Polar Code Bit-Channel Ranking for SCL Decoder Reliability
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Solution Overview
Problem
The existing polar coding methods, particularly the Polarization Weight (PW) sequence, impose artificial relationships among bit channels' reliabilities and are optimized for Successive Cancellation (SC) decoders rather than more commonly used Successive Cancellation List (SCL) decoders, leading to suboptimal performance in wireless communication systems.
Innovation Solution
The disclosure provides numerically optimized information sequences for specific code lengths that account for the performance of SCL decoders at different Block Error Rate (BLER) levels, offering better performance compared to traditional PW sequences by individually optimizing bit channel assignments for SCL decoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the Polarization Weight (PW) sequence is used to assign information bits to bit channels, then the coding structure is simple and easy to implement, but the performance is suboptimal because it imposes artificial relationships among bit channel reliabilities and is optimized for SC decoders rather than SCL decoders
Solution Approach 1:
The patent changes the parameter of information sequence from the conventional PW sequence to a numerically optimized sequence specifically designed for SCL decoders. This optimized sequence is derived through numerical optimization methods that account for the specific characteristics of SCL decoding, thereby improving error correction performance while maintaining implementation feasibility through standardized sequence tables for common code lengths.
2Device complexity
If the PW sequence is used, then the information sequence can be generated using a simple weight function, but the bit channel assignments are not optimally matched to SCL decoder performance requirements
Solution Approach 1:
The patent applies preliminary action by pre-computing and storing optimized information sequences for common code lengths (128, 256, 512, 1024) in lookup tables. This allows the system to directly retrieve the optimal sequence without performing complex numerical optimization at runtime, thus maintaining low implementation complexity while achieving optimal SCL decoder performance.
3Reliability
If information sequences are individually optimized for specific code lengths, then the performance for those specific lengths is improved, but the solution requires separate sequences for each code length rather than a universal generation method
Solution Approach 1:
The patent applies local quality by providing customized information sequences tailored to specific code lengths (128, 256, 512, 1024) and their corresponding SCL decoder configurations. Each code length has its own optimized sequence that accounts for the specific reliability requirements and decoding characteristics of that code length, thereby achieving locally optimal performance for each scenario.
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 SN 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.