# LPWAN-Based Vehicular Monitoring Platform with a Generic IP Network Interface
## 2 Related Work  
Monitoring vehicles, to locate or manage them, is a field that has recently been widely explored. However, most of the proposed systems are based on short- or medium-range communication technologies, such as IEEE 802.11p [15; 16], cellular-based solutions [17; 18], or even Radio-Frequency Identification (RFID) [19]. These transmission technologies present important drawbacks, related to their limited coverage range. In the case of short-range alternatives, such as the extensively studied IEEE 802.11p protocol, the vehicles need to support each other in order to forward the generated data toward the infrastructure elements, namely road side units (RSU), which give access to these data from the outside world (e.g., by the internet). This fact severely increases the complexity of the network management, as well as its instability due to the difficulties of 802.11p to properly work in  
Figure 1: Concept of the proposal for monitoring vehicles using LPWAN. highly dense scenarios [20]. In turn, the use of cellular-based alternatives (e.g., 4G or the upcoming 5G) has been also used for providing vehicles with seamless connectivity [21]. This technology has been especially exploited in the last ten years for fleet management purposes. However, although the previous approaches present acceptable coverage levels in urban environments [6; 22], they are not able to cover large extensions per base station, especially in rural areas due to the lack of a pre-existent and expensive cellular infrastructure. In turn, the application of LPWAN communication systems for vehicle monitoring may overcome the coverage limitations of the transmission technologies employed so far. Thus, the deployment of LPWAN networks will allow better monitoring of vehicles in remote areas, due to the long distances covered by a single gateway [4]. In fact, some European countries (such as Spain, France, and the Netherlands, among others) are now fully covered by the LPWAN solution called Sigfox [23]. Although LPWAN technologies were not designed for this specific scenario, they present interesting characteristics that make them suitable for employment in vehicular monitoring, such as great communication link budget, resilience to interference, and good performance at low power, while being robust to multi-path propagation fading and the Doppler effect. In fact, some works have evaluated LPWAN-based solutions in different network configurations valid for the vehicular ecosystem, such as single-hop [4; 5], multi-hop [24; 25], or Device-to-Device (D2D) [14] architectures. Thus, works in Refs. [4; 5] presented two different extensive performance evaluations of LoRaWAN in different experimental scenarios, with the aim of exploring the maximum transmission distances reached depending on the environmental conditions. Authors of Ref. [4] found a maximum range of 18 km in rural areas without obstacles. In addition, authors of Ref. [5] also evidenced the robustness of LoRa against the Doppler effect. Authors of Refs. [24; 25] focused on deploying multi-hop uplinks, in order to extend the communication capabilities of end-devices towards the gateway. Concretely, these works studied the optimum network routing organization, with the aim of finding the routes with the lowest energy consumption for the end-devices acting as relays. Observe that this architecture may be also valid for vehicular scenarios, as one vehicle could help another to reach the gateway. Further, considering this network topology, the number of deployed gateways may be reduced with the aim of reducing infrastructure costs. Finally, work in Ref. [14] also explored the application of LoRaWAN in vehicular scenarios, but under the opportunistic/intermittent network paradigm. The attained simulation-based results demonstrated better performance of LoRaWAN, in comparison with WiFi technology, in this type of scenario. This solution may be also valid, together with a multi-hop strategy, in order to transmit delay-tolerant data.