Mobility challenges and issues in unmanned aerial vehicle (UAV) path planning: A systematic review

Unmanned aerial vehicles (UAV) are unavoidable in various real-world applications, including surveillance, agricultural and industrial monitoring, search and rescue, and other scientific applications. The flying ability and speed of UAVs make them perfect for emergency and disaster management applications. Moreover, since UAVs are pilotless vehicles, especially in disaster management operations, their deployment as an ad hoc network is crucial and safe. However, these operations present numerous challenging hurdles that must be overcome for the successful deployment of UAV networks. For example, ground user mobility, handover scheme of the user equipment from UAV to UAV, topology model for the intra-UAV communication, energy efficiency and time efficiency, obstacle avoidance, dynamic or static approach, and centralized or decentralized technique for the UAV management. In this study, a systematic literature review is carried out to find existing ways to deal with problems like autonomous path planning in 3D environments, the effects of static and dynamic altitudes on UAVs, how the UAV deals with mobile ground users on its own, and how mobility might affect packet loss during communication in the UAV network. Following a thorough screening of current studies, we selected 57 studies that addressed four research questions. We critically reviewed these studies to identify the UAV path planning models. These techniques were categorized based on different path planning approaches deployed especially related to static and mobile ground users, coverage of the area, and 3D mobility of the UAV. Studies concerning the 3D mobility of the UAV and how to handle the mobility of ground users reveal research gaps. The current evaluation metrics are also extracted from the selected studies that were used by the researchers.