Three-Conductor CAN-Bus Topology for High Data Rate Transmission

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Solution Overview

Problem

Current CAN-bus systems are limited by their modulation format, which restricts bandwidth efficiency and data rates, necessitating the use of sophisticated modulation techniques that require extensive modifications to the bus.

Innovation Solution

The proposed CAN-bus system employs a multi-conductor topology with at least three communication conductors and resistors between each pair of conductors, allowing for the modulation of multiple bits into a single symbol and enabling higher bit rates without extending the arbitration phase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If sophisticated modulation techniques like QPSK and m-QAM are employed to enhance bandwidth efficiency and data rates, then data transmission capability is improved, but device complexity and implementation difficulty increase significantly

Engineering Contradiction:
Improvedata rateVSAvoidmodulation technique complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of the communication system by transitioning from a two-conductor to a three-conductor CAN-bus topology. This structural parameter change enables the system to achieve higher bandwidth efficiency and data rates through the additional degree of freedom provided by the third conductor, without requiring complex modulation schemes like QPSK or m-QAM. The three-conductor configuration allows for more signaling states and improved spectral efficiency while maintaining implementation simplicity.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the sampling time in the arbitration phase is increased to ensure proper arbitration between nodes, then arbitration reliability is improved, but data transmission rate deteriorates

Engineering Contradiction:
Improvearbitration reliabilityVSAvoiddata rate
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the communication functions by utilizing the three conductors to separate arbitration signaling from data transmission. The additional conductor provides dedicated pathways that allow arbitration to proceed reliably while simultaneously enabling higher data rates during the transmission phase. This segmentation of functions across multiple conductors resolves the trade-off between arbitration reliability and data rate.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By adding a third conductor dimension to the CAN-bus system, the patent creates additional signaling dimensions that decouple the arbitration phase timing constraints from the data transmission rate. The extra dimensional space provided by the third conductor allows for parallel or differentiated signaling paths, enabling faster data transmission without compromising arbitration reliability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If two conductors are used with distinct voltage levels to encode bits, then implementation simplicity is maintained, but bandwidth efficiency and data rate are limited

Engineering Contradiction:
Improveimplementation simplicityVSAvoidbandwidth efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent merges multiple signaling functions into the three-conductor configuration, combining the benefits of simple voltage-level encoding with enhanced bandwidth efficiency. By integrating the additional conductor into the existing CAN-bus architecture, the system maintains ease of implementation while achieving superior data transmission capability through the combined effect of the three-conductor topology.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The transition from two to three conductors adds a spatial dimension to the signaling system. This dimensional expansion provides additional voltage level combinations and signaling states that increase bandwidth efficiency while preserving the simplicity of voltage-level encoding. The third conductor creates a three-dimensional voltage space that enables more information to be transmitted per unit time without complicating the basic encoding mechanism.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP4572240A1Can-bus-system for transmitting data between can-nodes
Publication Date: 2025.06.18 CARIAD SE
  • EP4572240A1 patent drawingFigure 1~2
  • EP4572240A1 patent drawingFigure 3~4
  • EP4572240A1 patent drawingFigure 5~6

AI summary

The invention relates to a CAN-bus-system for transmitting data between CAN-nodes, comprising at least the following components: - a CAN-bus with a plurality of communication-conductors; - at least two CAN-nodes which are in a data-transmitting connection by means of the communication-conductors; and - at least one resistor between each two of the communication-conductors. The CAN-bus-system is characterized in particular by the fact that the CAN-bus comprises at least three communication-conductors. A CAN-bus-system with at least three communication-conductors is provided, which makes it possible to send communication messages with more than three different symbols.