Four-ary Symbol Mapping for Storage Device Inter-Symbol Interference
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Solution Overview
Problem
In storage devices like magnetic disk devices, increasing record density leads to inter-symbol interference, degrading the quality of the reproduced signal, making it difficult to achieve both improved information record density and signal quality.
Innovation Solution
The storage device employs mapping rules that convert data into four-ary symbols, prioritizing patterns with higher noise tolerance, allowing for improved record density while reducing inter-symbol interference by recording these symbols as four-level signals on the medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If record density is increased, then information storage capacity is improved, but inter-symbol interference increases causing signal quality degradation
Solution Approach 1:
The patent changes the parameter of signal encoding from binary (2-level) to quaternary (4-level) symbols, allowing two bits to be encoded into one symbol. This parameter change enables higher record density while maintaining signal quality by reducing the number of transitions and minimizing inter-symbol interference effects
Solution Approach 2:
The patent transitions from a two-dimensional binary encoding approach to a four-dimensional quaternary encoding approach, effectively adding a dimension to the signal representation. This allows the system to store more information per symbol without increasing the physical density that causes interference
Data Source
AI summary
According to one embodiment, there is provided a storage device including a data converter, a recording medium, and an equalizer. The data converter converts data into sets of n number of four-ary symbols according to mapping rules in which 22n-1 or fewer types of bit labels are mapped onto the n number of four-ary symbols, where n is an integer of two or greater. Onto the recording medium, the converted n number of four-ary symbols are recorded in the form of a signal of one level among four levels. The equalizer equalizes a signal read from the recording medium into sets of the n number of four-ary symbols.