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C-V2X Explained: What Is It and How Does It Work?

Updated: Aug 22, 2023

By: Natasha Taylor


What is C-V2X? Image showing connected cars through wireless communication on the highway

Cellular Vehicle-to-Everything (C-V2X) is a communication technology that allows vehicles to connect with other vehicles, pedestrians, cyclists, and roadside infrastructure.

By connecting these entities, C-V2X allows for the exchange of critical information that can improve road safety and make journeys more efficient by saving time and reducing emissions.

C-V2X communication is enabled through the use of two complementary transmission modes; direct communication (PC5) and network communication (Uu).

It is the combined use of both direct and network communication that makes C-V2X.

An illustration showing direct and network communication between entities on the road

Direct and network communication connect entities on and around the road to enhance safety and efficiency.

Direct communication (PC5) allows entities to communicate with one another without the need for cellular network communication. This method can also be referred to as ‘Sidelink’ communication.

The communication is enabled through the use of On-Board Units (OBUs) used by drivers and vulnerable road users such as pedestrians and cyclists, and Roadside Units (RSUs) attached to infrastructure, for example, traffic lights and signal poles.

Network communication (Uu), also called indirect communication, makes use of existing cellular networks to provide drivers with information about traffic and road conditions.

When network communication is utilized, information is transmitted from a vehicle up to a third-party telecommunication satellite and then sent back down to other road entities, and vice versa. This process is known as ‘uplink’ and ‘downlink’ communication.

The use of the two complementary transmission modes therefore provides short-range communication through vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P) transmission, and longer-range communication through the addition of vehicle-to-network (V2N) transmission.

Standardized in 2017, C-V2X is defined by 3GPP (3rd Generation Partnership Project) standards. As a worldwide Standardization Development Organization (SDO), 3GPP develops standards for the various generations of mobile networks.

Due to this, C-V2X will continue to evolve under new standards developed and set by 3GPP.

The initial standardization of C-V2X in 2017 is referred to as LTE-V2X. It was formalized in Release 14 and finalized in Release 15.

Through LTE-V2X the use of both direct and mobile communication enables the delivery of advanced and automated use cases, in addition to supplementary support for the delivery of basic safety use cases.

Specific examples of advanced use cases include High Definition Sensor Sharing, Speed Harmonization, Vehicle Platooning, and Cooperative Lane Merging.

Through the evolution of 5G within 3GPP standards and technology, 5G-V2X is expected to provide higher throughput, lower latency, and increased reliability for both existing and future V2X use cases.

With the use of both transmission modes, the most appropriate and efficient communication method can be allocated depending on the specific use case.

For example, fatal safety messages can be delivered through direct communication, while other less urgent messages can be delivered through indirect communication.

With the addition of cellular network usage, users will benefit from commercial services from third parties. This can include in-vehicle entertainment or remote diagnostics delivered by a network provider at an additional cost.



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