Packet-Based Clock Distribution With Propagation Delay Compensation
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Solution Overview
Problem
In distributed computing environments, synchronizing time across multiple computing devices is challenging due to independent notions of time, leading to difficulties in determining the priority of conflicting requests and the complexity of existing synchronization techniques like NTP, which are not sufficiently accurate or scalable.
Innovation Solution
A method is employed to transmit a clock signal within network packets, adjusting for propagation delay using a round-trip packet, and embedding additional information such as authentication and timestamps to ensure synchronized timing across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NTP is used to synchronize time across distributed computing devices, then time synchronization is achieved, but accuracy is insufficient and system complexity increases
Solution Approach 1:
The patent replaces the software-based NTP protocol with a hardware-based clock signal distribution system. Clock signals are transmitted through dedicated clock distribution networks using hardware circuits, eliminating the need for complex software timestamp exchange and calculation mechanisms. This substitution of hardware for software provides both higher accuracy and reduced complexity.
Solution Approach 2:
The patent extracts the clock signal transmission function from the general data communication network and creates a separate dedicated clock distribution network. By separating the time synchronization function from data traffic, the system achieves higher precision without the complexity of negotiating time protocols over shared communication channels.
2Measurement precision
If clock signals are transmitted through a distributed network, then time synchronization is provided across devices, but propagation delay causes timing inaccuracies
Solution Approach 1:
The patent measures propagation delay in advance by transmitting test clock signals through the distribution network and calculating the round-trip time. These pre-measured delay values are stored and used to compensate for timing offsets in subsequent clock signal transmissions, eliminating the need for real-time delay calculation and providing continuous accurate synchronization.
Solution Approach 2:
The patent implements a feedback mechanism where clock signals are transmitted to downstream devices, and the transmission delay is measured and fed back to the source device. The source device uses this feedback information to adjust future clock signal transmission timing, continuously compensating for propagation delays and maintaining synchronization accuracy.
3Reliability
If only clock signals are transmitted without additional information, then transmission simplicity is maintained, but authentication and validation capabilities are lost
Solution Approach 1:
The patent merges the clock signal transmission with data packet transmission by embedding clock signals within existing network protocol packets. Authentication metadata and validation information are combined with the clock signal in the same packet structure, allowing simultaneous transmission of timing information and security credentials without requiring separate communication channels.
Solution Approach 2:
The patent creates a universal packet structure that serves multiple functions: carrying clock signals for synchronization, embedding authentication metadata for security validation, and transporting timing information for timestamp generation. This multi-functional packet design eliminates the need for separate protocols for each function.
Data Source
AI summary
A clock signal in a clock distribution network is transmitted using network packets with the clock signal embedded within a bit of the network packets. The clock signal is adjusted to account for propagation delay in transmitting the clock signal throughout a clock distribution network. The propagation delay is computed using a round-trip packet. When a previous clock signal is received, a timer is set to a local clock's estimate of when the next clock signal will occur minus the propagation delay to the downstream device. When this timer expires, the clock signal is sent to the downstream device, which will allow it to arrive at the downstream device at the same time as the next clock signal is received on the local device.