This paper investigates the physical-layer security (PLS) of a single-input-multiple-output (SIMO) underlay cognitive radio network (CRN) over cascaded $\kappa $ - $\mu $ fading channels. A secondary user (SU) transmitter communicates with a secondary user receiver over cascaded $\kappa $ - $\mu $ channels. Moreover, an eavesdropper residing in the SUs transmission’s range would be capable of intercepting the SUs’ transmission. The SU destination and the eavesdropper are both assumed to be equipped with multiple antennas. Both of the receivers adopt maximal-ratio combining (MRC) over the multiple copies of the signal. In an underlay CRN, the SU transmitter should keep adjusting the transmission power to ensure not to disturb the primary users’ (PUs) transmission. PLS is analyzed in terms of the secrecy outage probability ( SOP ) and the probability of non-zero secrecy capacity $(P_{nz})$ . Results indicate the evident effect of the cascade level and the number of antennas at the eavesdropper over the secrecy of the SUs pair. In addition, results reveal that PLS can be strengthened by increasing the number of antennas at the legitimate receiver. The impact of the interference level tolerable by the PU receiver over SUs’ secrecy is also analyzed. Monte-Carlo simulations and analytical results are presented to assess the system performance.

In this paper, the physical-layer security (PLS) for an underlay cognitive radio network (CRN) with multiple non-colluding eavesdroppers is studied. We assume that a secondary user (SU) transmitter communicates with an SU receiver over a cascaded $\kappa$-$\mu$ fading channel and under the threat of eavesdropping. A cooperative jammer exists to improve the SUs’ security by harvesting energy from the SU transmitter using power splitting technique. This harvested energy is utilized to generate jamming signals to deteriorate the eavesdroppers’ reception quality. Moreover, the eavesdroppers are assumed to be randomly distributed according to a homogeneous Poisson point process (HPPP), in which the $k^{th}$ closest eavesdropper to the SU transmitter will be selected in our analysis. Additionally, the legitimate receiver is assumed to harvest energy from the SU transmitter using the power splitting technique. In this context, we propose an optimum power splitting factor at the legitimate receiver that achieves the best privacy while constraining the amount of the harvested energy. Furthermore, on enhancing system security, we investigate the effectiveness of the jamming technique. The impact of distances over security is also examined. The results reveal an improvement in privacy as the legitimate receiver utilizes the adaptable power splitting factor. PLS is evaluated in terms of the probability of non-zero secrecy capacity and the intercept probability.

In this paper, secrecy performance is studied over the cascaded fading channel for the κ-μ distribution. The probability density function (PDF) and the cumulative distribution function (CDF) for the multiplication of “n” κ-μ random variables are derived. A communication system operating over the cascaded κ-μ fading channel is studied, where the outage probability, the average symbol error probability (ASEP), and the average channel capacity (ACC) are obtained in terms of the Meijer G-function. In addition, the secrecy performance is studied for a system model where we have a transmitter, a receiver, and multiple colluding eavesdroppers attempting to overhear the information received. The secrecy performance is studied in terms of the secrecy outage probability (SOP) and the probability of non-zero secrecy capacity. The analyses illustrate that increasing the number of eavesdroppers in the network degrades the secrecy of the system. Furthermore, increasing the cascade level in the channel degrades the system performance as well as the security of the system.

In this paper, the physical-layer security for a three-node wiretap system model is studied. Under the threat of multiple eavesdroppers, it is presumed that a transmitter is communicating with a legitimate receiver. The channels are assumed to be following cascaded $\kappa$-$\mu$ fading distributions. In addition, two scenarios for eavesdroppers’ interception and information-processing capabilities are investigated: colluding and non-colluding eavesdroppers. The positions of these eavesdroppers are assumed to be random in the non-colluding eavesdropping scenario, based on a homogeneous Poisson point process (HPPP). The security is examined in terms of the secrecy outage probability, the probability of non-zero secrecy capacity, and the intercept probability. The exact and asymptotic expressions for the secrecy outage probability and the probability of non-zero secrecy capacity are derived. The results demonstrate the effect of the cascade level on security. Additionally, the results indicate that as the number of eavesdroppers rises, the privacy of signals exchanged between legitimate ends deteriorates. Furthermore, in this paper, regarding the capabilities of tapping and processing the information, we provide a comparison between colluding and non-colluding eavesdropping.

Cognitive radio networks (CRNs) are acknowledged for their ability to tackle the issue of spectrum under-utilization. In the realm of CRNs, this paper investigates the energy efficiency issue and addresses the critical challenge of optimizing system reliability for overlay CRN access mode. Randomly dispersed secondary users (SUs) serving as relays for primary users (PUs) are considered, in which one of these relays is designated to harvest energy through the time switching-energy harvesting (EH) protocol. Moreover, this relay amplifies-and-forwards (AF) the PU’s messages and broadcasts them along with its own across cascaded κ-μ fading channels. The power splitting protocol is another EH approach utilized by the SU and PU receivers to enhance the amount of energy in their storage devices. In addition, the SU transmitters and the SU receiver are deployed with multiple antennas for reception and apply the maximal ratio combining approach. The outage probability is utilized to assess both networks’ reliability. Then, an energy efficiency evaluation is performed to determine the effectiveness of EH on the system. Finally, an optimization problem is provided with the goal of maximizing the data rate of the SUs by optimizing the time switching and the power allocation parameters of the SU relay.

This paper studies the physical-layer security (PLS) of a system model consisting of a transmitter, a receiver, and multiple eavesdroppers. Cascaded general fading channel, which is the κ -µ distribution is assumed at the main and the wiretap links of the network. The impacts of the cascade level, the number of eavesdroppers attempting to overhear the confidential information, and the wiretap channel's parameters on the system's secrecy are investigated. Two of the main secrecy metrics are used to evaluate the secrecy level of the system, which are the secrecy outage probability (OP sec ) and the probability of non-zero secrecy capacity (P nsc ). Exact and asymptotic form expressions for (OP sec ) and (P nsc ) are derived. Asymptotic analysis is performed to gain a clear vision about the impact of some key parameters over the secrecy. The results show that the fading channel cascade level has a significant effect on the system's secrecy. Also, the results show that the system is less protected when increasing the number of eavesdroppers or when improving the wiretap channel's conditions. Analytical results are validated using Monte-Carlo simulations.