequence S N . The information sequence S N is a ranked sequence of N information bit locations among a plurality of input bits for the polar encoding where N is equivalent to a code length. A size of the information sequence S N is greater than or equal to K. The information sequence S N is optimized for the specific value of the code length (N). The method may further comprise transmitting the set of polar-encoded information bits.