Understanding V2X Technology: Day-1 vs. Advanced Use Cases

Technology is transforming the way we navigate roads and the broader transportation system. At the forefront of this innovation is Vehicle-to-Everything (V2X) communication, a key enabler for connected mobility.

V2X communication is implemented through Dedicated Short Range Communication (DSRC) or Cellular Vehicle-to-Everything (C-V2X), both of which deliver a range of use cases categorized as ‘day-1’ or ‘advanced’.

Day-1 Use Cases: Foundation of V2X Technology

The day-1 use cases are those that were initially implemented through the development of V2X and set the foundations for the usage of the technology. These use cases largely focus on improving road safety by delivering basic safety messages using V2X communication.

Advanced Use Cases: The Future of V2X Communication

Advanced use cases build upon the functionalities of the day-1 use cases. However, as well as improving road safety and enhancing traffic management, these use cases enable applications such as autonomous driving, cooperative intersection control, lane merging, and platooning through the use of advanced communication protocols.

Compared to day-1 use cases, advanced use cases typically require advanced communication protocols that support high throughput, low latency, and improved reliability.

Features of day 1 and advanced use cases

Continual vs. Event-Triggered Messages in V2X Communication

Both day-1 and advanced use cases can employ different messages, these being either ‘continual messages’ or ‘event-triggered messages’.

Continual Messages

Continual messages are shared continuously between vehicles, road users, infrastructure, and networks. These messages might include information about vehicle location, speed, sensor data, or collision risks.

Continual messages are essential for providing timely information that aids in safety-related decision-making. Day-1 use cases typically rely on continual messages to ensure ongoing safety by constantly sharing data between vehicles and infrastructure.

Event-Triggered Messages

Event-triggered messages, on the other hand, are sent only when a specific event occurs. Examples include emergency vehicle alerts, collision warnings, or notifications about a vehicle performing a special maneuver.

Depending on the situation, event-triggered messages can be either repetitive or non-repetitive, depending on how often road users need the information. These messages play a significant role in traffic management, and road safety, and are vital for enabling autonomous driving. As such, event-triggered messages are typically associated with advanced use cases.

Example V2X Use Cases

V2X use case examples depending on message type

Source: 5GAA ‘Study of spectrum needs for safety related intelligent transportation systems - day 1 and advanced use cases’’, published October 2021

Spectrum Requirements for V2X Communication

According to the 5G Automotive Association (5GAA), the spectrum requirements for delivering day-1 use cases via LTE-V2X are expected to require 10 to 20 MHz of the 5.9 GHz spectrum. For advanced use cases, LTE-V2X or 5G-V2X communication will require at least 40 MHz of spectrum to support advanced driving services. As the market evolves, the need for additional spectrum may increase as new use cases and functionalities are developed and deployed.

A number of groups have been identified by 5GAA to categorize both day-1 and advanced use cases.

Source: 5GAA ‘C-V2X Use Cases Methodology, Examples and Service Level Requirements’’, published June 2019

Future V2X Use Cases and Timeline

The first expectation is for a mass deployment of basic safety and traffic efficiency use cases as a baseline for V2X usage across regions worldwide. Building upon this, there is the anticipation for a large-scale introduction of use cases that allow for advanced safety features and automated driving - something 5GAA expects to be implemented from 2024 onwards. From 2026, other additional connected automated driving functionalities, such as HD sensor sharing, are expected.

About Ettifos:

Founded in 2018, Ettifos is a 5G-focused V2X solutions provider invested in enabling the most advanced smart city/smart intersection deployments and connected vehicles (CV) technology.

The company supplies innovative and versatile OBU and RSU systems tailored to customers’ specific project and service requirements, with the vision of connecting all entities in motion to create a world with safer, smarter, and more efficient roads.