Cell Service Timer Based Cell Selection in Non-Terrestrial Networks
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Solution Overview
Problem
In non-terrestrial networks, especially those with Earth Moving Beams (EMB), efficient cell selection and reselection are challenging due to high satellite speeds and large distances between satellites and User Equipment (UE), making traditional Reference Signal Received Power (RSRP)-based methods insufficient for maintaining continuous communication services.
Innovation Solution
A method and apparatus for UE that compares cell service timers with neighboring cells, configures a candidate cell set based on satellite service timers, and performs connection establishment procedures, incorporating variable measurement configurations to optimize cell selection and reselection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional RSRP-based cell selection method is used in NTN, then the method is simple to implement, but it cannot provide sufficient performance due to high satellite speeds and large distances
Solution Approach 1:
The patent changes the selection parameter from RSRP (signal strength) to cell service timer (time-based parameter). This parameter change allows the system to account for satellite movement and coverage duration, improving reliability in high-speed NTN environments without requiring complex additional measurements
Solution Approach 2:
The patent introduces dynamic timer-based cell selection where the cell service timer is updated based on satellite position, UE movement, and coverage characteristics. This dynamic approach adapts to changing conditions in NTN, improving performance while maintaining manageable complexity through standardized timer mechanisms
2Reliability
If frequent cell measurements are performed to ensure continuous service in EMB-based NTN, then service continuity is improved, but power consumption and signaling overhead increase
Solution Approach 1:
The patent implements periodic cell service timer updates based on satellite orbital parameters and coverage predictions rather than continuous measurements. This periodic approach maintains service continuity by anticipating cell availability changes while significantly reducing measurement frequency, thereby lowering power consumption
Solution Approach 2:
The patent performs preliminary cell service timer configuration based on satellite ephemeris data and predicted coverage areas before the UE actually needs to switch cells. This advance preparation enables seamless handovers without requiring frequent real-time measurements, reducing both power consumption and signaling overhead
3Reliability
If cell service timer-based selection is implemented in EMB-based NTN, then service continuity is improved, but the complexity of timer management and configuration increases
Solution Approach 1:
The patent makes the cell service timer a universal parameter used for multiple purposes: cell selection, cell reselection, handover triggering, and service continuity maintenance. This multi-functionality reduces the need for separate mechanisms, simplifying overall timer management despite the enhanced capabilities provided
Solution Approach 2:
The patent introduces the cell service timer as an intermediary parameter that mediates between satellite orbital dynamics and UE cell selection decisions. This intermediary abstracts the complexity of satellite movement and coverage changes, providing a simple timer-based interface for cell management while maintaining service continuity
4Measurement precision
If satellite service timer is used for candidate cell configuration, then cell selection accuracy is improved, but signaling overhead for timer configuration increases
Solution Approach 1:
The patent extracts the cell service timer configuration from frequent signaling exchanges and incorporates it into periodic system information broadcasts or RRC messages. This extraction reduces signaling overhead by consolidating timer information transmission while maintaining accurate cell selection capabilities through the timer values
Data Source
AI summary
In a method and device for cell (re)selection in an EMB-based non-terrestrial network. the method of a UE includes the steps of: configuring a candidate cell set which is a set of one or more neighboring cells having a cell timer value greater than the sum of a cell service timer value of a serving cell and a second value among at least one neighboring cell; selecting a candidate cell among the one or more neighboring cells on the basis of the SAT service timer value of each of the one or more neighboring cells belonging to the candidate cell set; and performing a procedure for configuring a connection with the candidate cell.