NTN Timing Advance Control for Long-Delay Satellite Transmission
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Solution Overview
Problem
The challenge of achieving reliable communication in non-terrestrial networks (NTNs) with ultra-long distances and high-speed base station movements, such as in satellite systems, due to the extended point-to-point distances and rapid satellite movement speeds, is not adequately addressed by conventional terrestrial cellular systems.
Innovation Solution
A transmission method involving the use of timing advance (TA) related information, including target values and adjustment parameters, to facilitate accurate transmission timing in NTN systems, utilizing various information carriers like system information, random access responses, and RRC messages, to account for satellite-specific characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional terrestrial cellular system timing methods are used, then communication is simple and straightforward, but timing alignment becomes inaccurate due to ultra-long distances and high-speed satellite movement
Solution Approach 1:
The network device pre-calculates and provides timing advance (TA) information to the terminal before actual transmission occurs. This TA information includes target values and adjustment parameters that enable the terminal to proactively adjust its transmission timing, compensating for the effects of satellite movement and long propagation delays before they cause misalignment.
Solution Approach 2:
The system implements a feedback mechanism where the network device monitors transmission timing and provides continuous TA adjustment information to the terminal. This feedback loop allows dynamic correction of timing alignment based on current satellite position and movement, ensuring accurate synchronization despite the challenging NTN environment.
2Measurement precision
If timing advance information is provided frequently and precisely, then transmission timing accuracy improves, but signaling overhead and system complexity increase
Solution Approach 1:
The TA information is provided in a targeted and differentiated manner. The network device determines which terminals require TA adjustments and provides specific adjustment parameters only to those terminals, rather than broadcasting comprehensive timing information to all terminals. This localized approach reduces unnecessary signaling overhead while maintaining precise timing control where needed.
Solution Approach 2:
The system uses compact parameter representations for TA information, including target values and adjustment parameters that efficiently encode timing data. By optimizing the parameter structure and using differential encoding where applicable, the system reduces the amount of signaling required while maintaining the precision needed for accurate timing alignment.
Data Source
AI summary
A transmission method, a terminal, and a network device are provided. The transmission method is applied to a non-terrestrial network (NTN) system and includes: receiving, by a terminal, first information which includes timing advance (TA) related information; determining, by the terminal, a TA for transmission from the TA related information; and performing, by the terminal, transmission based on the TA, wherein the TA related information indicates a target value of a TA offset parameter and a target value of a TA parameter; the first information is carried in system information.