Read-detection in solid-state storage devices

摘要

A method for detecting codewords of a length-N, qary-symbol code, the symbols of each codeword stored in respective q-level cells of solid-state memory, where q>2, includes reading from memory cells storing a group of codewords to obtain respective read signals each comprising N signal components corresponding to respective symbols of a codeword. The signal components of the read signals are ordered according to signal level to produce an ordered component sequence. The ordered component sequence is partitioned to obtain segments corresponding to respective memory cell levels. Each segment contains a number of components dependent on predetermined frequency data indicative of expected frequency of occurrence of the corresponding level in use of the code. A reference signal level corresponding to each q memory cell level is determined in dependence on the signal components. The codeword corresponding to each read signal is then detected in dependence on the reference signal levels.

主权项

1. A method for detecting codewords of a length-N, qary-symbol code, the symbols of each codeword being stored in respective q-level cells of solid-state memory, where q>2, the method comprising:
reading the memory cells storing a group of codewords to obtain respective read signals each comprising N signal components corresponding to respective symbols of a codeword; ordering the signal components of the group of read signals according to signal level to produce an ordered component sequence; partitioning the ordered component sequence to obtain segments corresponding to respective memory cell levels, each segment containing a number of components dependent on predetermined frequency data indicative of expected frequency of occurrence of the corresponding level in use of the code; determining a reference signal level corresponding to each of the q memory cell levels in dependence on the signal components in at least a plurality of the segments; and detecting the codeword corresponding to each read signal in dependence on the reference signal levels.