Aerial UE Mobility State Estimation via Altitude-Based Cell Tiering
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Solution Overview
Problem
In wireless communication systems, especially in 5G networks, aerial user equipment (UE) experiences frequent handovers/reselections due to its high altitude, leading to incorrect mobility state estimation and application of wrong speed-related parameters, resulting in estimation errors.
Innovation Solution
The method involves configuring tier groups for neighbor cells based on their distance from the serving cell, with UE counting cell changes only when moving to cells in a tier group with a tier value equal to or above a threshold, and using this information to estimate its mobility state, taking into account the UE's altitude to differentiate between aerial and ground UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE counts all cell changes for mobility state estimation, then the mobility state can be tracked, but aerial UEs experience estimation errors due to frequent handovers caused by high altitude
Solution Approach 1:
The patent applies local quality by differentiating cell groups based on their distance from the serving cell. Cells are divided into a first group (closer cells with tier value below threshold) and a second group (farther cells with tier value equal to or above threshold). The UE selectively counts cell changes only when moving to the second group, thereby adapting the counting criterion to the local spatial characteristics of cell deployment and UE altitude, which resolves the estimation error for aerial UEs.
2Measurement precision
If the UE uses tier values to differentiate cell groups, then mobility estimation accuracy improves, but the device complexity increases due to additional configuration and detection mechanisms
Solution Approach 1:
The patent applies preliminary action by having the network pre-configure tier values for neighbor cells before the UE performs mobility measurements. The serving cell provides information about neighbor cells including their tier values, allowing the UE to have the classification structure ready in advance. This eliminates the need for the UE to perform complex real-time calculations, reducing device complexity while maintaining estimation accuracy.
3Measurement precision
If the UE detects altitude and adjusts counting behavior, then estimation accuracy for aerial UEs improves, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent introduces tier values as an intermediary that mediates between the physical quantity (altitude) and the mobility state estimation. Instead of requiring the UE to directly measure and interpret altitude, the network provides tier values that already encode the relationship between cell distance and UE altitude characteristics. The UE simply uses these pre-processed tier values to determine whether to count cell changes, significantly reducing the difficulty of detection and measurement.
Data Source
AI summary
Provided are a method of estimating mobility state of UE and a device supporting the method. According to one embodiment of the present disclosure, the method includes: receiving information on neighbor cell from a serving cell, wherein the information informs to which group the neighbor cell belongs; performing cell change from the serving cell to the neighbor cell; when the neighbor cell belongs to a first group, counting the cell change; when the neighbor cell belongs to a second group, skipping counting the cell change; and reporting a number of counted cell change for estimating mobility state of the UE, wherein the first group and the second group are configured based on altitude of the UE.