Dynamic Holdover Interval for Energy-Efficient Clock Synchronization
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Solution Overview
Problem
In distributed real-time computer systems, synchronizing local clocks with an external time reference while minimizing energy consumption is challenging, especially for battery-powered devices, as frequent synchronization with high-energy external references like GPS is required, leading to reduced battery life.
Innovation Solution
A method to dynamically determine the holdover interval (HOI) based on environmental conditions, allowing local clocks to operate independently for longer periods before synchronization, using a safety factor and drift rate calculations to adjust the granularity and extend the HOI, thereby reducing the frequency of energy-consuming synchronization events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequent synchronization with external reference time is performed, then timekeeping accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent implements dynamic adjustment of the holdover interval based on environmental conditions. The system monitors temperature and other environmental factors that affect oscillator stability, and adaptively extends or shortens the synchronization interval accordingly. When environmental conditions are stable, the system extends the holdover interval to reduce synchronization frequency and save energy. When conditions change, it shortens the interval to maintain accuracy, thus dynamically balancing accuracy and energy consumption.
Solution Approach 2:
The system changes the parameter of synchronization interval based on environmental conditions. By monitoring temperature and oscillator stability characteristics, the system adjusts the holdover interval parameter to optimize the trade-off between timekeeping accuracy and energy consumption. This parameter adaptation allows the system to operate efficiently under varying environmental conditions.
2Use of energy by moving object
If holdover interval is extended to reduce synchronization frequency, then energy consumption is reduced, but timekeeping accuracy deteriorates
Solution Approach 1:
The system employs feedback mechanisms by continuously monitoring environmental conditions (temperature, humidity) and oscillator performance metrics. Based on this feedback, the system dynamically adjusts the holdover interval to maintain timekeeping accuracy within acceptable bounds while minimizing synchronization frequency. The feedback loop ensures that accuracy requirements are met while optimizing energy consumption.
Solution Approach 2:
The system performs preliminary monitoring of environmental conditions and oscillator stability before determining the appropriate holdover interval. By assessing environmental factors in advance, the system can predict oscillator drift and set an appropriate synchronization interval that maintains accuracy without excessive synchronization events.
3Measurement precision
If environmental monitoring is performed continuously, then holdover interval accuracy is improved, but device complexity increases
Solution Approach 1:
Instead of continuous monitoring, the system performs environmental measurements periodically at predetermined intervals during the holdover interval. This periodic measurement approach provides sufficient data to assess environmental stability and adjust the holdover interval appropriately, while significantly reducing the computational and hardware complexity compared to continuous monitoring. The periodic sampling captures essential environmental variations without requiring constant resource allocation.
Data Source
Figure 1~2
AI summary
The invention relates to a method for synchronizing the clocks of the node computers of a distributed real-time system with an external time reference, such as GPS time, requiring minimal energy expenditure, and for structuring a sparse time-base. By considering the influence of changing physical environmental parameters on the period of oscillation of local oscillators, the holdover interval, according to which an external synchronization must occur, can be dynamically determined and the frequency of the energy-intensive external synchronization processes can be significantly reduced.