Rank modulation for flash memories

Abstract

We investigate a novel storage technology, Rank Modulation, for flash memories. In this scheme, a set of n cells stores information in the permutation induced by the different charge levels of the individual cells. The resulting scheme eliminates the need for discrete cell levels, and overshoot errors when programming cells (a serious problem that reduces the writing speed), as well as mitigate the problem of asymmetric errors. We present schemes for Gray codes, rewriting and joint coding in the rank modulation paradigm.