Proactive spectrum sharing incentive for physical layer security enhancement using outdated CSI

We investigate the spectrum sharing possibility as an incentive to enhancing the physical layer security. The concept behind this is that a legitimate source-destination pair, communicating in the presence of a passive eavesdropper, stimulates the help of another source-destination node looking for transmission opportunities, referred to as secondary network (SN). We thus propose a cooperative scheme, whereby the secondary transmitter will act as a friendly jammer to confound the eavesdropper and be granted to share the spectrum of the legitimate pair, referred to as primary network (PN), as a reward. To evaluate the performance of our cooperative scheme, we derive the closed-form expression of the secrecy outage probability (SOP). However, to assess its usefulness, we introduce the mutual outage probability (MOP) and we carry out analysis to derive its expression. We show that a satisfactory SOP is a necessary condition for triggering the cooperation, whereas a satisfactory MOP is a sufficient condition to guarantee that the PN-SN collaboration leads to a win-win situation. Results have been presented considering outdated channel state information, thus giving more insights for practical setups. 2002-2012 IEEE.Scopu