Passive Synchronization for Multi-Sink LLN Routing

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Solution Overview

Problem

Conventional routing methods for low-power and lossy wireless networks (LLNs) are not optimized for multi-sink routing and lack synchronization, leading to inefficiencies and increased overhead, particularly in large-scale deployments where packet losses are common and retransmissions increase network traffic.

Innovation Solution

Nodes in the LLN can synchronize with multiple data sinks without transmitting synchronization packets by receiving packets from neighboring nodes, using either active or passive synchronization methods, which reduce communication overhead and allow for adaptive switching between data sinks without updating synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional routing methods are used in LLNs, then multi-sink routing can be implemented, but synchronization overhead increases and network efficiency decreases

Engineering Contradiction:

Improvemulti-sink routing capabilityVSAvoidsynchronization overhead

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Nodes perform passive synchronization by autonomously observing and processing synchronization packets transmitted by other nodes or data sinks, without requiring active participation in synchronization exchanges. This self-service approach allows nodes to derive synchronization information from existing network traffic, eliminating the need for dedicated synchronization transmissions and reducing overall network overhead.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If active synchronization is performed by all nodes, then synchronization accuracy improves, but communication overhead increases

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidcommunication overhead

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

Instead of requiring all nodes to perform active synchronization, the system implements partial action where only certain nodes (such as data sinks or gateway nodes) actively transmit synchronization packets, while other nodes perform passive synchronization by observing these packets. This selective approach achieves sufficient synchronization accuracy for network operations without the excessive overhead of universal active synchronization.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If multiple copies of data are transmitted to multiple data sinks, then reliability improves, but network overhead becomes excessive

Engineering Contradiction:

Improvedata delivery reliabilityVSAvoidnetwork overhead

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The system merges data transmission with synchronization operations by carrying synchronization information within existing data packets transmitted to multiple data sinks. This combining approach allows nodes to simultaneously achieve data delivery reliability through multi-sink transmission and synchronization without requiring separate synchronization message exchanges, thereby reducing overall network overhead while maintaining both reliability and synchronization accuracy.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9226253B2Passive synchronization in wireless networks

Publication Date: 2015.12.29 MITSUBISHI ELECTRIC RESEARCH LABORATORIES INC

AI summary

A method for synchronizing a node to a data sink determines a first time of receiving by the node a packet transmitted by a neighboring node and a second time of receiving by the data sink or a synchronized neighboring node the packet transmitted by the neighboring node. The node is synchronized to the data sink based on the difference between the first time and the second time.