# Structured Urban Airspace Capacity Analysis: Four Drone Delivery Cases
## 5 Conclusions  
This work investigated the capacity analysis for the route network-based very low-level urban airspace with regard to the four cases of drone delivery operations. Two different flight planning algorithms were compared for each operation type using the Monte Carlo simulations. From the analysis, the following implications can be made. Firstly, for efficient operation on the same operation type, flight planning should be carefully determined depending on operation factors such as the number of retail points, number of service points, number of sUASs, etc. Secondly, in this study, the FCFS and LCFS flight planning algorithms were used for homogeneous sUASs. For practical operations, however, it is required to consider the airspace users' priorities, i.e., non-cooperative operation cases with heterogeneous sUASs. Further simulation and verification methodologies will be necessary for future studies because decentralised cases are more complex than the centralised instances studied in this research. Finally, such analyses and results could be used for designing airspace structures depending on urban airspace situations and environments. We expect that the results could give the following support to policymakers, urban airspace designers, and regulators: (1) When the stakeholders configure a new structure of the urban airspace, they can utilise the metrics to estimate the capacity according to the situation and environment; (2) it is easy to analyse the entry of new stakeholders by increasing the number of retail points; and (3) it is also available as a test-bed for new algorithms. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multicolumn{2}{c}{\# of sUASs} & \multicolumn{1}{c}{**5**} & \multicolumn{1}{c}{**10**} & \multicolumn{1}{c}{**15**} & \multicolumn{1}{c}{**20**} & \multicolumn{1}{c}{**25**} & \multicolumn{1}{c}{**30**} & \multicolumn{1}{c}{**35**} & \multicolumn{1}{c}{**40**} & \multicolumn{1}{c}{**45**} & \multicolumn{1}{c}{**50**} \\ \hline \multirow{2}{*}{1-to-\(\mathcal{M}\)} & \(M_{mct}\) & 19.3 & 32.0 & 38.8 & 40.3 & 39.6 & 37.6 & 36.3 & 34.7 & 33.4 & 32.2 \\ \cline{2-11}  & \(M_{cnf}\) & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline \multirow{2}{*}{\(\mathcal{M}\)-to-1} & \(M_{mct}\) & \(-10.2\) & \(-21.1\) & \(-32.6\) & \(-45.2\) & \(-59.5\) & \(-68.9\) & \(-73.4\) & \(-76.4\) & \(-79.7\) & \(-86.0\) \\ \cline{2-11}  & \(M_{cnf}\) & \(-\infty\) & \(-\infty\) & \(-45,300.0\) & \(-9475.0\) & \(-3600.0\) & \(-1281.8\) & \(-623.0\) & \(-297.5\) & \(-200.0\) & \(-146.5\) \\ \hline \multirow{2}{*}{\(\mathcal{N}\)-to-\(\mathcal{M}\)} & \(M_{mct}\) & 6.1 & 16.9 & 21.5 & 23.1 & 20.0 & 18.6 & 16.8 & 16.5 & 15.0 & 12.4 \\ \cline{2-11}  & \(M_{cnf}\) & \(-36.3\) & \(-20.6\) & \(-21.3\) & \(-22.8\) & \(-26.3\) & \(-23.3\) & \(-27.5\) & \(-24.4\) & \(-27.4\) & \(-27.3\) \\ \hline \multirow{2}{*}{\(\mathcal{M}\)-to-\(\mathcal{N}\)} & \(M_{mct}\) & \(-15.6\) & \(-28.5\) & \(-46.4\) & \(-54.1\) & \(-59.0\) & \(-58.9\) & \(-51.9\) & \(-43.1\) & \(-34.9\) & \(-28.4\) \\ \cline{2-11}  & \(M_{cnf}\) & \(-178.6\) & \(-181.9\) & \(-181.5\) & \(-131.1\) & \(-70.8\) & \(-51.0\) & \(-22.8\) & \(-7.7\) & 11.7 & 18.2 \\ \hline \end{tabular}
\end{table} 
Table 6: The improvement in \(M_{mct}\) and \(M_{cnf}\) between the FCFS and LCFS algorithms (%). **Author Contributions:** Conceptualization, S.B., H.-S.S. and A.T.; methodology, S.B., H.-S.S. and A.T.; software, S.B. ; validation, H.-S.S. and A.T.; formal analysis, H.-S.S. and A.T.; investigation, S.B., H.-S.S. and A.T.; resources, S.B., H.-S.S. and A.T.; data curation, S.B. ; writing--original draft preparation, S.B. and H.-S.S.; writing--review and editing, H.-S.S.; visualization, S.B. ; supervision, H.-S.S. and A.T.; project administration, H.-S.S.; funding acquisition, H.-S.S. and A.T. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.