  Unmanned aerial vehicles (UAVs) can be used to provide wireless coverage
during emergency cases where each UAV serves as an aerial wireless base station
when the cellular network goes down. They can also be used to supplement the
ground base station in order to provide better coverage and higher data rates
for the users. In this paper, we aim to maximize the indoor wireless coverage
using UAVs equipped with directional antennas. We study the case that the UAVs
are using one channel, thus in order to maximize the total indoor wireless
coverage, we avoid any overlapping in their coverage volumes. We present two
methods to place the UAVs; providing wireless coverage from one building side
and from two building sides. In the first method, we utilize circle packing
theory to determine the 3-D locations of the UAVs in a way that the total
coverage area is maximized. In the second method, we place the UAVs in front of
two building sides and efficiently arrange the UAVs in alternating upsidedown
arrangements. We show that the upside-down arrangements problem can be
transformed from 3D to 2D and based on that we present an efficient algorithm
to solve the problem. Our results show that the upside-down arrangements of
UAVs, can improve the maximum total coverage by 100% compared to providing
wireless coverage from one building side.
