Fault-Tolerant Time Server for Distributed Real-Time Systems
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Solution Overview
Problem
Distributed real-time computer systems require a fault-tolerant global time synchronization method to ensure reliability in safety-critical applications, but existing solutions lack robustness in maintaining accurate and synchronized time across all components.
Innovation Solution
A time server system comprising four components with bi-directional communication channels, each equipped with an oscillator and local tick counter, uses a fault-tolerant clock synchronization algorithm to initialize and maintain synchronized time across the system, ensuring accurate time transmission and correction through start-up, internal, and external synchronization messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a global time synchronization system is implemented in a distributed real-time computer system, then time coordination across all computers is improved, but system complexity and vulnerability to failures increase
Solution Approach 1:
The time server is divided into four independent components, each with its own oscillator and local tick counter. This segmentation ensures that a failure in one component does not affect the others, maintaining system reliability while achieving global time synchronization through coordinated message exchange between components.
Solution Approach 2:
Each component maintains its own local time reference (oscillator and tick counter) rather than relying on a centralized time source. This local quality approach allows each component to independently track time while participating in the global synchronization protocol, improving both accuracy and fault tolerance.
2Reliability
If multiple components with local tick counters are used to achieve fault tolerance, then system reliability is improved, but device complexity increases
Solution Approach 1:
The four components are merged into a single logical time server entity that presents a unified time interface to external receivers. While physically distributed for fault tolerance, the components work together as an integrated system, managing complexity through standardized message protocols and coordinated operation.
Solution Approach 2:
Each component is designed with universal functionality, possessing its own oscillator, tick counter, and message handling capability. This multi-functionality allows any component to potentially serve as the primary time source, simplifying the overall architecture while maintaining reliability through redundancy.
3Measurement precision
If frequent synchronization messages are transmitted to maintain accurate global time, then time synchronization precision is improved, but communication overhead and energy consumption increase
Solution Approach 1:
Synchronization messages are exchanged at periodic intervals rather than continuously. The system uses predetermined synchronization points where components transmit their tick counter values, achieving adequate time synchronization accuracy while minimizing communication overhead and energy consumption between periodic updates.
Data Source
AI summary
The invention relates to a method for providing a fault-tolerant global time via a time server in a distributed real-time computer system, wherein the time server comprises four components which are connected to one another via a bi-directional communication channel. At a priori defined periodic, internal synchronization times, each of the four components transmits an internal synchronization message, which is simultaneously transmitted to the other three components, from which each internal computer of a component determines a correction term for the tick counter contained in its component and corrects the reading of the local tick counter by this correction term.