Coexistence of Terrestrial and Aerial Users in Cellular Networks

Abstract

Enabling the integration of aerial mobile users into existing cellular networks would make possible a number of promising applications. However, current cellular networks have not been designed to serve aerial users, and hence an exploration of design parameters is required in order to allow network providers to modify their current infrastructure. As a first step in this direction, this paper provides an in-depth analysis of the coverage probability of the downlink of a cellular network that serves both aerial and ground users. We present an exact mathematical characterization of the coverage probability, which includes the effect of base stations (BSs) height, antenna pattern and drone altitude for various types of urban environments. Interestingly, our results show that the favorable propagation conditions that aerial users enjoy due to their altitude is also their strongest limiting factor, as it leaves them vulnerable to interference. This negative effect can be substantially reduced by optimizing the flying altitude, the base station height and antenna down-tilt angle. Moreover, lowering the base station height and increasing down-tilt angle are in general beneficial for both terrestrial and aerial users, pointing out a possible path to enable their coexistence.

Toward a Connected Sky: Performance of Beamforming With Down-Tilted Antennas for Ground and UAV User Co-Existence

“…To enable such communications, it is imperative to connect UAVs, seen as aerial users (AUs), to the ubiquitous wireless cellular network. Such cellular-connected UAVs have recently attracted attention in cellular network research in both academia and industry [5]- [10] due to their ability to pervasively communicate. However, cellular networks have been designed to provide connectivity to ground users (GUs) rather than AUs [5].…”

“…Such cellular-connected UAVs have recently attracted attention in cellular network research in both academia and industry [5]- [10] due to their ability to pervasively communicate. However, cellular networks have been designed to provide connectivity to ground users (GUs) rather than AUs [5]. For instance, cellular-connected UAV communication possesses substantially different characteristics that pose new technical challenges which include: dominance of line-of-sight (LoS) interference and reduced ground base stations (GBSs) antenna gain [5].…”

“…In [9], the authors showed that cooperative transmission significantly improves the coverage probability for high-altitude AUs. However, while the works in [5], [7], [9], and [10] have analyzed the performance of cellular-connected UAVs, their approaches can not be used to effectively improve the performance of AUs while enhancing spectral efficiency (SE) by spatial multiplexing. Also, even though the work in [8] has proposed MIMO beamforming for an AU co-existing with multiple GUs, this work provides no analytical characterization of the performance of AUs or the impact of the antennas' down-tilt angles.…”

Q-Learning Based Aerial Base Station Placement for Fairness Enhancement in Mobile Networks

“…To mitigate this sensitivity, many studies have investigated the optimal placement of aerial-BSs in wireless networks [3]- [15]. It should be noted that, although the optimal placement of aerial-BSs is an important issue, the opportunities and challenges related to the use of aerial-BSs are not limited to their placement [16]- [18]. Ensuring high levels of fairness among users and a good cell-edge performance are some of the expectations of the next-generations of wireless networks.…”

Mobility in the Sky: Performance and Mobility Analysis for Cellular-Connected UAVs

“…Unlike the static UAV assumptions in [13]- [18], the study of mobile UAVs has been conducted in [19]- [27]. Prior works in the literature followed two main directions pertaining to trajectory design for mobile UAVs.…”