Mission-based PTR triangle for multi-UAV systems flight planning

The Unmanned Aerial Vehicle (UAV) domain, especially the design of UAV cooperative systems, is one of the most important research and applied fields nowadays. The multi-UAV system design is a wealth of research points under the flight planning umbrella, including the design of communication protocols for the Flying Ad-hoc Network (FANET) connecting UAVs, and the inevitable flight design aspects which are the mission planning and path planning. With the fact that topology and routing are the communication design parts most affected by FANET's highly dynamic 3D movement, this paper introduces a design concept for multi-UAV system flight plan that has been named mission-based PTR triangle to indicate the importance of joint optimization of the three design pillars: Path planning, Topology control, and Routing strategy based on mission requirements. These aspects are very interconnected; they determine the UAV positions and relative placement and how the UAVs are connected; any of them can influence or be influenced by the other. They can be regarded as a single process and the trade-off between their parameters controls their influence. In addition, most of the flight planning opera-tions are confined to a PTR triangle its edges represent cross-layer or joint optimization associations, results in different optimization cases to support adaptive optimality suitable to the dynamic nature of FANET, design constraints, and variety in mission scenarios. To this end, this paper sheds light on and reviews the work done on each process and on the mission analysis, including classifications, approaches, and examples of separate and cross-layered optimization. The paper drew a roadmap for flight planning employing the mission-based PTR triangle design approach with a proof-of-concept to the PTR joint optimization ideas. The paper serves as an entry point to the interested researchers in the field of UAV systems design.