Propagation Delay Measurement in Point-to-Multipoint Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In networked systems, synchronizing clocks within a node is challenging due to unaccounted delays in distributing a local clock signal, leading to module-dependent timestamp offsets that are difficult to compensate for, especially when delays vary over time or involve internal buffers.
Innovation Solution
A method and system for measuring propagation delay in a multi-point communication system by generating a timing signal from a central module, transmitting it to line cards with local time counters, receiving timing responses, and calculating propagation delay based on the responses to synchronize clocks accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a local clock signal is distributed from a central module to multiple modules within a node, then clock synchronization is achieved, but propagation delays cause module-dependent timestamp offsets that are difficult to compensate for
Solution Approach 1:
The patent replaces direct time signal distribution with a measurement and compensation approach. Instead of relying on perfect signal distribution, the system measures propagation delays using timing messages and compensates for them computationally, substituting physical signal synchronization with mathematical correction
Solution Approach 2:
The system implements feedback by measuring the actual propagation delay through timing messages exchanged between the central module and line cards, then using this measured delay information to adjust and compensate timestamp values, creating a closed-loop synchronization system
2Measurement precision
If propagation delay compensation is implemented, then timestamp accuracy improves, but system complexity increases due to additional measurement and compensation mechanisms
Solution Approach 1:
The timing messages serve multiple functions: they are used both for normal time synchronization and for measuring propagation delays. This multi-functionality reduces the need for separate measurement infrastructure, thereby limiting the increase in system complexity while still achieving accurate delay compensation
3Measurement precision
If timing messages are exchanged between central module and line cards, then propagation delay can be measured, but communication overhead increases
Solution Approach 1:
The same timing messages used for clock synchronization are also utilized for propagation delay measurement. This approach avoids sending additional dedicated measurement messages, thereby achieving accurate delay measurement while minimizing increases in communication overhead
Data Source
AI summary
A system and method for measuring a propagation delay in a point to multipoint network. The system includes a central timing module which provides a timing signal to a plurality of line cards. Each of the line cards includes a local clock that is frequency locked to a 1588 clock and is configured to generate a return timing signal to the central timing module after a predetermined number of clock cycles. The central timing module measures the propagation delay based on the clock cycles of the local clock counted before the return signal is generated and the period of the local clock.