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What is V2X communication? Creating connectivity for the autonomous car era

Cars are becoming ever more connected to other cars, to transport infrastructure, to pedestrians, and to datacentres. But which standards will underpin all this 'vehicle to everything' (V2X) communication?
Written by Charles McLellan, Senior Editor

Original article from March 2018 (scroll down for November 2019 update)

Unless you're a hardcore vintage car enthusiast, you'll have noticed that vehicles are becoming increasingly connected, both to each other and to the outside world.

With car operating systems running everything from infotainment to autonomous driving, vehicles are becoming ever more intelligent and less reliant on human operation. Vehicle users stand to benefit from safer, greener, and more efficient journeys thanks to copious sensors and onboard connectivity, while car manufacturers, tech companies, and communications providers have a whole new market to compete in.

V2X, which stands for 'vehicle to everything', is the umbrella term for the car's communication system, where information from sensors and other sources travels via high-bandwidth, low-latency, high-reliability links, paving the way to fully autonomous driving.

There are several components of V2X, including vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-pedestrian (V2P), and vehicle-to-network (V2N) communications. In this multifaceted ecosystem, cars will talk to other cars, to infrastructure such as traffic lights or parking spaces, to smartphone-toting pedestrians, and to datacentres via cellular networks. Different use cases will have different sets of requirements, which the communications system must handle efficiently and cost-effectively.

What kind of transportation experience can we expect in a V2X world? Researchers from Huawei's German Research Center in Munich outlined their vision in a December 2017 paper:


(1) User hails an on-demand car via an app; (2) Vehicle self-drives or is tele-operated to the user, whose personal transportation app connected over the mobile radio network adjusts the car to selected presets; (3) Vehicle searches for the platoon best suited to the user's preferences and performs cooperative maneuvering to join the selected platoon, saving energy by allowing car following at very short gaps; (4) Two-way navigation guides the vehicle around a congested stretch of road; (5) User takes control to exit the highway and drive on a particularly scenic road suggested by the connected navigation system; (6) Vehicle drops the user off at the destination; (7) The vehicle self-drives, either to an automated parking lot (7a) or to a different user (7b).

Image & legend (edited): Use Cases, Requirements, and Design Considerations for 5G V2X (Huawei German Research Center, 2017)

The Huawei researchers noted that: "While this example might seem far into the future, most of the technology needed to enable it (high precision maps, real time traffic information, sensors inside the vehicle such as radars, cameras, ultrasonic, etc.) are either already available or will be in the near future. The most prominent missing component is a high reliability, low latency communications system."

As with any new field of technology, there are competing standards in play for V2X.

IEEE 802.11p

The original V2X standard is based on a Wi-Fi offshoot, IEEE 802.11p (part of the IEEE's WAVE, or Wireless Access for Vehicular Environments program), running in the unlicensed 5.9GHz frequency band. IEEE 802.11p, which was finalised in 2012, underpins Dedicated Short-Range Communications (DSRC) in the US, and ITS-G5 in the European Cooperative Intelligent Transport Systems (C-ITS) initiative.

V2X communication via 802.11p goes beyond line-of-sight-limited sensors such as cameras, radar and LIDAR, and covers V2V and V2I use cases such as collision warnings, speed limit alerts, and electronic parking and toll payments.

Functional characteristics of 802.11p include short range (under 1km), low latency (~2ms) and high reliability -- according to the US Department of Transportation, it "works in high vehicle speed mobility conditions and delivers performance immune to extreme weather conditions (e.g. rain, fog, snow etc.)". Essentially, 802.11p extends a vehicle's ability to 'see' the environment around it, even in adverse weather.

See also: Our autonomous future: How driverless cars will be the first robots we learn to trust (PDF download)

IEEE 802.11p is not dependent on the presence of cellular network coverage, and solutions -- onboard units (OBUs) and road-side units (RSUs) -- are available now from silicon vendors including NXP, Marvell, Renesas Electronics, and Redpine Signals.

Cellular V2X

An up-and-coming alternative to IEEE 802.11p is C-V2X, or Cellular V2X, whose main proponents are the 5G Automotive Association and chipmaker Qualcomm.

Image: Qualcomm

A key advantage of C-V2X is that it has two operational modes which, between them, cover most eventualities. The first is low-latency C-V2X Direct Communications over the PC5 interface on the unlicensed 5.9GHz band, and is designed for active safety messages such as immediate road hazard warnings and other short-range V2V, V2I, and V2P situations. This mode aligns closely with what's offered by the incumbent IEEE 802.11p technology, which also uses the 5.9GHz band.

Image: Qualcomm

The second mode is communications over the Uu interface on the regular licensed-band cellular network, and can handle V2N use cases like infotainment and latency-tolerant safety messages concerning longer-range road hazards or traffic conditions. Because it doesn't use cellular connectivity, IEEE 802.11p can only match this mode by making ad hoc connections to roadside base stations.

The current C-V2X Rel-14 specification -- part of the global 3GPP Rel-14 standard and LTE Advanced Pro -- was finalised in March last year, while Qualcomm's first C-V2X chipset, the 9150, was announced in September and is expected to be available for commercial sampling in the second half of 2018. Qualcomm also introduced a C-V2X Reference Design featuring the 9150 C-V2X chipset with integrated GNSS capability, an application processor running the ITS V2X stack and a Hardware Security Module (HSM). Compared to IEEE 802.11p, C-V2X is several years behind in terms of deployment in the V2X market.

Here are some technical and use case comparisons between 802.11p and current and future C-V2X specifications (from C-V2X supporter Qualcomm):

Image: Qualcomm
Image: Qualcomm

Testing of current C-V2X technology is underway with Ford in the US, with Audi and Groupe PSA in Europe and with SAIC in China. Going forward, the C-V2X roadmap will include 5G NR (New Radio) features such as high throughput, wideband carrier support, and high reliability.

This technological evolution, combined with estimates that 45 percent of the estimated 2.2 billion cellular connections in 2025 will be in the connected car sector, should provide strong arguments in favour of C-V2X over 802.11p as the basis for V2X. However, doubt has been expressed over whether C-V2X will be able to leverage the presence of standard cellular modems in cars due to different safety requirements and technology needs.

Which standard will win?

IEEE 802.11p has the advantage of earlier development and deployment, and therefore incumbency. On the other hand, C-V2X offers arguably better performance, the ability to employ both direct and network-assisted communication, and an evolutionary path to 5G.

Download now: IT leader's guide to the future of autonomous vehicles

This is not just an arcane technology standards debate: the stakes are high, with the incumbent 802.11p still the favourite in many regions. In Europe, this prompted the GSMA to make its position clear in a September 2017 briefing paper:

"The GSMA is concerned that Europe's rollout plans of C-ITS do not take into account the very high potential of C-V2X. The GSMA notes that the European Commission wishes to prevent a fragmented deployment of two different vehicle-to-vehicle communications. It therefore clearly favours the 'incumbent' technology, 802.11p, that forms the radio standard within the C-ITS framework called ITS-G5. The Commission is considering whether to announce a European Delegated Act on C-ITS soon, which would mean that by 2019 any future technology on the market would need to be able to communicate with cars deployed with 802.11p technology over their entire lifetime. This would, effectively, lock-in 802.11p as the central communications V2X technology for decades."

Volkswagen has already thrown its (considerable) weight behind 802.11p, which it will start fitting on selected models from 2019.

It's possible that 802.11p and C-V2X will coalesce in future, combining the strongest points of each technology. Indeed, the researchers at Huawei's German Research Center also expect upcoming technologies such as high-frequency (eg 60GHz), high-bandwidth mmWave and VVLC (Vehicular Visible Light Communication) "to be incorporated in the 5G V2X access network architecture to support specific V2X use cases." This will allow the industry to present regulators with solutions that maximise the benefits for all vehicle users.

Here are some use case requirements considered by the Huawei researchers, and their assessment of the ability of different technologies to support them:

Use Case TypeV2X ModeEnd-to-End LatencyReliabilityData Rate per vehicle (Kbps)Comm. Range
Cooperative Awareness V2V/V2I 100ms-1s 90-95% 5-96 Short to medium
Cooperative Sensing V2V/V2I 3ms-1s 95% 5-25000 Short
Cooperative Maneuver V2V/V2I 3ms-100ms 99% 10-5000 Short to medium
Vulnerable Road User V2P 100ms-1s 95% 5-10 Short
Traffic Efficiency V2N/V2I 1s 90% 10-2000 Long
Teleoperated Driving V2N 5-20ms 99% 25000 Long
Use Case TypeLTE-V2X802.11pmmWaveVVLC
Cooperative Awareness

Emergency Vehicle Warning

Forward Collision Warning







Cooperative Sensing


Sensor sharing









Cooperative Maneuver


High-Density Platooning

Cooperative Adaptive Cruise Control

Cooperative Intersection Control









Vulnerable Road User



Traffic Efficiency ✔︎✔︎


Teleoperated Driving


Tables: Use Cases, Requirements, and Design Considerations for 5G V2X (Huawei German Research Center, 2017)

Update: November 2019

Image: VW

Although the V2X standards debate continues, testing and even production implementation is now underway in some regions. Here's a summary of the state of play as 2019 draws to a close.

As noted in the March 2018 article, there has been much wrangling over which vehicle-to-everything technology — 802.11p-based ITS-G5 or cellular-based C-V2X — should be adopted in Europe. In March 2019, the European Commission put forward legislation (the Delegated Act on C-ITS) favouring the 'incumbent' ITS-G5 over the newer but arguably more future-proof C-V2X, with its evolutionary path to 5G.

This prompted a flurry of activity from the C-V2X-supporting GSMA, including open letters from its director Mats Granryd and a joint missive from the GSMA and ETNO (the association of European Telecommunications Network Operators).

Arguing that 802.11p "is not future-proof, is a standalone technology and cannot be integrated into 4G and 5G networks," Granyrd noted division among member states and auto manufacturers over which technology to choose, and said that starting with 802.11p "will lock out C-V2X from Europe for the foreseeable future, while wasting billions of euros in taxpayers' money on roadside infrastructure investments." There would be major implications for the rollout of 5G in Europe too, Granyrd said, as connected cars are a major 5G use case.

The GSMA/ETNO letter highlighted the proposed legislation's demand for interoperability between 802.11p and future communication infrastructure, noting that "C-V2X cannot 'talk' to 802.11p — "It is like putting a DVD into a VHS player."

Both open letters urged the EU to reject the Commission's proposed legislation, which 21 member states duly did in July, causing Granyrd to comment that "Europe just got back in the connected car race against the US and China. Thousands of lives on the roads and thousands of jobs in our factories will be saved with this cutting-edge technology."

The European legislation is currently being redrafted in preparation for another vote. 

Meanwhile, Volkswagen is pressing ahead with its 802.11p-based Car2X system, in partnership with Siemens, and has conducted field tests in Wolfsburg, Braunschweig and Frankfurt in Germany. On the competing C-V2X standard, Thomas Biehle, Director of Cooperative Security and Electronic Processes at Volkswagen, had this to say: "If new possibilities exist after the introduction of 5G, we can upgrade the technology. But there is no reason not to make a start right now, surmount some obstacles and learn from the experience." One of the first mass-market VW models to showcase Car2X will be the 2020 Golf 8.

The US has proven to be fertile ground for 802.11p-based DSRC (Dedicated Short-Range Communications) up to now, with Toyota and General Motors (GM) the main proponents. In April 2018, for example, Toyota announced plans to deploy DSRC on vehicles sold in the US starting in 2021, aiming to adopt it across most of its lineup by the mid-2020s.

However, a year later the company suspended these plans, with Hilary M Cain, director, technology and innovation policy at Toyota, explaining in a letter to the FCC that: "Although there continues to be general excitement about DSRC and the benefits of widespread deployment among key stakeholders, since our product announcement, we have not seen significant production commitments from other automakers."

Cain also cited regulatory uncertainty surrounding the 5.9GHz frequency band (used by both DSRC and C-V2X), noting that the FCC "recently initiated a second proceeding to explore the possibility of reallocating channels away from DSRC to Cellular Vehicle to Everything (C-V2X)".

Cain reiterated Toyota's broad support for DSRC on the basis that it is "the only proven and available technology for collision avoidance communication and is a technology that offers these important safety benefits without reliance on a potentially costly subscription or data service plan," adding that "based in part on the significant DSRC-related investment that has already occurred in the United States, DSRC is the only technology that we believe is capable of garnering wide industry consensus in the United States."

As in Europe, the rise of C-V2X as an alternative to the incumbent 802.11p-based technology is causing US regulators and car manufacturers to reconsider their positions.

China is a leading supporter of cellular V2X, with LTE-based solutions incorporated into the government's current plans for intelligent transportation systems (ITS) and spectrum in the 5.9GHz band allocated for C-V2X. In January 2018, the country's National Development and Reform Commission (NDRC) strategy for Intelligent Vehicle Innovation & Development laid out the following roadmap:

  • By 2020, the strategy projects that 50% of new cars sold will be intelligent vehicles, the coverage of LTE-V2X in big cities and on highways will reach 90%, and Beidou high precision positioning services will achieve a full coverage.

  • By 2025, the strategy projects that most new cars sold will be intelligent vehicles, the "person-vehicle-road-cloud" model will achieve a high degree of collaboration, and new generation wireless communication network for vehicles (5G-V2X) will be able to meet the needs of intelligent vehicle development.

  • By 2030, intelligent vehicles based on Chinese standards will have good reputation across the globe, making China the leader of intelligent vehicles.

China has a National Intelligent Vehicle Pilot Zone in Shanghai, and is also running a city-wide LTE-V2X pilot project in Wuxi. Among leading car-makers, Ford has announced plans to deploy C-V2X technology in China in 2021 (as well as in the US starting in 2022). Anning Chen, president and CEO of Ford China commented: "With China's fast 5G development, and our own rapid progress in C-V2X, we are working at China speed to equip our vehicles with C-V2X technology. Ford customers in China will be the first to receive the benefits of this smart technology, which will help make local streets safer and less congested."

Outlook for V2X: 2020 and beyond

The V2X standards debate is in full flow around the world and is clearly a long way from resolution, although the fact that China has nailed its colours firmly to the cellular mast may prove influential in the long run.

As well as safer assisted and autonomous driving, V2X will also deliver serious business opportunities for those who back the right horse. According to the latest (March 2019) research from market intelligence firm SNS Telecom & IT: "Despite the ongoing 802.11p/DSRC versus C-V2X debate, regulatory uncertainty and other challenges, global spending on V2X communications technology is expected to grow at a CAGR of more than 170% between 2019 and 2022. SNS Telecom & IT predicts that by the end of 2022, V2X will account for a market worth $1.2 Billion, with an installed base of nearly 6 Million V2X-equipped vehicles worldwide."

Image: SNS Telecom & IT

Other key findings of The V2X (Vehicle-to-Everything) Communications Ecosystem: 2019-2030 – Opportunities, Challenges, Strategies & Forecasts were: 

  • While DSRC proponents are pushing ahead with their plans to roll out IEEE 802.11p in North America, Europe and Japan,  pre-commercial C-V2X deployments have recently gained considerable momentum, spearheaded by cellular industry giants such as Qualcomm and Huawei -- with support from automakers including Ford, BMW, Daimler, Groupe PSA, SAIC, Geely, Volkswagen's luxury brand Audi, and JLR (Jaguar Land Rover).

  • Regional markets are also visibly divided with the Chinese Government backing C-V2X, Europe leaning towards IEEE 802.11p through its recently published delegated act on C-ITS (Cooperative Intelligent Transport Systems), and heated debates ensuing in the United States as a result of the 5GAA's waiver request to allow C-V2X deployments in the 5.9 GHz band.

  • As a result, a number of automotive OEMs are beginning to adopt a flexible approach by choosing to deploy different technologies in different regions as they commit to V2X. For example, although GM has equipped its Cadillac CTS sedan vehicles with IEEE 802.11p in North America, the automaker is actively working with business partners to prepare for C-V2X deployment in China.

  • Besides becoming a standard safety feature on an increasing number of vehicles, V2X communications technology -- through its unique non line-of-sight sensing capability -- will play a critical role in ensuring the safe and efficient operation of autonomous driving systems, particularly with the commercialization of next-generation V2X standards, specifically 5G-V2X and IEEE 802.11bd.

  • The globally harmonized 5.9GHz band continues to remain the preferred spectrum for V2X communications technology, with the exception of Japan – where the national regulator has allocated a single 9MHz channel in the frequency range 755.5–764.5MHz for safety-related applications based on V2V and V2I communications.

  • Early discussions are ongoing for the potential use of new bands, most notably in the 3.4-3.8GHz and 5.9-7.2GHz frequency ranges, as well as millimeter wave spectrum for LOS (Line-of-Sight) and high data rate V2X applications. Recent field trials using 39GHz spectrum in the United States have demonstrated that millimeter propagations for V2V communications can work well in the distance range of 100 meters, without advanced beamforming techniques.


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