# A LoRaWAN Architecture for Communications in Areas without Coverage: Design and Pilot Trials
## 2 Related Work  
This section relates different research to the main lines of investigation in this work. This work is innovative because it employs wireless networking technology in a field for which it is not intended. For this reason, the works mentioned below focus on only one of the lines of research. These lines of research consist of LoRaWAN technology and wireless networks used in mountainous areas or areas without cellular coverage. [PERSON] et al. [4] proposed establishing multi-hop or peer-to-peer communication to increase the coverage of LoRaWAN networks. They set up a network of interconnected peer-to-peer gateways to relay devices in urban areas. This work focused on a solution for monitoring smart water grids (SWGs). Different routing protocols in the mesh network were presented in the paper. The main problem of this type of network is its high energy consumption, as highlighted by the authors. In our work, a network with mobility using  
Figure 1: Areas without mobile coverage in _“Sierra Morena”_ (Andujar) and _“Sierra Nevada”_ (Granada). The green areas correspond to areas where the intensity of coverage is high, the purple areas correspond to areas of medium intensity, and the unmarked areas are shaded areas. LoRaWAN is proposed. This network is centralized, with a wide coverage range and low energy cost. Therefore, users can move in a similar way. The solution proposed by [PERSON] et al. was intended for monitoring in urban areas. The network will transmit messaging and positioning asynchronously. [PERSON] et al. [5] proposed a LoRaWAN-based system for monitoring smart sanitation systems in urban environments. In this paper, they described the system that detects the status of manhole covers and alerts the cloud server in real time. This server notifies the responsible person to solve the problem as soon as possible. LoRaWAN is also used in our work. Instead of monitoring, our solution proposes messaging and user tracking services. Similar to the work of [PERSON] et al., the information is stored on servers and used to improve the system. [PERSON] et al. [6] presented signal quality analysis for an IoT disaster solution using LoRaWAN. The work proposed the deployment of a LoRaWAN network with multiple gateways and validation of the system by a driving test in an urban area. The results showed that the average RSSI was \(-100\) dBm, with the RSSI varying between \(-24\) dBm and \(-131\) dBm, while the SNR varied between \(-24\) dBm and \(13\) dBm. In our work, we only tested the system using a gateway. Validation was performed in three environments: urban, rural and natural). The results obtained in our analysis are similar to the one presented by [PERSON] et al. [PERSON] et al. [7] investigated how LoRaWAN networks are affected in their packet transmission performance in various scenarios. Their work presents a detailed study of the packet loss rate using measurements obtained over eight months in Shanghai. In addition, the study includes an analysis of the circumstances leading to data packet losses. The analysis employed in our work considers the packet loss circumstances of the study by [PERSON] et al. In addition, we focused on analysis of the signal strength. For this reason, it is necessary that the transmissions arrive correctly at the receiver. [PERSON] et al. [8] proposed a network architecture that integrates a long-range linear network using LoRa. This linear network consists of a multi-hop network within a larger LoRaWAN network structure. The linear network elements act as data relays. They collect the LoRa-modulated packets and encapsulate them within the LoRaWAN network until they reach the application server. The operation of the intermediate nodes is controlled by an ad hoc routing protocol that aims to reduce power consumption and increase the lifetime of the system. On the other hand, the nodes are synchronized to reduce packet losses. The results showed that the proposed configuration was robust and guaranteed a long uptime. The proposal seems interesting.