Mesh Network Clock Synchronization Using Temperature Calibration
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Solution Overview
Problem
In low power consumption networks, devices often rely on precise clocks to synchronize communication, but precise clocks are expensive and power-intensive, while wider time slots for imprecise clocks are inefficient in bandwidth usage and increase receiver power consumption.
Innovation Solution
Adaptive synchronization is achieved by storing a calibration curve for oscillators based on temperature, adjusting it using calibration points, and using received timing information to adjust local clocks, allowing for reduced guardband times and keep alive intervals when clocks are synchronized, thereby reducing power usage and improving bandwidth efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If precise clocks are used at each transmitter and receiver, then time slot alignment is maintained, but cost and power consumption increase
Solution Approach 1:
The patent uses inexpensive, low-power oscillators instead of precise clocks at each node. These cheap oscillators drift over time but the system compensates through adaptive synchronization and guard bands, making the expensive precise clocks unnecessary while maintaining communication reliability
Solution Approach 2:
The system dynamically adjusts guard band durations and time slot parameters based on observed clock drift rates. By changing these temporal parameters adaptively, the system maintains synchronization despite using imprecise oscillators, resolving the contradiction between precision and power consumption
2Reliability
If wider time slots are used to accommodate imprecise clocks, then communication remains effective, but bandwidth efficiency decreases and receiver power consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of time slot parameters and guard bands based on actual clock drift observations. Rather than using fixed wide time slots, the system adapts the timing parameters to match the actual drift characteristics, maintaining reliability while improving bandwidth efficiency
Solution Approach 2:
The system uses feedback from timing information exchanged between nodes to continuously monitor and adjust synchronization parameters. This feedback mechanism allows the system to maintain effective communication with tighter time slots by compensating for drift through adaptive parameter adjustment
3Reliability
If longer time slots are used for imprecise clocks, then sufficient overlap is maintained for communication, but receiver power consumption increases due to longer listening periods
Solution Approach 1:
The system performs preliminary calibration and characterization of oscillator drift rates during manufacturing or initial operation. This preliminary action allows the system to pre-configuring appropriate guard bands and time slot parameters that maintain communication overlap while minimizing receiver activation time and power consumption
Data Source
AI summary
Timing synchronization for mesh networks is disclosed. A temperature calibration data is received. A plurality of previously stored calibration values each corresponding to different temperatures is adjusted based at least in part on the received temperature calibration data. A temperature measurement is received. A first clock offset is determined based at least in part on the adjusted plurality of previously stored calibration values and the temperature measurement.