NTN Cell Reselection Using Distance Prediction
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Solution Overview
Problem
Current cell reselection methods in non-terrestrial networks often result in unnecessary measurements, leading to increased power consumption and inefficiency, especially when dealing with Earth-moving cells and overlapping terrestrial network coverages.
Innovation Solution
A method and apparatus for a terminal to acquire system information from a non-terrestrial network base station, determining whether to perform cell reselection based on distance comparisons with threshold distances and ephemeris information, and selectively obtaining and using terrestrial network coverage information to avoid unnecessary measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terminal performs cell reselection measurements based on distance threshold in NTN, then cell reselection accuracy is improved, but unnecessary measurements increase power consumption
Solution Approach 1:
The terminal performs preliminary actions by acquiring ephemeris information and predicting future distance changes before executing measurements. This allows the terminal to anticipate whether a measurement would be necessary, avoiding unnecessary power consumption while maintaining accurate cell reselection decisions.
Solution Approach 2:
The measurement execution is made dynamic by continuously monitoring distance changes and predicting future states. Instead of static threshold-based measurement triggering, the system adapts measurement decisions based on predicted distance trends, enabling the terminal to skip measurements when distances are predicted to remain above thresholds.
2Reliability
If the terminal continuously monitors distance and performs measurements, then cell reselection reliability is improved, but measurement redundancy increases inefficiency
Solution Approach 1:
The terminal performs preliminary distance prediction using ephemeris information before executing measurements. This preliminary action ensures that measurements are only performed when truly necessary, maintaining reliability by avoiding missed reselection events while eliminating redundant measurements that reduce overall efficiency.
Solution Approach 2:
The system implements feedback by continuously updating distance predictions based on ephemeris data and comparing predicted distances against thresholds. This feedback mechanism ensures reliable cell reselection decisions are made only when conditions warrant measurement, optimizing the balance between reliability and measurement efficiency.
3Loss of energy
If the terminal acquires and processes ephemeris information, then unnecessary measurements are reduced, but information processing complexity increases
Solution Approach 1:
The terminal performs preliminary processing of ephemeris information to predict future distances before measurement decisions are made. This upfront processing, while adding some complexity, eliminates the need for continuous measurement processing and reduces overall energy waste by avoiding redundant measurements.
Solution Approach 2:
The terminal uses its own computational resources to process ephemeris information and make autonomous measurement decisions. This self-service approach allows the device to optimize its own measurement behavior based on predicted conditions, reducing energy waste without requiring additional network infrastructure or external processing assistance.
Data Source
AI summary
A method of a terminal may comprise: acquiring, from a non-terrestrial network (NTN) base station, system information (SI) including information indicating either a (quasi-) Earth-fixed cell or an Earth-moving cell (EMC); in response to the SI indicating an EMC, calculating a first distance between a location of the terminal and a reference location; and determining whether to perform measurement for cell reselection based on a comparison result between the first distance and a threshold distance included in the SI and ephemeris information of a satellite included in the SI.