NTN Uplink Timing Control With Feeder-Link Reference Points
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Solution Overview
Problem
In non-terrestrial networks (NTN) such as satellite communications, the varying propagation delays due to satellite movement and high speeds pose challenges in accurately controlling transmission timing for signals, leading to potential inaccuracies in estimating satellite location and feeder link delays.
Innovation Solution
A method for improving transmission timing accuracy by using control information including satellite ephemeris and common TA parameters, with a terminal receiving and processing epoch time and reference point information to adjust transmission timing based on location and orbital data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional timing control methods are used in NTN, then device complexity is reduced, but transmission timing accuracy deteriorates due to varying propagation delays from satellite movement
Solution Approach 1:
The base station performs preliminary calculations of satellite position and propagation delay using ephemeris data before transmitting control information to the terminal. This allows the terminal to use pre-computed reference values rather than performing complex real-time calculations, thereby improving timing accuracy while limiting the increase in terminal device complexity.
Solution Approach 2:
The patent introduces an intermediary reference point (RP) in the feeder link between the base station and satellite. By defining timing control relative to this intermediary point rather than directly to the moving satellite, the system simplifies the timing reference framework while maintaining accuracy, as the RP serves as a stable reference that accounts for satellite movement effects.
2Measurement precision
If real-time satellite position tracking is implemented, then transmission timing accuracy is improved, but loss of time increases due to continuous calculation requirements
Solution Approach 1:
The base station calculates satellite position and propagation delay in advance using ephemeris information and transmits these pre-computed values to the terminal via control information. This eliminates the need for the terminal to perform time-consuming real-time calculations, thereby improving timing accuracy while reducing processing time loss.
Solution Approach 2:
The system dynamically updates satellite ephemeris data and recalculates propagation delays at appropriate intervals rather than continuously. This allows the system to maintain accurate timing control while avoiding excessive processing time consumption, adapting the calculation frequency to the actual rate of satellite movement.
3Reliability
If simple timing control is used without reference point information, then device complexity is reduced, but reliability deteriorates due to inability to compensate for propagation delay variations
Solution Approach 1:
The patent introduces an intermediary reference point (RP) in the feeder link as a mediator between the base station and the moving satellite. By defining timing control relative to this stable intermediary point rather than directly to the satellite's moving position, the system achieves reliable synchronization while maintaining a manageable control information structure. The RP acts as a reference that automatically compensates for propagation delay variations caused by satellite movement.
Solution Approach 2:
The base station performs preliminary calculations of the reference point timing and propagates this reference information to the terminal through control messages. This preliminary establishment of a stable timing reference enables reliable synchronization without requiring the terminal to implement complex real-time compensation algorithms.
Data Source
AI summary
This terminal comprises: a reception circuit that receives control information regarding a reference point for a reference time in control of the transmission timing of an uplink signal in a first cell to a second cell different from the first cell; and a control circuit that controls the transmission timing on the basis of the control information.