Nonuniform Codes for Correcting Asymmetric Errors

Codes that correct asymmetric errors have important applications in storage systems, including optical disks and Read Only Memories. The construction of asymmetric error correcting codes is a topic that was studied extensively; however, the existing approach for code construction assumes that every codeword could sustain t asymmetric errors. The authors' main observation is that in contrast to symmetric errors, where the error probability of a codeword is context independent (since the error probability for 1s and 0s is identical), asymmetric errors are context dependent.