Asymmetric error-correcting codes for Flash memories in high-radiation environments

Research works exploring coding for Flash memories typically seek to correct errors taking place during normal device operation. In this paper, we study the design of codes that protect Flash devices dealing with the unusual class of errors caused by exposure to large radiation dosages. Significant radiation exposure can take place, for example, when Flash is used as on-board memory in satellites and space probes. We introduce an error model that captures the effects of radiation exposure. Such errors are asymmetric, with the additional feature that the degree (and direction) of asymmetry depends on the stored sequence. We develop an appropriate distance and an upper bound on the sizes of codes which correct such errors. We introduce and analyze several simple code constructions.