Secure Communication with Non-Causal Side Information in the Low-SNR Regime

The concept of secrecy capacity per unit cost was introduced in the study of cost-efficient secure wide-band communications. It has been established that for a degraded memoryless wiretap channel, a structured orthogonal code achieves the secrecy capacity per unit cost. In this paper, we consider a memoryless wiretap channel with channel state, where the state is available non-causally to the transmitter as side information. Under the assumption of the existence of a zero cost input “0”, it is shown that a lower bound on the secrecy capacity per unit cost for such a channel can be achieved using a nested orthogonal random binning coding scheme.