In-vehicle Ethernet will become the next generation of automotive network

The evolution of automotive electrical architecture towards centralization

Centralized architecture has become the mainstream of intelligent driving, and Ethernet occupies an advantageous position in the central node. The evolution of electronic and electrical architecture has provided a solid foundation for improving intelligent driving capabilities. Driven by trends such as autonomous driving, smart cockpits, and electrification, the functions required for automobiles have increased, and the amount of information transmission and computing power requirements have continued to grow. Traditional distributed architectures are difficult to meet product requirements in terms of scalability and communication performance. Domain/cross-domain centralized architecture has gradually become the mainstream of intelligent driving vehicles. At the same time, multiple domain controllers will continue to merge to form the final form of the central computing unit and each regional controller; superimposed Ethernet and TSN meet the needs of real-time computing, high-speed data transmission, low latency and time synchronization, and maximize the software requirements required for the development of intelligent connected vehicles. In vehicle communications, Ethernet has gradually occupied an advantageous position in the central node.

Centralized architecture has become the mainstream of intelligent driving, and Ethernet occupies an advantageous position in the central node. The evolution of electronic and electrical architecture has provided a solid foundation for improving intelligent driving capabilities. Driven by trends such as autonomous driving, smart cockpits, and electrification, the functions required for automobiles have increased, and the amount of information transmission and computing power requirements have continued to grow. Traditional distributed architectures are difficult to meet product requirements in terms of scalability and communication performance. Domain/cross-domain centralized architecture has gradually become the mainstream of intelligent driving vehicles. At the same time, multiple domain controllers will continue to merge to form the final form of the central computing unit and each regional controller; superimposed Ethernet and TSN meet the needs of real-time computing, high-speed data transmission, low latency and time synchronization, and maximize the software requirements required for the development of intelligent connected vehicles. In vehicle communications, Ethernet has gradually occupied an advantageous position in the central node.

Figure 1: EE architecture continues to evolve towards centralization

In-vehicle Ethernet will become the next generation of automotive network

Key technologies

After years of development, the in-vehicle network has formed a solution with CAN bus as the mainstream and multiple bus technologies coexisting. The bus technologies currently used in vehicles include CAN, LIN, FlexRay, MOST, LVDS and in-vehicle Ethernet, mainly CAN bus and LIN bus as the auxiliary. CAN is mainly used for the transmission of control data on the vehicle and is the most widely used standard protocol for in-vehicle networks; LIN is a low-cost universal serial bus that provides auxiliary functions for the CAN bus and is mainly used for door, sunroof, seat control, etc. in the car. The cost and transmission rate of CAN and LIN are relatively low. FlexRay is a new generation of automotive control bus technology after CAN and LIN. Compared with CAN, it has a higher bandwidth, but it needs to join the standard organization and has a higher cost. It is mainly suitable for wire control systems in mid-to-high-end cars; MOST is widely used in in-vehicle multimedia data transmission, but due to the single supplier and high basic development cost. LVDS is a low-voltage differential signal technology interface , which is mainly used for image data signal transmission between display screens and cameras in the automotive field.

Figure 2: Architecture of mainstream automotive network systems

In-vehicle Ethernet provides high bandwidth and lightweight wiring harnesses, and is cost-effective. It will become a key technology for the next generation of automotive networks. Since the CAN bus can only achieve half-duplex communication and has a low transmission speed, it does not meet the demand for real-time high-speed two-way data interaction under the trend of automotive intelligence and networking. With the rapid development of the wave of automotive electronics in recent years , the number and complexity of electronic and electrical components in automobiles have increased significantly. The number of ECUs per vehicle has gradually increased from 20-30 to more than 100, and the length of wiring harnesses of some vehicles has reached 2.5 miles. The traditional distributed architecture can no longer meet the development needs of the era of automotive intelligence. Therefore, the trend of in-vehicle networks turning to domain control and centralized control is becoming more and more obvious, and the in-vehicle communication architecture will gradually upgrade to Ethernet. Unlike traditional in-vehicle networks, in-vehicle Ethernet can provide higher data transmission capabilities required for bandwidth-intensive applications. At the same time, its technical advantages can well meet the requirements of high reliability, low electromagnetic radiation, low power consumption, bandwidth allocation, low latency, and lightweight of automobiles, and will become a key technology for the next generation of automotive networks.

Table 1: Performance comparison of automotive Ethernet and other buses

Ethernet continues to advance towards higher transmission rates, gradually

Penetrating the vehicle network

Automotive Ethernet has economies of scale and interoperability, and mainly uses copper twisted pair cables for transmission. According to the Ethernet Alliance's forecast in 2020, there will be more than 100 million cars equipped with Ethernet ports in the world in 2021 , and the total number of deployed automotive Ethernet ports will reach 500 million. Automotive Ethernet has economies of scale and interoperability, can provide data and power transmission at the same time, greatly reducing the cost and weight of vehicles, and is one of the main development trends of Ethernet in recent years. In terms of transmission media, automotive Ethernet mainly uses copper twisted pair cables. Because copper twisted pair cables have good mechanical strength, strong weather resistance, and small bending radius, and can be used directly without optoelectronic conversion equipment, they have become the optimal solution for the "last 100 meters" of data transmission. According to Ethernet Alliance data, the current transmission rate of Ethernet based on copper media is mainly between 10Mbit/s and 10Gbit/s. With the continuous enrichment of terminal forms and data types, the total amount of data and transmission requirements continue to rise to new levels. In the future, Ethernet based on copper media will continue to evolve to higher transmission rates.

Figure 3: Ethernet application classification

Gigabit Ethernet is the first choice for high-speed network technology. Ethernet has gone through 50 years of development. With its many advantages such as mature technology, high standardization, high bandwidth and low cost, it has replaced other networks to become the most commonly used LAN technology in the world today, laying the foundation for the Internet of Everything. In terms of transmission rate, Ethernet has a variety of rate standards. In the early days, it was customary to increase it by 10 times, such as standard Ethernet (10Mbps), Fast Ethernet (100Mbps), and Gigabit Ethernet (1Gbps). In recent years, in order to adapt to diversified needs, a variety of new rate standards such as 2.5G E, 5GE, 25GE, and 50GE have begun to appear. Taking into account the application scenarios and cost factors, the current mainstream technology of Ethernet based on twisted pair is Gigabit Ethernet 1000BASE-T based on the 802.3ab standard, which can transmit 1000Mbit/s data stream on Category 5 twisted pair cables with a speed of more than 100M. Most companies use it when setting up.

Gigabit Ethernet is the preferred high-speed network technology when networking.

Figure 4: Development path of automotive Ethernet technology

Automotive Ethernet will gradually expand from local applications such as smart cockpits to become the backbone network for in-vehicle communications. Automotive Ethernet is the communication solution with the fastest transmission rate among all types of buses. With the development of automotive intelligence, automotive Ethernet technology is expected to be first applied to intelligent driving and smart cockpits, and will gradually replace the existing in-vehicle communication technology of the whole vehicle in the future. The development of automotive Ethernet can be divided into three stages. The first stage is the promotion and application of DoIP protocol for on-board diagnostic systems and ECU software refresh, as well as driver assistance systems using IP cameras; the second stage will integrate several subsystems for the promotion and application of in-vehicle smart cockpits and intelligent assisted driving, such as combining multimedia, driver assistance and diagnostic interfaces; the third stage will use Ethernet as the in-vehicle backbone network, integrating powertrain, chassis and body control, smart cockpit, etc., to form a cross-domain automotive network, and gradually introduce new generation Ethernet technologies such as TSN.

Figure 5: Evolution of automotive Ethernet (Phase I and II)