# Maritime Coverage Enhancement Using UAVs Coordinated with Hybrid Satellite-Terrestrial Networks

## TL;DR

This paper proposes a joint optimization framework for UAV trajectory and power control to enhance maritime communication coverage by coordinating UAVs with hybrid satellite-terrestrial networks, considering practical CSI limitations.

## Contribution

It introduces a novel joint optimization approach for UAV deployment in hybrid maritime networks using only large-scale CSI, addressing practical constraints and system integration.

## Key findings

- UAVs effectively enhance maritime coverage when coordinated with satellites and terrestrial systems.
- The proposed optimization improves UAV energy efficiency and interference management.
- Simulation results validate the effectiveness of the joint optimization framework.

## Abstract

Due to its agile maneuverability, unmanned aerial vehicles (UAVs) have shown great promise for ondemand communications. In practice, UAV-aided aerial base stations are not separate. Instead, they rely on existing satellites/terrestrial systems for spectrum sharing and efficient backhaul. In this case, how to coordinate satellites, UAVs and terrestrial systems is still an open issue. In this paper, we deploy UAVs for coverage enhancement of a hybrid satellite-terrestrial maritime communication network. Under the typical composite channel model including both large-scale and small-scale fading, the UAV trajectory and in-flight transmit power are jointly optimized, subject to constraints on UAV kinematics, tolerable interference, backhaul, and the total energy of UAV for communications. Different from existing studies, only the location-dependent large-scale channel state information (CSI) is assumed available, because it is difficult to obtain the small-scale CSI before takeoff in practice, and the ship positions can be obtained via the dedicated maritime Automatic Identification System. The optimization problem is non-convex. We solve it by problem decomposition, successive convex optimization and bisection searching tools. Simulation results demonstrate that the UAV fits well with existing satellite and terrestrial systems, using the proposed optimization framework.