Master Hello Packet Activation Count for Multihop Key Sync

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Solution Overview

Problem

In a multihop communication system, a slave that communicates with a master via another slave as a relay station cannot directly determine the operating state of the master, leading to potential issues when the encryption key is updated, causing communication failures.

Innovation Solution

A communication device in the multihop system transmits a 'hello' packet with activation count information, allowing slaves to determine the cumulative activation state of the master, enabling them to update their encryption keys and maintain communication effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the master changes the encryption key upon activation, then security is improved, but slaves cannot determine whether to use the updated key, causing communication failures

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidkey update information
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces an intermediary information element (activation count) that mediates between the master's key update action and the slave's key selection decision. This intermediary allows indirect communication of the master's state to slaves through relay nodes, resolving the information asymmetry problem.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The master provides feedback to slaves about its activation state through the activation count field in hello packets. This feedback mechanism enables slaves to make informed decisions about key usage based on the master's current state, preventing communication failures.

Inventive Principle:
Principle #23Feedback

2Area of stationary object

If slaves relay hello packets through intermediate nodes, then network coverage is improved, but slaves cannot directly obtain master's operating state information

Engineering Contradiction:
Improvenetwork coverageVSAvoidmaster state information
Core Design Contradiction:
Area of stationary objectVSLoss of information

Solution Approach 1:

The hello packet is designed to serve multiple functions: it announces the master's presence, provides activation count information, and enables key update synchronization. This multi-functional design ensures that even when relayed through intermediate nodes, the packet carries all necessary information for slaves to determine master state.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The activation count is incremented and included in hello packets before slaves need to make key selection decisions. This preliminary provision of state information ensures that when slaves receive the packets (even through relays), they have the necessary information to synchronize with the master's current state.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If activation count information is transmitted in hello packets, then key synchronization is improved, but packet size and processing complexity increase

Engineering Contradiction:
Improvekey synchronizationVSAvoidpacket processing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The activation count information is merged into the existing hello packet structure rather than being transmitted as a separate message. This combination leverages the already-established hello packet transmission mechanism, adding functionality without requiring additional communication overhead or complex processing protocols.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3358782B1Communication device, multihop communication system, and communication method
Publication Date: 2021.12.22 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP3358782B1 patent drawingFigure 1
  • EP3358782B1 patent drawingFigure 2
  • EP3358782B1 patent drawingFigure 3

AI summary

A communication device that operates as a master (10) and is included in a multihop communication system (100) includes: a first communicator (11) that transmits a hello packet to at least one slave included in the multihop communication system (100); and a first controller (12) that causes the first communicator (11) to transmit activation count information that indicates a cumulative activation count of the communication device, the activation count information being included in the hello packet.