CoAP over Ethernet LAN for Resource-Constrained Devices

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Solution Overview

Problem

Conventional CoAP implementations are resource-consuming for very low-end devices and lack support for multicast capabilities, particularly in automotive and industrial applications, due to the use of UDP or DTLS protocols.

Innovation Solution

Implementing CoAP directly over the data link layer of a local area network (LAN) protocol such as Ethernet, without requiring secure Internet Protocol transport, using MACsec for security at Layer 2, allowing larger message sizes and supporting multicast capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional CoAP is implemented over UDP or DTLS, then secure Internet Protocol transport is provided, but resource consumption increases and multicast capabilities are lost

Engineering Contradiction:

Improvesecure transportVSAvoidresource consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts CoAP from the IP-based transport layer (UDP/DTLS) and places it directly on the data link layer (Ethernet). This removes the unnecessary IP and transport protocol overhead for local area network communications, reducing resource consumption while maintaining security through MACsec at layer 2.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces MACsec as an intermediary security mechanism at the data link layer, replacing the need for IP-based security protocols. MACsec provides encryption and authentication for Ethernet frames, enabling secure CoAP communications over LAN without requiring UDP or DTLS.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If conventional CoAP is implemented over UDP, then Internet protocol transport is provided, but multicast capabilities and larger message sizes are limited

Engineering Contradiction:

Improvemulticast capabilityVSAvoidprotocol stack complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the IP layer and UDP transport layer from the protocol stack, placing CoAP directly on Ethernet. This extraction eliminates IP address requirements and enables native Ethernet multicast support, while also allowing larger message sizes up to the Ethernet frame limit.

Inventive Principle:

Principle #2Taking out (Extraction)

3Quantity of substance

If CoAP is implemented for very low-end devices, then resource constraints are addressed, but conventional CoAP implementations remain too resource-consuming

Engineering Contradiction:

Improvedevice resourcesVSAvoidprotocol overhead

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

The patent adopts a simplified protocol approach that uses lightweight Ethernet frames instead of bulky IP packets. By eliminating redundant protocol headers and using MAC addresses instead of IP addresses, the implementation reduces memory requirements and processing overhead, making CoAP viable for very low-end devices with limited resources.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS11902406B2Data communication using Constrained Application Protocol over local area network

Publication Date: 2024.02.13 NXP BV

AI summary

A system for data communication between electronic devices comprises a first electronic device that is a resource-constrained device; and a second electronic device that exchanges data with the first electronic device. One of the first electronic device and the second electronic device generates a message in a data unit frame complying with a protocol stack that includes a Constrained Application Protocol (CoAP) message on a data link layer in the absence of a User Datagram Protocol (UDP) layer.