Time Offset Measurement for Non-Terrestrial Network Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In non-terrestrial networks (NTN), the ephemeris data transmitted by satellite control centers may be out of sync with the actual satellite position due to propagation delays and Doppler effects, leading to propagation errors.
Innovation Solution
A time offset measurement method that involves listening to downlink signals with known interval times, calculating reception time differences, and using satellite distance and movement functions to estimate the satellite's actual position, thereby calculating a broadcast time offset value to compensate for synchronization errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ephemeris data is transmitted by satellite control center to gNB, then network service coverage is expanded to remote areas, but propagation errors occur due to synchronization issues and variable transmission times
Solution Approach 1:
The patent implements a feedback mechanism where the user device measures the actual reception time of downlink signals and compares it with the expected reception time based on ephemeris data. The measured time offset is fed back to correct the ephemeris timing, thereby compensating for propagation delays and synchronization errors in the NTN network.
Solution Approach 2:
The patent replaces the traditional mechanical time synchronization system with an electromagnetic-based measurement system. Instead of relying on pre-calculated ephemeris timing, the system uses electromagnetic signal reception time measurement and offset calculation to dynamically determine the actual satellite position and timing.
2Measurement precision
If ephemeris data is used for satellite position estimation, then user device can determine satellite position, but frequency offset occurs due to Doppler effect and propagation delay
Solution Approach 1:
The patent introduces a time offset measurement mechanism as an intermediary between the ephemeris data and the actual satellite position estimation. The measured time offset acts as a mediator that corrects the discrepancy between ephemeris-based position estimation and actual satellite position, thereby reducing frequency offset caused by Doppler effect.
3Adaptability or versatility
If transmission time between NTN network components is variable, then network flexibility is improved, but time synchronization accuracy deteriorates
Solution Approach 1:
The patent implements a self-service time synchronization mechanism where each user device independently measures the time offset by listening to downlink signals and calculating the difference between expected and actual reception times. This self-measured offset is then used to correct local timing, eliminating the need for complex centralized time synchronization.
4Adaptability or versatility
If signal processing time of NTN network components is variable, then processing adaptability is improved, but event triggering synchronization deteriorates
Solution Approach 1:
The patent performs preliminary time offset measurement by having the user device listen to downlink signals and calculate the time offset before actual data transmission and event triggering. This pre-calculated offset is then applied to anticipate and correct synchronization issues in subsequent operations, ensuring proper event triggering timing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables synchronization of ephemeris data with the current satellite channel status, reducing frequency offsets caused by Doppler effects and improving the accuracy of satellite position estimation in NTN networks.
Implementation Method 1
listening to the first downlink signal and the second downlink signal respectively through the user device to obtain the first reception time and the second reception time, wherein the first downlink signal and the second downlink signal are signals with a known interval time
Implementation Method 2
obtaining multiple satellite movement time variations through dividing multiple satellite distance difference values by the electromagnetic wave propagation speed
Implementation Method 3
since the low earth orbit (LEO) satellite flies along a fixed orbit at a speed of 7.7 kilometers/second, plus the frequency offset caused by network propagation delay and Doppler effect
Data Source
AI summary
A time offset measurement method suitable for Non-Terrestrial Network includes: listening to the first downlink signal and the second downlink signal through the user device to obtain the first reception time and the second reception time; using the known interval time as the unit time length to calculate multiple satellite distance difference values corresponding to multiple unit time lengths through a satellite distance function, obtaining multiple satellite movement time variations through dividing multiple satellite distance difference values by the electromagnetic wave propagation speed, generating a satellite movement function based on each sampling time and each of the satellite movement time variations corresponding to each sampling time; setting the reception time difference to calculate the corresponding sampling time through the satellite movement function as the downlink signal reception time; and obtaining the current distance between the user device and the satellite at the second reception time according to the ephemeris data.