  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.
