# A Performance-Based Airspace Model for Unmanned Aircraft Systems Traffic Management
## 5 Conclusions and Future Research  
The envisioned spread of Urban Air Mobility (UAM) and low altitude UAS services prompts the need to introduce new airspace structures and classifications, particularly in dense urban and suburban areas. This paper presented a new approach to the design of urban airspace based on the combined performance of avionics systems and supporting traffic management infrastructure. In particular, the airspace was discretized into fundamental volume elements (elementary cells) as a function of the Communication, Navigation and Surveillance (CNS) systems performance and a dedicated study was presented exploring the relevance of Global Navigation Satellite System (GNSS) performance to both aircraft navigation and Automatic Dependent Surveillance-Broadcast (ADS-B) cooperative surveillance. Additionally, the paper introduced a methodology to determine the optimal sector dimension as a combination of multiple elementary cells, considering on one hand the traffic complexity, and on the other hand the overheads due to sector handovers. The proposed airspace structuring methodology was then verified in two simulation case studies that utilized representative GNSS measurements gathered from an urban measurement campaign. The case studies showed that the performance-based discretization is numerically feasible and, based on the conservative assumptions and the principles adopted, it promotes operational safety while at the same time maximising the efficiency of airspace resource exploitation, particularly by efficiently accommodating unmanned aircraft with diverse avionics equipment. It is expected that the progressive transition from an RNP-based formulation to a full CNS performance-based approach, including other parameters from the communication system (e.g., signal to noise ratio, bit error rate, etc.), will offer significant benefits in all planning and operational UTM timeframes from strategic offline to tactical online scenarios. In this perspective, the proposed airspace sectorisation concept will contribute significantly to enhance decision support for demand-capacity balancing and dynamic airspace management in low-level ATM operations. Future work will also investigate the synergies between the proposed concept and adaptive/cognitive forms of Human-Machine Interfaces and Interactions (HMI\({}^{2}\)) to enhance the cooperation between human operators and the increasingly automated (and trusted autonomous) system functions required in the UTM operational context. Application of directional volume inflations (as opposed to the conservative omnidirectional inflations adopted in this paper) to account for factors such as aircraft relative dynamics, weather effects, wake turbulence and downwash will also be investigated.  
Conceptualization, N.P., S.B., A.G. and R.S.; Methodology, N.P, S.B, A.G., A.S. and Y.X.; Software, N.P., S.B. and A.G.; Formal Analysis, N.P. and S.B.; Investigation, R.S., N.P., S.B., A.S. and Y.X.; Resources, S.B. and A.G.; Writing-Original Draft Preparation, N.P, S.B, A.S. and Y.X.; Writing-Review & Editing, A.G., R.S. and T.K.; Supervision, R.S. and A.G.; Project Administration, R.S. and T.K. All authors have read and agreed to the published version of the manuscript.  
The authors wish to thank and acknowledge Thales Australia--Airspace Mobility Solutions for supporting this work under the collaborative research project RE-02544-0200315666. The authors also wish to thank and acknowledge the Australian Cooperative Research Centre on Intelligent Mobility and Vehicle Evolutions (iMOVE CRC) for supporting this work as part of the iMOVE industry-based student projects initiative.  
The authors declare no conflict of interest.