One-way and Two-way Physical Layer Security Protocols for the Gaussian Satellite Channel

We present the comparative modelling and analysis of one-way and two-way physical layer security protocols using privacy amplification for the Gaussian satellite channel. It is known that one-way protocols based on the classic Wyner?s wiretap channel require Eve's channel to be degraded w.r.t. Bob?s channel. Here, to overcome this limiting performance condition, we introduce a two-way protocol inspired in Maurer?s protocol in IEEE TIT (1993), which differently to other proposals of two-way protocols, fully eliminates the channel degradation condition (i.e. secrecy capacity is always guaranteed to be positive). We present the description of the two protocols and the comparison of secrecy capacity when Eve uses any type of orbit. We show their realistic performance taking into consideration orbital dynamics, i.e. the only assumption made on Eve is that she has to comply with orbit mechanics. Our numerical security analysis results confirm that the two-way protocol outperforms the one-way protocol in different degrees depending on the orbit and legitimate antenna radiation patterns.