# A LoRaWAN Architecture for Communications in Areas without Coverage: Design and Pilot Trials
## 1 Introduction  
Natural disasters are unanticipated and damaging events. Nowadays, natural disasters are beyond our control and have a great impact on society. Some of the disasters that occur annually are volcanic eruptions, snowstorms, torential rains and floods, as well as fires, mostly forest fires, which have devastated thousands of hectares. These natural disasters require management, monitoring and action by professionals such as the country's security forces, including rescue teams and firefighting teams, among others. These professionals act according to their duty and face extreme conditions in the interest of public safety, but they also act in times of emergency which endanger people or their property. To give a little more context with data, the number of fires reported in Spain in a year is over 500. These fires are usually reported to the Spanish National Center for Tracking and Coordination of Emergencies (CENEM) [1]. Approximately one fifth of these cases happened in the mountain areas of Andalusia, and with regard to civil emergency cases, there were more than 30 active searches for missing people per 100,000 people in Andalusia, as well as almost 1000 rescues performed by the Guardian Civil mountain rescue team in Spain [2, 3]. In addition to the problem of natural disasters, there is also the problem of connectivity for these professionals when their work is carried out in areas where there is no cellular coverage. These areas without coverage are called shadow zones and are found in rural and natural areas where mobile network operators (MNOs) have not deployed their infrastructures, as shown in Figure 1.  
Being aware of acknowledging the occurrence of natural disasters that might lead to emergency situations, joined with the existence of areas without cellular coverage and the lack of solutions to face these connectivity issues, motivated the realization of this work and thus the idea of developing a backup system for radio communications. This system offersan additional enhancement such as connectivity via chat and geolocation. Moreover, this network, called TeamUp, was tested by a civil protection team in _\"Sierra Morena\"_ of Andujar.  
This work is motivated by the need for communication in areas without cellular coverage. There are several alternatives for deploying this type of communication. In this work, LoRaWAN technology is used. This technology is not intended to work on the move, but it offers features such as low energy cost and a low cost for long-range communications. This technology has not been used in previous work for person-to-person communications. For these reasons, the following objectives are covered in this paper:  
* Design a centralized network employing LoRaWAN architecture. This architecture provides end-to-end security and a wide range of coverage.
* Prototype the network with mobility, minimizing energy and economic costs.
* Analyze the data rate required for sending end-to-end network information.
* Conduct an experimental study of the performance of the proposed solution in different real environments: urban, rural and natural.  
This article is structured as follows. The related works are described in Section 2. Section 3 presents an overview of the LoRaWAN technology. The proposed design of the network, called TeamUp, and its operation are described in Section 4. Then, Section 5 provides the hardware and software materials and the experimental set-up for the development of the work. In addition, the results obtained in the experiments are shown and explained. Finally, in Section 6, the theoretical and experimental results obtained are discussed. To conclude, the lines of future work are also depicted.