NTN-TN Handover Triggering at Service Boundaries
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Solution Overview
Problem
Existing communication networks face challenges in efficiently handling handovers between non-terrestrial and terrestrial networks, particularly in service boundary regions, due to complexities in measurement triggering, signaling, and determining handover timing.
Innovation Solution
A method and apparatus for handover between non-terrestrial and terrestrial networks that involve determining measurement triggering conditions based on proximity to service boundaries, measuring reception signal strengths, and performing handovers based on threshold comparisons, supported by user equipment and base stations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measurement triggering conditions are continuously monitored for handover between NTN and TN, then handover reliability is improved, but measurement complexity and terminal burden increase
Solution Approach 1:
The base station pre-configures measurement triggering conditions including service boundary information, signal strength thresholds, and measurement object lists before the terminal enters the handover region. This preliminary configuration allows the terminal to perform measurements only when specific conditions are met, reducing continuous monitoring burden while maintaining handover reliability
Solution Approach 2:
Different measurement configurations are provided for different regions: terminals in service boundary regions receive specific measurement objects and triggering conditions related to that boundary, while terminals in other regions receive different configurations. This localized approach reduces unnecessary measurements and terminal burden while ensuring reliable handover detection where needed
2Measurement precision
If comprehensive measurement objects are monitored for handover decision, then handover precision is improved, but signaling overhead increases
Solution Approach 1:
The base station provides differentiated measurement configurations based on terminal location and service boundary information. Terminals in service boundary regions receive measurement objects specific to that boundary, while terminals in other regions receive different or reduced measurement configurations. This reduces signaling overhead by avoiding transmission of unnecessary measurement object information while maintaining precise handover decisions where required
Solution Approach 2:
Measurement objects are segmented and organized by service boundary regions. The base station identifies which measurement objects are relevant to each terminal's current service boundary and provides only those specific measurements. This segmentation reduces the total number of measurements signaled to terminals while maintaining comprehensive coverage of all possible handover scenarios
3Loss of time
If measurement triggering is based on service boundary proximity, then handover timing accuracy is improved, but device complexity increases
Solution Approach 1:
The base station acts as an intermediary that receives positioning information from the terminal and processes service boundary proximity determination. Instead of requiring the terminal to independently calculate distances to service boundaries and make handover timing decisions, the terminal provides positioning data to the base station, which then determines proximity and triggers appropriate measurement configurations. This reduces terminal complexity while maintaining accurate handover timing
Solution Approach 2:
Service boundary information and positioning reference data are pre-configured in the base station before terminals enter service boundary regions. When terminals provide positioning information, the base station can immediately determine service boundary proximity without requiring complex real-time calculations at the terminal, thus achieving accurate handover timing while reducing terminal device complexity
Data Source
AI summary
A technology for handover between a non-terrestrial network and a terrestrial network may be provided. This method for a user equipment (UE) may be provided, the method comprising the steps of: determining whether or not a measurement triggering condition for measurement targets is satisfied; if the measurement triggering condition is satisfied as the result of the determination, measuring received signal strengths for the measurement targets; transmitting the measured received signal strengths to a base station; receiving, from the base station, a handover command based on the received signal strengths; and performing handover with one of the measurement targets, according to the handover command.