3D Placement and Orientation of mmWave-based UAVs for Guaranteed LoS Coverage

TL;DR

This paper addresses the challenge of optimally positioning and orienting UAVs in 3D space to ensure guaranteed line-of-sight coverage for users in mmWave communication networks, using an ILP formulation and a greedy algorithm.

Contribution

It formulates the 3D UAV placement and orientation problem for LoS coverage as an NP-hard ILP and proposes an efficient greedy algorithm for practical solutions.

Findings

The greedy algorithm nearly always guarantees LoS coverage in simulations.

The ILP formulation proves the problem's NP-hardness.

Simulation results demonstrate the effectiveness of the proposed approach.

Abstract

Unmanned aerial vehicles (UAVs), as aerial base stations, are a promising solution for providing wireless communications, thanks to their high flexibility and autonomy. Moreover, emerging services, such as extended reality, require high-capacity communications. To achieve this, millimeter wave (mmWave), and recently, terahertz bands have been considered for UAV communications. However, communication at these high frequencies requires a line-of-sight (LoS) to the terminals, which may be located in 3D space and may have extremely limited direct-line-of-view (LoV) due to blocking objects, like buildings and trees. In this paper, we investigate the problem of determining 3D placement and orientation of UAVs such that users have guaranteed LoS coverage by at least one UAV and the signal-to-noise ratio (SNR) between the UAV-user pairs are maximized. We formulate the problem as an integer linear programming(ILP) problem and prove its NP-hardness. Next, we propose a low-complexity geometry-based greedy algorithm to solve the problem efficiently. Our simulation results show that the proposed algorithm (almost) always guarantees LoS coverage to all users in all considered simulation settings.