Moving-TRP UE Positioning With RTT, TDOA, AOA, and AOD
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Solution Overview
Problem
In non-terrestrial networks (NTN), the current methods for determining user equipment (UE) location, such as cell-based tracking area and GNSS, are not precise enough due to large cell sizes and the absence of GNSS in some UEs, respectively, making it challenging to apply country-specific regulations and positioning techniques like E-CID and TDOA.
Innovation Solution
A system and method for determining UE position using measurements with moving transmission reception points (TRPs), such as low earth orbit satellites, by performing RTT, TDOA, AOA, and AOD measurements, and utilizing TRP position information to estimate UE location through least square positioning equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cell-based tracking area method is used for UE positioning, then the system is simple to implement, but the positioning precision deteriorates due to large cell sizes in NTN
Solution Approach 1:
The patent segments the positioning measurement process into multiple components: RTT measurements between UE and multiple TRPs, TDOA calculations using reference signals, and AOA estimations. By dividing the positioning function into these separate measurement types and combining them through least square positioning equations, the system achieves precise positioning without requiring complex infrastructure changes.
Solution Approach 2:
The patent transitions from two-dimensional terrestrial positioning methods to three-dimensional positioning in NTN by incorporating satellite orbital parameters, elevation angles, and azimuth angles. This dimensional expansion allows accurate positioning despite large cell sizes by utilizing the vertical dimension and spherical geometry of satellite orbits.
2Measurement precision
If GNSS is used for UE positioning, then positioning precision is improved, but the method becomes inapplicable to UEs without GNSS equipment
Solution Approach 1:
The patent creates a universal positioning method that functions for both GNSS-equipped and non-GNSS UEs. The network-based RTT and TDOA measurements can be performed by any UE regardless of GNSS capability, while the system can optionally fuse with GNSS data if available. This multi-functional approach ensures broad compatibility across different UE types.
Solution Approach 2:
The patent introduces network infrastructure elements (gNBs, LMF, positioning reference signals) as intermediaries between the UE and the positioning function. Instead of relying on the UE's own GNSS receiver, the network mediates the positioning process by providing reference signals and processing measurements, enabling positioning for UEs without GNSS while maintaining high precision.
3Ease of manufacture
If traditional E-CID or TDOA methods are applied, then positioning can be performed, but accuracy deteriorates due to TRP movement in NTN
Solution Approach 1:
The patent dynamically adapts the positioning method to account for TRP movement by continuously updating satellite ephemeris data and orbital parameters. The system performs real-time calculations of TRP positions based on orbital mechanics, and adjusts the least square positioning equations accordingly. This dynamic adaptation maintains measurement precision despite the moving TRPs characteristic of NTN.
Solution Approach 2:
The patent performs preliminary actions by pre-calculating and providing assistance data to the UE before positioning measurements. This includes satellite orbital parameters, ephemeris information, and predicted TRP positions. By preparing this data in advance, the system enables accurate real-time positioning without requiring complex real-time tracking calculations, thus maintaining both ease of implementation and precision.
Data Source
AI summary
An apparatus for determining a position of a user device, UE, in a wireless communication system, the wireless communication system comprising one or more of moving transmission reception points, TRPs, wherein the apparatus is configured to: initiate one or more procedures to perform one or more measurements between the UE and the moving TRP, and to obtain one or more measurement results; and receive at least one message from the moving TRP comprising a position information of the moving TRP; wherein the apparatus is capable to estimate the position of the UE using the measurement result and the position of the moving TRP.