# LoRa Architecture for V2X Communication: An Experimental Evaluation with Vehicles on the Move
## 3 Related Works in LoRa V2X and Applications
addressed the communication latency and data packet size in their research work of the V2X network with LoRa protocol [12]. This research group proposed a LoRa and LoRaWAN based system which improves the overall performances by reducing latency in V2X communications. This system has four components-end-nodes, gateways, server, and applications. Different sensors remain embedded in the end-nodes which collect data and send them to the things network (TTN) server through gateways. TTN then processes these data and route them for different applications. The system is tested and evaluated with one vehicle and four gateways. This has been tested by sending only five packets every minute, but it doesn't show how many data packets the end-nodes can send in every unit distance, which would have presented the reliability in time-critical applications. Many researchers have also worked on intelligent transportation systems (ITS) with LoRa. [PERSON] et al. designed a communication protocol with LoRa for electric vehicle charging solutions [62]. Though it offers good performances for the vehicle charging architecture, this architecture is not adequate for V2X communication. [PERSON] et al. investigated the software-defined internet of vehicles with LoRa communications in [63]. This work also proposes a laboratory test bench that facilitates simulation and field experiments under different user scenarios. The authors addressed how different nodes communicate among themselves. But the reliability of the network under different speeds and an increasing number of vehicles are ignored in this work. [PERSON] et al. also explored vehicle monitoring platforms with low power-wide area network (LPWAN) technology LoRaWAN [64]. This work designed an end-to-end architecture for vehicle data monitoring with on-board diagnostics II (OBD-II) and a novel IETF compression scheme over LoRaWAN. The LoraWAN server also facilitates data visualization with a web-based dashboard. The system has also been tested on a university campus showing higher reliability and a packet delivery ratio of 95%. Though this work considers the mobility of the vehicles and the dynamic environment of the roads, it doesn't mention how the higher speeds may affect the performance of the system. [PERSON] et al. implemented V2V and V2I communication with BLE and LoRaWAN [65]. This work focuses on the development of a fundamental framework with BLE and LoRaWAN technology. It also addresses some preliminary analyses for different applications of V2X, but mobility issues are not addressed in this work. [PERSON] et al. proposed a vehicle tracking system as a proof of concept with LoRa [66]. This work shows that LoRa has the potential to address the mobility challenges for ITS applications. Moreover, this work has implemented the prototype and performed evaluations with experiments under practical circumstances. As the architecture is primarily designed for the vehicular tracking system, it is not adequate for V2X communication. A few researchers have also worked on drone-based ITS in [38] where they use drones as LoRaWAN access points and design the system for uninterrupted surveillance. But drones have higher chances of failures which may cause network holes making the system vulnerable. These state of the art LoRa V2X architectures have their respective research focus, advantages, and also the drawbacks which are depicted in Table 2.  
The table depicts the focus of the research works including their drawbacks. Most of the research works do not focus on the challenges caused by higher vehicular speeds and the dynamic environment of the roads. The key limitation in all these works is the lack of testing these systems in a real fast-paced scenario which is drastically different than indoor or outdoor testbeds under controlled environments. The higher vehicular speeds make the data handover from one RSU to another or one gateway to another more challenging. This may cause severe packet loss hampering the reliability of the communication.