NTN UE Positioning Using RSTD and Multi-Satellite Reports
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Solution Overview
Problem
Existing wireless communication systems, particularly in non-terrestrial networks like 5G NR, face challenges in accurately determining the location of user equipment (UE) due to the lack of efficient network-based positioning methods, which are crucial for supporting high-density mobile broadband users with low latency and low battery consumption.
Innovation Solution
Implementing network entities such as base stations and LMFs to transmit and receive location requests and reports, utilizing Reference Signal Time Difference (RSTD) measurements and timing advance reports from multiple satellites, to derive UE location accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If network-based positioning is implemented in non-terrestrial networks, then location accuracy is improved, but device complexity increases
Solution Approach 1:
The positioning function is segmented between the UE and network entities. The UE performs local measurements (RSTD, timing advance reports) while the network entities (LMF, base station) perform location derivation. This segmentation reduces the complexity burden on individual devices while maintaining high location accuracy through collaborative processing.
Solution Approach 2:
Measurement reports serve as intermediaries that carry positioning information between UEs and network entities. These standardized reports (containing RSTD measurements, timing advance reports, satellite location information) act as mediators that enable location derivation without requiring direct complex interactions between all system components.
2Measurement precision
If multiple satellites and timing advance reports are used for location derivation, then location accuracy is improved, but measurement and processing time increases
Solution Approach 1:
The network entity performs preliminary actions by requesting specific measurement types (RSTD, timing advance reports) and configuring measurement parameters before location derivation is needed. This allows UEs to prepare and collect required measurements in advance, reducing real-time processing time while maintaining accuracy through multiple satellites.
Solution Approach 2:
The system uses partial measurements (RSTD from selected satellites, timing advance reports) rather than requiring all possible measurements. This partial action approach achieves sufficient location accuracy without the time penalty of processing every conceivable measurement, optimizing the trade-off between precision and time.
3Adaptability or versatility
If location requests and reports are transmitted between network entities and UE, then location derivation capability is improved, but energy consumption increases
Solution Approach 1:
The UE performs self-service by autonomously measuring and reporting positioning information (RSTD, timing advance reports) without continuous network intervention. The UE independently collects measurements from multiple satellites and transmits only when location derivation is requested, reducing energy consumption compared to continuous monitoring while maintaining full location derivation capability.
Data Source
AI summary
Apparatuses, systems, and methods for UE location determination in a non-terrestrial network (NTN), e.g., in 5G NR systems and beyond. A network entity, such as base station and/or location management function, may be configured to transmit, to a UE, a location request. The network entity may be configured to receive, from the UE, at least one report associated with UE location. The at least one report may include Reference Signal Time Difference (RSTD) measurements of at least two DL-PRS transmissions and/or three or more reports (e.g., each report of the three or more reports may include a RSTD measurement. Further, the network entity may be configured to derive and/or calculate, based on the at least one report, UE location.