Polar Coding for BeiDou Short Messages With Lower Encoding Complexity
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Solution Overview
Problem
The existing turbo code used in the Beidou satellite's short message communication system requires performance improvement and complexity reduction for effective channel encoding.
Innovation Solution
A polar code encoding and decoding method that utilizes a specially designed information bit sequence to determine channel locations, incorporating cyclic redundancy check (CRC) and parity check (PC) bits, with pre-stored sequences and fixed rate matching, to enhance performance and reduce complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If turbo code is used for channel encoding in Beidou satellite short message communication, then communication functionality is provided, but performance and complexity need further improvement
Solution Approach 1:
The patent changes the encoding scheme from turbo code to polar code, which has different structural parameters and characteristics. Polar code uses a specific matrix structure (Kroner product of identity matrix and F matrix) that simplifies the encoding process while maintaining or improving error correction performance, directly addressing the need for both performance improvement and complexity reduction
Solution Approach 2:
The patent segments the encoding process into distinct functional components: information bit sequence generation, polar code matrix construction, and encoding operation. This segmentation allows for optimized implementation of each component, particularly the use of pre-stored sequences and fixed rate matching that reduce overall system complexity
2Productivity
If polar code encoding with pre-stored sequences is used, then performance is improved and complexity is reduced, but system storage overhead increases
Solution Approach 1:
The patent implements a nested structure where channel location sets for different to-be-encoded bit lengths are nested within each other. The sequence for shorter bit lengths is a subset of the sequence for longer bit lengths, allowing the system to store only the maximum-length sequence and derive all shorter sequences from it, thereby minimizing storage overhead while maintaining encoding efficiency
Solution Approach 2:
The pre-stored sequence is designed to serve multiple functions: it provides channel location information for various to-be-encoded bit lengths (235, 470, 940, 1880, 2820, 3760 bits), eliminates the need for separate sequences for each length, and enables fixed rate matching across different message sizes, making the system universally applicable to multiple communication scenarios
Data Source
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AI summary
A polar encoding and decoding method and apparatus are provided. The method includes: obtaining K to-be-encoded bits (401); selecting K sequence numbers from a first sequence, where the to-be-encoded bits are placed on polar channels corresponding to the K sequence numbers (402); and performing polar code encoding on the K to-be-encoded bits to obtain encoded bits (403), where the first sequence includes sequence numbers of N polar channels, and the first sequence is one or a sub-sequence of a related sequence. This technical solution is applicable to a short message communication system of a BeiDou satellite. The method can effectively improve performance of the communication system and reduce complexity.