The growth of communication technologies has led to a corresponding increase in the need for information security. The use of covert communication techniques has the potential to significantly reduce the likelihood of the transmitted signal being intercepted by unintended receivers, thereby significantly increasing the security of the information. In this paper, we propose an energy-dispersed random time-hopping (ED-RTH) covert communication scheme. Building on existing time uncertainty schemes, this scheme further enhances time uncertainty through random time-hopping, while dispersing signal energy to achieve stronger covertness. We present a model for analyzing the covertness of the ED-RTH scheme. Given the complexity of the likelihood ratio distribution, the Kullback-Leibler (KL) divergence is used to analyze the lower bound of Willie’s detection error probability. Through constructing behavioral-level simulations for validation, we investigated the impact of the number of dispersed time slotsKon both Willie’s detection error probability and the system’s covert throughput. Finally we compared the proposed ED-RTH scheme with existing time uncertainty scheme, and the results demonstrate that the ED-RTH scheme achieves significantly enhanced covertness.

Efficient and reliable neighbor discovery is critical for UAV networks equipped with directional antennas, particularly in dynamic and energy-constrained environments. We present a novel optimization framework that jointly minimizes delay and power consumption using the power-delay product as the optimization metric. The framework is formulated for both synchronous and asynchronous schemes, leveraging upper-bound metrics and a convex-concave procedure to achieve tractable convex formulations. Simulation results validate the theoretical models and show significant improvements over baseline methods. We also conducted real-world experiments, where our method reduced power-delay product by 11% compared to the baseline, though the dual-sector hardware configuration limited the achievable gains. This work provides a comprehensive solution for UAV neighbor discovery, with high potential for scalability in more complex and dynamic environments.

Unmanned aerial vehicles (UAVs) communications have been widely exploited in our daily life, which leads to rising concerns about the security issue. This work investigates the secrecy performance of a UAV-to-vehicle (UAV-2-V) communication system, where the information delivered over both downlink and uplink between a UAV ($S$) acting as a temporary aerial base-station and a legitimate vehicle ($D$) moving along a road which is overheard by an eavesdropping vehicle ($E$) on the same road. The location of$S$is assumed to be uniformly distributed in the sky, while the locations of$D$and$E$are uniformly distributed on the highway. The statistical characteristics, including the cumulative distribution function and probability density function of the received signal-to-noise ratio over both downlink and uplink, are characterized respectively. Closed-form expressions for the approximate and asymptotic secrecy outage probability (SOP) of the downlink experiencing Rician fading channels have been derived accordingly. Moreover, the secrecy outage performance of the uplink is investigated by deriving the closed-form expression of the exact and asymptotic SOP in two cases: the eavesdropping channel suffers Rician and Weibull fading, respectively. Finally, Monte-Carlo simulations are shown to verify our proposed analytical models.

In this study, a wireless powered dual‐hop relay system, which consists of a source, a destination and a relay that is equipped with ( ) receiving antennas and finite energy storage, is considered. Antenna selection scheme is employed for the relay to harvest energy from the received signals, under which the ( ) strongest received signals are combined for information processing and the other copies of signals are used for energy harvesting. Considering Nakagami‐ m fading scenarios, the authors first derive the closed‐form expressions for the probability density function and the cumulative distribution function of the signal‐to‐noise ratio with generalised selection combining (GSC), and then the exact and asymptotic analytical expressions for outage probability are derived, respectively. Finally, simulation results are presented to verify the proposed analysis model.

We investigate the secrecy outage performance of maximal ratio combining (MRC) in cognitive radio networks over Rayleigh fading channels. In a single-input multiple-output wiretap system, we consider a secondary user (SU-TX) that transmits confidential messages to another secondary user (SU-RX) equipped with M ( M ≥ 1) antennas where the MRC technique is adopted to improve its received signal-to-noise ratio. Meanwhile, an eavesdropper equipped with N ( N ≥ 1) antennas adopts the MRC scheme to overhear the information between SU-TX and SU-RX. SU-TX adopts the underlay strategy to guarantee the service quality of the primary user without spectrum sensing. We derive the closed-form expressions for an exact and asymptotic secrecy outage probability.

In this study, secrecy outage performance is studied for partial relay selection (PRS) schemes in cooperative systems over Rayleigh fading channels. In the considered systems, there are one source (S), one destination (D), one eavesdropper, one jammer that can send interference to the eavesdropper, and N ( N > 1) relay candidates, one of which is selected as the relay (R). By considering the practical scenarios and to protect the transmitted information over R–D link from being eavesdropped, the authors propose a new transmission scheme: let D send random information to R while S sending information to R. Then, R processes the messages from S and D by XOR operation in order to prevent the eavesdropper's interception while the information is delivered between R and D. They study the secrecy outage performance for two PRS schemes: (i) the optimal source–relay link (OSRL) scheme; and (ii) the optimal source–relay–destination link (OSRDL) scheme. The closed‐form expressions for the secrecy outage probability (SOP) of the two PRS schemes are derived, as well as the closed‐form upper bound for SOP under OSRL scheme and the lower bound for SOP under OSRDL scheme. Finally, simulation results are given to verify the presented analytical models and the proposed transmission scheme.

In this paper, a single-input multiple-output (SIMO) simultaneous wireless information and power transfer system consisting of one base station, one desired information receiver and N (N > 1) energy-harvesting receivers is considered. Each link in the considered system suffers not only from small-scale fading but also path-loss. In particular, we focus on the physical layer security performance including secrecy outage and secrecy capacity in the presence of eavesdroppers. We derive the closed-form analytical expression for the exact and the asymptotic secrecy outage probability while considering each eavesdropping link experiences independent but not necessarily identical Rayleigh fading. The closed-form analytical expression for the average secrecy capacity has also been derived for the case that all eavesdropping links experience independent and identical Rayleigh fading. Numerical and Monte Carlo simulation results are presented to verify our derived analytical models.