In this paper, we address the problem of path planning for a cellular-enabled UAV with connectivity and battery constraints. The UAV’s mission is to deliver a payload from an initial point to a final point, while maintaining connectivity with a BS and adhering to the battery constraint. The UAV’s battery can be replaced by a fully charged battery at a charging station, which takes some time. Our key contribution lies in proposing an algorithm that efficiently computes an optimal path that minimizes the mission completion time, solvable in polynomial time. We achieve this by transforming the problem into an equivalent two-level shortest path finding problem over weighted graphs and leveraging graph theoretic approaches to solve it. In more detail, we first find an optimal path and speed to travel between each pair of charging stations without replacing the battery, and then find the optimal order of visiting charging stations. To demonstrate the effectiveness of our approach, we compare it with previously proposed algorithms and show that our algorithm outperforms those in terms of both computational complexity and performance.

For multi-band wireless ad hoc networks of multiple users, an anti-jamming game between the users and a jammer is studied. In this game, the users (resp. jammer) want to maximize (resp. minimize) the expected rewards of the users taking into account various factors such as communication rate, hopping cost, and jamming loss. We analyze the arms race of the game and derive an optimal frequency hopping policy at each stage of the arms race based on the Markov decision process (MDP). It is analytically shown that the arms race reaches an equilibrium after a few rounds, and a frequency hopping policy and a jamming strategy at the equilibrium are characterized. We propose two kinds of collision avoidance protocols to ensure that at most one user communicates in each frequency band, and provide various numerical results that show the effects of the reward parameters and collision avoidance protocols on the optimal frequency hopping policy and the expected rewards at the equilibrium. Moreover, we discuss about equilibria for the case where the jammer adopts some unpredictable jamming strategies.

We study the effect of node mobility on the throughput scaling of the covert communication over a wireless adhoc network. It is assumed that n mobile nodes want to communicate each other in a unit disk while keeping the presence of the communication secret from each of Θ(ns) non-colluding wardens (s > 0). The wardens can be mobile or fixed. Our results show that the node mobility greatly improves the throughput scaling, compared to the case of fixed node location. In particular, for s ≤ 1, the aggregate throughput scaling, i.e., the maximally achievable throughput scaling of the total network when each source-destination pair communicates with the same rate, is shown to be arbitrarily close to linear in n when the number of channel uses l that each warden uses to judge the presence of communication is not too large compared to n. More specifically, the aggregate throughput scaling is arbitrarily close to linear when s ≤ 1 and l = O(n(α-2)(1-s)), where α ≥ 2 denotes the path loss exponent. For the achievability, we modify the two-hop based scheme by Grossglauser and Tse (2002), which was proposed for a wireless ad hoc network without a covertness constraint, by introducing a preservation region around each warden in which the senders are not allowed to transmit and by carefully analyzing the effect of covertness constraint on the transmit power and the resultant transmission rates. This scheme is shown to be optimal for 0 <; s ≤ 1 under an assumption that each node outside preservation regions around wardens uses the same transmit power.

We study the capacity scaling of the covert communication over a wireless ad hoc network where n mobile nodes want to communicate each other in a unit disk while keeping the presence of the communication secret from each of Θ(ns) non-colluding wardens (0 <; s <; 1). We modify the two-hop based scheme by Grossglauser and Tse (2002), which is proposed for a wireless ad hoc network without a covertness constraint, by introducing a preservation region around each warden in which the senders are not allowed to transmit. This scheme is shown to be optimal under an assumption that each node outside the preservation regions uses the same transmit power. Our results show that the node mobility greatly improves the aggregate throughput, compared to the case of fixed node location. In particular, the aggregate throughput scaling is shown to be linear in n when the number of channel uses that each warden uses to judge the presence of communication is not too large compared to n.