# Vehicular Visible Light Communication for Intersection Management +
## 3 V-VLC Vehicular Communication
### Mesh Cellular Hybrid Structure and Multi-Vehicle Cooperative Localization  
The term \"Intelligent Control System\" refers to any combination of hardware and software, which operates autonomously according to the information received and processed. After processing, it is able to act towards the desired control through rational choices. In this case, it is intended to apply it to the Connected Vehicles (CV) systems. The computing  
Figure 2: V2X optical infrastructure and generated joint footprints in a crossroad (LED array = RGBV color spots). (**a**) Standard intersection. (**b**) Split intersection. and communication workload for CVs may also vary over time and locations, which poses challenges to capacity planning, resource management of computation nodes, and mobility management of the CVs. Thus, a well-designed computing architecture is very important for CV systems. Figure 3a, presents a draft of a mesh cellular hybrid structure that can be used to create a gateway-free system. As illustrated the streetlights are equipped with one of two types of nodes: A \"mesh\" controller that connects with other nodes in its vicinity. These controllers can forward messages to the vehicles (I2V) in the mesh, acting similar to routers nodes in the network. The other one is the \"mesh/cellular\" hybrid controller that is also equipped with a modem provides IP base connectivity to the Intersection Manager (IM) services. These nodes act as border-router and can be used for edge computing [29]. This architecture enables edge computing and device-to-cloud communication (I2 IM) and enables peer-to-peer communication (I2I), to exchange information, by ensuring a secure communication from a street light controller to the edge computer or datacenter, through a neighbor traffic light controller with an active cellular connection and enable peer-to-peer communication, to exchange information between V-VLC ready connected cars (Figure 3b). It performs much of the processing on embedded computing platforms, directly interfacing to sensors and controllers. It supports geo-distribution, local decision making, and real-time load-balancing. Figure 3: (**a**) Mesh and cellular hybrid architecture. (**b**) Communication links. A highly congested traffic scenario will be strongly connected. As exemplified in Figure 4, the vehicle movement along the road can be thought as a queue, where the vehicles arrive at a lane, wait if the lane is congested and then move once the congestion reduces. To determine the delay, the number of vehicles queuing in each cell at the beginning and end of the green time is determined by V2V2I observation, as illustrated in Figure 4. The distance, \(d\), between vehicles can be calculated based on a truncated exponential distribution [30]. For the Intersection Manager crossing coordination (Figure 4a), the vehicle and the IM exchange information through two types of messages, \"request\" (V2I) and \"response\" (I2V). Each driver, approaching the intersection area from each side has previously selected and stays in the appropriate lane for their destination (left turn only or shared by right-turn and through movements). Inside the request distance, an approach \"request\" is sent, using as emitter the headlights. The request message is received and decoded by the receiver in the traffic light facing the lane (local controller) which is interconnected to the Intersection Manager (V2I). The \"request\" contains all the information that is necessary for a vehicle's space-time reservation for its intersection crossing (speeds, and flow directions). IM uses this information to convert it in a sequence of timed rectangular spaces that each assigned vehicle needs to occupy the intersection. The objective is to let the IM knows the position of vehicles inside the environment at each step. An Intersection Manager's acknowledgement is sent from the traffic signal over the facing receiver to the in car application of the head vehicle.