# An OCARI-Based Wireless Sensor Network for Heat Measurements during Outdoor Fire Experiments
## 6 Conclusions  
The study presented a solution to overcome the limitations of WSN for heat measurements during outdoor fires and specifically for the ones observed with the Zigbee communication protocol [6]. The advantages of using an OCARI-WSN for this type of applications include cost compression due to wire suppression as the modularity and flexibility of the measurement system in an open-source WSN. During the detailed presentation of the WSN solution, sensors, and standard datalogger, we discussed the different opportunities ranging from cable heat transducers to voltage amplifiers for interfacing sensors with the WSN node. Subsequently, we evaluated the performance of the OCARI-based WSN for temperature and heat flux measurements. We compared the data recorded on the wireless system to the ones gained on a standard wired dataslogger during a series of fire experiments in the open. This led to a more compact and lower energy-consuming solution for a given financial cost, and the results exhibited a convenient recording of the temperature signal with the wireless system, despite a significantly lower sampling frequency when compared with that of the wired one. Specifically, the data are conveniently timestamped in the OCARI version of the solution, and this is in contrast to the Zigbee one in Reference [6]. Differences between wired and wireless solutions in temperature signals are due to the error of each transducer and the bit-error and result from the differences in the 12-bit WSN and 16-bit of the wired solution. The recording of radiant heat flux is more subject to caution with sensors calibrated for a high level of heat radiation (up to 200 kW/m\({}^{2}\)). In this case, a solution of signal amplification must be specially designed to reduce the error in the HFM signal when implemented on the OCARI-based WSN. Furthermore, when the limitations are overcome, it allows the deployment of the solution over a larger spanned area and involves a larger number of nodes. Thus, it is necessary to investigate the parametrisation of a large network with respect to the time interval for sending/receiving messages, data packet generation rate, and output power level for transmission to scale the possible congestion of the communication channel [26]. Under the aforementioned conditions, the optimisation of the algorithm to reduce delay and energy consumption could constitute a problematic question due to intense traffic near the CPAN (sink) node [28]. At the end, another outlook of this work is the following: The lower energy consumption skill of the OCARI-based solution can probably also serve to break another limitation observed with Zigbee, i.e., performing long-term measurements because of its energy consumption. Let us recall as a conclusion that except Reference [6], the literature does not report on Zigbee-based WSN systems able to perform fire measurements. The list [7; 8; 9; 10; 11] refers merely to detection. The contribution of each author can be described according to the following statement: conceptualization, T.C., E.I. and X.S. ; methodology, F.M. and X.S. ; software, T.C., E.I. ; validation, T.C., E.I., F.M. and X.S. ; formal analysis, F.M. and X.S. ; investigation, T.C., F.M. and X.S. ; resources, T.D. ; data curation, X.S. ; writing-original draft preparation, T.C., E.I., F.M., T.D.and X.S. ; writing-review and editing, N.B. and X.S. ; visualization, E.I. and X.S. ; project administration, X.S. ; funding acquisition, T.D., N.B. and X.S. The study is financially supported by the Research Contract 2015-021 with Electricite De France--Systemes Energeticus Insulaires (2015-2017). The authors thank [PERSON] and his entire technical team for their helpful contribution to the tests. The tests were performed on the military ground of the N5 Basecamp of the French Civil Safety Department (Securite Civile) based in Corte, Northern Corsica, France. The authors declare no conflict of interest.