1 research outputs found
-imbalance WOM Codes for Reduced Inter-Cell Interference in Multi-Level NVMs
In recent years, due to the spread of multi-level non-volatile memories
(NVM), -ary write-once memories (WOM) codes have been extensively studied.
By using WOM codes, it is possible to rewrite NVMs times before erasing the
cells. The use of WOM codes enables to improve the performance of the storage
device, however, it may also increase errors caused by inter-cell interference
(ICI). This work presents WOM codes that restrict the imbalance between code
symbols throughout the write sequence, hence decreasing ICI. We first specify
the imbalance model as a bound on the difference between codeword levels.
Then a -cell code construction for general and input size is proposed.
An upper bound on the write count is also derived, showing the optimality of
the proposed construction. In addition to direct WOM constructions, we derive
closed-form optimal write regions for codes constructed with continuous
lattices. On the coding side, the proposed codes are shown to be competitive
with known codes not adhering to the bounded imbalance constraint. On the
memory side, we show how the codes can be deployed within flash wordlines, and
quantify their BER advantage using accepted ICI models