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Iran Workshop on Communication and Information Theory (IWCIT)

High SNR performance of amplify-and-forward relaying in Rayleigh fading wiretap channels

Frédéric Gabry, Somayeh Salimi, Ragnar Thobaben, Mikael Skoglund

Published May 1, 2013• 6 citations
Publisher

Abstract

This paper investigates amplify-and-forward (AF) relaying for secrecy in quasi-static Rayleigh fading channels. We consider a four-node network where a helping node intends to enhance secrecy of the transmission between the source and the destination in presence of a passive eavesdropper. In this scenario, the common assumption of full CSI on the eavesdropper's channels is not realistic, and thus, we study the performance of cooperation from an outage perspective. Starting from the secrecy outage probability, we introduce a novel measure, the conditional secrecy outage probability to analyze the performance of AF. In particular, we derive closed-form expressions for AF for these two secrecy measures under a high SNR assumption. Moreover, we use numerical examples to illustrate our results and to characterize the effect of the nodes' geometry. We also show numerically how AF improves the secrecy performance in comparison to direct transmission in terms of outage probability and secure throughput.

DOI
10.1109/iwcit.2013.6555771

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This paper investigates amplify-and-forward (AF) relaying for secrecy in quasi-static Rayleigh fading channels. We consider a four-node network where a helping node intends to enhance secrecy of the transmission between the source and the destination in presence of a passive eavesdropper. In this scenario, the common assumption of full CSI on the eavesdropper's channels is not realistic, and thus, we study the performance of cooperation from an outage perspective. Starting from the secrecy outage probability, we introduce a novel measure, the conditional secrecy outage probability to analyze the performance of AF. In particular, we derive closed-form expressions for AF for these two secrecy measures under a high SNR assumption. Moreover, we use numerical examples to illustrate our results and to characterize the effect of the nodes' geometry. We also show numerically how AF improves the secrecy performance in comparison to direct transmission in terms of outage probability and secure throughput.
In this paper, we investigate a secure semi-blind amplify-and-forward (AF) relaying system over Rayleigh fading channels. We consider a reactive relay selection where the relay is selected based on the highest instantaneous signal-to-noise ratio (SNR) of the second hop. We evaluate the ergodic secrecy capacity using source-assisted jamming (SAJ) and considering that relays act as eavesdroppers. In order to improve the secrecy performance, a direct link between the source and destination is considered. Numerical results are presented to verify the accuracy of the proposed mathematical analysis. Moreover, a comparison between secure semi-blind AF relaying system and secure channel-state-information (CSI)-assisted AF relaying system is performed to further prove the exactness of our analysis. The proposed secure semi-blind AF relaying system has a simpler mathematical analysis and a comparable secrecy performance as compared to secure CSI-assisted AF relaying system.
In this paper, we investigate the performance of cooperative amplify-and-forward (AF) multi-relay networks with relay selection strategy over independent and identically distributed (i.i.d.) Nakagami-m fading channels. In this system we study multiuser cooperative relaying to have a secure transmission from source to destination, since transmitted information may be wiretapped by multiple eavesdroppers. The secrecy outage probability is derived in closed-form using signal-to-noise-ratio statistics, while a useful expression is presented for the asymptotically low outage regime. Our results explicitly demonstrate significant improvement of the secrecy outage probability in the multi-relay scenario.
This paper presents the secrecy performance analysis of an amplify-and-forward relay-assisted cooperative communication system in the presence of a passive external eavesdropper. In contrast to existing works that assume high signal-to-noise ratio (SNR) approximations, we have investigated exact and secrecy outage probabilities. Furthermore, we consider a more challenging scenario where the source may not be reachable to the intended user directly. But the eavesdropper can tap both the source link and the relay link. First of all, the outage probability is analyzed at the intended user as well as the eavesdropper. Next, defining the secrecy rate for the amplify-and-forward (AF) relaying system, the expression of the secrecy outage probability (SOP) and the secrecy intercept probability (SIP) have been derived, respectively. Noticing the complexity involved in the integration of SOP and SIP expressions, the closed-form expressions have been derived for asymptotic cases. Finally, the exact and asymptotic analysis has been verified by performing Monte-Carlo simulations. It is observed that the relay position should be closer to the source compared to the eavesdropper to achieve improved SOP.
In this paper, we present a comprehensive investigation on the secrecy performance of opportunistic relay selection systems employing the decode-and-forward protocol over Rayleigh fading channels. Considering a practical setting where direct link between the source node (Alice) and the destination node (Bob) is available, we study the secrecy performance of three different diversity combining schemes, namely, maximum ratio combining (MRC), distributed selection combining (DSC), and distributed switch-and-stay combining (DSSC). Throughout the analysis, we consider two different scenarios based on the availability of the eavesdropper's channel state information (CSI), i.e., Scenario A, where the eavesdropper's CSI is not available at Alice and the relay, and Scenario B, where Alice and the relay have knowledge about the eavesdropper's CSI. For Scenario A, we derive exact closed-form expressions for secrecy outage probability and simple asymptotic approximations for the secrecy outage probability, which enable the characterization of the achievable secrecy diversity order and coding gains. For Scenario B, we derive closed-form expressions for the achievable secrecy rates. For both scenarios, we investigate the impact of feedback delay (outdated CSI) on the secrecy performance wherein exact and asymptotic secrecy outage probability and closed-form expressions of the secrecy achievable rates are obtained. Our analytical findings suggest that both the MRC and DSC schemes achieve the maximum diversity order of K+1 where K is the number of relays. In addition, the feedback delay has a significant impact on the achievable secrecy performance by reducing the achievable diversity order to two.
This paper quantifies the impact of correlated fading on secure communication of multiple amplify-and-forward (AF) relaying networks. In such a network, the base station (BS) is equipped with multiple antennas and communicates with the destination through multiple AF relays, while the message from the relays can be overheard by an eavesdropper. We focus on the practical communication scenario, where the main and eavesdropper's channels are correlated. In order to enhance the transmission security, transmit antenna selection is performed at the BS, and the best relay is chosen according to the full- or partial-relay selection criterion, which relies on the dual-hop relay channels or the second-hop relay channels, respectively. For these criteria, we study the impact of correlated fading on the network secrecy performance, by deriving an analytical approximation for the secrecy outage probability and an asymptotic expression for the high main-to-eavesdropper ratio. From these results, it is concluded that the channel correlation is always beneficial to the secrecy performance of full relay selection. However, it deteriorates the secrecy performance if partial-relay selection is used, when the number of antennas at the BS is less than the number of relays.
In this paper, we investigate the secrecy outage probability (SOP) for the cooperative amplify-and-forward (AF) two-way relay networks (TWRN) with channel estimation (CE) errors under Rayleigh fading channels.In the proposed system, two sources simultaneously broadcast their respective information to all the relays firstly.Then, the optimal relay performs AF protocol on the received signals sent from the two sources and forward them to both sources.In both phases, An eavesdropper receives the signals from sources and relay nodes illegally.The performance of the proposed system is quantified by deriving the upper bound of the overall outage probability.Impact of CEs on the system is illustrated by simulations.