The Evolution of In-vehicle Network Architectures in SDV Paradigm

The push for more fuel-efficient and safer vehicles has paved the way for electronic controls in cars, leading to the introduction of In-vehicle Networks (IVN). These networks have become essential to modern vehicles. The amount of data passing through these networks is growing rapidly due to the increasing demands of electric vehicles, advanced driver assistance systems (ADAS), radar, lidar, infotainment systems, cameras, and vehicle-to-vehicle communication systems.

To meet this need, the automotive industry and technology supplier have developed communications protocols and application-specific extensions to existing network technologies, standardized under the aegis of organizations like ISO and IEEE, and it continues to investigate new topologies and protocols to improve performance, increase reliability and lower the costs of IVNs.

A Software Defined Vehicle (SDV) is a vehicle where software plays a central role in its functionalities, features, and overall performance. It goes beyond simply using software to control individual systems; it fundamentally shifts the paradigm, making software the driving force behind the vehicle's capabilities.

• ?Over-the-Air Updates (OTA): SDVs receive continuous software updates wirelessly, enabling new features, bug fixes, and performance enhancements after the vehicle has been purchased.
• Dynamically Configurable Functions: Features can be activated, deactivated, or modified through software, allowing for personalization and customization based on user needs or driving conditions.
• Data-Driven Optimization: SDVs collect vast amounts of data from sensors, navigation systems, and user interactions, enabling continuous improvement through data analysis and machine learning algorithms.
• Open Software Platform: Software development kits (SDKs) and open APIs allow third-party developers to create new applications and services for the vehicle, fostering a vibrant ecosystem of innovation.
• Integration with Smart Infrastructure: SDVs seamlessly integrate with smart city infrastructure, traffic management systems, and other connected services, creating a more efficient and safe driving experience.

Let us relate the Software definition to the vehicle architecture in use. This will help us to deal with the vehicles and in vehicle functions mapping in designs.

Classic Network architecture (Low end cars)

In-vehicle Networks (IVNs) are structured using a composite architecture that integrates multiple networks in a logical arrangement.

In traditional car design, various electronic control units (ECUs) are scattered throughout the vehicle and connected to each other. These ECUs are typically positioned close to the sensors or motor they manage. This arrangement, however, leads to a complex network of wiring, making the system bulky, heavy, and expensive.

Key feature

• Decentralized Control: Each Engine Control Unit (ECU) is responsible for a specific function (engine, transmission, ABS, etc.). They operate independently, with minimal communication with other ECUs.
• Point-to-Point Connections: ECUs are connected to each other directly through individual wires. Think of it like a web of cables, with each ECU having its own dedicated pathways to the others.
• Location Proximity: ECUs are usually placed near the components they control. This minimizes the length of wiring harnesses.
• Limited Communication: The communication between ECUs is often limited to specific signals and messages, typically for basic coordination or sharing critical data.

Benefits

• Simplicity: This architecture was easier to develop and implement in the early days of vehicle electronics.
• Redundancy: If one ECU fails, it typically doesn't affect the operation of other systems.
• Cost-Effectiveness: In the past, the use of many smaller, dedicated ECUs was more economical than a single, powerful central control unit.

Domain Network architecture (Mid end vehicles)

The number of electronic control units (ECUs) in vehicles is continuing to rise. A current mid-range vehicle might have 70 ECUs, while a luxury vehicle might have as many as 150.? Connecting these devices is challenging, and vehicle manufacturers seek to consolidate capabilities into fewer devices to reduce complexity and cost. Hence, the evolution of the Domain architecture currently used in newer vehicles. This gives rise to domain network architecture.

Instead of having numerous ECUs scattered throughout the vehicle, this approach groups related functionalities into distinct "domains," each controlled by a powerful central computing unit (CCU) or Domain Controller.

Example Domains:

• Powertrain Domain: Controls engine, transmission, and related systems.
• Chassis Domain: Manages braking, steering, suspension, and driver assistance systems.
• Body Domain: Controls lighting, comfort features, and infotainment.
• Safety Domain: Manages safety-critical systems like airbags and collision avoidance.
• Infotainment and connectivity: Manages the external connectivity and infotainment.

Key feature benefits:

• Centralized Control:?Each domain has its own CCU responsible for managing and coordinating all related functionalities.
• High-Speed Communication:?Domains communicate with each other through high-speed communication networks, allowing for seamless information exchange and coordination.
• Software-Defined Functionality:?Domains can be easily reconfigured and updated through software updates, enabling new features and functionalities without the need for extensive hardware changes.
• Scalability:?The modular nature of domains allows for easier integration of new technologies and functionalities.
• Improved Security:?Centralized control and robust communication protocols can enhance security, making the vehicle more resistant to cyberattacks.

Zonal Network architecture (High end cars)

The “next generation” IVN architecture is called Zonal architecture. In the Zonal architecture, main controllers called zone controllers are in different sections of the car (e.g., front left, front right). The sensors and actuators are connected directly to the zone controller, and because the zone controller is close to the interfaced devices, the cable lengths required to connect them are relatively short, resulting in less weight and expense. This architecture reduces the number of wires in the harness, and there are fewer ECUs overall replaced by much more powerful, centralized ECUs for the different regions of the car.

A central controller linked to zone controllers via a high-speed data "backbone" handles data fusion and higher-level decision-making tasks. This backbone also ensures the necessary data redundancy, particularly crucial for autonomous driving. Due to the large volume of data exchanged between controllers and the need to connect to external high-speed networks, high speed and throughput are vital for this architecture, especially for the central controller and backbone functions. Therefore, it is essential to transfer data at speeds significantly exceeding 10 Mbit/s.

Here is a comparison of the latency needs.

Key Features:

• Zone-Based Control: Each zone has a dedicated ZCU responsible for managing the functionalities within its scope.
• Zone Communication: Zones communicate with each other through high-speed communication networks, enabling data exchange and coordination.
• Centralized Control & Distributed Execution: While ZCUs manage their zones independently, a central control unit (CCU) may oversee the overall system, coordinating functionalities and ensuring seamless operation across zones.
• Scalability and Flexibility: The modular nature of zones allows for easy adaptation to evolving technologies and changing vehicle configurations.
• Reduced Wiring Complexity: By optimizing communication pathways within zones, zonal architecture can minimize the number of wires required.

Examples of Zones:

• Cockpit Zone: Controls infotainment, instrument cluster, and driver assistance systems.
• Powertrain Zone: Manages engine, transmission, and drivetrain systems.
• Chassis Zone: Controls braking, steering, suspension, and vehicle dynamics.
• Body Zone: Manages comfort features, lighting, and exterior systems.
• Connectivity Zone: Handles vehicle communication with external networks, including cellular, Wi-Fi, and V2X (Vehicle-to-Everything).

Benefits of Zonal Architecture:

• Improved Performance: Faster communication within zones enhances system responsiveness and real-time control.
• Enhanced Security: Zonal architecture allows for better isolation of critical systems, enhancing security against cyberattacks.
• Greater Flexibility: Zones can be easily adapted to accommodate new technologies and functionalities.
• Reduced Development Costs: Modular design and standardized components can streamline development processes.
• Future-Proofing: The adaptability of zonal architecture enables seamless integration of future advancements.

What could be the future...

It is impossible for architecture to go end of life due to legacy price and needs of different customer in different part of world. However, the evolution and software definition of the vehicle will continue in all kind of architecture. ?This will pave in modification upgradation and re-development of the vehicles to accommodate the cloud centric service that may need to be active to make driving safe and fuel efficient.

For example, new vehicles may see more IVN technologies replacing like CAN FD with a maximum data rate of 5 Mbit/S with CAN XL (extended length CAN), which operates up to 20 Mbit/S in the data phase, and/or 10Base-T1S (10Mbit/s single-pair Ethernet), which operates at a maximum rate of 10 Mbit/S or 100base with 100 Mbit/S in parts of domain or zones.

What may be seen is a convergence and evolution of both domain and zonal architectures in vehicle networks.

• Domains will remain a crucial aspect of vehicle network architecture, defining functional groupings.
• Zonal architecture will be integrated within domains, enhancing control and communication for specific functionalities.
• This convergence will create a more robust, adaptable, and efficient in-vehicle network architecture for the future of automotive.