Satellite Switching Uplink Timing Advance Acquisition
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Solution Overview
Problem
In non-terrestrial networks, frequent satellite handovers and feeder link switching due to satellite mobility lead to significant signaling overhead, particularly in acquiring uplink synchronization after satellite switching without changing the physical cell identifier (PCI).
Innovation Solution
The proposed solution involves a satellite switching method where a terminal obtains uplink timing advance (TA)-related information from a first satellite for a second satellite during satellite switching, allowing for prompt synchronization without changing the PCI. This includes obtaining network-controlled common TA information or terminal-estimated TA information, and using it to determine and apply the appropriate uplink TA for communication with the second satellite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If satellite switching is performed without changing PCI to reduce signaling overhead, then signaling overhead is reduced, but uplink synchronization acquisition becomes difficult
Solution Approach 1:
The network pre-configures UL TA-related information (including common TA values, change amount parameters, epoch time, and ephemeris data) in the terminal before satellite switching occurs. This preliminary provisioning enables the terminal to rapidly calculate and apply the correct UL TA for the target satellite without requiring extensive signaling during the actual handover, thus resolving the contradiction between reduced signaling overhead and maintained synchronization reliability
Solution Approach 2:
The patent introduces UL TA-related information as an intermediary element that carries essential timing synchronization data from the network to the terminal. This intermediary information structure (containing common TA, change amount parameters, epoch time, and ephemeris) acts as a bridge that enables the terminal to derive accurate UL TA values for switched satellites without direct real-time signaling, thus maintaining reliability while minimizing signaling overhead
2Reliability
If traditional handover procedures are used to ensure reliable synchronization, then uplink synchronization is reliably acquired, but signaling overhead increases
Solution Approach 1:
The patent extracts the essential UL TA-related information (common TA, change amount parameters, epoch time, ephemeris) from the traditional handover signaling process and pre-provisions it in the terminal. By taking out these critical synchronization parameters from real-time handover signaling and providing them in advance, the system maintains reliable synchronization acquisition while dramatically reducing the signaling overhead required during actual satellite switching events
3Adaptability or versatility
If satellite switching is performed frequently due to satellite mobility, then network coverage is maintained, but service interruption time increases
Solution Approach 1:
The network performs preliminary configuration of UL TA-related information for multiple potential target satellites in advance, including common TA values, change amount parameters, epoch time, and ephemeris data. When satellite switching is triggered by mobility, the terminal can immediately calculate and apply the correct UL TA using pre-provisioned information, enabling rapid synchronization with the new satellite and minimizing service interruption time while maintaining continuous network coverage
Solution Approach 2:
The patent implements a dynamic satellite switching mechanism where the terminal can rapidly adapt to different satellites by calculating UL TA values based on pre-configured parameters and current satellite ephemeris. This dynamic capability allows frequent satellite switches to maintain network coverage while the pre-provisioned information structure enables each switch to occur quickly, reducing the time loss associated with frequent handovers
Data Source
AI summary
The present disclosure provides a satellite switching technique in a non-terrestrial network. A method of a terminal may comprise: obtaining, from a first satellite, uplink (UL) timing advance (TA)-related information for a second satellite; performing satellite switching from the first satellite to the second satellite; and performing communication with the second satellite based on the UL TA-related information.