Intelligent Transportation Systems

DSRC Versus C-V2X

The high-speed communication protocols that come into play here for vehicle safety are DSRC and C-V2X. These two protocols operate at very high speed with a high-frequency exchange of data at low latency. DSRC has a data rate of 6Mbps to 26Mbps in the 5850MHZ to 5925MHz band. C-V2x has a data rate of 26Mbps (RX) Max 26Mbps (TX). Both operate in the 5.9GHz band, and both use the same use cases and the same message sets (SAE J2735 and J2945), and both also use digital signatures for security and trust in message providers. DSRC and C-V2X radios do not connect, but they are broadcasting vehicle location, acceleration, and speed while listening to other radios.

The two technologies use different wireless standards. DSRC uses WAVE IEEE (802.11p), and C-V2X uses long-term evolution (LTE), which cellphones use. The FCC allocated the 5.9 GHz band to Wi-Fi and C-V2X in November 2020.

These two radio technologies cannot talk to each other, and their respective ranges are quite different. DSRC is around 300m, where C-V2X has lower latencies, 20 percent to 30 percent more range, and performs much better in the presence of obstructions than DSRC. Overall, C-V2X has significantly better performance. However, DSRC still does have sufficient range and reliability for key safety applications.

C-V2X Sidelinking

5G, Release 16, brought sidelinking to industry C-V2X with 5G New Radio (NR). This release advanced C-V2X applications such as platooning, advanced driving, extended sensors, and remote driving. Strict latency and high reliability must be guaranteed because of the need for emergency braking and collision avoidance in critical driving situations. C-V2X’s smallest transmission latency is at most 4ms and can be lower depending on the implementation. It is difficult to quantize reliability here, but each new Release has added another group of improvements in performance and safety, which has enhanced reliability. New releases are scheduled to continue on this path of safety and reliability improvements.

The bulk of the traffic that will be carried out by short-range communications, especially in the first phase of V2X deployment, will be periodic broadcasting messages by each vehicle communicating its status and movements.

In dense traffic areas, available channel resources will saturate and lead to an increase in packet losses. This could endanger driver and passenger safety. Congestion-control algorithms were examined and defined to modify certain parameters before these conditions reach critical levels. However, instead of looking at specific algorithms, researchers examined the Wi-Fi standard approach (IEEE 802.11p) versus the cellular standard approach (sidelinking LTE-V2X as defined by 3GPP as part of C-V2X in Release 14).

The C-V2X communication technology was developed by 3GPP to enable direct communications among vehicular user equipment (VUE) over the sidelink, also named PC5 interface. C-V2X sidelink is the first wireless system to introduce distance as a dimension at the physical layer. This will enable achieving a uniform communication range across widely varying radio environments for both LoS and non-LoS.

C-V2X includes two modes of communication from Release 14: direct mode (PC5) for the most immediate and latency-sensitive communications, and network mode (known as Uu) since it links User Equipment to the UMTS Terrestrial Radio Access Network. It uses an existing cellular network for broadcast-type communications.

For the PC5 mode:

• 1 Mode 3 (scheduled) in which the sidelink resource assignment is performed with the supervision of the eNodeB and requires cellular infrastructure support for radio resource management.
• 2 Mode 4 (autonomous), where resource and interference management is performed by vehicles in a distributed manner and does not involve cellular infrastructure (and can be used in areas without cellular coverage).

Security and Privacy in V2X Communication

LTE-based V2X communication uses a high capacity, large cell coverage range, and widely deployed infrastructure to support various types of vehicular communication services for safety and non-safety applications. Technical organizations such as 3GPP and Qualcomm have already prepared the roadmap toward 5G-based V2X services.

Security defined in 3GPP mainly includes confidentiality, integrity, authenticity, and resistance to replay attack.

New privacy and security challenges, including secure mobility management for group-oriented autonomous platoons, reliable cooperative driving, efficient and privacy-preserving vehicular big data sharing and processing, and more, demand more investigation in 5G vehicular networks.

In the scenario of the possible solutions for automotive security and safety assurance against any cyberattack, the full adoption of a double-key cryptosystem is advisable.

V2X applications depend on continuous, detailed location information, which can lead to privacy concerns. In a privately owned vehicle, location traces will reveal the movements and activities of the driver, who might or might not be the owner of the vehicle. In short, sending and disseminating V2X user location information might have a possible privacy concern for the owner and driver of the vehicle.

Other V2X applications include communication between vehicles that will augment existing methods to help with left- or right-turn assistance, emergency braking warnings, and improved situational awareness at intersections. Extending Waze concepts can control or suggest speed adjustments to account for traffic congestion and update a GPS map with real-time updates on lane closure and highway construction activity. V2X in some form is essential to support over-the-air (OTA) software updates for the now-extensive range of software-driven systems in your car, from map updates to bug fixes to security updates and more.

V2X safety messages can be made to include a Basic Safety Message (BSM) in U.S. standards or Cooperative Awareness Messages (CAM) and a Decentralized Environmental Notification Messages (DENM) in a European Union (EU) standard.

BSM contains position, velocity, and acceleration information and is transmitted up to 10 times per second. This message system also enables the vehicle receiving unit to predict collisions and warn the driver.

V2X Message Protection and Security

V2X and V2I communication needs strong security to protect messages against fraudulent or misleading use that might lead to safety and privacy issues. Another method for security is signed messages using Public Key Certificates that are used to prevent unauthorized parties from interfering with the exchange of data and to pseudonymize the communication securely.

Public key infrastructure (PKI) consists of policies and procedures used to create, manage, use, save and revoke digital security certificates. PKI allows for the transfer of electronic information securely and goes beyond just passwords as authentication with a requirement of more rigorous identity confirmation.

Security and Privacy in V2X Communication

Intention or trajectory sharing will enhance autonomous driving by providing a higher level of predictability and traffic efficiency in advanced path planning.

5G New Radio (5G NR) will enable intent sharing with:

• High throughput: 5G can provide the required high data rates needed, such as greater than 100Mbps in a 1km stretch.
• High reliability: 5G can ensure that trajectory information will be shared accurately and promptly.
• Low latency: 5G low latency capabilities will allow trajectory information to be shared within a few milliseconds.

C-V2X Performance in Crowded Highway Situations

The 5G Automotive Association (5GAA) ran V2X performance and functional tests in a test report entitled V2X Functional and Performance Test Report, in which C-V2X technology was tested for a highly congested scenario in a laboratory setting. Even in this congested scenario, C-V2X latency remained bounded by the 100ms latency budget configured for that scenario, which is a very positive result.

In a series of laboratory and field tests, it is observed that:

• C-V2X communication in 20MHz CH183 has the same reliability performance (Packet Reception Ratio vs. distance) as the identical BSM-like message transmission in 10MHz CH184.
• Impact of C-V2X high load transmissions in CH183 on DSRC basic safety transmissions in CH172 is negligible up to a 1.4-km range in Line of Sight (LOS) conditions.
• Impact of C-V2X high load transmissions in CH183 on V2I and I2V transmissions in CH178 is negligible up to a 1.4-km range in LOS conditions.
• Impact of C-V2X high load transmissions in CH183 on V2I and I2V transmissions in CH180 is negligible up to 1km in LOS conditions.

Ford and Qualcomm performed additional field tests supporting the latest 5GAA petition for waiver with the Federal Communications Commission (FCC) for C-V2X deployment. Those tests by Ford showed C-V2X with a very acceptable performance, especially in LOS conditions.

According to the 5GAA website, C-V2X was deemed ready for deployment with commercial chipsets and was also seen as ready to start in-vehicle deployment in the 2020/2021 timeframe globally. The 5GAA will partner with the relevant Standards Developing Organizations (SDOs) to drive the requirements of 5G V2X to create a successful V2X ecosystem.

Conclusion

The FCC effectively changed the vehicle communications Cooperative Intelligent Transport Systems (C-ITS) market in the U.S. via the restructuring of the 5.9GHz band.

The automotive industry must go forward on a narrowed spectrum with C-V2X technology instead of the widely used Dedicated Short Range Communication (DSRC). The changes announced pave the way for progress, eliminating the uncertainty caused by competing technologies.

V2X and 5G are fast-becoming integral technologies for automakers as it endeavors to commercialize fully autonomous vehicle technology in the years ahead. After the launch of C-V2X vehicles in China in 2021, Ford anticipates bringing the technology to all of its vehicles sold in the U.S. beginning in 2022. The 5GAA will partner with the relevant SDOs to drive the requirements of 5G V2X to create a successful V2X ecosystem.

IHS Markit, a financial services company, posted an analysis on 5G, C-V2X, and automotive connectivity for the 2021 year on its website in January 2021.

According to a news release about a C-V2X study published on Market Watch:

"The V2I communication segment is expected to grow at a CAGR of over 12% over the forecast period due to the increase in the adoption of smart traffic infrastructure. The smart traffic infrastructure involves smart traffic signals and smart surveillance cameras, which communicate with vehicles to provide information about traffic and road conditions."

More exciting vehicle advances are coming, which will significantly change the way we drive our vehicles for the better.

Photo/imagery credits (in order of display)
Akarat Phasura - stock.adobe.com, kinwun - stock.adobe.com, metamorworks - stock.adobe.com, Yury Gubin - stock.adobe.com

Inside the Connected Car

At first glance, the inside of tomorrow's connected car won’t appear too different from today’s vehicles. A large human machine interface (HMI) will likely dominate the dash in a similar way to those in contemporary vehicles. And because a modern car already contains a lot of networked electronics with proven reliability (and benefitting from commodity pricing beloved of a sector that looks to continually drive down costs), much of that technology will remain yet be adapted to suit connection to the IoT.

However, the adaptation required could be considerable. Modern vehicles encompass sophisticated networks formed from wired and wireless elements. Electronic control units (ECUs)––that power everything from dashboard instruments to safety features and powertrain components to in-vehicle infotainment (IVI) systems––form a key part of these networks. The number of these devices in the average car has doubled in the past ten years, and many vehicles now incorporate more than 125 separate ECUs. Today’s cars also boast a swarm of sensors monitoring everything from road conditions, distance to the vehicle in front, vehicle speed and acceleration, and location (via GPS) to internal temperature, seatbelt tension, and driver alertness.

Wireless connectivity such as Bluetooth® technology is typically used to connect smartphones and tablets to the vehicle;s dash-mounted HMI. Most of the other sensors in the contemporary car, like those monitoring powertrain, chassis, body, control and safety use wired Controller Area Network (CAN) or Local Interconnect Network (LIN) buses. The instrument cluster is also connected via a CAN bus to the network. All network connections terminate at a central gateway that supervises functions and can be accessed from an external computer via an on-board diagnostics data link connector (OBD DLC).

Changes to this conventional layout in an IoT-enabled vehicle are likely to include the use of Ethernet to link the various systems replacing CAN and LIN buses (particularly as Ethernet has recently been embraced by several automotive OEMs for vehicle infotainment buses) and the introduction of mini-hubs to aggregate groups of sensors or ECUs to simplify the network.

Conclusion

The IoT promises to improve the driving experience and save lives. However, in order to fully unlock this potential, a wide range of barriers need to be addressed, including security, safety, regulation, lack of cross-industry standards, widely varying industry dynamics and life cycles, and limited initial addressable market sizes. So while the future for the connected car is undoubtedly bright, the highway to its introduction is covered with speed bumps.  

Consistency of Road Signs and Signals

An associated headache for self-driving vehicle makers is the lack of consistency when it comes to signs, signals, and markings: Cross a state or national boundary and the design and format of these key elements can change.

Smarter Roads

Beyond simply improving conventional road elements, we're also seeing a shift towards smart solutions. A team of government researchers recently observed: "For autonomous vehicles to work well, roads, road signs, and signals may need to be mapped or made intelligent."

Vehicle-to-Vehicle and Vehicle-to-Infrastructure Communication

V2V and V2I technology were originally envisaged as a helper for human drivers. But both can also be extremely valuable for self-driving vehicles, complementing sensor data and sharing this with other road users to build up a better understanding of conditions. At Baidu in China, researchers have suggested further benefits. For example, the hand signals made by a police officer to a stream of oncoming traffic can’t be interpreted by a self-driving car; the human driver would need to take control to follow the instructions. Baidu has outlined how V2X technology could help overcome this issue, including by providing traffic control officers with beacons that send instructions to the traffic via V2I networks.

What Does This Mean for Human Drivers?

The push to alter roads for the benefit of autonomous vehicles could result in controversial results: We could end up with roads optimized for self-driving vehicles but that are less safe for human drivers. Take this a step further, and you could have a situation where human drivers are forbidden from driving on certain roads.

Here’s why: Autonomous vehicles have greater awareness of their surroundings than human drivers and can react faster. Consequently, roads for such vehicles could be narrower, thereby being less expensive to build and releasing valuable real estate. Cars could also travel faster and with less space between them, while V2I technology could eradicate the need for road signage and traffic lights. But all of this would rely on there being no human drivers, pedestrians, or other road users in the mix.

Gradual Changes

Let's come back to our question of whether changing our roads for the benefit of self-driving vehicles is the right thing to do. This is likely to remain a contentious issue, to which we may never get a definitive answer. More likely is that smaller-scale alterations will happen bit by bit, without specific intervention from governments.

Imagine for a moment the year 2035. One in four vehicles now has sophisticated self-driving features. When reviewing collision data, urban transport planners realize that a large proportion of accidents at a busy junction involve autonomous vehicles. On further investigation, it turns out that this is because the cars' sensors can't detect a traffic light when the sun shines at a certain angle. The authorities add a second set of lights (or move the first), which immediately cuts the collision rate. What they have done is adjust the roads for the benefit of autonomous vehicles.

What about all the other road users?