Secrecy Transmission in Large-Scale UAV-Enabled Wireless Networks

Abstract

This paper considers the secrecy transmission in a large-scale unmanned aerial vehicle (UAV)-enabled wireless network, in which a set of UAVs in the sky transmit confidential information to their respective legitimate receivers on the ground, in the presence of another set of randomly distributed suspicious ground eavesdroppers. We assume that the horizontal locations of legitimate receivers and eavesdroppers are distributed as two independent homogeneous Possion point processes (PPPs), and each of the UAVs is positioned exactly above its corresponding legitimate receiver for efficient secrecy communication. Furthermore, we consider an elevation-angledependent line-of-sight (LoS)/non-LoS (NLoS) path-loss model for air-to-ground (A2G) wireless channels and employ the wiretap code for secrecy transmission. Under such setups, we first characterize the secrecy communication performance (in terms of the connection probability, secrecy outage probability, and secrecy transmission capacity) in mathematically tractable forms, and accordingly optimize the system configurations (i.e., the wiretap code rates and UAV positioning altitude) to maximize the secrecy transmission capacity, subject to a maximum secrecy outage probability constraint. Next, we propose to use the secrecy guard zone technique for further secrecy protection, and analyze the correspondingly achieved secrecy communication performance. Finally, we present numerical results to validate the theoretical analysis. It is shown that the employment of secrecy guard zone significantly improves the secrecy transmission capacity of this network, and the desirable guard zone radius generally decreases monotonically as the UAVs' and/or the eavesdroppers' densities increase.Index Terms-UAV communications, physical layer security, homogeneous Poisson point process (PPP), secrecy transmission capacity, secrecy guard zone.

Physical Layer Security for UAV Communications in 5G and Beyond Networks

“…The LoS/NLoS condition of the A2G channel link has been described in alternative ways. In [55], it is assumed that when the elevation angle is larger than a threshold, i.e., the user is located inside a disk area below the UAV, then LoS propagation dominates the channel. In the urban scenario, the LoS probability can also be determined according to the location and height distribution of the buildings [56], [57].…”

“…An alternative method is to relate the UAV positions to the positions of ground nodes. In [55], multiple ground Rx's are randomly distributed following PPP, each associated with a UAV Tx located right above its position. Further taking into account the constraint on inter-UAV distance, MHC point process was used to model the distribution of UAV BSs in [62], which can be viewed as a dependent thinning process of a standard PPP, with the thinning probability determined by the minimum distance requirement.…”

“…At the end of this subsection, it should be highlighted that in the works where random node distribution is considered, defining an area, where Eves cannot be located in, is another important and practical research direction. Such an area was termed as protected zone in [103], and termed as secrecy guard zone in [55], [63]. Details of these stochastic geometry-related works are summarized in Table II.…”

Secure UAV Random Networks With Minimum Safety Distance

“…Therefore, it is improtant to study the PLS issue from a network-wide perspective. To characterize the location distribution of UAVs in a large-scale UAV network and study the average network-wide performance, stochastic geometry is a useful tool [7], and have been widely used in many works, e.g., [8]- [11]. Yao et al [8] studied the secrecy performance in a UAV network modeled as a Poisson point process (PPP) with security guard zone technique.…”

“…To characterize the location distribution of UAVs in a large-scale UAV network and study the average network-wide performance, stochastic geometry is a useful tool [7], and have been widely used in many works, e.g., [8]- [11]. Yao et al [8] studied the secrecy performance in a UAV network modeled as a Poisson point process (PPP) with security guard zone technique. Kim et al [9] studied the successful transmission probability and area spectral efficiency (ASE) of a multi-layer aerial networks with UAVs in each layer modeled as PPPs.…”