Wireless communication systems are vulnerable to eavesdropping attack in which the attacker overhear the transmitted data in the network. Hence, the physical-layer security is of utmost importance to protect the wireless communications against the eavesdropping attack. In this paper, we study the physical-layer security of a two-hops cognitive radio-based communication system where the secondary user sends some confidential information to a destination through a relay. This relay is assumed to be equipped with multiple antennas for reception, applies the maximum-ratio combining technique for the received signals, and uses only one antenna to forward the combined signal to the destination. The transmission is performed under the eavesdropper's attempt to listen to the communication channel. The secrecy outage probability and the intercept probability are both derived based on the statistical characteristics of the channels and under the constraint of avoiding the communication outage of the primary user. All results have been validated using Monte Carlo method.
Wireless communication systems are vulnerable to eavesdropping attack in which the attacker overhear the transmitted data in the network. Hence, the physical-layer security is of utmost importance to protect the wireless communications against the eavesdropping attack. In this paper, we study the physical-layer security of a two-hops cognitive radio-based communication system where the secondary user sends some confidential information to a destination through a relay. This relay is assumed to be equipped with multiple antennas for reception, applies the maximum-ratio combining technique for the received signals, and uses only one antenna to forward the combined signal to the destination. The transmission is performed under the eavesdropper's attempt to listen to the communication channel. The secrecy outage probability and the intercept probability are both derived based on the statistical characteristics of the channels and under the constraint of avoiding the communication outage of the primary user. All results have been validated using Monte Carlo method.
In this paper, the physical layer security in cognitive radio networks (CRNs) is investigated. We consider an underlay relay assisted CRN consisting of multiple secondary sources, multiple-antenna destination, a single relay, and multiple eavesdroppers. The destination node performs the maximal-ratio combining under uncorrelated Rayleigh fading channels. In more details, we consider, a secondary source is randomly selected to transmit its data, and a jammer is chosen from the remaining source nodes to send a jamming signal to the eavesdroppers. The closed-form expression of the secrecy outage probability is derived, based on the statistical characteristics of the communication channels, under the primary user's quality of service constraint. The derived analysis gives deep insights into the impact of network parameters on the performance of on the secrecy outage performance. Analytic results are corroborated through Monte Carlo simulation.
In this paper, we investigate the secrecy outage performance of maximal ratio combining (MRC) in cognitive radio networks (CRNs) over Rayleigh fading channels. In a single input multiple output wiretap system, we consider a secondary user SU-TX transmits confidential messages to another secondary user SU-RX equipped with K (K>1) antennas while MRC technique is adopted to improve its received signal-to-noise ratio. Meanwhile, an eavesdropper exists to overhear the information between SU-TX and SU-RX. SU-TX adopts the underlay strategy to meet the quality of service of the primary user without spectrum sensing. In this paper, we derive the closed-form expressions for the secrecy outage probability and the probability of nonzero secrecy capacity of MRC scheme in CRNs over Rayleigh fading channels. Simulations are conducted to validate the accuracy of our proposed analytical models.
Secure data transmission in future high-capacity high-coverage multi-tier hierarchical networks, for which cognitive radio(CR) has emerged as an essential recipe, is of utmost importance. This paper investigates the secrecy outage performance of selection combining(SC) in CR networks(CRNs) over Rayleigh fading channels. In a single-input multiple-output(SIMO) wiretap channel, a secondary user transmits confidential messages to another secondary user, which is equipped with( 1)B Bn n ≥ antennas. Meanwhile, a passive eavesdropper, which is equipped with( 1)E En n ≥ antennas, intends to overhear the messages. Both the legal receiver and the eavesdropper adopt SC scheme to process the received multiple signals. The secondary transmitter uses the underlay strategy to guarantee the quality of service of the primary user without spectrum sensing. Compared to the work proposed by Maged Elkashlan et al. in Ref. [1], we present an alternative method to derive the closed-form expression for the secrecy outage probability(SOP) and develop a simplified SOP when the maximal transmit power at the secondary user is sufficiently high. Our results reveal the impact of the primary network on the secondary network with a multi-antenna wiretap channel and simulations are conducted to validate the accuracy of our proposed analytical models.
In this paper, we consider a multi-hop decode-and-forward (DF) relaying transmission in underlay cognitive radio networks. Considering the presence of an eavesdropper that overhears the transmission, we address secure communications of multi-hop wireless communications in terms of physical layer security. In addition, we take in to account the effect of imperfect channel state information (CSI) which is of importance issue in underlay cognitive radio. We analyze the secrecy outage performance of the system over Rayleigh fading channels. In particular, we derive the closed-form expression of the system secrecy outage probability. The analysis results are validated by the Monte-Carlo simulation results. The numerical results show that the imperfect CSI issue does not effect on the security issue of the transmission in underlay cognitive radio networks. On the other hand, the number of hops plays a key role in the physical layer security.
In this paper, the physical layer security of a dual-hop underlay uplink cognitive radio network is investigated over Nakagami-m fading channels. Specifically, multiple secondary sources (Si)1≤2≤Nare taking turns in accessing the licensed spectrum of the primary users and communicating with a multi-antenna secondary base station (D) through the aid of a multi-antenna relay R in the presence of M eavesdroppers (Ek)1≤k≤Mthat are also equipped with multiple antennas. Among the remaining nodes, one jammer is randomly selected to transmit an artificial noise to disrupt all the eavesdroppers that are attempting to intercept the communication of the legitimate links, i.e., Si-R and R-D. The received signals at each node are combined using maximum-ratio combining. Secrecy analysis is provided by deriving closed-form and asymptotic expressions for the secrecy outage probability. The impact of several key parameters on the system's secrecy, e.g., transmit power of the sources, number of eavesdroppers, maximum tolerated interference power, and the number of diversity branches is investigated. Importantly, by considering two scenarios, namely (i) absence and (ii) presence of a friendly jammer, new insights are obtained for the considered communication system. Especially, we tend to answer to the following question: Can better secrecy be achieved without jamming by considering a single antenna at eavesdroppers and multiple-ones at the legitimate users (i.e., relay and end-user) rather than sending permanently an artificial noise and considering that both the relay and the destination are equipped with a single antenna, while multiple antennas are used by the eavesdroppers? The obtained results are corroborated through Monte Carlo simulation and show that the system's security can be enhanced by adjusting the aforementioned parameters.
In this paper, the physical layer security of a dual-hop underlay uplink cognitive radio network is investigated over Nakagami-m fading channels. Specifically, multiple secondary sources are taking turns in accessing the licensed spectrum of the primary users and communicating with a multiantenna secondary base station D through the aid of a multiantenna relay R in the presence of M eavesdroppers that are also equipped with multiple antennas. Among the remaining nodes, one jammer is randomly selected to transmit an artificial noise to disrupt all the eavesdroppers that are attempting to intercept the communication of the legitimate links i.e., S-R and R-D. The received signals at each node are combined using maximal-ratio combining. Secrecy analysis is provided by deriving closed-form and asymptotic expressions for the secrecy outage probability. The impact of several key parameters on the system's secrecy e.g., transmit power of the sources, number of eavesdroppers, maximum tolerated interference power, and the number of diversity branches is investigated. Importantly, by considering two scenarios, namely (i) absence and (ii) presence of a friendly jammer, new insights are obtained for the considered communication system. Especially, we tend to answer to the following question: Can better secrecy be achieved without jamming by considering a single antenna at eavesdroppers and multiple-ones at the legitimate users (i.e., relay and end-user) rather than sending permanently an artificial noise and considering that both the relay and the destination are equipped with a single antenna, while multiple antennas are used by the eavesdroppers? The obtained results are corroborated through Monte Carlo simulation and show that the system's security can be enhanced by adjusting the aforementioned parameters.