Polar Code Decoding With Weighted Path Metrics for Low-Bit LLRs
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Solution Overview
Problem
Polar code-based decoding methods using fast simplified successive cancellation list with single parity check (SPC) nodes (fast-SSCL-SPC) experience performance degradation when applied to channels with low resolution due to improper updating of path metrics (PMs) caused by extreme quantization with fewer than five bits.
Innovation Solution
A polar code-based decoding method that updates path metrics by multiplying the minimum log likelihood ratio (LLR) value by a preset weight, even when it is equal to the current LLR value, to ensure proper PM updating and prevent performance degradation in low resolution channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast-SSCL-SPC decoding algorithm is applied to reduce latency and increase throughput, then productivity is improved, but reliability deteriorates in low resolution channels due to improper PM updating
Solution Approach 1:
The patent modifies the path metric update rule by introducing a weight factor applied to the minimum LLR value. This parameter change ensures that PMs are properly updated even in low resolution channels, preventing the reliability deterioration that occurs with conventional fast-SSCL-SPC decoding while maintaining high throughput
2Device complexity
If extreme quantization with fewer than five bits is used to reduce complexity, then device complexity is reduced, but measurement precision deteriorates causing improper PM updating
Solution Approach 1:
The patent introduces a weight factor as an intermediary element that mediates between the quantized LLR values and the path metric update process. This weight factor compensates for the precision loss due to extreme quantization, allowing proper PM updating to be achieved even with fewer than five bits of resolution
Data Source
AI summary
A polar code-based decoding method may comprise: converting a plurality of LLRs of calculation-target bits into a plurality of absolute (ABS) LLR values; sorting the plurality of ABS LLR values in order of size so that a minimum ABS LLR value is designated from among the plurality of ABS LLR values; multiplying the minimum ABS LLR value by a preset weight; and updating path metrics (PMs) of the calculation-target bits in an order in which the plurality of ABS LLR values are sorted, wherein the updating of the PMs of the calculation-target bits comprises, even when a specific ABS LLR value of a specific calculation-target bit is equal or similar to the minimum ABS LLR value, updating a PM of the specific calculation-target bit with the minimum ABS LLR value multiplied by the preset weight.