Writing on dirty flash memory

TL;DR

This paper models flash memory with inter-cell interference as a dirty paper problem and demonstrates how side information can be used to improve data encoding, reducing failure probability.

Contribution

It introduces a novel model linking dirty flash memory to defective cell memory and applies additive encoding with side information for performance enhancement.

Findings

Dirty flash memory can be transformed into a defective cell model using a single pre-read.

Additive encoding with side information significantly reduces decoding failure.

The asymmetry in flash memory operations is crucial for the proposed model.

Abstract

The most important challenge in the scaling down of flash memory is its increased inter-cell interference (ICI). If side information about ICI is known to the encoder, the flash memory channel can be viewed as similar to Costa's "writing on dirty paper (dirty paper coding)." We first explain why flash memories are dirty due to ICI. We then show that "dirty flash memory" can be changed into "memory with defective cells" model by using only one pre-read operation. The asymmetry between write and erase operations in flash memory plays an important role in this change. Based on the "memory with defective cells" model, we show that additive encoding can significantly improve the probability of decoding failure by using the side information.