Bounds on the Ergodic Secret-Key Capacity for Dependent Fading Channels

Due to an increasing number of devices and applications which rely on wireless data transmission, more sensitive data will be processed and transmitted in the future. This makes confidential and secure data communications more important than ever. One way to achieve this goal is physical layer security where the physical properties of the wireless channel are exploited to provide security during the transmission. One new security primitive is secret-key generation. However, the uncertainty with respect to the eavesdropper’s channel and position is one main challenge which heavily influences the performance. In this paper, we derive upper and lower bounds on the ergodic secret-key capacity for fading channels with given marginals and a possible dependence structure. We apply results from mass transportation theory to obtain general bounds and evaluate them for specific fading distributions. In particular, explicit results for Rayleigh and cx-mu fading channels are presented, including multiple-antenna fading channels.