Mesh Network Time Synchronization via Dynamic Listening Windows
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Solution Overview
Problem
In mesh networks, time synchronization between nodes becomes increasingly inaccurate and delayed as the hop count from the root node increases, leading to power consumption issues and potential loss of synchronization, which affects reliable communication among nodes.
Innovation Solution
A technique that involves receiving periodic beacons from nodes, calculating a listening window based on the receive time, jitter uncertainty, and drift uncertainty, allowing nodes to maintain synchronization without matching local timing, thereby reducing power consumption and resource overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nodes use tree-based hierarchy with parent-child connections for time synchronization, then time synchronization can be established among nodes, but timing errors and delays accumulate as hop count from root node increases
Solution Approach 1:
The patent divides the time synchronization problem into independent pairwise synchronizations between neighboring nodes rather than a hierarchical chain. Each node independently synchronizes with its neighbors using bidirectional communication, eliminating the cumulative timing errors that occur in tree-based hierarchies where errors propagate from root to leaves through multiple hops.
Solution Approach 2:
The patent introduces a listening window mechanism as an intermediary that allows nodes to capture timing information from neighboring nodes' beacons. This listening window acts as a mediator that enables direct time synchronization between neighbors without requiring propagation through intermediate parent-child relationships, thus avoiding cumulative delays.
2Reliability
If nodes listen for beacons for extended periods to accommodate timing uncertainties, then time synchronization reliability improves, but power consumption increases
Solution Approach 1:
The patent makes the listening window duration dynamic by calculating it based on actual timing uncertainties (jitter and drift) observed in the network. Rather than using a fixed extended listening period, the system adapts the listening window size to match the actual synchronization needs, allowing nodes to conserve power when uncertainties are small while maintaining reliability when uncertainties are large.
Solution Approach 2:
The patent changes the parameter of listening window duration from a static value to a dynamically calculated value based on jitter uncertainty and drift uncertainty. This parameter adaptation allows the system to optimize the trade-off between synchronization reliability and power consumption by adjusting the listening window size according to actual network conditions.
3Reliability
If nodes match local timing of root node through hierarchical synchronization, then time synchronization is achieved, but device complexity and resource overhead increase
Solution Approach 1:
The patent inverts the traditional hierarchical synchronization approach by having each node independently synchronize with its neighbors rather than having all nodes synchronize to a root node through parent-child relationships. This inversion simplifies the synchronization logic at each node, eliminating the need to maintain complex hierarchical timing relationships while achieving the same synchronization goal through simpler peer-to-peer interactions.
Data Source
AI summary
Techniques for performing time synchronization within a network include a method comprising: determining, by a first node, a receive time at which a periodic beacon from a second node is expected to be received based on timing information associated with the second node; determining, by the first node, a first listening window for the periodic beacon based on the receive time and one or more of a drift uncertainty associated with an anticipated drift in a correction of a timing error between the first node and the second node or a jitter uncertainty associated with timing jitter in the first node or the second node; and listening, by the first node, for the periodic beacon during the first listening window.