Asymmetric Multilevel Diversity Coding Systems With Perfect Secrecy

Secure rate region of the asymmetric multilevel diversity coding systems (AMDCS) with perfect secrecy is investigated in this paper. The eavesdropper may have access to any one but not more than one subset of the channels but can get nothing about the sources, as long as the size of the subset is not above the security level. As the first nontrivial instance, the secure AMDCS (S-AMDCS) with three encoders and security level one is solved. It is shown that linear codes are optimal for this instance. In contrast with the secure symmetric multilevel diversity coding systems, superposition (source separation) is shown to be not optimal for S-AMDCS in general.