V2X communication stands for vehicle to anything communication. The backbone of V2X is based on Wi-Fi and 5G. C-V2X is part of the 3GPP standards, and was first introduced in the 3GPP Rel-14 in June 2017. The first version of C-V2X is based on LTE, and is referenced to as LTE-V2X. NR-V2X will be part of the Rel-16 coming in 2020.
The fundamental idea behind C-V2X is to use two complementary transmission modes:
- Short-range direct communications between vehicles (V2V), between vehicles and infrastructure (V2I), and between vehicles and other road users (V2P), such as bicyclists and pedestrians. C-V2X would in these cases not depend on the cellular networks.
- Long-range network communications (V2N), where the regular mobile networks would provide vehicles with information about road conditions and local traffic.
An introduction to C-V2X from the GSMA can be found here.
C-V2X is intended to improve the road safety in many ways, and to make efficient use of the transport networks and infrastructure. Approx 1.25 million people worldwide die from traffic accidents each year, and 20-50 million suffer non-fatal injuries. As an example the US NHTSA (National Highway Traffic Safety Administration) estimates that up to 80% of non-impaired crashes can be eliminated by safety applications enabled by V2V and V2I.
Examples of areas where C-V2X can make a difference are:
- Collision avoidance: By sharing position, speed and direction vehicles can map out the immediate surroundings and determine and thereby avoid potential collission dangers from other vehicles on the road.
- Platooning: Allowing vehicles to drive much closer together (like a convoy) making better use of road space, saving fuel and increasing goods transportation efficiency.
- Cooperative driving: Have vehicles work together to minimize disruptions due to sudden brakings and lane changes.
- Queue warning: Infrastructure warning vehicles about queues or road works ahead, allowing for speed and road planning adjustments in a timely manner.
- Emergency service support: The ability to warn other road users about emergency or priority vehicles on the road.
- Hazards ahead: Warn about unseen hazards, for example, around a blind corner or under bad road conditions (fog, landscape undulations etc.).
- Automatic road toll collection
- Avoiding vulnerable road users like pedestrians or bicyclists.
V2V - Vehicle-to-Vehicle
In today's vehicles you can already find plenty of sensors (camera, radar, lidar, ultrasonic...) that makes it possible for the vehicle to provide and use information about the surrounding environment. These sensors will be more prevalent and most likely smarter than today in the future's autonomous vehicles. Unfortunately the sensors can only react to what they can detect, and elements like hidden objects and unexpected behaviour from other vehicles can only be handled when they are detected. V2V is intended to allow the vehicles to communicate with each other directly and share information like position, speed and status. Technologies like (Left or Right) Turn Assistant and Intersection Movement Assistant will make use of the V2V functionality to avoid collisions when making a turn into another road or crossing an intersection.
V2I - Vehicle-to-Infrastructure
C-V2I is wireless communication between vehicles (cars, buses, trucks etc) and smart road infrastructure. Examples of smart road infrastructure are smart traffic lights and smart parking. The goal of C-V2I is to improve the road safety and thereby reduce the number of collisions as well as help with the traffic management.
In smart parking the parking lot communicates with the vehicle to let the vehicle know which spaces are available. Each parking space is connected, which makes supervision and occupancy tracking easier. Smart parking enables functions like automated vehicle identification and payment, with the ability for any parking control to easily identify meter payment and use data, which can be used to determine rates and timing. Real-time parking space data allows for autonomous vehicles to park the vehicle without human intervention.
Smart Traffic Lights
Smart traffic lights can adapt to road conditions to help enable efficient traffic flow. Normally the traffic lights have set interval times, and very often these times are changed based on pre-determined times of the day, for example, to handle rush hour or when pavement sensors detect a passing vehicle. Smart traffic lights have cameras and sensors, and can detect if there are cars waiting as well as how many cars are waiting in each lane. Through this the traffic light can calculate the most efficient way (time) to clear each side of the street. The smart traffic signals are connected with other traffic signals - nearby or in a full network - to enable maximum traffic efficiency.
This enables an easier flow for emergency and priority vehicles, but can also be used by the connected vehicle to inform about red lights for example.
V2P - Vehicle-to-Pedestrian
In V2P there is a direct communication between a vehicle and one or many pedestrians within close proximity. It can also be communication to other road users like bicyclists, who are considered vulnerable. V2P can warn the pedestrians/bicyclists etc. about an approaching vehicle and the vehicle can get warnings about vulnerable road users. Examples could be when the pedestrians are out of the line-of-sight of the vehicle or when visibility is low (nighttime, rain, snow, fog etc.).
V2N - Vehicle-to-Network
The V2N system connects the vehicle to the cellular infrastructure and the cloud, allowing the vehicle to make use of real-time traffic updates, that can be used for route planning, for example, as well as media streaming as another example. Communication here is between the vehicle and a V2X applications server.