Can Vehicles Talk and Listen to One Another, and to the Infrastructure? Yes, with Support for Sessions in C-V2X.

Friday 4/1/22 09:32am
Posted By Jim Misener
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Cellular-vehicle-to-everything (C-V2X) is a technology that allows vehicles to communicate directly with one another. It connects vehicle to vehicle (V2V), vehicle to roadside infrastructure (V2I), and potentially vehicle to pedestrians (V2P).

One goal of deploying C-V2X is to enhance safety for all road users, helping to advance the Toward Zero Deaths initiative that aims to eliminate deaths and serious injuries on U.S. roadways. C-V2X does that by exchanging messages. Most of the information broadcast in these exchanges is actionable for the recipient, such as an active safety alert to let someone know they’re about to run a red light.

But there’s more to it. Qualcomm Technologies Inc.’s C-V2X-equipped vehicles and roadside units (RSUs) are also capable of conversing.

Support for sessions in C-V2X

A vehicle and an RSU can send each other a lot of useful information that promotes safety. However, they must first trust each other, and C-V2X supports the kinds of sessions for establishing that trust.

For example, the certificates needed to authenticate V2V, V2I, and V2P safety messages trace to a protected root of trust. To obtain those certificates, a C-V2X-equipped vehicle that also has a 4G or 5G radio can send a request over cellular networks. But some road owner-operators prefer to replenish certificates from the RSU and a connection at 5.9 GHz. Therefore, with C-V2X there is an alternative: the vehicle can obtain the certificates by conversing directly with the Internet-connected RSU, using a C-V2X session to negotiate the transaction.

As another example, imagine a vehicle that can collect local probe data, such as information on stop-and-go traffic in the lane it has just traveled. An RSU can request this information, which the vehicle can send using standardized message sets. Having the ability to send and receive this information directly through RSUs, using a C-V2Xsession instead of the cellular network, is an essential path for maximizing the effectiveness of today’s active safety applications. C-V2X allows these conversations.

The role of Qualcomm Technologies, Inc. (QTI)

Qualcomm Technologies’ latest C-V2X chipsets already support these secure communications and sessions through wireless sidelink IP version 6 (also called global IPv6 addressing). And, some early devices being deployed in the U.S. can use link-local addressing to achieve similar functionality with some simple modifications in the application software.

To allow all vehicles using our C-V2X onboard units (OBUs) to access Internet application servers through an RSU, Qualcomm Technologies is providing detailed technical documentation and open-source samples. Road operators and automakers can use them to update their existing units.

Qualcomm Technologies is dedicated to working with the transportation community to support safer roads globally. Learn more about our automotive solutions at