By: Natasha Taylor
Both DSRC and C-V2X share the same fundamental goal to enhance road safety and make journeys more efficient for road users
Both technologies facilitate low-latency communication exchanges between vehicles, roadside infrastructure and pedestrians using direct communication
Both technologies use the 5.9GHz frequency band to send wireless short range communication
C-V2X makes use of cellular networks in its system, in addition to the 5.9GHz frequency band used by the DSRC standard
The DSRC standard only provides short range communication up to 1 km depending on the specific use case, whereas the C-V2X standard provides additional long range communication via networks that extends the range of transmission up to a few kilometers
DSRC and subsequent scenario usage have been well tested over the past two decades by government agencies and private organizations, whereas C-V2X is still in the early stages of development and testing
In recent years, vehicle-to-everything (V2X) technology has emerged as a solution to enable safer, reliable and more efficient road experiences for all users.
The technology that has been developed to do this is Dedicated Short Range Communication (DSRC) and Cellular Vehicle-to-Everything (C-V2X).
The fundamental goal of both wireless technologies is to connect all entities on the road, allowing them to communicate with one another and share critical information regarding the status of each road user, potential hazards, and the condition of the road and traffic flow.
As the automotive industry continues to advance, regions such as the U.S. and China are moving towards a full C-V2X deployment, with the European Union using DSRC (ITS-G5) for now.
Whilst the technologies have the same end goal, what are the key distinctions between them?
Dedicated Short Range Communication (DSRC)
DSRC is an IEEE (Institute of Electrical and Electronics Engineers) 802.11p-based WAVE technology that has been developed from standard Wi-Fi, specifically for use within the automotive and transportation sector.
DSRC uses WLAN technology to establish and create short range communication that allows vehicles to send and receive information.
DSRC was the initial V2X communication standard that the United States Federal Communications Commission (FCC) has been developing for the past two decades.
In Europe the technology is referred to as the ETSI ITS-G5 standard, and has been tailored to meet the requirements and regulations of the European market.
In both regions, the 5.9GHz spectrum band has been dedicated to intelligent transport systems to enable vehicular safety applications and ensure that DSRC communication is not affected by other devices or communications.
Since its standardization in 2010, DSRC has undergone significant testing by both government bodies and private companies through numerous field trials, and provides vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) and vehicle-to-pedestrian (V2P) communication, sent directly between the entities within a range of up to 1km.
An illustration depicting vehicle-to-everything communication with all road entities connected via V2V, V2I and V2P communication.
In these instances, DSRC relies on the use of on-board units in vehicles and roadside units on infrastructure to send and receive rapid short range basic safety messages using SAE J2735 message sets without the need for a third party cellular network.
Both the U.S. and EU have previously attempted to mandate the DSRC standard for full deployment.
In 1999, the US Federal Communications Commission (FCC) allocated a portion of the 5.9GHz band to DSRC. However, a delay in standardization, in addition to the development of C-V2X and concern from regulators and manufacturers regarding a lack of consideration for the alternative, meant that the U.S. moved away from mandating the DSRC standard in 2017.
Similarly, the European Commission had initially planned on mandating the DSRC standard for all member states, but the emergence of C-V2X also meant it shifted its approach. In 2019, the European Commission decided to be technologically-neutral and therefore consider both technologies for cooperative intelligent transport systems (C-ITS).
Cellular Vehicle-to-Everything (C-V2X)
C-V2X, standardized in 2017, is defined by 3GPP standards (LTE-V2X: Release 14 ,15; 5G-V2X: Release 16, 17).
Like the DSRC standard, C-V2X uses the 5.9GHz band to transmit the necessary information to deliver basic safety messages between the entities on the road.
In addition to using the 5.9GHz band, C-V2X also makes use of existing cellular networks, forming vehicle-to-network (V2N) communication alongside V2V, V2I and V2P.
As C-V2X uses both direct (PC5/sidelink) and indirect (Uu/network) communication methods, fatal safety messages can be delivered through direct communication, while other less urgent messages can be delivered through indirect communication. Therefore, the most appropriate and efficient communication method can be allocated depending on the specific use case.
With the addition of cellular network usage, supplementary assistance for safety-related features can be provided, as well as other commercial services from third parties. Leveraging existing LTE and upcoming 5G cellular networks can provide better coverage in rural areas and eliminate the requirement for additional roadside unit deployment.
As 5G networks are developed, 5G-V2X technology will be enabled and will serve as an addition to the current LTE-V2X functionalities. It is expected to provide higher throughput, lower latency, and increased reliability for existing and future V2X use cases.
It will also enable more advanced use cases such as sensor sharing. An example of this could be drivers receiving real-time, high-quality video feeds from cameras on other vehicles allowing them to increase their visibility which could have been limited by blind spots or obstructions.
As a relatively new advancement within vehicle-to-everything technology, C-V2X is subject to development and testing in relation to real life applications to ensure its evolution meets future demands of the auto industry.