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5G Moves C-V2X Into the Fast Lane
April 30, 2021 Blog



Authored by: Dylan McGrath, senior industry solutions manager at Keysight Technologies.

5G wireless communications will expand the functionality and use cases for many existing technologies. One prominent example is vehicle-to-everything (V2X) technology, which will enhance automotive safety, save lives, reduce fuel consumption, and enable more efficient vehicle transportation.

Thanks to enhancements contained in the 3rd Generation Partnership Project (3GPP)’s 5G standards, V2X communications based on cellular technology, or C-V2X, will gain significant functionality and achieve much wider deployment.

5G represents a massive opportunity for C-V2X to come into its own because 5G will ultimately be deployed on a massive scale — not just in cell phones, but also in all kinds of products equipped with 5G cellular capability.

This ubiquitous deployment is critical because C-V2X is a technology that becomes more useful with mass deployment. The ability to communicate does not do a car much good, unless there are enough cars and systems on the road that speak the same language.

5G Enhancements

Because 5G features significantly lower latency, greater responsiveness, higher reliability, and wider bandwidths, it enables the near-instantaneous exchange of traffic information, road conditions, location of pedestrians, and all manner of data to make road travel safer.  5G connectivity will be ubiquitous in populated urban areas, with connections available in everything from handsets to Internet of Things (IoT) parking meters, traffic signals, buildings, traffic cameras, buildings, and more.

Many of the enhancements in the 3GPP’s Releases 15, 16, and 17 are related to ultra-reliable low-latency communications (URLLC) —  composed of technologies that improve communications reliability and dramatically reduce latency — which work together to make transmission faster and more reliable. URLLC is necessary to enable many of the most advanced C-V2X features, including support for vehicle platooning, coordinated driving, remote driving, sensor data sharing for collective situational awareness and collision avoidance, and real-time traffic and infrastructure updates.

5G C-V2X enhancements will provide higher throughput, higher reliability, and ultra-low latency,  enabling the evolution of C-V2X to a ubiquitous wireless communications system that connects vehicles, roadside infrastructure, and vulnerable road users such as pedestrians and cyclists to improve safety, energy efficiency, and traffic speed.


Enhancements to sidelink communications technology, which enables direct device-to-device communication, are also a crucial feature for C-V2X, allowing vehicles to share information and other elements of the road system independent of the network. Sidelink enables cars to communicate with one another even when they are in remote areas that lack network infrastructure or cellular service. Sidelink is also an essential precursor for future autonomous driving applications that rely on C-V2X.

Functionality that will be available in the forthcoming Release 17 will support more complex use cases for C-V2X, including vehicle platooning and coordinated driving.

Reliability is Key

Many of the most advanced C-V2X features require near real-time communications with nearby vehicles, infrastructure, and the cloud. For example, blind intersection alerts which enable vehicles in the general proximity of another vehicle approaching a blind intersection to send warning messages notifying the car of something that the driver of that vehicle most likely cannot see, such as a pedestrian about to cross the vehicle’s path.

For a C-V2X alert to avert a tragedy in the above example, the car must receive the signal. If such an alert failed to reach its intended target, it would not only be useless, but the failure of the technology would only compound the sadness of the event.

3GPP Release 15 guarantees highly secure URLLC communications with no more than 1 millisecond (ms) latency, whereas the average reaction time of the human brain to audio stimulus is more than 150 milliseconds. The transmission speed of a URLLC communication is therefore much faster than it takes your mind to react to the sound of a horn honking.

Release 15 also mandates URLLC connection reliability of 99.999 per cent. In other words, 99,999 of 100,000 transmissions make it to the intended target.   The 5G standards implement several quality-of-service components to comply with these stringent targets, including time-sensitive networking, a new frame structure, flexible numerologies, dynamic time division duplex (TDD), and other physical layer procedures for data transmission.

Network engineers typically optimise mobile traffic management protocols for efficiency above all else.  However, URLLC turns that equation on its head, implementing resource-intensive components designed to maximise the transmission speed and reliability at the expense of efficiency.  Included among these brute-force innovations are several redundancy features designed to ensure that transmitted data reaches its destination — virtually at all costs.

Included in this category are techniques such as blind repetition, which entails sending the same packet multiple times in case a given packet is lost or arrives with errors. Frequency diversity — disseminating the same information at different frequencies or with different antennas to increase the odds that its intended target will receive a transmission — is another technique.

In addition to the speed and reliability offered by URLLC, new 3GPP enhancements introduce communications modes beyond broadcasting to enable concepts of C-V2X group casting and unicasting. These communications modes place greater emphasis on exchanging information from vehicle to vehicle and between vehicles and roadside infrastructure and other road users.

Life in the Fast Lane

The evolution of V2X technology has been long and slow. But the emergence of 5G  — which will reach more than 60% of the world’s population within five years — will bring C-V2X technology to the masses, enabling it to finally achieve its promise of improving the safety, speed, and efficiency of automotive travel.