NTN Mobility Handover Using GNSS Status and Conditional Handover
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Solution Overview
Problem
Existing wireless communication systems face challenges in maintaining seamless mobility and minimizing handover interruptions in non-terrestrial networks (NTN) due to high path loss, interference, and the need for efficient ephemeris data management.
Innovation Solution
Implementing conditional handover (CHO) procedures with enhanced ephemeris data provisioning and beam management techniques to optimize handovers in NTN, allowing UEs to autonomously execute handovers based on predefined conditions and reduce data forwarding uncertainties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures are used in NTN, then handover execution can be completed, but handover failures increase due to insufficient time for GNSS measurement and timing advance calculation
Solution Approach 1:
The network node configures the UE with conditional handover (CHO) parameters and multiple candidate target cells in advance, before the actual handover is needed. This includes pre-configuring timing advance values and GNSS measurement requirements, so that when handover conditions are met, the UE can execute the handover immediately without time-consuming setup procedures.
Solution Approach 2:
The system dynamically adjusts handover parameters based on UE capability and GNSS availability status. The network node receives GNSS availability information from the UE and adapts the CHO configuration accordingly, selecting appropriate target cells and timing advance values that match the UE's current state and capabilities.
2Measurement precision
If the network waits for GNSS measurement completion before handover, then timing advance can be calculated accurately, but handover latency increases
Solution Approach 1:
The network pre-configures multiple candidate target cells with their respective timing advance values and ephemeris data before the UE needs to handover. This allows the UE to have timing advance information ready in advance, eliminating the need to wait for GNSS measurement completion before handover execution.
Solution Approach 2:
The UE autonomously determines whether to execute the conditional handover based on pre-configured conditions and its current GNSS availability status, without requiring real-time network intervention or waiting for network commands after conditions are met.
3Reliability
If the network provides detailed ephemeris data for multiple candidate cells, then handover execution accuracy improves, but signaling overhead increases
Solution Approach 1:
The patent extracts and transmits only the essential ephemeris data elements needed for timing advance calculation and handover execution, rather than providing complete orbital parameter sets. This selective extraction reduces the volume of signaling data while maintaining the accuracy needed for successful handover.
4Measurement precision
If the UE performs GNSS measurement during handover, then location accuracy improves, but handover interruption time increases
Solution Approach 1:
The UE and network configure GNSS measurement requirements and timing advance parameters in advance, before the handover is triggered. This allows the UE to have location information and timing parameters ready when the handover condition is met, minimizing interruption time while maintaining measurement accuracy.
Data Source
AI summary
According to some embodiments, a method is performed by a wireless device. The method comprises obtaining global navigation satellite system (GNSS) location information associated with the wireless device and transmitting a status of the GNSS location information to a network node. The status may comprise a remaining amount of time that the GNSS location information is valid.