Flash Memory Temperature Compensation Using Q-Learning Reads
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Solution Overview
Problem
Flash memory devices face increased bit error rates due to temperature changes, as each storage element has a distinct cross-temperature coefficient, leading to shifting and widening of cell voltage distributions, which existing temperature compensation methods struggle to address efficiently.
Innovation Solution
Implementing a Q-learning process with a Q-table and BER estimation module to determine the current state of the flash memory device, select optimal read actions with maximum Q-values, and conduct read operations using appropriate temperature compensation parameters to minimize accumulative decoding latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional temperature compensation methods are used, then temperature compensation can be achieved, but the latency is long
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing optimal read parameters in a lookup table during manufacturing or idle periods. When temperature compensation is needed, the system retrieves pre-computed parameters rather than performing real-time search operations, significantly reducing latency while maintaining compensation accuracy.
Solution Approach 2:
The patent replaces the traditional mechanical search process (iterative reading and parameter adjustment) with an electronic lookup table approach. Instead of performing sequential searches through parameter spaces, the system directly queries pre-computed optimal parameters from memory, substituting computational search with data retrieval operations.
2Reliability
If multiple simple reads with different parameters are performed, then temperature compensation can be achieved, but the process complexity increases
Solution Approach 1:
The system performs the complex search process in advance during manufacturing or initialization, storing the results in a lookup table. During normal operation, the system simply retrieves pre-computed optimal parameters rather than executing complex search algorithms, reducing operational complexity while maintaining bit error rate reduction.
Solution Approach 2:
The patent creates a copy of the optimal parameter set in a lookup table structure. Instead of performing the full search process repeatedly, the system uses the stored copy of optimal parameters for temperature compensation, simplifying the operational process while maintaining compensation effectiveness.
3Reliability
If search over flash memory device parameters is performed, then temperature compensation can be achieved, but the latency increases
Solution Approach 1:
The system performs the parameter search and optimization in advance, storing results in a lookup table. During actual read operations, the system retrieves pre-computed parameters directly from memory, eliminating the need for real-time search operations and significantly improving read speed while maintaining compensation effectiveness.
Solution Approach 2:
The patent substitutes the time-consuming iterative search process with direct data retrieval from a lookup table. This replacement transforms the productivity bottleneck from computational search to memory access, which is much faster and does not scale with the parameter search space.
Data Source
AI summary
A method of temperature compensation to read a flash memory device includes determining a state of the flash memory device. An action is selected with a maximum Q-value from a Q-table for the current state during exploitation. A read operation of a code word from the flash memory device is conducted using one or more parameters according to the selected action. The code word is decoded with an error correction code (ECC) process.