Jun 3, 2021
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For nearly 20 years, stakeholders to the U.S. Department of Transportation (USDOT), infrastructure owner-operators (IOOs), automakers, equipment vendors, and other transportation safety advocates have been moving toward a connected vehicle environment to create safer, more intelligent transportation systems. Now is the time to take our lessons learned from dedicated short-range communication (DSRC) and embrace the opportunity to roll out cellular vehicle-to-everything (C-V2X) technology, moving the transportation industry toward active safety today, while paving the way for autonomy and more efficient mobility in the future.
The Federal Communication Commission’s (FCC) decision to transition from DSRC to C-V2X for V2X communication in the U.S. may have left many in the transportation industry with some open questions and concerns. Many of these are addressed below, with the hope of facilitating the realization of a future with safer transportation.
With DSRC being phased out, what are the options?
While there are various options for transitioning from DSRC to C-V2X, the ideal path is to be direct and decisive. For example, staying with DSRC and moving all existing equipment to channel 180 not only adds capital costs but also incurs a cost in experience. The applications in the end are the same, but the radios are different. Given that the at-scale rollout and deployment of V2X will be C-V2X, the time to start is now. Today is the window of opportunity to begin deploying use cases supported by C-V2X technology.
Another consideration is the added value of 4G and 5G cellular networks. When V2X was first contemplated, the smartphone and extensive mobile broadband networks and resulting services did not exist. To realize the synergy between direct communications for near real-time vehicle safety applications and the network for a host of other applications and services, safety and mobility should be thought of as an end-to-end proposition.
With studies showing improved range, are fewer C-V2X units needed?
Not necessarily. V2X technologies are designed to work at intersections and highways. Because of its link advantage, studies and trials have shown that C-V2X will deliver messages more reliably than DSRC, even with constrained lines-of-sights and shorter range at intersections. Higher reliability with C-V2X will also be advantageous for highway deployments, which generally benefit from increased range. It’s important to note that neither DSRC nor C-V2X were designed to be more than hot spots, with roadside units intended to cover a finite range at safety-critical locations. Ubiquitous coverage, while possible, would be a costly way of addressing safety. Applications that require broad coverage are generally better suited for 4G and 5G networks.
Will C-V2X units from different vendors be compatible?
- OmniAir Consortium is offering a C-V2X certification program, preceded by a series of plugfests to build upon experience from DSRC and segue into C-V2X-specific interoperability and performance tests and certification.
- With USDOT funding, the ITE has started the RSU Standardization project to create a technology-neutral hardware standard for roadside units (RSUs).
- Preceding this, NEMA has developed a technology-neutral RSU standard called NEMA TS10.
- The ITE is also leading the multi-SDO Connected Intersections project to produce documented guidance that will help ensure consistent and uniform RSU deployments for “day 1” red light violation warning, a comprehensive effort and will likely be extensible to other early C-V2X applications.
Will current applications using DSRC need to be modified?
Although the messages and underlying logic in the application won’t change when moving to C-V2X, the mechanics of how messages are exchanged will require further straightforward modifications. Prioritizing applications will be an essential part of the planning process, and SAE J3161 provides rules to give local implementations guidance in how application priority is affected, as additional messages must have minimal impact on V2V and key V2I safety messages. To begin, SAE J3161 recognizes and gives structure to how C-V2X accesses one 20 MHz channel. This is good news – the imminent deployment of C-V2X addresses the long-existing reality that OEMs are not likely to implement two V2X radios. DSRC’s multi-channel operation with a control channel would have needed two radios, one dedicated to channel 172 and V2V, and another for key V2I safety messages. This is not the case with C-V2X, as radio resources can be prioritized for certain messages within one device operating in a single wide channel.
Because C-V2X is based on LTE technology, will C-V2X communications be sent over broadband cellular networks?
Not necessarily. Although C-V2X is based on 4G LTE technology, the international specifications outlined by the 3rd Generation Partnership Project (3GPP) for operating C-V2X in the 5.9 GHz band uniquely target short-range communication. Designed to provide direct broadcast communications between vehicles, infrastructure, and eventually pedestrians without relying on cellular networks, today’s C-V2X deployments are intended to meet “day 1” V2X services. Because Qualcomm Technologies solutions such as the SA415M and SA515M give access to wide area networks while C-V2X provides short range direct broadcast communications, C-V2X and 4G and 5G networks can operate as complementary technologies. This is key because it allows the C-V2X system to deliver safety and mobility applications and services.
How will 5G impact C-V2X deployments?
5G V2X – a future version of C-V2X technology that has been standardized in 3GPP starting with Rel-16 – provides direct communication (sidelink) for automated vehicle applications. 5G V2X also provides increased situational awareness though richer sensor sharing and groupcast, allowing for use cases such as coordinated driving and real-time infrastructure updates. Services using complementary 5G networks will add low latency enhanced mobile broadcasts to the suite of possibilities. The takeaway is that C-V2X and 5G V2X are in fact additive. C-V2X will be able to support active safety use cases with direct communication, and 5G V2X will be able to further support connected and automated vehicles.
How is the auto industry responding to news of the C-V2X transition?
The automotive community has shown strong interest in deploying C-V2X technology. In the U.S., Ford has announced its intent to equip a portion of its vehicles with C-V2X in 2022 given regulatory certainty, and other automakers are expected to follow. In other global regions – and China in particular – C-V2X is being deployed by many global and Chinese automotive companies. To prepare for V2X production vehicles hitting roads in the U.S., the USDOT and ITE started developing and publishing guidance for Connected Intersections, building on the CAT Coalition’s efforts to provide documented best practices for implementing C-V2X technology.
Where can C-V2X roadside units (RSUs) be purchased?
The 5G Automotive Association (5GAA) has compiled a global list of commercial devices, which can be found here. You can also visit Qualcomm.com/Automotive for more information on purchasing equipment using our C-V2X technology.