Polar Code Puncturing and Shortening for Flexible Code Lengths
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Solution Overview
Problem
Existing methods for designing polar codes with arbitrary lengths and rates face high computational complexity due to the lack of structure in generating frozen sets, puncturing patterns, and shortening patterns, leading to increased latency and memory requirements.
Innovation Solution
An encoder and decoder system that uses a combination of puncturing and shortening techniques to optimize frozen, puncturing, and shortening bit indices, stored in look-up tables to minimize error rates, allowing for efficient generation of polar codes with various lengths and rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polar codes are designed with arbitrary lengths and rates using existing methods, then code flexibility is improved, but computational complexity increases
Solution Approach 1:
The patent segments the code design process into distinct operations: freezing bits (setting to known values), puncturing (removing specific bits), and shortening (truncating the code). Each operation has predefined rules and lookup tables, breaking down the complex arbitrary code design into manageable, structured segments that reduce overall computational burden.
Solution Approach 2:
The patent pre-computes and stores lookup tables for frozen bit indices, puncturing patterns, and shortening patterns during code construction. These preliminary actions allow the encoder and decoder to quickly reference pre-determined bit positions rather than computing them in real-time, significantly reducing operational complexity while maintaining code flexibility.
2Adaptability or versatility
If polar codes are designed with arbitrary lengths and rates using existing methods, then code flexibility is improved, but latency increases
Solution Approach 1:
The patent pre-determines frozen bit indices, puncturing patterns, and shortening patterns during code construction and stores them in lookup tables. This preliminary computation eliminates the need for complex real-time calculations during encoding and decoding operations, directly reducing processing latency while allowing arbitrary code lengths and rates.
Solution Approach 2:
The patent applies different operations (freezing, puncturing, shortening) to specific local portions of the code based on pre-determined patterns. Each operation targets specific bit positions identified in advance, allowing parallel and efficient processing that reduces overall latency compared to global optimization approaches.
3Adaptability or versatility
If polar codes are designed with arbitrary lengths and rates using existing methods, then code flexibility is improved, but memory requirements increase
Solution Approach 1:
The patent pre-computes and stores only the essential parameters (frozen bit indices, puncturing patterns, shortening patterns) in lookup tables during code construction. This preliminary action stores minimal necessary information rather than full code specifications, reducing memory requirements while enabling flexible code design.
Solution Approach 2:
The patent extracts and stores only the critical parameters needed for encoding and decoding (frozen bit positions, puncturing/shortening patterns) in compact lookup tables. By separating and storing only these essential elements rather than complete code descriptions, memory requirements are significantly reduced while maintaining code flexibility.
4Adaptability or versatility
If puncturing and shortening operations are applied to polar codes, then code rate flexibility is improved, but error rate may increase
Solution Approach 1:
The patent applies puncturing and shortening operations to specific local portions of the code determined by pre-computed patterns. By carefully selecting which bits to puncture or shorten based on their positions in the lookup tables (which are optimized during code construction), the patent maintains good error rate performance while achieving desired code rates.
Solution Approach 2:
The patent pre-determines the optimal positions for puncturing and shortening operations during code construction, storing these patterns in lookup tables. This preliminary optimization ensures that when puncturing and shortening are applied, they remove bits in positions that minimize error propagation and maintain code reliability, rather than arbitrarily removing bits.
Data Source
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Figure 2
Figure 3(a)~3(b)
AI summary
Encoder (400) for encoding K information bits into a code word of length N´ on the basis of a polar code of length N, wherein N is a power of 2 and greater than or equal to N´. The encoder (400) comprises a memory (403) storing a plurality of bit indices, wherein the plurality of bit indices comprise a set of N frozen bit indices associated with the polar code of length N, a set of N/2 puncturing bit indices and/or a set of N/2 shortening bit indices and a processor (401) configured to retrieve at least a subset of the plurality of bit indices from the memory (403), to encode the K information bits using the polar code of length N for obtaining encoded data of length N and to reduce the number of bits of the encoded data to the length N´ for obtaining the code word of length N´.