Secrecy Analysis in DF Relay Over Generalized-[Formula Omitted] Fading Channels

In this paper, we analyze the secrecy performance of the decode-and-forward (DF) relay system in generalized-[Formula Omitted] fading channels. In a typical four-node communications model, a source ([Formula Omitted]) sends confidential information to a destination ([Formula Omitted]) via a relay ([Formula Omitted]) using DF strategy in two time slots, while an eavesdropper ([Formula Omitted]) wants to overhear the information from [Formula Omitted] to [Formula Omitted] over generalized-[Formula Omitted] fading channels. To be more realistic, we assume that [Formula Omitted] can receive the signals of two time slots, and there is no direct link between [Formula Omitted] and [Formula Omitted] because of heavy fading. Based on those assumptions, we derive closed-form expressions for the secrecy outage probability (SOP) and ergodic secrecy capacity (ESC) by using a tight approximate probability density function of the generalized-[Formula Omitted] model. Furthermore, asymptotic expressions for the SOP and ESC are also derived in the high signal-to-noise ratio region, not only because we can get some insights about SOP and ESC, but also because expressions for SOP and ESC can be simplified significantly. The single relay system is subsequently extended into a multi-relay system, where the asymptotic SOP analysis of three proposed relay selection strategies is investigated. Moreover, the security-reliability tradeoff analysis in the multi-relay system is also presented given that [Formula Omitted] adopts a constant code rate. Finally, the Monte-Carlo simulation is used to demonstrate the accuracy of the derived closed-form expressions.