C-V2X Technology

C-V2X is V2X communication technology that is gaining momentum around the world. C-V2X is defined by 3GPP standard based on cellular modem technology which uses PC5 interface in the 5.9 Ghz band to send and receive messages to and from vehicles, motorcycles, and Road Side Units (RSU).

C-V2X technology, includes two communication links: Vehicle to Network (V2N), based on the existing cellular network (Uu) and Vehicles to Vehicle (V2V) direct communication without using the cellular network. It is of utmost importance to note, that all V2V safety use-cases require a direct communication link between road users. Safety-critical V2V messages and cellular V2N infotainment messages have different requirements, for example, real-time vs. non real-time, different security targets, and more. C-V2X, as discussed below, refers solely to the direct communication link (PC5). The separation between the communication devices handling network communication and direct communication, is essential to assure safe and secure vehicle control.

C-V2X was first introduced in 3GPP Release 14 LTE standard in 2017, as an extension of LTE’s Proximity Services (ProSe) used for device to device (D2D) / Ad-hoc direct communication services. The physical layer utilizes the technology (SC-FDMA) and frame structure as in LTE uplink communication.
C-V2X supports two communication modes:
• Mode 3: Network assisted communication. C-V2X communication relies on the cellular network for scheduling and resource management.
• Mode 4: Out-of-coverage/SIM-less operation. C-V2X communication is completely autonomous and independent from cellular network.
All C-V2X deployments are Mode 4 only. Multiple challenges, like who will pay for the scheduling services and data cost and feasibility of scheduling algorithm, should be solved before Mode 3 will be viable, which is unexpected in the foreseeable future.

China, who is taking major strides to be the first to deploy V2X on its roads, has adopted C-V2X as its preferred technology. It is also being seriously considered as the preferred technology by several automakers, some are even promoting it as the only V2X technology.
Autotalks C-V2X capabilities consist of a 3GPP Rel. 14/15 compliant top-performance PC5 modem, with dual antenna and diversity for both transmission and reception. In addition, Autotalks developed an optimized closed-loop remote antenna solution enabling diagnostics and accurate dynamic power setting.
In October 2019, Autotalks successfully showcased its chipset’s conformance to the Chinese C-V2X standard and the Chinese OSCCA security standard in the first-ever large-scale interoperability demonstration of multi-brand C-V2X communication. In early 2020, Autotalks chipset was selected for a mass production C-V2X programs in China.


In May 2020, Autotalks conducted a very interesting field test and study on antenna installation for C-V2X. The field test was documented in a video and the analysis and results can be found in technical report.