# Software-Defined Vehicular Cloud Networks: Architecture, Applications and Virtual Machine Migration
## 3 The Architecture of Software-Defined Vehicular Cloud
### The Components of SDVC
#### 3.1.2 V2X Cloud in SDVC  
The V2X access cloud includes vehicles and road users. Moreover, SDVC includes infrastructures to infrastructure links, a vehicle to network links, a vehicle to infrastructure links, a vehicle to vehicle links, vehicle to network links, and vehicle to vulnerable road users links. In addition, the V2X access cloud includes vehicles and UE-type RSU, which are considered as SDN devices similar to data planes in the SDN concept. Functions of the SDN devices in the V2X cloud are concentrated on data collection, forwarding, queuing, and sending data into the MEC micro-data center. Therefore, the vehicle-enabled V2X could be built with the following functional modules:  
* Information collection module of vehicles: The information collection module includes different types of sensors (safety and diagnostics sensors) in the vehicles. Availability of these sensors in the vehicle allows the information such as speed and revolutions per minute (RPM). Furthermore, surrounding or adjacent vehicles, pedestrians on the roads information, and weather conditions are collected for SDVC.
* V2X application module of vehicle: This module is considered to act as the traditional On-Board Unit (OBU) integrated in-vehicle wireless communication interface. It allows broadcasting information such as geo-messaging to MEC micro-data center to notify when the vehicles enter or exit certain regions of the roads. The V2X application of the vehicle will receive the message corresponding to the routing rules defined by the SDVC's SDN OpenFlow controller. Moreover, the V2X application module receives and stores the current position information of the vehicle provided through the global position system (GPS) [37].
* Communication capable 3 GPP LTE UE module of vehicle: The communication module includes the V2I, V2V, and V2N communications modules. V2I, V2V, and V2N communications should comply with both the requirements of LTE and service requirements for cloud-based V2X services. The V2V communication requires the communication module of a vehicle to get an exact subscription and authorization from a network operator. The communication module of the vehicle allows V2V applications to transmit no safety messages such as locations. The V2V communication module provides direct communication (LTE PC5) as it is defined under Release 12's proximity services communications (\"ProSe\") function [38]. Radio communication interference caused by direct interoperability communication between the vehicle's communication interface limits the transport of information. The vehicle should use either cellular infrastructure (LTE-Uu) supporting V2X communication or DSRC depending on C-ITS safety messages.  
Enhanced node BS (eNBs) type RSU deployment provides cellular communications to vehicles. In SDVC, UE-type RSU transmits wireless signals from or to the communication module of the vehicle through LTE-Uu. The communication module of UE-type RSU sends unicast messages to a MEC computing server. Furthermore, the information provided by the central cloud are distributed to all the vehicles into the relevant geographical area through either UE-type RSU or evolved Multimedia Broadcast Multicast Service (eMBMS).