LDPC Decoder Mode Switching Using Failed-Check LLR Seeding
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Solution Overview
Problem
Low-density parity check (LDPC) decoders face inefficiencies in hard decision hard decoding, as they require multiple iterations before switching to soft decision decoding modes, which increases power consumption and decoding time due to the lack of initial soft information.
Innovation Solution
A method that uses a first decoder in hard decision mode to generate log-likelihood ratio (LLR) values from failed check nodes, creating a look-up table to convert this information into soft information, which is then used by a second decoder in soft decision mode, allowing for early termination and efficient switching between decoding modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hard decision hard decoding is used, then power consumption is reduced, but decoding time increases due to multiple iterations required before switching to soft decision mode
Solution Approach 1:
The patent applies preliminary action by generating soft information (LLR values) in advance during the hard decision hard decoding process. Instead of waiting until soft decision mode is activated, the system pre-calculates and stores log-likelihood ratio values in a look-up table based on failed check node information, so that when soft decision mode becomes necessary, the soft information is already available, eliminating the need for additional iteration cycles.
2Reliability
If multiple decoding iterations are performed before mode switching, then decoding accuracy is improved, but the number of iterations increases leading to higher power consumption
Solution Approach 1:
The patent introduces an intermediary mechanism - a look-up table that stores pre-calculated soft information (LLR values) derived from hard decision decoding results. This intermediary structure allows the system to bridge hard decision and soft decision modes efficiently, providing accurate soft information without requiring extensive iteration, thus reducing power consumption while maintaining decoding accuracy.
3Use of energy by moving object
If hard decision hard decoding is used initially, then power efficiency is improved, but soft information is delayed until mode switching occurs
Solution Approach 1:
The system performs preliminary action by generating and storing soft information during the hard decision phase. The look-up table is populated with LLR values calculated from failed check node data before soft decision mode is activated, ensuring that soft information is immediately available when needed without delaying the power-efficient hard decision process.
4Productivity
If the decoder switches to soft decision mode, then decoding efficiency is improved, but power consumption increases due to lack of initial soft information
Solution Approach 1:
The patent uses copying by creating a look-up table that stores copies of soft information (LLR values) derived from hard decision decoding results. This copied information is then readily available when soft decision mode is activated, allowing the decoder to switch modes efficiently without the power penalty that would otherwise result from generating soft information from scratch.
Data Source
AI summary
A method for performing low-density parity check (LDPC) decoding includes: in a first decoder which operates in a first mode, performing a plurality of decoding iterations of a codeword using a first algorithm, including: decoding the codeword to generate first information including a number of failed check nodes; linking the number of failed check nodes to a log-likelihood ratio (LLR) value to generate second information; and performing parity check equations for the codeword at check nodes. When a predetermined number of decoding iterations in the first decoder is reached without the parity check equations being solved, decoding of the codeword using the first decoder is stopped, the codeword is input to a second decoder and decoding of the codeword in the second decoder using a second algorithm and the second information is started.