The development and recent changes that took place in infotainment electronics, together with the steep increase in the demand for ADAS and safety features, is demanding that OEMs re-think the electronic architecture of the car. The increasing complexity in the design of car’s electrical and electronic (E/E) systems makes engineers define common functionalities among various electronics systems and to cluster those, when possible, in a fewer number of control units.
Although this rationalization is easily understandable on paper, the above statement hides several practical difficulties in the design of electronic control units (ECUs), and engineers often need to combine different requirements of performance, bandwidth, security, reliability and finally flexibility and cost in the different ECUs. In particular, cost and flexibility in automotive platforms are compelling this innovation process to cope with system simplification on one hand, and ECU interoperability on the other.
The major requirements for future networks could be translated into the ability for a shared in-vehicle network able ensuring ECU interconnection and bandwidth requirements, but also guaranteeing security, fault-tolerance coverage, as well as granting the ability to transmit critical events in real-time while being flexible in managing event-driven functions.
To handle this complex mix of functionalities, the E/E architecture should support the following
- A separation between physical and logical network. The network is split into “functional domains”, each one resulting in a separated “Virtual Local Area Network” (VLAN).
- A gateway function to act as router for different networks and protocols, being also the access point for diagnostic and OTA (e.g. DoIP traffic)
- A hierarchical approach, in developing and organizing ECUs
- A ubiquitous network, where all units are accessible and univocally addressable (MAC/IP), even from the Cloud.
The above elements push the evaluation and implementation of car Ethernet networks, and take advantage of the experience of the well-established IT industry.
Architecture: from flat, to central gateway to domain controllers
In terms of an overall electronic system, the industry is witnessing an in-vehicle architecture (r)-evolution, moving from being a simply CAN-based flat architecture to a more structured network. The aim is to develop a network configuration able to add flexibility, performance, and to allow a scalable integration of new advanced functionalities, while maintaining safety and security.
Central gateways started to appear in the premium brands, which are typically the first to face the challenges of advanced systems. The major advantages in relying on a central gateway are
- A physical isolation of the various automotive functional domains
- A stronger firewall solution for security purpose
- An opportunity to increase safety and performance with more adequate networking technologies, such as MOST, Ethernet and FlexRay
In the next development step, a distributed gateway is the expected approach, with the introduction of several functional domain controllers. The enabler for such centralized solution is the availability of high performance semiconductor components such as SoC and memory ICs, but also fast, reliable wired and wireless communication links. Fast data transceivers must tackle real-time safety-critical operations. Ethernet TSN, 802.11p and 5G will be among the technologies that grow fast and enable fast data sharing as well as systems update (OTA).
The advantage for a domain controller approach is summarized as follows:
- High performance, safe distribution and processing of the I/O data coming from several sensors and ECU
- Lower latency and deterministic behaviour
- Higher and layered security level
- Fault tolerance
The architectures depicted above and based on IP networking will also give the OEMs a lot of flexibility in the design as well as in the operation of all the electronics in the car, and also the chance to consolidate ECUs and scale the system using a VLAN concept.
Figure Vehicle Networking evolution (IHS Markit)
The status of Ethernet in Automotive
That several OEMs have invested in the car Ethernet suggests that this solution will not arrive just to replace MOST (Media Oriented Systems Transport) in the infotainment area. MOST per se would have been enough to cope with purely Multimedia requirements. The interest is broader, to the extent that BMW foresees a complete Ethernet-based vehicle in the near future. As part of this effort there is evaluation of different Ethernet speed ranges such as a sub-100Mb/s (i.e.10Mb/s) and a high-speed link in the range of 1 to 10 Gb/s.
Several OEMs are already implementing a portion of in-vehicle network to Ethernet. Nonetheless, as of today, such implementations are mostly in the segment of infotainment or surround-park applications.
In the opinion of IHS Markit, there are major barriers to Ethernet….
- Limited bandwidth, available today up to 100Mbit/s
- Ethernet TSN (time deterministic) toolkit and specification are not completely finalised
Both the above points constrain Ethernet implementation in a fast and dynamic market, faster than the Ethernet standardisation process itself.
Actually, FlexRay will likely remain the preferred choice for safety critical applications (controlling actuators like brake and steering wheel). Similarly, some camera-based systems have already moved to Ethernet bus, rather than LVDS. However, due to the fast growth in camera resolution, FPS and the transmission of uncompressed data, the high bandwidth of LVDS is expected to be favoured in next generation camera systems.
There are several reasons to deploy Ethernet in the car, and while this will certainly come to pass, IHS Markit believes implementation will be gradual rather than explosive. Already today, IHS Markit forecasts good growth of Ethernet nodes connecting various vehicle ECUs. With the implementation of centralized domain architecture, Ethernet will play the role in the backbone in the new network architecture. Furthermore, once the toolkit for Ethernet TSN is finalised, Ethernet deployment will be boosted for safety-critical ADAS functions as well as in controlling actuators.
Overall, Ethernet looks to be a promising solution, even if the bandwidth is still of concern in addressing the fast growing in-vehicle communication data rates.
During the last Automotive Ethernet Congress (Munich), the key message delivered by OEMs and Tier1s is that automotive needs at least 1Gb/s of Ethernet bandwidth in the coming years. Unfortunately, such a speed implies that the technical community still faces big hurdles regarding standardisation and complexity associated with the increasing signal frequency –EMC, physical layer, safety and their impact in cost will have a key role in defining the success of Ethernet in the following 5 years.