In this study, we investigate the secrecy outage performance achieved by opportunistic relaying for a low-altitude unmanned aerial vehicle (UAV) swarm secure communication system in the presence of multiple UAV-eavesdroppers. In the primary channel, multiple UAV-transmitters are connected to a ground station via the ground-to-air (G2A) wireless backhaul and a UAV-transmitter and UAV-relay are selected to transmit the source signal to a far ground destination under air-to-air and air-to-ground Nakagami-m fading links. In the eavesdropping channel, maximum ratio combining is applied across multiple UAV-eavesdroppers for intercepting the legitimate transmissions from both the selected UAV-transmitter and UAV-relay. The backhaul reliability and eavesdropping probability are introduced to reflect the practical constraints on the G2A wireless backhaul and UAV-eavesdropper cooperation, respectively. The closed-form expression for the secrecy outage probability is derived in terms of the UAV cooperation, backhaul reliability, eavesdropping probability, and Nakagami-m fading parameters. In the high signal-to-noise ratio region, the asymptotic secrecy outage probability is also derived. It is shown that the secrecy diversity gain achieved by opportunistic relaying is jointly determined by the UAV cooperation and shape factors of Nakagami-m fading links in the primary channel. The analytical secrecy outage metrics achieved by opportunistic relaying are verified by Monte Carlo simulation results.
In this study, we investigate the secrecy outage performance achieved by opportunistic relaying for a low-altitude unmanned aerial vehicle (UAV) swarm secure communication system in the presence of multiple UAV-eavesdroppers. In the primary channel, multiple UAV-transmitters are connected to a ground station via the ground-to-air (G2A) wireless backhaul and a UAV-transmitter and UAV-relay are selected to transmit the source signal to a far ground destination under air-to-air and air-to-ground Nakagami-m fading links. In the eavesdropping channel, maximum ratio combining is applied across multiple UAV-eavesdroppers for intercepting the legitimate transmissions from both the selected UAV-transmitter and UAV-relay. The backhaul reliability and eavesdropping probability are introduced to reflect the practical constraints on the G2A wireless backhaul and UAV-eavesdropper cooperation, respectively. The closed-form expression for the secrecy outage probability is derived in terms of the UAV cooperation, backhaul reliability, eavesdropping probability, and Nakagami-m fading parameters. In the high signal-to-noise ratio region, the asymptotic secrecy outage probability is also derived. It is shown that the secrecy diversity gain achieved by opportunistic relaying is jointly determined by the UAV cooperation and shape factors of Nakagami-m fading links in the primary channel. The analytical secrecy outage metrics achieved by opportunistic relaying are verified by Monte Carlo simulation results.
In this work, we analyze the secrecy outage probability of unmanned aerial vehicle (UAV)-aided selective relaying networks with M UAV-transmitters (UTs), N UAV-relays(URs), and K collaborative UAV-eavesdroppers (UEs). In the main channel, the best UT-UR pair is selected to transmit the source message to the destination, while unreliable ground-to-air (G2A) wireless backhaul across multiple UTs is considered. In the eavesdropper channel, the UEs intelligently exchange the information received form the UTs and URs, while eavesdropping probability among UEs is considered. Due to non-ideal line of sight transmission, network congestion, and synchronization, we introduce backhaul reliability to reflect the practical constraint on G2A wireless backhaul. To reflect UEs' synchronization to the main channel and their consumed communication resources for inner-information exchange, we introduce eavesdropping probability to describe the cost of UE collaboration. The exact secrecy outage probability is presented in a closed form. It is shown that the asymptotic secrecy outage probability is exclusively determined by M, N, and backhaul reliability. Simulation results verify the accuracy of the analytical expressions.
In this article, we study the secrecy performance of an unmanned aerial vehicle (UAV)-assisted relay communication system, where a ground base station (GBS) intends to send confidential information to the ground legitimate user Bob with the help of a UAV relay in the presence of multiple aerial and ground eavesdroppers. We consider the height-dependent probabilistic line-of-sight and the generalκ-μshadowed channel fading model in the system. To enhance the secrecy performance, the GBS and UAV relay apply directional beamforming transmission while implementing protection zones around their intended receiving destinations. We then derive the approximate closed-form expressions of the secrecy outage probability (SOP) under different aerial and ground eavesdropperscolluding strategies. To get insights, we also obtain the SOP expression over Rayleigh fading as a special case. After discussing the impacts of transmitting and multiple aerial and ground eavesdropping parameters on the SOP, we show that the optimal altitude of UAV relay exists with the minimal SOP value under different urban environments. We also show that UAV eavesdroppers have a larger effect on the system performance than ground eavesdroppers.
This paper proposes a novel cooperative secure unmanned aerial vehicle (UAV) aided transmission protocol, where a source sends confidential information to a destination via an energy-constrained UAV-mounted amplify-and-forward relay in the presence of a ground eavesdropper. We adopt destination-assisted cooperative jamming as well as simultaneous wireless information and power transfer at the UAV-mounted relay to enhance physical-layer security and transmission reliability. Assuming a low-altitude UAV, we derive connection probability, secrecy outage probability, instantaneous secrecy rate, and average secrecy rate of the proposed protocol over Air-Ground channels, which are modeled as Rician fading with elevation-angel dependent parameters. Further, we analyze the asymptotic average secrecy rate performance of the proposed UAV-relaying scheme and derive high signal-to-noise ratio measures of the average secrecy rate to highlight the effect of various channel features on the system performance. By simulations, we verify our novel theoretical exact and approximate results and demonstrate significant performance improvement of our protocol, when compared to conventional transmission protocol with ground relaying and UAV-based transmission protocol without exploiting destination jamming. Finally, we evaluate the impacts of various system parameters, specifically, find the optimal UAV placement on the proposed protocol in terms of the aforementioned secrecy metrics.
In this paper, we study the strictly positive secrecy outage probability (SOP) and the ergodic secrecy capacity of a wiretap unmanned aerial vehicle (UAV) system where a UAV transmitter (Alice) is trying to send a message to a ground receiver (Bob) while an eavesdropper (Eve) is attempting to eavesdrop on the legitimate communication link. We study the performance of the system in two cases, first, when Eve is on the ground and an Air-to-Ground channel model is adopted between Alice, Bob and Eve. In the second case, Eve is a UAV drone that is located at the same altitude as Alice and the channel between Alice and Eve follows an Air-to-Air channel model. We derive closed form expressions of the SOP and ergodic secrecy capacity for the two scenarios. Simulation results verify the analytical derivations, where the results highlight the importance of the derived secrecy metrics, especially the impact of the distance between Alice and Eve on the overall performance.
Unmanned aerial vehicles (UAVs) have been extensively utilized in various scenarios due to their flexible mobility and rapid on-demand deployment. It becomes necessary and urgent to examine the secrecy performance of the UAV communication systems due to the open characteristics of the transmission technologies employed in UAV systems. In this paper, we investigate the physical layer security of the UAV communication system, in which the ground base station sends secret messages to the UAV hovering in the air, while a random number of eavesdroppers are randomly located around the ground base station. Using the Poisson point process theory, we obtain the exact and approximate expressions of the cumulative distribution function for the signal-to-noise ratio of the ground-to-air link, and then the analytical expressions of the secrecy outage probability and the average secrecy rate are derived. Finally, the accuracy of the analytical results is validated by Monte Carlo simulation.
Employing unmanned aerial vehicles (UAVs) in millimeter-wave (mmWave) networks as relays has emerged as an appealing solution to assist remote or blocked communication nodes. In this case, the network security becomes a great challenge due to the presence of malicious eavesdroppers. In this paper, we perform a secrecy analysis for a UAV-based mmWave relaying network. We first investigate the relaying scheme without jamming where the UAV decodes and forwards the information from the source to the destination with malicious eavesdropping. Furthermore, to enhance the secrecy performance, we propose a cooperative jamming scheme via utilizing the destination and an external UAV to cooperatively disrupt the eavesdroppers at the two stages of relaying, respectively. Using the probability of line-of-sight (LoS) between the UAV and ground nodes, the three-dimensional (3D) antenna gain, and the Nakagami-m small-scale fading model, the secrecy outage probability (SOP) of the two schemes with and without jamming is analyzed. Closed-form expressions for the SOP of the two schemes are obtained by employing the Gauss-Chebyshev quadrature. Simulation results are presented to validate the theoretical expressions of SOP and to show the effectiveness of the proposed schemes.