Rank-modulation rewriting codes for flash memories
View Patent ↗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.
1. A method to operate 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 the 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 write once memory (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 to create a new data vector; and
writing the new data vector to the candidate cells.
2. The method of claim 1 , wherein the WOM code includes a polar WOM code.
3. The method of claim 1 , wherein a cost to write is defined as a maximum level of the plurality of cells after the new data vector is written minus a maximum level of the candidate cells before the new data vector is written.
4. The method of claim 3 , wherein the cost is 1.
5. The method of claim 1 , wherein the method further comprises:
reading the new data vector from the candidate cells;
modifying the new data vector to recreate the binary WOM vector; and
using the WOM code on the binary WOM vector to separate the binary representation from the data set.
6. The method of claim 5 , wherein the WOM code includes a polar WOM code.
7. A computer method to operate a memory device, the method comprising:
receiving a new data set m for a rank to store in the memory device, wherein the memory device comprises a plurality of cells;
reading a current state of the plurality of cells, wherein the plurality of cells are arranged according to a rank modulation scheme and the plurality of cells are used to store the received new data set m;
determining a new multi-permutation to be written to the plurality of cells representing the received new data set m determined in accordance with a particular cost; and
writing the new multi-permutation to the memory device.
8. A computer method to operate a memory device, the method comprising:
receiving a data value comprising a plurality of data sets, wherein each data set includes a set of values representing a rank in a plurality of ranks; and
repeating for the plurality of data sets in the data value:
receiving a new data set for a rank of the 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 the 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 write once memory (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; and
writing the new data vector to the candidate cells.
9. The method of claim 8 , wherein the WOM code includes a polar WOM code.
10. A computer method of operate a memory device, the method comprising:
reading a plurality of cells and determining a multi-permutation stored in the plurality of cells;
identifying a group of cells in the plurality of cells, contained within each rank of a plurality of ranks; and
for each rank:
reading a new data vector from the rank;
modifying the new data vector to recreate a binary write once memory (WOM) vector; and
using a WOM code on the binary WOM vector to separate a binary representation from a data set.
11. The method of claim 10 , wherein the WOM code includes a polar WOM code.
12. A memory controller, comprising:
an interface configured to receive a new data set for a rank of a plurality of ranks to be stored in a memory comprising a plurality of cells; and
a processor coupled to the interface and configured to:
read a current state of candidate cells within the plurality of cells,
wherein the candidate cells are used to store the new data set;
create a binary representation of the plurality of cells used to store the new data set;
use a write once memory (WOM) code to combine the binary representation with the new data set to create a binary WOM vector;
modify the binary WOM vector to equal quantities of 1's and 0's within the candidate cells to create a new data vector; and
write the new data vector to the candidate cells.
13. The memory controller of claim 12 , wherein the WOM code includes a polar WOM code.
14. The memory controller of claim 12 , wherein a cost to write is defined as a maximum level of the plurality of cells after the new data vector is written minus a maximum level of the candidate cells before the new data vector is written.
15. The memory controller of claim 14 , wherein the cost is 1.
16. The memory controller of claim 12 , wherein the processor is further configured to:
read the new data vector from the candidate cells;
modify the new data vector to recreate the binary WOM vector; and
use the WOM code on the binary WOM vector to separate the binary representation from the data set.
17. The memory controller as in claim 16 , wherein the WOM code includes a polar WOM code.
18. A memory controller, comprising:
an interface configured to receive a new data set m for a rank to be stored in a memory device, wherein the memory device comprises a plurality of cells; and
a processor coupled to the interface and configured to:
read a current state of the plurality of cells within the plurality of cells that are arranged according to a rank modulation scheme and the plurality of cells are used to store the received new data set m;
determine a new multi-permutation to be written to the plurality of cells that represents the received new data set m determined in accordance with a particular cost; and
write the new multi-permutation to memory.
19. A memory controller, comprising:
an interface configured to receive a data value comprising a plurality of data sets, wherein each data set is a set of values that represent a rank in a plurality of ranks; and
a processor coupled to the interface and configured to perform operations repeated for the data sets in the data value, wherein the operations include:
receive a new data set for a rank of the plurality of ranks to be stored in a memory device, wherein the memory device comprises a plurality of cells;
read a current state of candidate cells within the plurality of cells, wherein the candidate cells are used to store the new data set;
create a binary representation of the plurality of cells used to store the new data set;
use a write once memory (WOM) code to combine the binary representation with the new data set to create a binary WOM vector;
modify the binary WOM vector to equal quantities of 1's and 0's within the candidate cells to create a new data vector; and
write the new data vector to the candidate cells.
20. The memory controller of claim 19 , wherein the WOM code includes a polar WOM code.
21. A memory controller, comprising:
an interface configured to provide access to a plurality of cells in a memory device; and
a processor coupled to the interface and configured to:
access the plurality of cells through the interface;
read the plurality of cells; and
perform operations that include:
determine a multi-permutation stored in the plurality of cells;
identify a group of cells in the plurality of cells contained within each rank of a plurality of ranks; and
for each rank:
read a new data vector from the rank;
modify the new data vector to recreate a binary write once memory (WOM) vector; and
us a WOM code on the binary WOM vector to separate a binary representation from a data set.
22. The memory controller of claim 21 , wherein the WOM code includes a polar WOM code.
23. A data device, comprising:
a memory configured to store data values; and
a memory controller coupled to the memory and that is configured to store the data values in the memory by performance of operations that include:
receive a new data set for a rank of a plurality of ranks to be stored in the data device, wherein the data device comprises a plurality of cells;
read a current state of candidate cells within the plurality of cells, wherein the candidate cells are used to store the new data set;
create a binary representation of the plurality of cells used to store the new data set;
use a write once memory (WOM) code to combine the binary representation with the new data set to create a binary WOM vector;
modify the binary WOM vector to equal quantities of 1's and 0's within the candidate cells to create a new data vector; and
write the new data vector to the candidate cells.
24. The data device of claim 23 , wherein the WOM code includes a polar WOM code.
25. The data device of claim 23 , wherein a cost to write is defined as a maximum level of the plurality of cells after the new data vector is written minus a maximum level of the candidate cells before the new data vector is written.
26. The data device of claim 25 , wherein the cost is 1.
27. The data device of claim 23 , wherein the operations further include:
read the new data vector from the candidate cells;
modify the new data vector to recreate the binary WOM vector; and
use a WOM code on the binary WOM vector to separate the binary representation from the data set.
28. The data device as in claim 27 , wherein the WOM code includes a polar WOM code.
29. A data device, comprising:
a memory configured to store data values; and
a memory controller coupled to the memory and that is configured to store the data values in the memory by performance of operations that include:
receive a new data set m for a rank to store in the data device, wherein the data device comprises a plurality of cells;
read a current state of the plurality of cells, wherein the plurality of cells are arranged according to a rank modulation scheme and the plurality of cells are used to store the received new data set m;
determine a new multi-permutation to be written to the plurality of cells that represent the received new data set m determined in accordance with a particular cost; and
write the new multi-permutation to the data device.
30. A data device, comprising:
a memory configured to store data values; and
a memory controller coupled to the memory and that is configured to store the data values in the memory by performance of operations that include:
receive a data value comprising a plurality of data sets, wherein each data set is a set of values that represent a rank in a plurality of ranks, and repeat for the data sets in the data value operations include to:
receive a new data set for a rank of the plurality of ranks to be stored in the data device, wherein the data device comprises a plurality of cells;
read a current state of candidate cells within the plurality of cells, wherein the candidate cells are used to store the new data set;
create a binary representation of the plurality of cells used to store the new data set;
use a write once memory (WOM) code to combine the binary representation with the new data set to create a binary WOM vector;
modify the binary WOM vector to equal quantities of 1's and 0's within the candidate cells to create a new data vector; and
write the new data vector to the candidate cells.
31. The data device of claim 30 , wherein the WOM code includes a polar WOM code.
32. An apparatus, comprising:
a data device configured to:
read a plurality of cells and determine a multi-permutation stored in the plurality of cells;
identify a group of cells in the plurality of cells, contained within each rank of a plurality of ranks; and
for each rank:
read a new data vector from the rank;
modify the new data vector to recreate a binary write once memory (WOM) vector; and
use a WOM code on the binary WOM vector to separate a binary representation from a data set.
33. The data device of claim 32 , wherein the WOM code includes a polar WOM code.