UAV-Aided Cellular Operation by User Offloading

Aiding cellular networks by unmanned aerial vehicles (UAVs) is a leap forward to address the ever-rising, multifarious, and dynamic traffic demands. The UAV utilization in wireless communication presents essential advantages, such as position control and appealing Line-of-Sight (LoS) components. In this article, we consider a UAV deployed as an aerial base station (ABS) to assist a terrestrial base station (TBS), serving several users in a hotspot area, via user offloading. Considering unavailable knowledge of the user's locations, the ABS is assumed to hover at the cell center (geometric center) above the TBS as a best-effort location for all the users. Taking into account the mutual interference between the aerial and terrestrial communication links due to spectrum reuse, we study the impact of the ABS altitude and transmit power, as well as the offload portion, on the user's downlink sum rate under the settings of the LoS channel. The results show that the optimal values for the design variables are either the maximum or the minimum boundaries. Also, the results demonstrate that our method outperforms benchmark schemes with appreciable amounts of gain. We also investigate the method's behavior with the ABS horizontal position optimization, probabilistic LoS channel, uplink communication, and orthogonal spectrum allocation.