Polar Code Rate Matching for Flexible Target Code Lengths
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Solution Overview
Problem
Existing polar code encoding and decoding methods face challenges in managing complexity and achieving efficient rate matching, particularly when dealing with target code lengths that are not integer powers of 2, leading to increased overhead and complexity.
Innovation Solution
The proposed solution involves a rate matching method that dynamically selects between repetition and shortening/puncturing based on the target code length, using polar codes with mother code lengths that are integer powers of 2, thereby reducing complexity and maintaining encoding gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If polar codes with mother code lengths that are integer powers of 2 are used for encoding, then the encoding and decoding complexity is reduced, but the ability to achieve exact target code lengths is limited
Solution Approach 1:
The patent segments the rate matching process into two distinct approaches: repetition for when N1 ≤ M and shortening/puncturing for when N2 ≥ M. This segmentation allows the system to select the most appropriate method based on the relationship between mother code length and target code length, thereby reducing overall complexity while maintaining adaptability to various target code length requirements.
Solution Approach 2:
The patent introduces dynamic selection between different rate matching methods (repetition vs. shortening/puncturing) based on the target code length M and mother code length N. The encoding apparatus dynamically determines which method to use by comparing M with N and checking whether M is an integer power of 2, allowing the system to adapt its operation mode to minimize complexity while achieving the desired code length.
2Manufacturing precision
If rate matching is performed using traditional methods for non-power-of-2 target code lengths, then exact target code length is achieved, but overhead and complexity increase
Solution Approach 1:
The patent changes the approach by introducing a conditional parameter check: whether M is an integer power of 2. Based on this parameter change, the system selects different processing paths - using repetition when M ≥ N1 (where N1 is the largest power of 2 less than or equal to M) and using shortening/puncturing when M < N1. This parameter-based decision-making simplifies the rate matching process while maintaining accurate target code length achievement.
3Reliability
If repetition is used for rate matching when N1 ≤ M, then encoding gain is maintained, but code length extension is required
Solution Approach 1:
The patent applies partial action by using repetition only for the necessary number of bits to reach the target code length M. Specifically, when N1 ≤ M, the system repeats (M-N1) bits from the encoded sequence, which is exactly the amount needed to achieve the target length without unnecessary extension. This partial repetition maintains encoding gain while avoiding excessive code length increase.
4Manufacturing precision
If shortening or puncturing is used for rate matching when N2 ≥ M, then target code length is achieved, but encoding gain may be reduced
Solution Approach 1:
The patent performs preliminary action by carefully selecting which bits to shorten or puncture based on their positions in the encoded sequence. When using shortening, the system removes bits from positions that minimize impact on encoding gain. When using puncturing, the system selectively removes bits while maintaining the ability to recover information at the receiver. This preliminary planning preserves encoding gain while achieving the exact target code length M.
Data Source
AI summary
Embodiments of the application provide a method for rate matching in a wireless communication network. A device obtains K information bits and a target code length M of a polar code, determines, according to a minimum value of a set of values, a mother code length N, polar encodes the K information bits to obtain an encoded sequence of N bits, obtains a target sequence of M bits from the N bit encoded sequence, and outputs the M-bit target sequence.