332 research outputs found
Trajectory Optimization for Cellular-Enabled UAV with Connectivity and Battery Constraints
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 as soon as possible, 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 may take some time depending on waiting time. Our key contribution lies
in proposing an algorithm that efficiently computes an optimal UAV path 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. 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. Furthermore, we propose another
algorithm that computes the maximum payload weight that the UAV can deliver
under the connectivity and battery constraints.Comment: This article was presented in part at the IEEE Vehicular Technology
Conference (VTC) 2023-Fal
A Transfer Learning Approach for UAV Path Design with Connectivity Outage Constraint
The connectivity-aware path design is crucial in the effective deployment of
autonomous Unmanned Aerial Vehicles (UAVs). Recently, Reinforcement Learning
(RL) algorithms have become the popular approach to solving this type of
complex problem, but RL algorithms suffer slow convergence. In this paper, we
propose a Transfer Learning (TL) approach, where we use a teacher policy
previously trained in an old domain to boost the path learning of the agent in
the new domain. As the exploration processes and the training continue, the
agent refines the path design in the new domain based on the subsequent
interactions with the environment. We evaluate our approach considering an old
domain at sub-6 GHz and a new domain at millimeter Wave (mmWave). The teacher
path policy, previously trained at sub-6 GHz path, is the solution to a
connectivity-aware path problem that we formulate as a constrained Markov
Decision Process (CMDP). We employ a Lyapunov-based model-free Deep Q-Network
(DQN) to solve the path design at sub-6 GHz that guarantees connectivity
constraint satisfaction. We empirically demonstrate the effectiveness of our
approach for different urban environment scenarios. The results demonstrate
that our proposed approach is capable of reducing the training time
considerably at mmWave.Comment: 14 pages,8 figures, journal pape
Federated Learning for Cellular-connected UAVs: Radio Mapping and Path Planning
To prolong the lifetime of the unmanned aerial vehicles (UAVs), the UAVs need
to fulfill their missions in the shortest possible time. In addition to this
requirement, in many applications, the UAVs require a reliable internet
connection during their flights. In this paper, we minimize the travel time of
the UAVs, ensuring that a probabilistic connectivity constraint is satisfied.
To solve this problem, we need a global model of the outage probability in the
environment. Since the UAVs have different missions and fly over different
areas, their collected data carry local information on the network's
connectivity. As a result, the UAVs can not rely on their own experiences to
build the global model. This issue affects the path planning of the UAVs. To
address this concern, we utilize a two-step approach. In the first step, by
using Federated Learning (FL), the UAVs collaboratively build a global model of
the outage probability in the environment. In the second step, by using the
global model obtained in the first step and rapidly-exploring random trees
(RRTs), we propose an algorithm to optimize UAVs' paths. Simulation results
show the effectiveness of this two-step approach for UAV networks.Comment: to appear in IEEE GLOBECOM 202
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