# Review of Communication Technologies for Electric Vehicle Charging Management and Coordination
## 2 Vehicular Radio Access Technologies
* **Throughput**: Based on the 2010 US Department of Energy report [26; 32], the throughput required for home EV charging systems can vary between 10 and 100 kbps. Nevertheless, most of the current vehicular applications are bandwidth-hungry and demand a significantly higher data rate [38]. Since the communication link is expected to carry charging-related messages as well as other information in variable-sized packets, the higher the throughput, the more effective the communication link. * **Reliability**: This is a crucial metric for the coordination and management of EV charging services since charging decisions require robust, uninterrupted data exchange with ubiquitous coverage and quality-of-service (QoS) guarantees, i.e., high reliability is required. Reliability is also particularly important for safety-critical applications and is hence an important factor in the selection of effective charge-enabling vehicular communication networks. The reliability of the communication channel is also an important factor in vehicular communications due to the expected channel fading and other impairments during vehicular mobility [39]. * **Security and Privacy**: One of the most critical requirements in vehicular communications is the security and privacy of the information shared between the EVs and the other network entities. An end-to-end secure data transfer is essential to provide protection against unauthorized transactions and other potential attacks [40; 41; 42; 43]. In addition, privacy-sensitive data, such as EV location, EV ID, and payment information, must be protected against potential misuse by other network entities [44]. With these performance requirements in mind, different radio access technologies (RATs) are proposed in the literature for wireless vehicular communications, including cellular networks (3G, 4G, and 5G), direct short-range communication (DSRC), and Wi-Fi [45]. A general comparison between the specifications of these RATs is reported in Table 1. \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Feature** & **DSRC** & **3G-UMTS** & **4G-LTE** & **5G * & **Wi-Fi** \\  & & & & & **Sub-6 GHz** & \\ \hline Coverage & 1 km & 10 km & 30 km & 1–2 km & 100 m \\ Max. throughput & 3–27 Mbps & 2 Mbps & 300 Mbps ** & 2.4 Gbps ** & 6–54 Mbps \\ Mobility support & Medium & High & Very high & Ultra high & Low \\ Bandwidth & 10 MHz & 5 MHz & 1.4–20 MHz & 5–100 MHz & 20 MHz \\ Spectrum & Licensed & Licensed & Licensed & Licensed & Unlicensed \\ \hline \hline \end{tabular}  
* FR1 mid-band. ** assuming 4 \(\times\) 4 MIMO with no carrier aggregation (CA).  
\end{table} 
Table 1: Comparison between some wireless communication technologies for on-the-road vehicular communications [46; 47]. The different RATs presented in Table 1 vary greatly in terms of their throughput and coverage ranges as well as in their support for user mobility, which impacts their utilization in vehicular communications. Accordingly, several comparative studies are reported in the literature, comparing the performance of these technologies in V2V and V2I communications. The authors in [48] study the feasibility of vehicular communications using digital broadcasting, cellular (3G-UMTS), and DSRC technologies, based on coverage and capacity requirements. In their work, the authors illustrate that UMTS and DSRC technologies have extended their capabilities to support V2V and V2I communications, while the digital broadcast technology is shown to be capacity limited and can only accommodate a small number of users. A comparison between different communication technologies is also presented in [24] including cellular, DSRC, FM radio, Wi-Fi, and WiMAX. However, due to the high latency of WiMAX and the limited coverage and capacity of Wi-Fi, the most feasible schemes for vehicular communication are highlighted by the authors in [24] to be cellular technologies and DSRC.