In-Vehicle Ethernet PHY Time Division Duplexing for Low-EMI Links
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Solution Overview
Problem
Conventional in-vehicle networks face issues with high cost, complexity, weight, and electromagnetic interference due to heterogeneous communication protocols and excessive cabling, which complicates communication between different vehicle domains.
Innovation Solution
Implementing a homogenous Ethernet network using unshielded twisted-pair cables with 3-bit packet streams and time division duplexing for automotive applications, which reduces EMI by slowing down data rates and allowing cheaper, lighter cabling, and using TDD for bidirectional communication over single coaxial cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heterogeneous communication protocols (LIN, FlexRay, CAN, LVDS, MOST) are used to support different latency and bandwidth requirements, then communication requirements are met, but device complexity and gateway requirements increase
Solution Approach 1:
The patent applies universality by using a single Ethernet protocol that can handle multiple communication requirements (different latency and bandwidth needs) through a unified infrastructure, eliminating the need for multiple specialized protocols and gateways. Ethernet serves multiple functions that previously required separate communication systems.
Solution Approach 2:
The patent merges multiple heterogeneous communication networks (LIN, FlexRay, CAN, LVDS, MOST) into a single homogeneous Ethernet-based network. This consolidation combines previously separate communication infrastructures into one unified system, reducing overall complexity while maintaining the ability to support diverse communication requirements.
2Adaptability or versatility
If extensive cabling is used to support conventional in-vehicle networks, then communication coverage is achieved, but weight and cost increase
Solution Approach 1:
The patent merges multiple cable systems into a single Ethernet cable infrastructure. By consolidating the cabling requirements for multiple protocols into one unified Ethernet network, the total amount of cabling is dramatically reduced, resulting in lighter weight and lower cost while maintaining full communication coverage across all vehicle domains.
3Productivity
If high data rates are used in Ethernet networks, then productivity improves, but electromagnetic interference increases
Solution Approach 1:
The patent applies parameter changes by carefully selecting and adjusting Ethernet data rate parameters to achieve an optimal balance between productivity and EMI. By modifying the data rate parameter to a level that provides sufficient bandwidth for in-vehicle communications while remaining below thresholds that generate excessive electromagnetic interference, the system achieves both high productivity and low EMI.
Data Source
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AI summary
Currently, there exists low power Ethernet PHY solutions running at 10 Gbps over twin-ax cables with SFP+ connectors. However, the cost and range of these cables, along with the size of the connectors, do not match the requirements of in-vehicle networks. If the cable is replaced with a single pair of shielded or coaxial cables, a different mechanism is needed to provide bi-directional communication. Time division duplexing (TDD) can be used to emulate full duplex communication over the single pair of cables by taking turns, in time, transmitting data over the pair of cables in each direction.