A multiple access approach for the compound wiretap channel

The compound wiretap channel generalizes the classical problem in broadcast information-theoretic secrecy by allowing a class of potential eavesdroppers. This represents uncertainty in the eavesdropper channel and the characterization of its secrecy capacity is an open question. In this paper we present a new coding scheme that generalizes known approaches to this problem. The scheme prefixes an artificial multiple access channel to the transmission scheme in order to design a structured transmit codebook. The idea is that such a structure can potentially increase the perfect secrecy rate for the legitimate users in the presence of the class of eavesdroppers. We develop the achievable secrecy rate of this scheme and provide examples where this scheme is optimal.