In the emergency communication scenario, unmanned aerial vehicle (UAV) relay can provide long-distance communication service for indoor users. Different from providing services for outdoor users, there is a signal through wall loss when providing services for indoor users. The process of signal passing through the wall leads to the rapid attenuation of the signal, the significant reduction of the signal-to-noise ratio, and further leads to the decline of the system throughput. In order to improve the system throughput as much as possible, it is necessary to optimize the three-dimensional location of UAV, adjust the elevation angle of signal through the wall, and reduce the through wall loss. Users have the right to enjoy the same communication quality, but the optimization of UAV location cannot meet the fairness requirements of users.Therefore, under the constraints of user fairness and information causality, we construct the objective problem of maximizing system throughput. Due to the difficulty of solving the original problem, we decompose the original problem into two subproblems (location optimization and bandwidth allocation), and use successive convex approximation theory to solve them, respectively. Then we propose a joint location and bandwidth optimization (JLBO) algorithm.Simulation results show that the JLBO algorithm has good convergence performance and can maximize system throughput on the premise of ensuring user fairness.

In emergency communication scenarios, unmanned aerial vehicles (UAVs) can be used as an air relay to provide higher-quality communication for indoor users. When bandwidth resources are scarce, the use of free space optics (FSO) technology will greatly improve the resource utilization of the communication system. Therefore, we introduce FSO technology into the backhaul link of outdoor communication, and use free space optical/radio frequency (FSO/RF) technology to realize the access link of outdoor indoor communication. The deployment location of UAVs will affect not only the through wall loss of outdoor–indoor communication but also the quality of FSO communication, and, therefore, it needs to be optimized. In addition, by optimizing the power and bandwidth allocation of UAVs, we realize the efficient utilization of resources and improve the system throughput on the premise of considering information causality constraints and user fairness. The simulation results show that, by optimizing the location and power bandwidth allocation of UAVs, the system throughput is maximized, and the throughput between each user is fair.

This paper investigates the throughput optimization strategy in an unmanned aerial vehicle (UAV)-enabled emergency outdoor–indoor fairness communication scenario, with the UAV as a mobile relay station in the air, to provide outdoor–indoor communication services for users inside buildings. The occurrence of severe signal fading caused by outdoor transmission loss through wall loss as well as indoor transmission loss when the UAV forwards the information to the indoor users reduces the channel gain and degrades the system downlink throughput. To improve the downlink throughput of the system and ensure communication fairness for indoor users, we designed a joint UAV location deployment and resource allocation (JLRO) algorithm that optimized UAV three-dimensional (3D) deployment location, power and bandwidth resource allocation. The simulation results demonstrate the convergence and validity of the proposed JLRO algorithm, as well as its superiority compared to benchmark algorithms.