Data encoding method for 3D NAND flash memory

A computer-implemented data encoding method for encoding data to be stored in a solid-state storage device, comprising the steps of:

• a) providing a source data;
• b) calculating an entropy of the source data;
• c) applying a first encoding scheme to encode the source data into an encoded data, if the entropy is below a threshold;
• the first encoding scheme adapted to encode most frequently combined characters in the source data into predetermined characters to increase ratio of the predetermined characters in the encoded data;
• wherein the step of applying a first encoding scheme to encode the source data into an encoded data further comprises:
• i. counting frequencies of all combinations of characters, wherein each said combination contains a first number of the characters;
• ii. sorting the combinations according to their frequencies;
• iii. identifying one said combination that has a highest frequency as the most frequently combined characters;
• iv. determining a second number of said combinations, of which said frequencies immediately follow that of the most frequently combined characters;
• and
• v. encoding the second number of said combinations and the most frequently combined characters into different combinations of the predetermined characters;
• d) applying a second data encoding scheme to encode the source data into the encoded data, if the entropy is equal to or higher than the threshold;
• the second data encoding scheme adapted to encode evenly distributed combined characters into a plurality of patterns with said predetermined characters, in order to increase the ratio of the predetermined characters in the encoded data;
• wherein Step v) is conducted based on a mapping table, the mapping table created upon a first write request into the solid-state storage drive.

A computer-implemented data encoding method for encoding data to be stored in a solid-state storage device, comprising the steps of:

• a) providing a source data;
• b) calculating an entropy of the source data;
• c) applying a first encoding scheme to encode the source data into an encoded data, if the entropy is below a threshold;
• the first encoding scheme adapted to encode most frequently combined characters in the source data into predetermined characters to increase ratio of the predetermined characters in the encoded data;
• and
• d) applying a second data encoding scheme to encode the source data into the encoded data, if the entropy is equal to or higher than the threshold;
• the second data encoding scheme adapted to encode evenly distributed combined characters into a plurality of patterns with the predetermined characters, in order to increase the ratio of the predetermined characters in the encoded data;
• wherein the step of applying the second data encoding scheme to encode the source data into the encoded data further comprises:
• i) identifying a pair of combinations of characters including a first combination and a second combination, the first combination having more the predetermined characters than the second combination;
• ii) encoding the first combination into a first one of the plurality of patterns;
• and
• iii) encoding the second combination into a second one of the plurality of patterns;
• wherein the first combination and the second combination each contain a first number of the characters;
• the first and second ones of the plurality of patterns each containing a second number of the predetermined characters;
• the first number being smaller than the second number;
• and
• wherein a first number of most significant characters in the first one of the plurality of patterns are identical to a first number of most significant characters in the second one of the plurality of patterns.