Decentralized edge computing, service provisioning, network orchestration, security have been explored within the co-funded by the European Commission RAINBOW project as well relevant topics in the field of 5G networks. Stellantis-CRF, Links Foundation and Politecnico di Torino, collaborated on the Urban Mobility Demonstrator (UMD) automotive use case to assess those topics thought the RAINBOW framework.
5G will be the enabling factor for a real revolution in the automotive sector. To support complex traffic situations by improving safety and efficiency (e.g. reducing congestion), connected vehicles will have to rely not only on their own sensors but also on other vehicles sensors and on road and mobile network infrastructures. These trends challenge to the underlying communication system, as information must be exchanged with low latency and high reliability. 5G promises to improve performance in terms of improve latency time, reliability and higher throughput with greater mobility and connectivity density on many automotive scenarios: Safety, Mobility, E-road, Entertainment, on-board software updates, Telemetry management…
In order to address the scenarios requirements, 5G provides various technologies such as network functions virtualization, new radio access techniques, network slicing and edge computing. Referring to the “standard” 5G service classes, the automotive sector could find answer to some of its requirements:
- URLLC: low latencies necessary for some high automation levels
- mMTC: for collection and analysis of data from vehicles
- eMBB: streaming video information (eg: from Road Side Units) or entertainment.
5G will benefit all layers of the intelligent transportation system (ITS) stack: Access, Network, Transport, Facilities, and Applications.
Access: As a part of a mobile network, implements radio access techniques. Relevant 5G access technologies are:
- Millimeter waves: provides adequate bandwidth and throughput even in high-density cooperative sensing scenarios, bulk data transfer (to and from Road Side Units).
- Multi-RAT (radio access technologies): 5G will be a deploy mashup of existing networks, new 3GPP and non-3GPP networks (ex: 802.11).
- NOMA (non-orthogonal multiple access): improvement of spectrum efficiency and reduction of latency in environments with high movement density (eg 2000-4000 vehicles / km2).
- MIMO (Multiple Input Multiple Output): improve the system capacity multiplying the radio link capacity. The vehicles will house multiple antennas, and their integration could lead to new approaches to vehicular architecture.
Network & Transport: At this level, typical standards (IPv6, TCP, UDP) are present but also dedicated protocols to support ITS applications. Two typical protocols that allow end-to-end communication are BTP (Basic Transport Protocol) and GeoNetworking for packet forwarding of geographic locations. These protocols support a facilities layer in which the messages that the V2X world uses are defined.
Facilities: ITS applications typically require communicating in V2X mode with a continuous exchange of messages. The basic messages are:
- CAM (Cooperative Awareness Message): device status info (time, speed, position, movement status, etc) and related attributes (size, type of vehicle, role in traffic, etc). The sending frequency of CAM messages is 0.1 s.
- DENM (Decentralized Environmental Notification Message): occurrence of specific events (e.g. accidents). They persist as long as the event in question has not ended.
- MAP / SPAT: Map Data to define the precise geometries of the intersections and Signal Phase and Timing to provide the status of the intersection.
In Europe the standard messages are ETSI EN 302 637 and ITS-G5, in the USA SAE J2735 on DSRC/WAVE.
Applications: It will be necessary to architecturally support the ITS functionalities by instantiating and managing application elements distributed between vehicle and network (Cloud + MEC). In the case of the virtualization and orchestration architectural elements, there must be a particular attention to the decentralized Cloud (Edge Computing) and in particular to the ETS MEC (Multi-access Edge Computing) standard. The edge is the ideal place to host server components of infrastructures based on V2X communications due to the very low latency that this environment is able to offer and for its computational capability.