NTN Timing Advance via Cell Common Time Delay
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Solution Overview
Problem
Current NTN systems lack a suitable mechanism for establishing and maintaining timing advance, particularly due to the unique transmission time delays inherent in satellite communication systems, which affects the uplink transmission timing position of PRACH Preambles.
Innovation Solution
A method and device that determine timing advance by acquiring cell common time delay information, estimating relative transmission time delay, and calculating uplink timing advance, incorporating this information into the configuration message to adjust the uplink transmission timing position, ensuring accurate synchronization in NTN systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the current downlink timing position is taken as reference timing position with NTA=0, then the timing advance calculation is simplified, but the uplink transmission timing becomes delayed and cannot be applied to NTN systems
Solution Approach 1:
The patent changes the reference timing position from current downlink timing to a previous downlink timing position, and introduces a new parameter NTA that accounts for propagation time delay. This parameter change enables the timing advance calculation to accommodate the ultra-large propagation delays in NTN systems while maintaining computational feasibility through the formula: uplink transmission timing = reference timing - NTA - NTA offset
Solution Approach 2:
The patent performs preliminary calculation of the NTA parameter based on downlink propagation time delay before uplink transmission. By pre-determining the timing advance value using downlink timing information and propagation characteristics, the system prepares the correct uplink transmission timing in advance, avoiding real-time timing adjustments and ensuring accurate synchronization
2Ease of operation
If timing advance is not considered in NTN systems, then the system operation is simpler, but the uplink PRACH Preamble transmission timing is delayed and synchronization is lost
Solution Approach 1:
The patent introduces NTA as an intermediary parameter that mediates between downlink timing and uplink transmission timing. This intermediary accounts for the propagation time delay caused by the satellite link, allowing the system to maintain simple operation procedures while ensuring reliable synchronization through the timing relationship: uplink transmission timing = downlink reference timing - NTA - NTA offset
3Area of stationary object
If the cell radius is increased to cover larger areas in NTN, then the coverage area is improved, but the propagation time delay increases significantly
Solution Approach 1:
The patent changes the timing reference parameter from current downlink timing to previous downlink timing, and introduces NTA to compensate for propagation delay. This parameter change allows the system to maintain accurate timing synchronization even when the cell radius is increased to cover larger geographic areas, as the timing advance calculation explicitly accounts for the increased propagation time
Data Source
AI summary
The embodiments of the present application relate to a method and device for determining a timing advance, applied to the establishment of a timing advance in a random access process of an NTN system. The method in the embodiments of the present application includes: receiving and acquiring relevant parameters in a configuration message, and the relevant parameters include cell common time delay information; and determining, according to the cell common time delay information, an uplink timing advance of an uplink transmission timing position with respect to a configuration message receiving position. With regard to cell common time delay information existing in the NTN system, an uplink transmission timing position is determined, and a PRACH Preamble is sent in advance, so that the problem when applied to the establishment of the timing advance in the random access process of the NTN system is solved, and the calculation accuracy of the timing advance in a data transmission process after the random access process is ensured.