We consider an underlay cognitive radio system, in which a source in a secondary system transmits information to a full-duplex (FD) wireless-powered destination node in the presence of an eavesdropper. In particular, the destination node is equipped with a single receiving antenna and a single transmitting antenna to enable FD operation. The receiving antenna can simultaneously receive information and energy from the source through power-splitter architecture. The received energy is then used in the transmitting antenna to send jamming signals to degrade the eavesdropper’s decoding capacity. Upper and lower bounds of probability of strictly positive secrecy capacity (SPSC) have been derived. Numerical results show that under the condition that the interference from the source and destination at primary user’s receiver is smaller than the interference temperature limit, upper and lower bounds merge together to become the exact SPSC.
We consider an underlay cognitive radio system, in which a source in a secondary system transmits information to a full-duplex (FD) wireless-powered destination node in the presence of an eavesdropper. In particular, the destination node is equipped with a single receiving antenna and a single transmitting antenna to enable FD operation. The receiving antenna can simultaneously receive information and energy from the source through power-splitter architecture. The received energy is then used in the transmitting antenna to send jamming signals to degrade the eavesdropper’s decoding capacity. Upper and lower bounds of probability of strictly positive secrecy capacity (SPSC) have been derived. Numerical results show that under the condition that the interference from the source and destination at primary user’s receiver is smaller than the interference temperature limit, upper and lower bounds merge together to become the exact SPSC.
Physical-layer security (PLS) for an underlay cognitive radio network (CRN)-based simultaneous wireless information and power transfer (SWIPT) over cascaded κ-µ fading channels is investigated. The network is composed of a pair of secondary users (SUs), a primary user (PU) receiver, and an eavesdropper attempting to intercept the data shared by the SUs. To improve the SUs’ data transmission security, we assume a full-duplex (FD) SU destination, which employs energy harvesting (EH) to extract the power required for generating jamming signals to be emitted to confound the eavesdropper. Two scenarios are presented and compared; harvesting and non-harvesting eavesdropper. Moreover, a trade-off between the system’s secrecy and reliability is explored. PLS is studied in terms of the probability of non-zero secrecy capacity and the intercept probability, whereas the reliability is studied in terms of the outage probability. Results reveal the great impact of jamming over the improvement of the SUs’ secrecy. Additionally, our work indicates that studying the system’s secrecy over cascaded channels has an influence on the system’s PLS that cannot be neglected.
Recently, combination of full-duplex (FD) technology with existing wireless devices are gaining much interest due to their spectrum efficient usage. In this work, a cognitive radio network (CRN) with FD relay for secondary user (SU) is proposed and physical layer security (PLS) issue is analyzed in the presence of passive eavesdropper by using maximum ratio transmission (MRT) and zero forcing beamforming (ZFBF) techniques. The restriction of self interference at FD relay is cancelled by using ZFBF technique when the number of transmit antenna at relay is greater than the number of receive antenna; on the other hand, null space projection (NSP) is applied for the reverse scenario. For information sharing, both ZFBF and MRT techniques are used. The FD relay is used for generating artificial noise (AN) to degrade the received signal-to-noise ratio (SNR) of the eavesdroppers while simultaneously receive data from secondary transmitter. The ergodic physical layer secrecy capacity and physical layer secrecy outage of both primary user (PU) and SU are evaluated. Finally, Monte-Carlo simulation is performed to compare the proposed approach with other existing techniques.
Physical Layer Security in Underlay Cognitive Radio Networks Over α−μ Fading Channels
This paper investigates physical layer security of underlay cognitive radio networks with interference constraint over α-μ fading channels. Specifically, in the secondary network, a secondary source sends its confidential information to a secondary destination in the presence of a passive eavesdropper, under the constraint imposed by the primary receiver in the primary network. Specifically, we derive the exact expressions of intercept probability and ergodic secrecy capacity (ESC) for the considered system under α-μ fading channels. To extract more valuable insights, we also present the asymptotic analysis of intercept probability, which reveals that the system secrecy diversity order only depends on the fading parameters of the secondary source-secondary destination link, not on the fading parameters associated with the secondary source-secondary eavesdropper link and secondary source-primary receiver link. We also present some key observations for ESC when secondary source power with interference constraint is very large. The numerical and simulation results corroborate the validity of our analytical framework, and show the effects of channel parameters on the system secrecy performance.
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.
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.