User Equipment Cell Reselection in Non-Terrestrial Networks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Non-terrestrial network (NTN) cells exhibit low signal strength variation from cell center to cell edge, making signal strength-based cell reselection ineffective, and cell switching due to satellite movement or load optimization complicates UE reselection, as traditional methods struggle to distinguish cell center from edge or predict cell availability.
Innovation Solution
Implementing location-assisted and time-assisted cell reselection techniques for UE, where UE configures to exclude cells with short serving time, apply relaxed measurements based on proximity to the serving cell, and use thresholds for cell selection, such as excluding cells with remaining serving time less than a threshold or applying relaxed measurements for low mobility or close proximity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If signal strength-based cell reselection is used in NTN cells, then the cell reselection process can be simplified, but the ability to distinguish between cell center and cell edge is lost due to low signal strength variation
Solution Approach 1:
The patent introduces location information as an additional dimension beyond signal strength for cell reselection decisions. By combining signal strength measurements with location data (such as GPS coordinates or inferred position from serving cell identity), the system can distinguish between cell center and cell edge even when signal strength variation is minimal, thus resolving the contradiction between simplified operation and measurement precision.
Solution Approach 2:
The patent uses location information as an intermediary parameter that mediates between the simplified cell reselection process and the need for precise cell center/edge distinction. Instead of relying solely on signal strength (which shows minimal variation in NTN cells), the location intermediary provides the necessary discrimination capability while maintaining process simplicity.
2Adaptability or versatility
If traditional cell reselection methods are used in NTN, then the system can operate with existing protocols, but cell switching due to satellite movement complicates UE reselection and predicts cell availability poorly
Solution Approach 1:
The patent applies preliminary action by having the network provide advance information about cell availability and satellite movement to the UE. This allows the UE to proactively prepare for cell reselection before the serving cell becomes unavailable, improving reliability of cell availability prediction while maintaining compatibility with existing protocols through standardized information exchange mechanisms.
Solution Approach 2:
The patent implements feedback mechanisms where the network provides information about satellite movement, cell switching events, and serving cell status to the UE. This feedback enables the UE to make more reliable cell reselection decisions by understanding upcoming cell availability changes due to satellite motion, while still operating within existing protocol frameworks.
3Measurement precision
If UE performs measurements on all candidate cells, then cell selection accuracy is maximized, but measurement overhead and power consumption increase
Solution Approach 1:
The patent applies local quality by differentiating measurement requirements based on UE location. Instead of uniformly measuring all candidate cells regardless of position, the system adjusts measurement behavior according to whether the UE is near cell centers or cell edges, and based on proximity to known cell boundaries. This location-aware approach maintains cell selection accuracy while reducing unnecessary measurements and associated power consumption.
Solution Approach 2:
The patent changes measurement parameters dynamically based on location information. When the UE is determined to be in a region where full measurements are unnecessary (e.g., clearly within a serving cell's coverage area with strong signal), the system adjusts measurement parameters to reduce overhead. This adaptive parameter adjustment maintains accuracy where needed while minimizing energy consumption elsewhere.
Data Source
AI summary
A method performed by a user equipment (UE) configured to communicate via a network including a non-terrestrial network portion is disclosed. The method comprises performing a procedure. The procedure includes performing measurements with respect to at least one cell in a set of candidate cells; and performing a cell selection based on a result of the measurements. The procedure is performed based on at least one parameter for the at least one cell including at least one of remaining serving time of each of the at least one cell, distance between a current location of the UE and each of the at least one cell, distance between the current location of the UE and a serving cell, and mobility of the UE.