## 5 Discussion  
The results obtained in the six experiments show the behavior of LoRa transmission (with respect to the percentage of packets received and the RSSI level) is quite variable when the distance, and the number of LoRa devices are scaled, using the same values for SF, BW and CR. It was not possible to determine a setting that had a constant behavior for all the tested distances and for different number of nodes. However, one setting had an adequate behavior in most of the experiments, mainly in the final three: SF = 9, BW = 250 kHz, CR = 4/5, where the percentage of packets received was between 87%, 81%, and 75% the RSSI level was acceptable (between \(-\)95 and \(-\)103 dBm) and the maximum distance reached was adequate (between 848 and 820 m). This setting is important, because it scaled well in terms of distance, number of vehicles and vehicle speed in most of the six performed experiments (except for Experiment 3). Results obtained in each of the experiments are relevant, because they identify some suitable transmission settings of LoRa for each of the types of experiments, in addition to presenting the ranges of RSSI and percentage of packets received. This information can be useful for implementing services using this communication technology. The detailed information of the results obtained in each of the settings of each of the experiments can be consulted with the authors to collaborate in related researches. The linear relationship identified between the RSSI level and the BW in Experiment 2 may not be very useful for a mobility service such as transit vehicle tracking service, however for other types of services in which LoRa is used at a distance of approximately 20 m between devices and gateway, this relationship may be relevant, being able to predict (with some accuracy, approximately 70%) an expected RSSI value for a given BW. Although in the experiments with variable distance (Experiments 4, 5, and 6) the maximum distance reached by a packet received by the gateway was relatively low, this may be mainly due to the fact to the interruption of LoS. It was shown that direct LoS between devices has a strong influence in the operation of LoRa. In the process of searching for suitable locations for the gateway and the route of the vehicles, several options were tested. When there was no adequate LoS (too many obstacles), the LoRa gateway stopped receiving packets. The best distance reached in experiments 4\(-\)6 was 890 m. This can be improved by placing the gateway in a high enough place, which was not possible in the used test environments. However, with a linear distance to the gateway of 890 m, a vehicle could make a route of several kilometers around the gateway (with an adequate LoS), which is positive regarding the transmission range in the proposed service. The decrease on the percentage of packets received when the number of nodes was increased from 1 to 3, or from 1 to 4, was approximately between 10% and 20%. To improve this percentage, future work could be done to configure the LoRa devices (operating at the same time) with different SFs, to minimize the probability of packet collisions. Another option that can improve the percentage of received packets is the dynamic and automatic variation of the parameters during transmission, using network protocols such as LoRaWAN or algorithms that allow such variation. A total of 6% less packets were received in the increased speed scenario. This could be considered manageable, because transit vehicles in the evaluated context reach this speed range (20-60 Km) in very few sections of their route and during short periods of the day.