Some Codes Correcting Unbalanced Errors of Limited Magnitude for Flash Memories

In multilevel flash memories, leakage of charges results in errors, and the errors are asymmetric, of increasing type and of limited magnitude. On the other hand, low data retention may result in asymmetric errors of decreasing type and usually of smaller magnitude. Therefore, we have unbalanced error types. In this paper, some codes for correcting such errors are presented.