# Toward Collaborative Intelligence in IoV Systems: Recent Advances and Open Issues
## 3 Networking Technologies toward Collaborative Intelligence  
Internet of Vehicles is a large system network composed of an intra-vehicle network, an inter-vehicle network, and a vehicle-cloud network for radio communication and information interaction. Through the integration of the three networks, V2X communication can be more seamless, more efficient, and less communication dead zone. However, with the development of the IoT and vehicle-related technologies and the increasing demand for new service applications, more and more devices are being connected or are ready to be connected to the network. This requires the transmission and exchange of a large amount of data to achieve the purpose of sensing, transmission, and application. ITS has been revolutionary to change, and every device has the potential to become an intelligent node in IoV to participate in collaboration. This results in the transmission of large-scale signals and data, which must rely on stable, trusted, low-latency communication technology. At the same time, the diversity of access devices and communication approaches, the high dynamic and mobility of vehicles, and frequent topological changes in IoV pose challenges to V2X communication. Considering CI, networking technologies in IoV are classified from multiple perspectives below:  
* **From the perspective of communicating object** It can be divided into V2V, V2I, V2P, and V2N, such as the urban traffic scene in Figure 2. Through V2V communication, the information of the surrounding vehicles can be obtained in the process of vehicle driving, and the vehicles can also constitute an interactive platform, which is often used to transfer control information or safety information between vehicles. Generally, the time delay requirements are high. V2I allows vehicles to communicate with roadside infrastructure (such as traffic cameras, roadside units, bus stations, traffic lights, and parking lots), and through the roadside infrastructure, vehicles can also obtain information about nearby vehicles and send various real-time information. Usually, the amount of data transmission is large, which is mainly used in real-time information service and vehicle monitoring and management. V2P involves communication between vehicles and mobile devices used by vulnerable traffic groups (such as pedestrians and cyclists). V2P communication can be implemented via Bluetooth or Near Field Communication (NFC) technology, and it is often used to avoid traffic accidents and information services. V2N is the connection and information exchange between vehicle or driver and cloud platform or internet through an access network/core network. After storing and processing the acquired data, various applications and services are provided for vehicle users and management departments [33]. * **From the perspective of communicating range** Communication in IoV can be classified as short-range, medium-range, and long-range communication [34], as shown in Figure 5. Short-range communication technology can be used for in-vehicle device connection or V2P scenarios, including Bluetooth, UWB, ZigBee, etc. At present, Wireless Local Area Network (WLAN) and DSRC are able to provide wireless communication within approximately 300 meters for IoV, which can be used in V2V and V2I scenarios and classified as medium-range communication. Cellular Communication technology enables vehicles to communicate with objects thousands of meters away. Nowadays, there is no one communication method that can meet all the communication needs of IoV. Therefore, how to select and formulate a scheme to ensure the CI between vehicle and vehicle, and vehicle and environment, is a key concern when the above multiple access methods coexist.