# LoRa Architecture for V2X Communication: An Experimental Evaluation with Vehicles on the Move
## 2 Wireless Technologies and the Challenges for V2X Communication  
Different wireless technologies have been developed and standardize over the years for internet of things (IoT) applications like vehicular communications. These standards are regulated and maintained by organizations like IEEE, the Internet Engineering Task Force (IETF), ITU, 3 GPP, Zigbee, and the LoRa Alliance [21]. These protocols are developed in different frequency bands and transmission distances. The most popular IoT wireless technologies are Zigbee, LoRaWAN, LTE-M, Z-wave, NB-IoT, BLE, IEEE 502.15.4, IEEE 802.11 ah, and IEEE 802.11 af [22; 23]. The Zigbee standard is based on IEEE 802.15.4 for low power and low bandwidth applications. Zigbee is used in applications that involve a standalone wireless ad-hoc network with limited data transmission rate. It supports a wireless mesh network with a bandwidth ranging from 20-250 kbps depending on the transmission distances [24]. It works with the industrial, scientific, and medical (ISM) band of 2.4 GHz (global), 915 MHz (America), and 868 MHz (Europe) with transmission distances ranging from 10-100 m. This standard is widely used in low proximity monitoring and control as it is popular for its reliability, low power consumption, and cost-effectiveness. It is also used for intelligent transport systems like Embedded Middleware in Mobility Applications (EMMA) project [25]. This project has emphasized the architectural suitability of vehicle to infrastructure communication with Zigbee standard. This project has also considered and compared the performances of Bluetooth 802.15.1 and IEEE 802.11g in vehicular communications. [PERSON] and [PERSON] have considered Zigbee for Intelligent Transport Systems (ITS) in [26] for its low power consumption and rapid deployability. They have also suggested that intra-vehicular wires can be reduced by wireless transmission of the vehicle's sensors information to the Electronic Control Unit (ECU) with Zigbee. Zigbee is also used by [PERSON] in [27] for vehicle tracking localization. [PERSON] et al. have also used the Zigbee standard for V2V communication and vehicle relative positioning [28]. One of the disadvantages of Zigbee is that it cannot handle a high user load as it is based on the Personal Area Network (PAN). Moreover, it has a large data overhead in comparison to LoRa which increases the latency and worsens the time criticality of the applications like V2X [29]. Unlike Zigbee, LoRa is based on wide area networks (WANs) which also operate with low power and low transmission rates. LoRaWAN is maintained by the LoRa Alliance and it operates on the sub-gigahertz ISM band of 433 MHz, 915 MHz (Australia and America), and 868 MHz (Europe) [30]. LoRaWAN offers ubiquitous connectivity both in indoor and outdoor applications with a raw maximum data rate of 27 kbps [31]. It has a transmission range of 2-5 km in urban areas whereas the range is extended up to 15 km in a suburban area with direct line-of-sight. There are three types of devices--Class A, Class B, and Class C--which have different capabilities depending on their class [32]. It is popular with long-range applications like agriculture and environmental monitoring [33; 34; 35], healthcare monitoring [36; 37], traffic monitoring [38], localization [39; 40], and various smart city applications [41]. Lora and LoRaWAN have also been vastly used in V2X communication. One of the advantages of LoRa communication is the higher transmission range, versatility, and low energy consumption. It also has some challenges like lower transmission throughput and limited bandwidth which is really a challenge for handling multiple duplex transmission. Dedicated short-range communications (DSRC) are dedicatedly designed for vehicular communication as the name suggests. In the United States, DSRC is standardized on IEEE 802.11p which is based on IEEE 802.11 [42].