IEEE Transactions on Information Forensics and Security | 2019
Secrecy Capacity Region of Fading Binary Z Interference Channel With Statistical CSIT
Abstract
We characterize the secrecy capacity region of a fast Fading Binary 2-user Z-Interference Channel (FBZIC), assuming that only the Statistical Channel State Information is available at the Transmitters (S-CSIT). The converse is proved by constructing a new channel which is stochastically stronger than both the direct and cross-links emerging from the interfering transmitter. We also show that a capacity optimal code for a point-to-point binary erasure channel can be used at the non-interfering transmitter, a secrecy capacity optimal code for a binary erasure wiretap channel can be used at the interfering transmitter, and received signals can be decoded treating interference as erasure, to achieve all the secrecy rate pairs within the secrecy capacity region of the FBZIC. It turns out that the secrecy capacity region is a trapezoid and we explicitly characterize its corner points in terms of erasure probabilities of the various links of the channel. Comparing it with the capacity region of a fast fading no-secrecy binary 2-user ZIC, we quantify the loss due to the additional secrecy constraint. Our results reveal that, when the non-interfering user operates at its maximum rate, the interfering user cannot operate at a non-zero secrecy rate.