In this paper, secrecy outage probability is analyzed in a cooperative network for an independent but non-identically distributed (i.n.i.d) Rayleigh fading channel. By using multi-trusted decode and forward relays, the model assumes direct links between a sender (Alice) and receiver nodes (Bob and an eavesdropper). The protocol employed herein selects the best relay with the highest signal-to-noise ratio (SNR) in relation to the destination (Bob). The eavesdropper's channel state information (CSI) is neither available to the sender nor to the best relay, while maximum ratio combining (MRC) is employed at Bob and the eavesdropper. Finally, the theoretical analysis is validated through simulation, and the results show that performance is enhanced with an increasing number of relays in the event of a direct link between the sender and the receiver's terminals.
In this paper, secrecy outage probability is analyzed in a cooperative network for an independent but non-identically distributed (i.n.i.d) Rayleigh fading channel. By using multi-trusted decode and forward relays, the model assumes direct links between a sender (Alice) and receiver nodes (Bob and an eavesdropper). The protocol employed herein selects the best relay with the highest signal-to-noise ratio (SNR) in relation to the destination (Bob). The eavesdropper's channel state information (CSI) is neither available to the sender nor to the best relay, while maximum ratio combining (MRC) is employed at Bob and the eavesdropper. Finally, the theoretical analysis is validated through simulation, and the results show that performance is enhanced with an increasing number of relays in the event of a direct link between the sender and the receiver's terminals.
In this paper, ergodic secrecy capacity is analyzed in a cooperative communication network, for an independent but non-identically distributed (i.n.i.d) Rayleigh fading channel. By using multi-trusted decode and forward relays, the model assumes direct links between a sender (Alice) and receiver nodes (Bob and an eavesdropper); in addition both Alice and the relay have perfect knowledge about the eavesdropper's channel state information (CSI). The protocol employed herein selects the best relay with the highest signal-to-noise ratio (SNR) in relation to the destination (Bob), while maximum ratio combining (MRC) is employed at Bob and the eavesdropper's terminals. Finally, the theoretical analysis is validated through simulation, and the results show that performance is enhanced with an increasing number of relays, in the event of a direct link between the sender and the receiver's terminals.
In this paper, a source communicates to the destination with the cooperation of a relay, in the presence of an eavesdropper. All the links undergo Rayleigh fading and perfect decoding at the relays is not considered. The secrecy outage probability expression is evaluated for a decode-and-forward (DF) dual-hop cooperative relay network, both with and without the presence of direct source to eavesdropper transmission link. The performance of the maximal ratio combining (MRC) and selection combining (SC) diversity at the eavesdropper is investigated. Asymptotic and diversity gain analysis for both the single relay and multi-relay system is obtained, when average SNRs of source-relay and relay-destination links are balanced or unbalanced. We have shown that the increase in target secrecy rate and eavesdropper channel quality significantly affects the outage performance of the system. 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 and have shown that there is improvement in the secrecy performance with the increase in the number of relays.
In this paper, the secrecy outage probability of threshold-based decode-and-forward (DF) cooperative relay network is evaluated. Unlike other works to date, we assume combining of direct and relayed signals both at the destination and the eavesdropper. All the links undergo Rayleigh fading and the relay can perfectly decode the message, only if the received SNR meets a particular threshold. The secrecy performance is compared for the system with either selection combining (SC), or with maximal ratio combining (MRC) or with the combination of both, at the destination and eavesdropper. We have shown that the eavesdropper channel quality, required secrecy rate, pre-defined threshold and the choice of diversity scheme significantly affects the secrecy performance of the system.
In this paper, we consider an active eavesdropping scenario in a cooperative system consisting of a source, a destination, and an active eavesdropper with multiple decode-and-forward relays. Considering an existing assumption in which an eavesdropper is also a part of network, a proactive relay selection by the eavesdropper is proposed. The best relay which maximizes the eavesdropping rate is selected by the eavesdropper. A relay selection scheme is also proposed to improve the secrecy of the system by minimizing the eavesdropping rate. Performances of these schemes are compared with two passive eavesdropping scenarios in which the eavesdropper performs selection and maximal ratio combining on the relayed links. A realistic channel model with independent non-identical links between nodes and direct links from the source to both the destination and eavesdropper are assumed. Closed- form expressions for the secrecy outage probability (SOP) of these schemes in Rayleigh fading channel are obtained. It is shown that the relay selection by the proactive eavesdropper is most detrimental to the system as not only the SOP increases with the increase in the number of relays, but its diversity also remains unchanged.
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.
The traditional relay selection scheme only considers the channel state information (CSI) of legitimate users, and does not consider the power allocation between the source node and relay node. However, in the actual transmission system, there will be potential eavesdropper, and the traditional relay selection scheme will greatly reduce the security of the system. In this letter, we evaluate the secrecy outage probability (SOP) of relay selection scheme with a decode-and-forward (DF) protocol over independent and non-identically distributed Rayleigh fading. With the CSI of eavesdropper and the power allocation of source node and relay nodes are considered, the secrecy performance of cooperative communication system can be improved effectively.