# Review of Communication Technologies for Electric Vehicle Charging Management and Coordination
## 7 Communication in EV Charging Coordination
### Cellular Technologies in Charging Coordination  
Cellular networks are generally selected for enabling centralized coordination due to their ubiquitous communication range and high reliability of the physical link. Considering LTE as the communication network between a group of charging stations and EV aggregators, the authors in [132] study the effect of communication delay on the performance of EV aggregators. In their simulations, the communication delay is defined as the time from the arrival of a message from the control center to an aggregator until the EV receives the scheduling message. Accordingly, the authors in [132] consider queuing and transmission delays assuming that scheduling and processing delays are negligible. Their results reveal that the communication delay is approximately constant when the number of charging points is less than 300, beyond which the delay encounters an exponential increase as the number of EVSEs increases, and the power system becomes unstable. Thislarge delay in high density scenarios reduces the efficiency of the coordination process and negatively impacts the user's QoE, particularly for users with urgent requirements such as low SoC, high demand, etc. This accordingly motivates the utilization of 5G NR-V2X communications for EV charging coordination. The ultra-low latency, high reliability, and high capacity of this technology provides robust operation in high density scenarios and improves the QoE encountered by the users.  
In addition to the high density operation, large network capacity, and significantly high throughput are other desirable characteristics that motivate the use of NR-V2X for charging coordination. This is because, in an IoEV with intelligent vehicles and extensive data generated from different on-board and off-board sensors, effective coordination of the charging process involves massive V2V, V2I, and I2V data exchange, demanding significantly higher data rates and little delay tolerance. Reliability requirements as high as 99.9% are also desired to guarantee the accuracy of the charging information exchanged between the different network entities and to avoid unfavorable impacts on the energy grid due to inefficient charging coordination [27; 133]. A comprehensive radio interface design based on 5G technologies, named 5 GCar, is proposed in [134; 135] to address these requirements by integrating different technology components to meet the stringent ultra-low latency, ultra-high reliability, and high connection density requirements of V2X communications.  
For DWC systems, charging coordination involves coordinating the activation of charging lanes sections, optimizing the vehicle routes to the nearest charging lanes, and prioritizing low energy vehicles to receive a larger amount of power from the corresponding charging lanes. The authors in [136] discuss wireless dynamic charging in a highway scenario, taking into account the vehicle's motion and battery characteristics while considering V2I communication for information exchange.