Timing Advance Prediction for Satellite Uplink Stability
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Solution Overview
Problem
In satellite communication, the rapid change in timing advance (TA) due to high-speed satellite movement leads to large overheads in closed-loop adjustment, and the long-time open-loop adjustment causes TA error accumulation and intersymbol interference, especially when transmission opportunities are discontinuous.
Innovation Solution
A communication method where a terminal device determines TA based on received TA information after a time domain start location, reducing TA error accumulation and intersymbol interference by aligning resource information with transmission opportunities, and performing closed-loop TA adjustment when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed-loop TA adjustment is used, then TA accuracy is improved, but signaling overhead increases
Solution Approach 1:
The terminal device performs open-loop TA adjustment in advance between discontinuous transmission opportunities, predicting TA changes based on historical data and satellite movement patterns. This preliminary action reduces the need for frequent closed-loop adjustments, thereby maintaining TA accuracy while reducing signaling overhead.
2Loss of information
If open-loop TA adjustment is used, then signaling overhead is reduced, but TA error accumulation increases
Solution Approach 1:
The system implements a hybrid feedback mechanism where the terminal device uses open-loop adjustment with periodic closed-loop corrections. The terminal monitors TA error trends and triggers closed-loop adjustments when error accumulation reaches a threshold, or when transmission opportunities occur, thereby controlling TA error accumulation while maintaining reduced signaling overhead.
3Area of stationary object
If transmission opportunities are discontinuous, then beam scanning coverage is improved, but TA synchronization deteriorates
Solution Approach 1:
The terminal device performs TA prediction and open-loop adjustment in advance before each transmission opportunity, using historical TA data and satellite ephemeris information. This preliminary synchronization action ensures TA accuracy is maintained even during discontinuous transmission, while the satellite can still perform comprehensive beam scanning.
Data Source
AI summary
This application provides a communication method and a communication apparatus, to reduce TA error accumulation caused by an open-loop adjustment manner, reduce intersymbol interference of an uplink signal, and improve stability of a communication system. In the method, a terminal device receives and obtains first configuration information, where the first configuration information includes time domain information of a first transmission opportunity; the terminal device sends a first signal, where the first signal is used to determine TA information; the terminal device obtains the TA information; and the terminal device determines a TA between the terminal device and a network device based on the TA information, where the TA is used for data transmission after a time domain start location corresponding to the time domain information of the first transmission opportunity.