Network Clock Offset Measurement via Ping-Pong Byte Exchanges
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Solution Overview
Problem
Software-only solutions for clock synchronization in networks face limitations due to 'system noise' and high jitter, while hardware solutions like IEEE 1588 are expensive and difficult to modify, making them unsuitable for microsecond-level synchronization.
Innovation Solution
A method involving a 'ping pong' series of single-byte exchanges between network nodes, where each exchange has a unique byte value, allowing for private timestamp recording and return, simplifying timeout recovery and reducing latency by eliminating the need for re-initialization after a timeout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If software-only solutions are used for clock synchronization, then cost and ease of modification are improved, but synchronization accuracy deteriorates due to system noise and high jitter
Solution Approach 1:
The system performs preliminary actions by sending multiple timing messages before the actual timestamp measurement is needed. The client sends a series of timing messages to the server, and the server prepares timestamp data in advance, reducing the impact of system noise during the critical measurement moment.
Solution Approach 2:
The patent implements continuous timestamp collection and averaging over multiple exchanges. Instead of relying on a single timestamp measurement that is susceptible to jitter, the system continuously exchanges timing messages and averages the results, maintaining useful action throughout the measurement process to reduce random errors.
2Measurement precision
If hardware solutions like IEEE 1588 are used, then synchronization accuracy is improved, but cost and device complexity increase
Solution Approach 1:
The patent replaces hardware-based timestamping mechanisms with software-based timestamping. The system uses software to capture timestamps at the application layer rather than relying on specialized hardware timestamping circuits, thereby reducing device complexity while maintaining acceptable synchronization accuracy through statistical averaging.
Solution Approach 2:
The system creates multiple copies of timing messages and timestamp data through repeated exchanges. By sending multiple identical timing message sequences and collecting multiple timestamp sets, the system uses data redundancy to compensate for the lack of specialized hardware, achieving accurate measurements through software-based replication.
3Measurement precision
If multiple timestamp exchanges are performed, then measurement precision is improved through averaging, but loss of time increases due to additional communication rounds
Solution Approach 1:
The system implements periodic timestamp exchanges at optimized intervals. Rather than continuous exchanges that would waste time, the system performs exchanges at periodic intervals that balance the need for accurate averaging with the cost of communication delays, sending timing messages at regular intervals sufficient to reduce jitter impact.
Solution Approach 2:
The patent applies partial action by performing a limited number of timestamp exchanges (e.g., 3-7 rounds) rather than excessive exchanges. This number is sufficient to achieve the desired accuracy level through averaging while avoiding unnecessary communication overhead, representing the optimal point where additional exchanges provide diminishing returns.
Data Source
AI summary
In an exemplary aspect, method, apparatus, and program products are disclosed suitable for clock offset determination. One method includes performing a number of exchanges of at least single bytes with another network node, where values of the single bytes are different for the exchanges. The method also includes capturing and storing timestamps for each of the number of exchanges performed on the network node. A second method includes capturing and saving arrival timestamps for each of a number of timing messages in a set of timing messages received from another network node. This second method also includes sending the timestamps to at least the another node in response to completion of the set of timing messages.