Segmented PAC Coding for Lower-Latency Polar Decoding
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Solution Overview
Problem
Existing polar codes in wireless communications face challenges with decoding latency and complexity for longer codewords, which affect performance and hardware efficiency, especially for small to moderate size codewords.
Innovation Solution
Implementing a Polarization-Adjusted Convolutional (PAC) code that includes an outer convolutional code and a polar code, with separate encoding of segments of convolutionally encoded input bits, allowing for segmentation transforms like interleaving or reverse polar transforms to reduce decoding latency and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polar codes are used for channel coding in wireless communications, then error correction performance is improved, but decoding latency and complexity increase for longer codewords
Solution Approach 1:
The patent divides a long codeword into multiple shorter sub-codewords through segmentation transforms (interleaving or reverse polar transforms). Each sub-codeword is decoded separately and independently, reducing the overall decoding latency and complexity while maintaining the error correction performance of the original long codeword. This directly addresses the contradiction by breaking down the large decoding task into smaller, parallelizable units.
2Reliability
If polar codes are used for channel coding in wireless communications, then error correction performance is improved, but hardware complexity increases for longer codewords
Solution Approach 1:
The patent segments the polar code into multiple sub-codewords that can be decoded in parallel using separate hardware decoders. This segmentation reduces the complexity of each individual decoder while maintaining the overall error correction performance, making the system more hardware-efficient for longer codewords.
3Loss of time
If segmentation transforms are applied to polar codes, then decoding latency is reduced, but code structure complexity increases
Solution Approach 1:
The patent applies segmentation transforms (interleaving or reverse polar transforms) to divide the codeword into independent sub-codewords. This segmentation enables parallel decoding that reduces latency, while the transforms themselves are designed to be computationally efficient and reversible, managing the added structural complexity.
Solution Approach 2:
The segmentation transform acts as an intermediary step between encoding and decoding. It reorganizes the codeword structure into segments that can be independently processed, facilitating parallel decoding while maintaining the ability to reconstruct the original message. This intermediary transformation manages the complexity by providing a structured approach to segmentation.
Data Source
AI summary
A codeword is generated based on a segmentation transform and a Polarization-Adjusted Convolutional (PAC) code that includes an outer convolutional code and a polar code, and based on separate encoding of respective different segments of convolutionally encoded input bits according to the polar code. Each segment of the respective segments includes multiple bits of the convolutionally encoded input bits for which the separate encoding of the segment is independent of the separate encoding of other segments. Separate decoding may be applied to segments of such a codeword to decode convolutionally encoded input bits corresponding to the separately encoded segments of the convolutionally encoded input bits.