The Cellular V2X is a 3GPP standard describing a technology to achieve the V2X requirements. C-V2X is an alternative to 802.11p, the IEEE specified standard for V2V and other forms of V2X communications. Pre-commercial C-V2X deployments have recently gained considerable momentum with support from multiple automakers.
History
Cellular V2X uses 3GPP standardised 4GLTE or 5Gmobile cellular connectivity to send and receive signals from a vehicle to other vehicles, pedestrians or to fixed objects such as traffic lights in its surroundings. It commonly uses the 5.9 GHz frequency band to communicate – this being the officially designated intelligent transportation system frequency in most countries. C-V2X can function without network assistance and has a range that exceeds a mile. In 2014, 3GPP Release 13 spurred studies to test the applicability of the then current standards to V2X. This resulted in the 3GPP Release 14 specifications for C-V2X communications, finalised in 2017. 3GPP Release 15 introduced 5G for V2N use-cases, and 3GPP Release 16 includes work on 5G NR direct communications for V2V/V2I. C-V2X was developed within the 3rd Generation Partnership Project, to replace the US promoted Dedicated short-range communications and the Europe originated Cooperative Intelligent Transport Systems As such standards are decisive steps towards the target autonomous driving and clues to market influence, especially as the National Highway Traffic Safety Administration plans to propose the compulsory introduction of vehicle-to-everything technology off 2020 for all US vehicles. In Europe, the EU announced in July 2019 that it was adopting a technology-neutral approach to C-ITS, leaving the way forward for 4G, 5G and other advanced technologies to be part of V2X applications and services. In the United States, the Federal Communications Commission proposed late in 2019 that 20 MHz and possibly 30 MHz of the 5.9 GHz band be allocated to C-V2X.
Modes
The modes, Cellular V2X may be implemented, are: Device-to-network i.e. Vehicle-to-Network communication using the conventional cellular links to enable cloud services to be part of the end-to-end solution. Device-to-device, which includes Vehicle-to-vehicle , Vehicle-to road and infrastructure also including the use with toll systems and the direct communication and Vehicle-to-pedestrian – also without use of network involvement for scheduling – for the protection of the most vulnerable road users, the pedestrians. The Cellular V2X mode 4 communication relies on a distributed resource allocation scheme, namely sensing-based semipersistent scheduling which schedules radio resources in a stand-alone fashion in each user equipment .
Limited data rates, considering, that just one autonomous car will use 4,000 GB of data per day.
Wireless communication is susceptible to external influences, which may be hostile.
In metropolitan areas, limits of data propagation due to surroundings such as buildings, tunnels and also Doppler effects, causing propagation speed reduction by repetitive transmissions required.
The costs to provide a comprehensive appropriate network such as LTE or 5G are enormous.
