Iterative Decoder Stall Recovery With Dynamic Stop Limits
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Solution Overview
Problem
Iterative decoders in memory subsystems often get stuck in stall conditions, leading to increased latency and Quality of Service (QoS) issues due to repeated parity violations, which can trigger unnecessary error handling even at low raw bit error rates, especially in energy-conscious applications like mobile devices.
Innovation Solution
The memory subsystem dynamically adjusts the maximum iteration count and modifies bit flipping rules, such as updating the bit flipping criterion and order, to detect and mitigate stall conditions by increasing the maximum iteration count or decoding time, allowing the decoder to exit the stall condition and improve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the maximum iteration count is increased to allow the decoder to exit stall conditions, then the reliability of error correction is improved, but the latency and energy consumption increase
Solution Approach 1:
The patent implements dynamic adjustment of the maximum iteration count based on detected stall conditions. The system transitions from a static iteration limit to a dynamic one that adapts during decoding operations. When a stall condition is detected (repeated parity violations), the system increases the iteration count threshold, allowing the decoder to continue iterating beyond the original limit to potentially exit the stall condition and successfully decode the codeword.
Solution Approach 2:
The patent changes the parameter of maximum iteration count from a fixed value to a dynamically adjustable value. The system monitors decoding progress and modifies the iteration count parameter in response to detected stall conditions. This parameter change enables the decoder to adapt its behavior during operation, increasing iterations when needed to resolve stall conditions while maintaining normal operation under typical conditions.
2Reliability
If the maximum iteration count is increased to exit stall conditions, then the reliability of error correction is improved, but the energy consumption increases
Solution Approach 1:
The system dynamically adjusts the iteration count based on actual decoding needs rather than using a fixed high limit. By monitoring for stall conditions and only increasing iterations when necessary, the system minimizes energy consumption during normal operation while maintaining the capability to increase effort when reliability is compromised by stall conditions.
Solution Approach 2:
The maximum iteration count parameter is changed from a static high value to a dynamic value that adjusts based on detected stall conditions. This allows the system to consume minimal energy during typical decoding operations while having the capability to increase energy expenditure only when stall conditions threaten decoding success, thus improving the reliability-energy tradeoff.
3Adaptability or versatility
If the maximum iteration count is dynamically adjusted, then the adaptability to stall conditions is improved, but the device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the decoder monitors its own performance during iteration. When repeated parity violations indicate a stall condition, this feedback triggers an increase in the maximum iteration count. The system continuously observes decoding progress and adjusts parameters based on this feedback, enabling automatic adaptation without requiring complex external control logic.
Solution Approach 2:
The decoder performs self-diagnosis and self-adjustment by monitoring its own decoding progress. When it detects a stall condition through repeated parity violations, it autonomously increases the iteration count to attempt to exit the stall. This self-service approach reduces the need for complex external control systems while maintaining high adaptability to varying decoding conditions.
Data Source
AI summary
Methods, systems, and apparatuses detect and mitigate a stall condition in an iterative decoder. A codeword is received and one or more of the plurality of bits in the codeword are flipped by a bit flipping decoder in each of a plurality of error correction iterations. In response to detecting a stall condition in the plurality of error correction iterations, a maximum stop condition is increased. The maximum stop condition is a maximum iteration count threshold or a maximum decoding time threshold. The maximum stop condition triggers a stopping of the bit flipping decoder if the codeword is not decoded when the maximum stop condition is satisfied.