## 6 Conclusions and Outlook  
The LoRa mid-range radiofrequency communication coverage area was spatially mapped in an urban environment and observed to be highly dependent on the building arrangement of the city. In this work, we report using the wave-propagation O-FDTD method combined with Google Maps data to obtain high-resolution simulated RSSI maps. The method reproduces both diffraction and scattering radiation-matter interactions, characteristic of the selected LoRa frequency and distance regime. This is a significant improvement from previous models, which usually consider such effects independently, often either suited for much smaller or much larger distance ranges or not easily adaptable to take complex real-world building maps into account. Also, we report a low-cost method to experimentally determine the binary \"on-off\" signal coverage area by mapping the cityscape time gap between packets and introducing a connection-determining threshold. A spatial overlap of 84% was obtained between the simulated and experimental signal-coverage areas. Furthermore, the deviations at the coverage area margins were far reduced compared to the best-fitting circular area that an average path-loss range model could yield. The simulations hold the advantage of providing highly detailed RSSI maps that display building fingerprints such as signal shadowing or hot spot formations, which would nearly be impossible to access experimentally. Future application of the proposed technique beyond this proof-of-concept demonstration may include the comparison of experimentally measured against O-FDTD simulated quantitative RSSI maps. We conclude that this O-FDTD with spatial mapping is a versatile approach from which a vast set of applications may benefit. We foresee the wide use of this methodology for shorter-range wireless networks, such as Wi-Fi, Zigbee, or Z-wave in closed environments, or well-known LoRa alternatives such as NB-IoT or Sigfox. For indoor applications, besides the selected building wall position, other parameters may be included, such as furniture objects featuring different materials modeled via dedicated dielectric permittivity values, thus further enriching this simulation tool's predictive power. This would provide value to city planners, engineers involved in smart city developments and improving the end-user experience by assuring homogenous signal coverage of information communication technology (ICT) networks. The following are available online at [[https://www.mdpi.com/article/10.3390/s21082717/s1](https://www.mdpi.com/article/10.3390/s21082717/s1)]([https://www.mdpi.com/article/10.3390/s21082717/s1](https://www.mdpi.com/article/10.3390/s21082717/s1)): Computer program O-FDTD simulation toolbox wavebox.m, MATLAB scripts used for data treatment and visualization: importGPX, convertGPXtoXY, importSensor, correlateSensorPos, mapSpreadLine, and example.m script calling the functions and representative data files: example.gpx, temp.txt. Conceptualization, R.M.R.A., H.M. and J.B.N. ; LoRa device development, R.M.R.A., A.V.C. and E.B., H.M.; modeling software, R.M.R.A. ; validation R.M.R.A., A.V.C., H.M and J.B.N. ; formal analysis, R.M.R.A. ; investigation, R.M.R.A. ; data curation, R.M.R.A. ; writing--original draft preparation, R.M.R.A. ; writing--review and editing, A.V.C., H.M and J.B.N. ; visualization, R.M.R.A. and J.B.N. ; supervision, H.M. and J.B.N. ; project administration, H.M. and J.B.N. ; funding acquisition, H.M. and J.B.N. All authors have read and agreed to the published version of the manuscript. This research was funded by ERDF via the project with grant number: 0181 NANOETERS 1 EP, the CCDR-N via the project with grant: number NORTE-01-0145-FEDER-000019, the EC via the FETOPEN-01-2018-2019-2020 program with project grant number: 828841, and the Conselleria de Educacion, Universidade e Formaciono Profesional, grant number ED431B 2018/57 and by Ministerio de Economia, Industria y Competitividad, grant number FIS2017-83762-P.  
Not applicable.