Polar Code Bit-Location Sequences for Finite-Length SCL Decoding
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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 existing information sequences impose artificial relationships among bit channel reliabilities, which are not optimized for SC List (SCL) decoders.
Innovation Solution
Numerically optimized information sequences for specific code lengths are developed, accounting for the performance of SCL decoders at different Block Error Rate (BLER) levels, which are used to map information bits to optimal bit locations in polar encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional Polarization Weight (PW) sequences are used for polar encoding, then the encoding process is simple and systematic, but the finite-length performance is not competitive with other modern channel coding schemes
Solution Approach 1:
The patent applies parameter changes by replacing the traditional Polarization Weight (PW) sequence with a numerically optimized information sequence that is specifically designed for SC List decoders. This optimized sequence changes the fundamental parameters of bit channel reliability assignment, achieving better finite-length performance while maintaining compatibility with the polar encoding structure.
Solution Approach 2:
The patent implements preliminary action by pre-computing and storing optimized information sequences for specific code lengths before actual communication occurs. These pre-optimized sequences account for SCL decoder performance at different BLER levels, eliminating the need for real-time optimization during encoding operations.
2Reliability
If information sequences are optimized for SCL decoders, then the decoding performance improves, but the sequences become specific to particular code lengths rather than universal
Solution Approach 1:
The patent applies segmentation by dividing the universal information sequence into code-length-specific segments. Each code length (e.g., N=64, 128, 256, 512, 1024) has its own optimized information sequence that is extracted from or tailored for that specific length, allowing optimal performance for each code length while maintaining a systematic approach to sequence generation.
3Reliability
If numerically optimized information sequences are used, then performance at different BLER levels improves, but the sequence design becomes more complex and less systematic
Solution Approach 1:
The patent implements preliminary action by performing numerical optimization in advance during the sequence design phase. The optimized information sequences are pre-computed to account for SCL decoder performance at different BLER levels (e.g., 10%, 1%, 0.1%), so that during actual communication, the pre-optimized sequences can be directly applied without real-time optimization complexity.
Data Source
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 SN. The information sequence SN 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 SN is greater than or equal to K. The information sequence SN is optimized for the specific value of the code length (N). The method may further comprise transmitting the set of polar-encoded information bits.