RANK-MODULATION REWRITING CODES FOR FLASH MEMORIES

摘要

Rank modulation has been recently proposed as a scheme for storing information in flash memories. Three improved aspects are disclosed. In one aspect the minimum push-up scheme, for storing data in flash memories is provided. It aims at minimizing the cost of changing the state of the memory. In another aspect, multi-cells, used for storing data in flash memories is provided. Each transistor is replaced with a multi-cell of mm transistors connected in parallel. In yet another aspect, multi-permutations, are provided. The paradigm of representing information with permutations is generalized to the case where the number of cells in each level is a constant greater than one. In yet another aspect, rank-modulation rewriting schemes which take advantage of polar codes, are provided for use with flash memory.

主权项

1. A method of operating a memory device, the method comprising:
receiving a new data set for a rank of a plurality of ranks to be stored in the memory device wherein the memory device comprises a plurality of cells; reading a current state of candidate cells within the plurality of cells wherein candidate cells are used to store the new data set; creating a binary representation of the plurality of cells used to store the new data set; using a WOM code to combine the binary representation with the new data set to create a binary WOM vector; modifying the binary WOM vector to equal quantities of 1's and 0's within the candidate cells creating a new data vector; writing the new data vector to the candidate cells.