NTN Cell Reselection Using Distance Thresholds for Stability
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Solution Overview
Problem
Existing cell reselection methods based on S-criteria and R-criteria for non-terrestrial networks (NTN) with larger cell radii face challenges in configuring reasonable reselection parameters due to small differences in reference signal received powers or qualities at the cell's center and edge, leading to frequent back-and-forth reselections.
Innovation Solution
Implementing a reference distance threshold based on cell location information to determine the actual distance between the terminal and the cell center, combining this with existing S-criteria and R-criteria to guide cell reselection, ensuring stable network connectivity in NTN networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cell reselection is performed based on S-criteria and R-criteria in NTN networks with large cell radii, then the terminal can maintain network connectivity, but frequent back-and-forth reselections occur due to small differences in RSRP or RSRQ between cell center and edge
Solution Approach 1:
The patent introduces a distance threshold parameter to the cell reselection process. The terminal determines the actual distance to the cell center and compares it with the distance threshold. When the actual distance exceeds the threshold, the terminal prioritizes reselection to neighboring cells even if their RSRP/RSRQ values are similar to the current cell. This parameter change (adding distance consideration) resolves the contradiction by providing an additional criterion that prevents futile reselections between cells with similar signal quality, thereby improving reselection stability while maintaining network connectivity.
2Area of stationary object
If the cell radius is increased in NTN networks to cover larger areas, then the network coverage is improved, but the overlapping area of cells becomes larger leading to more frequent reselections
Solution Approach 1:
The patent applies a distance threshold parameter that is specifically adapted for NTN networks with large cell radii. By setting the distance threshold appropriately (e.g., based on cell radius or as a configurable parameter), the system allows terminals to remain in the current cell even when in overlapping areas with neighboring cells, as long as the actual distance to the cell center is within the threshold. This resolves the contradiction by providing stability control in large-cell scenarios without sacrificing the coverage benefits of large cell radii.
3Reliability
If the terminal frequently reselects cells based on small RSRP or RSRQ differences, then the terminal attempts to maintain optimal signal quality, but unnecessary measurements and reselections increase network overhead
Solution Approach 1:
The patent adds a distance threshold parameter that acts as a filter for cell reselection decisions. Before performing measurements and evaluating RSRP/RSRQ differences, the terminal checks whether the actual distance to the current cell center exceeds the distance threshold. If the distance is within the threshold, the terminal can skip detailed measurements and maintain the current cell, even if signal quality differences are small. This resolves the contradiction by reducing unnecessary measurements and reselections (improving network efficiency) while still allowing signal quality optimization when the terminal is in appropriate positions.
Data Source
AI summary
A method for cell reselection is performed by a terminal, and includes: obtaining a reference distance threshold of a cell and determining an actual distance between the terminal and a center of the cell; and performing cell reselection based on the reference distance threshold and the actual distance.