Abstract
In this paper, we investigate the secrecy outage performance of a dual-hop decode-and-forward (DF) threshold-based cooperative relay network, both with and without the direct links between source-eavesdropper and source-destination. Without assuming that all the relays can always perfectly decode, here we consider that only those relays who satisfy predetermined threshold can correctly decode the message. We have investigated the outage probability of optimal relay selection scheme, when either full instantaneous channel state information (ICSI) or statistical channel state information (SCSI) of all the links is available. We have shown that CSI knowledge at the transmitter can improve secrecy, and the amount of improvement for the outage probability is more when the required rate is low and for low operating SNR. Asymptotic and diversity gain analysis of the secrecy outage for both the single relay and multi-relay system is obtained, when average SNRs of source-relay and relay-destination links are equal or unequal. We have shown that the improvement in predetermined threshold, eavesdropper channel quality, direct links, and required secrecy rate significantly affects the secrecy performance of the system.
Highlights
Cooperative communication plays a promising role to expand the coverage of wireless networks, save uplink transmit power of source due to highly constrained wireless resources [1–3], and increase the spatial diversity without increasing the number of antennas [4]
3.3.2 channel state information (CSI) completely known at transmitter We evaluate outage probability for single ith relay in the third scenario where no direct link between S − D and S − E exists, and full CSI knowledge is available at the transmitter as
We have shown that improvement in desired secrecy rate, eavesdropper channel quality, and predetermined threshold has a significant impact on outage performance of the system
Summary
Cooperative communication plays a promising role to expand the coverage of wireless networks, save uplink transmit power of source due to highly constrained wireless resources [1–3], and increase the spatial diversity without increasing the number of antennas [4]. In contrast to the above study, our work investigates the secrecy outage for a dual-hop threshold-based cooperative DF relay network, both with and without the direct link between source-eavesdropper and sourcedestination. - Without assuming that the direct transmissions are absent owing to deep shadow fading or large distance between nodes, the expression for secrecy outage of DF threshold-based cooperative relay network is derived, both with and without the direct link between source-eavesdropper and source-destination. We have derived the expression for secrecy outage probability of this dual-hop DF threshold-based cooperative relay network, both with and without the direct link between source-eavesdropper and source-destination. Se is the maximal ratio combined SNR of the eavesdropper link at E and when the relay node does not meet the predetermined threshold due to shadow fading [39], the secrecy capacity is defined as Csse , where only direct link between sourceeavesdropper exists and se E. From (6), when the relay node meets the predetermined threshold, the secrecy capacity is defined as Csnd where nd M ri d is the SNR of the main link at D, and nd E rie is the SNR of the eavesdropper link at E and when the relay node does not meet the predetermined threshold due to shadow fading [39], no relay is selected for communication
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