One-Way Delay Time Estimation for Clock Synchronization
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Solution Overview
Problem
Existing methods for synchronizing clocks between two hosts without direct timing information from a satellite or base station are limited by low utilization due to the need for expensive equipment and have accuracy limitations, particularly in estimating one-way delay time using the mid round-trip value method.
Innovation Solution
A method and apparatus for estimating one-way delay time by measuring transmission times at both hosts, calculating time differences, and determining a value equal to or less than the calculated one-way delay time, which can be used for improved clock synchronization, even in environments without direct timing information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the mid round-trip value method is used to estimate one-way delay time, then clock synchronization can be achieved without expensive satellite reception equipment, but the synchronization accuracy is limited to no better than one half the round-trip delay time
Solution Approach 1:
The patent divides the round-trip delay measurement into multiple one-way delay measurements by introducing a third host and measuring delays in different directions (A→B, B→A, A→C, C→A). This segmentation allows the system to calculate more accurate one-way delay times without requiring expensive satellite equipment, thereby resolving the contradiction between low cost and high accuracy.
Solution Approach 2:
The patent introduces a third host (C) as an intermediary to facilitate more accurate delay measurements. Host C acts as a mediator that enables the calculation of one-way delay times between hosts A and B by providing additional measurement paths, thus improving synchronization accuracy without increasing equipment costs.
2Measurement precision
If satellite timing information is used for clock synchronization, then high synchronization accuracy can be achieved, but expensive reception equipment such as antennas is required
Solution Approach 1:
The patent replaces expensive satellite reception equipment with ordinary network communication infrastructure. By using standard network packets and hosts to measure and calculate delay times, the system achieves high synchronization accuracy using cheap, readily available components instead of expensive satellite antennas and receivers.
Solution Approach 2:
The patent substitutes the physical satellite reception system with a software-based network measurement system. Instead of using hardware antennas to receive satellite timing signals, the system uses network packets transmitted between hosts to measure delay times and achieve clock synchronization, replacing a mechanical/physical system with an information-processing system.
3Measurement precision
If multiple transmission time measurements are performed between hosts, then more accurate one-way delay time estimation can be achieved, but the complexity of the synchronization protocol increases
Solution Approach 1:
The patent designs a universal synchronization protocol where each host performs multiple functions: acting as a client requesting delay measurements, a server providing measurements, and a calculator processing results. This multi-functionality allows the same basic protocol structure to be used for all delay measurements between different host pairs, reducing overall system complexity despite performing multiple measurements.
Data Source
AI summary
An apparatus for and method of estimating a one-way delay time between two hosts and an apparatus and method of clock synchronization using the same. The two hosts are connected to a network and communicate a predetermined packet; k-th, (k+1)-th, and (k+2)-th transmission times are measured at the first host, and k-th, and (k+1)-th transmission times are measured at the second host; a time difference of the m-th transmission time is measured at the first and second host, where m is k or k+1, and by using the measured transmission times, an m-th one-way delay time is calculated. If the time difference is identical to the calculated one-way delay time, a value equal to or less than the calculated one-way delay time is determined as the estimated one-way delay time. Accordingly, the estimation error of a one-way delay time is reduced for both symmetrically and asymmetrically connected hosts.