# LoRa Architecture for V2X Communication: An Experimental Evaluation with Vehicles on the Move
)1 College of Science and Engineering, Central Michigan University, Mount Pleasant, MI 48859, USA; haque1k@cmich. In V2X, vehicles share their instantaneous information such as their speed, coordinates, and acceleration to other vehicles and necessary infrastructure [7]. A few of the major challenges of V2X communication include time criticality, latency intolerance, security, and privacy [8; 9; 10]. Building a reliable architecture and choosing the right communication technology is vital for addressing these challenges. In V2X communication, the vehicles have an embedded system containing necessary sensors and processing units which is termed as on-board unit (OBU). OBUs are also equipped with a wireless transceiver to communicate wirelessly with other vehicles and infrastructure. On the other hand, the surrounding infrastructures are equipped with a processing unit and transceiver, combinedly termed as road side unit (RSU), capable of communicating with the vehicles. Both OBU and RSU have the capability of communicating with each other. All the vehicles carrying OBU collect the necessary data with the integrated sensors and send the data to the processing unit of the OBU. The processing unit parses, refines, and stabilize the received data and make the data packet ready to be sent by the transceiver. The vehicles and infrastructure which will receive this data are predefined by the system architecture. Upon receiving the data from other vehicles, they can warn themselves of accidents and suggest directions if necessary. Similarly, the receiving RSUs also warn and suggest a direction to the other vehicles depending on the data received by them. One of the fundamental challenges of V2X communication is the vehicle mobility along the road and the dynamic environment. While moving along the roads, the vehicles need to perform data handover from one RSU to another RSU. The higher speed of the vehicles makes this challenging. Moreover, vehicular density and other road side infrastructures play an important role in smooth data handover, as they might affect the link quality of the communication by obstructing the direct line of sight. V2X communication aims to offer different intelligent transportation system (ITS) applications, including accident avoidance and autonomous driving, so another challenge of V2X communication is how to ensure real-time data transmission. Thus, the transmission latency should be given higher priority in a robust and reliable V2X communication architecture. Another concern regarding implementing V2X architecture is that most of the legacy vehicles do not have embedded circuitry in their ECU to facilitate V2X communication, so the modularity of the OBU and RSU is another challenge that needs to be addressed to provide V2X capability to the legacy vehicles. This is work is motivated by these challenges in reliable V2X communication. Extensive research has been going on with the suitability of different wireless technologies for V2X communication. Few researchers have suggested medium and long-range low-power wireless  
Figure 1: Constituents of V2X communication. technologies like long range (LoRa) communication, Zigbee, BLE, and WIFI [11; 12; 13] On the other hand, researchers have adopted wireless technologies such as the Third Generation Partnership Project (3 GPP) LTE and 5G new radio (NR), Wi-Max, IEEE 802.11p, and IEEE 802.16e [14; 15]. There are different challenges associated with using these technologies also. Communication latency, transmission range, transmission throughput, and power consumption are a few important challenges that need to be considered while choosing any of those technologies for V2X [16]. WiMAX towers and 4G cell towers have a transmission range of around 50 km and 16 km, respectively [17]. However, these technologies are energy-hungry, and their frequency bands are not dedicated to V2X communication.