UE Location-Based Paging for Moving NTN Cells
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Solution Overview
Problem
The challenge of reusing terrestrial NR and LTE tracking area concepts in Non-Terrestrial Networks (NTN) is complicated by moving satellites and cells, leading to dynamic cell-ID to TA associations and fuzzy TA borders, which complicates core network and radio access network interactions.
Innovation Solution
A UE-centric approach where each UE tracks its location using GNSS and informs the network of its registration area, allowing the network to map this area to cells for paging, eliminating the need for broadcast TAs and enabling stepwise paging based on the UE's location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional location tracking methods (LAC/RAI) are used for paging, then network infrastructure complexity is maintained, but location accuracy deteriorates to cell-level precision only
Solution Approach 1:
The patent introduces a Location Management Function (LMF) entity as an intermediary between the UE and the gNBs. The LMF receives positioning requests from the AMF, determines appropriate positioning methods, and coordinates the positioning process between UEs and multiple gNBs. This intermediary handles the complexity of location tracking centrally, allowing individual gNBs to maintain simpler architectures while achieving accurate UE location determination through coordinated measurements across multiple network nodes.
2Productivity
If cell-level location tracking is used, then network complexity is reduced, but paging efficiency deteriorates due to inability to select specific paging occasions
Solution Approach 1:
The patent implements preliminary location determination before the paging process. The AMF obtains UE location information in advance (at least at RRC_inactive state), which enables it to pre-determine the appropriate paging occasion and paging message routing. This preliminary action allows the network to efficiently direct paging messages to specific UEs based on their known locations, improving paging efficiency without requiring complex real-time location tracking during the paging event itself.
3Measurement precision
If continuous location tracking is implemented, then location accuracy is maintained, but energy consumption increases for both network and device
Solution Approach 1:
The patent implements periodic location tracking rather than continuous tracking. The AMF determines whether to trigger location tracking based on whether the UE is in idle or inactive state, and only initiates location determination when needed for paging operations. The location information is updated periodically or event-driven (e.g., when UE transitions between states), rather than continuously, thereby maintaining sufficient location accuracy for paging purposes while significantly reducing energy consumption compared to continuous tracking.
4Measurement precision
If multiple gNBs coordinate for location tracking, then location accuracy improves, but signaling overhead increases
Solution Approach 1:
The patent merges the location tracking and paging functions at the AMF level. Instead of having separate signaling paths for location tracking and paging, the AMF combines these operations by determining UE location as part of the paging preparation process. The LMF consolidates positioning requests from multiple gNBs and coordinates measurements in a unified manner, reducing redundant signaling while maintaining the benefits of multi-gNB coordination for improved location accuracy.
Data Source
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AI summary
A method performed by a wireless device in a wireless communication network includes obtaining geographic location information indicating a geographic location in which the wireless device is located, providing the geographic location information to a network node, and receiving a paging message from the wireless communication network based at least in part on the geographic location information. A method performed by a network node includes obtaining, from a wireless device, a geographic location associated with the wireless device, determining, in response to obtaining the geographic location of the wireless device, at least one cell of the wireless communication network that covers the geographic location associated with the wireless device, and transmitting a paging message to the wireless device in the at least one cell.