Why Legacy Distributed ECU Architectures Are Being Replaced

Modern passenger vehicles routinely contain over 100 separate electronic control devices — a fact documented in Sonatus’s patent filings — resulting in networks densely distributed throughout the vehicle, multiple overlapping connection paths, and significantly more hardware than is needed simply to connect devices. The traditional distributed ECU approach, where each function such as window control, powertrain management, or ADAS resides in its own dedicated ECU, produces excessive ECU counts, complex hardware interface wiring, and non-unified software development at the base layer. As Shanghai Qifanggke Technology’s 2025 patent states directly, these characteristics are incompatible with the demands of increasingly intelligent vehicles.

The patent corpus analyzed here spans over 50 filings and applications across China, the United States, Germany, Japan, South Korea, and WIPO. The dominant technical theme is the transition away from these legacy designs toward consolidated computational topologies. Two competing — and increasingly converging — approaches dominate: centralized (central computing platform) architectures and zonal architectures. Leading assignees include Aptiv Technologies, Sonatus Inc., Robert Bosch GmbH, Toyota/Woven by Toyota, Rivian IP Holdings, Marelli, Denso Corporation, and numerous Chinese OEMs such as GAC, Zeekr (零束科技), Xiaomi Automotive, SERES, and FAW Jiefang.

The technical debate centers on how to simultaneously minimize wiring harness complexity, consolidate compute resources, support software-defined vehicle features, and enable functional safety. The answer, as the patent record shows, is not a single winner — it is an architectural convergence that borrows from both paradigms.

Centralized E/E Architecture: Compute Consolidation by Function

Centralized E/E architecture consolidates vehicle control logic into one or more high-performance central computing units (CCUs) that serve as the primary processing hub for the entire vehicle, grouping ECUs and compute resources by functional domain rather than physical location. Audi AG’s 2022 patent for a Central Computing Unit for a Motor Vehicle describes a processor capable of operating at least two different functional systems of a motor vehicle simultaneously, featuring standardized connection interfaces for multiple predetermined component types and executing recognition routines to identify connected functional components — a plug-and-play paradigm where a single compute node logically governs diverse vehicle functions.

At the software layer, centralization enables Service-Oriented Architecture (SOA). Woven by Toyota’s 2024 service-oriented data architecture patent describes a central computing system that executes multiple virtual machines (VMs) to isolate different vehicle services. Microservices are self-contained, standardized independently of programmed functionality, and interoperate via a unified communication plane spanning both VM and mechatronics/sensor layers. This architecture directly enables over-the-air (OTA) updates and rapid feature deployment without hardware changes — a core requirement for software-defined vehicles, as recognized by standards bodies including ISO in their work on automotive software frameworks.

Zeekr Technology (零束科技) provides a layered taxonomy for centralized architectures in its 2023 patent, decomposing the vehicle E/E system into four layers: a minimum control system layer (basic safe driving functions), a standard control system layer (platform-configurable standard features), a customer-specific layer, and a value-added software services layer. Critically, the minimum control layer can independently govern vehicle operation if higher layers fail — embedding fault tolerance directly into the architecture’s design philosophy.

Xiaomi Automotive Technology’s 2024 domain control architecture illustrates the hardware substrate of centralized design: an architecture that integrates a Vehicle Control Unit, Ethernet switch, PCIe switch, and functional domain processors via PCIe and Ethernet, forming a central computing platform that pools compute, communication, and storage resources across all functional domains. This domain-centric approach routes all inter-domain communication through a central gateway — a design that maximizes compute consolidation but can create overlapping communication paths at scale.

Zonal E/E Architecture: Geographic Distribution and Power-Data Integration

Zonal E/E architecture organizes ECUs and their connected devices according to their physical location in the vehicle rather than by functional domain — typically front-left, front-right, rear-left, rear-right, or similar geographic divisions — with each zone managed by a Zone Controller (ZC) that aggregates local sensors, actuators, and low-voltage loads, then communicates with a central compute node via a high-speed backbone network such as Ethernet. This geographic organizing principle is the fundamental departure from both legacy distributed and pure centralized approaches.

Robert Bosch GmbH’s 2022 Chinese patents formalize a three-tier zonal architecture: a compute layer (central vehicle computer), an intermediate layer (zone/regional controllers), and an execution layer (sensors, actuators, and ECUs). Zone controllers serve specifically as energy and data distributors, while actual control logic is executed at the central computer. This is the most cited structural framework for zonal E/E design in the patent corpus — a principle adopted implicitly across nearly all hybrid CCU+ZCU implementations analyzed. According to IEEE publications on automotive networking, Ethernet-based backbone architectures such as those described in these patents are becoming the industry standard for high-bandwidth vehicle communication.

Aptiv Technologies has developed the Power and Data Center (PDC) as the hardware node for zonal deployment. Across at least six active Korean and Chinese patents spanning 2019–2023, the PDC functions as a combined data concentrator and power distributor delivering scalable network and power redundancy. In smart E/EA implementations, the vehicle is divided into zones, each containing one or more PDCs supplying and aggregating sensors and actuators. Sensors provide data to the PDC through cost-efficient, short-range data links, and actuators receive control data via a high-speed data bus from the PDC — eliminating the need for long-running wires from each device back to a central gateway. The ability to embed small ECU functions directly into PDC hardware reduces total ECU count per vehicle and decreases wiring between PDC and loads.

“Zone controllers serve specifically as energy and data distributors, while actual control logic is executed at the central computer — breaking and significantly simplifying the previously star-topology cable network and achieving considerably shorter wiring overall.”

Rivian IP Holdings’ 2025 German patents provide a production-oriented implementation of zonal logic. The vehicle is divided along its longitudinal axis into an eastern ECU (first side) and a western ECU (second side), with a third ECU at the rear. This left-right-rear zonal partitioning enables redundancy: if the primary east or west unit fails, the opposing unit or the rear ECU can assume backup operations. Rivian’s related circuit design patent further incorporates a low-voltage DC-DC backup circuit block within the eastern ECU, explicitly enabling backup operations in the event of primary unit failure — demonstrating that zonal architecture is not merely a wiring optimization but a functional safety mechanism.

Sonatus, Inc. has been particularly prolific in defining zonal architecture communication schemes, holding three active US and WO patents (2024–2025). Its architecture includes a network management controller overseeing a multi-zone network, where each zone manager controls communications between endpoints within its own zone and endpoints in at least one other zone — establishing inter-zone messaging without necessarily routing through the central node, a significant departure from purely hub-and-spoke centralized designs.

Head-to-Head: How the Two Architectures Differ Across Five Dimensions

Centralized and zonal E/E architectures differ not just in topology but in their implications for wiring, safety, software, and scalability. The table below summarizes the five most critical dimensions of comparison as documented across the patent corpus.

The Wiring Harness Argument: Different Mechanisms, Same Goal

Both architectures reduce wiring versus legacy distributed systems, but through fundamentally different mechanisms. FAW Jiefang’s 2023 patent on commercial vehicle E/E architecture makes the distinction explicit: in purely functional domain architectures, body controllers must connect to both cab components and chassis components, requiring large wiring runs from the cab to the chassis. Zonal sub-controllers for cab and chassis eliminate these long runs by ensuring each device connects only to its nearest zone controller. This geographic proximity principle is the core wiring advantage of zonal design — and it is independent of, and complementary to, the ECU count reduction achieved by centralized compute consolidation.

Diagnostic Architecture: A Window Into Hybrid Thinking

Jaguar Land Rover’s 2025 distributed diagnostic architecture patent illustrates how the two paradigms are being synthesized in practice. Application functions are hosted on a central computing platform (CCP) for system-level fault monitoring, while Remote Input/Output Concentrators (RIOs) — effectively zone nodes — perform component-level fault monitoring locally and report to a central Vehicle Diagnostic Manager (VDM). This division of diagnostic labor — system intelligence at the center, local sensing at the zone — mirrors the broader hybrid convergence trend.

Key Patent Assignees and the Emerging Hybrid Paradigm

The dominant trend in recent filings is convergence: a central computing platform (CCU/CCP) paired with geographically distributed zone controllers (ZCU), achieving software centralization and hardware distribution simultaneously. Chinese OEMs and technology companies — including Zeekr (零束科技), Xiaomi Automotive, GAC, NIO (蔚来), SERES (赛力斯), FAW Jiefang, and Beijing NEVTECH — collectively represent the largest volume of recent active or pending filings, almost uniformly targeting this hybrid CCU+ZCU architecture. This reflects the Chinese automotive industry’s rapid push toward software-defined vehicle platforms, a trend tracked by McKinsey and other industry analysts as one of the most significant shifts in global automotive R&D investment.

Langtu Automotive’s 2024 Vehicle Central Integrated Architecture patent defines the hybrid model directly: a central computing platform plus multiple zone controllers (front cabin ZCU, left cabin ZCU, right cabin ZCU), where software function modules within zone controllers can be individually enabled or disabled for customization across vehicle variants. This combination of centralized compute governance with zonal hardware distribution — and per-variant software configurability — represents the architecture that most recent filings are converging toward.

From the Tier-1 supplier perspective, Marelli’s 2025 Japanese patent explicitly notes that zone architecture, alongside domain and SOA architectures, is among the primary proposed responses to wiring harness complexity and component cost — framing the architectural choice not as a binary decision but as a set of complementary strategies that can be combined. Denso Corporation’s 2021 vehicle network system patent describes zone ECUs placed in each of a plurality of zones, each controlling devices installed in the corresponding zone, with a central ECU managing them collectively — a formulation that aligns with the Bosch three-layer model and has become the de facto reference architecture for zonal implementations across the industry, as reflected in filings submitted to patent offices tracked by EPO.