UE Mobility State Detection for Adaptive Cell Reselection
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Solution Overview
Problem
There is a need for efficient methods to determine the mobility state in wireless communication systems, particularly in advanced mobile communication systems like 5G and beyond, to support the increasing demands of connected devices and diverse services.
Innovation Solution
A method and device for user equipment (UE) in a wireless communication system that receives configuration information for cell reselection, determines mobility state based on threshold values related to cell reselection count or movement distance, and performs cell reselection accordingly, using information such as size of count value, threshold values, or movement distance-based thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mobility state determination uses multiple parameters (cell reselection count, movement distance, time period), then measurement precision is improved, but device complexity increases
Solution Approach 1:
The mobility state determination is segmented into multiple independent measurement dimensions: cell reselection count measurement, movement distance measurement, and time period measurement. Each dimension is measured separately using specific configuration parameters (N_CR, T_CRmax, sf_M, sf_H, Q_CRmax), allowing the system to achieve high measurement precision through multi-parameter analysis while managing complexity by treating each parameter as a separate measurable entity that can be configured and processed independently
Solution Approach 2:
The system employs parameter changes by introducing multiple configurable parameters (N_CR for cell reselection count threshold, T_CRmax for time period, sf_M and sf_H for speed-dependent scaling factors, Q_CRmax for quality threshold) that can be adjusted based on UE mobility characteristics. This allows the mobility state determination to adapt to different scenarios (low mobility, medium mobility, high mobility) by changing parameter values rather than changing the fundamental measurement approach, thereby improving precision without proportionally increasing complexity
2Reliability
If cell reselection is performed frequently to track mobility state, then reliability is improved, but loss of time increases
Solution Approach 1:
The system implements periodic cell reselection actions based on the time period parameter T_CRmax, which defines the maximum evaluation period for mobility state determination. Instead of continuous or event-driven reselection, the UE performs cell reselection measurements periodically at intervals defined by T_CRmax, which reduces unnecessary reselection operations while maintaining reliable mobility tracking. The periodic action is triggered by timers and configured parameters, ensuring that reselection occurs at optimal intervals rather than continuously
Solution Approach 2:
The system performs preliminary measurements and evaluations before actual cell reselection is executed. The UE continuously monitors cell quality parameters (Q_CRmax) and accumulates cell reselection counts (N_CR) during the evaluation period T_CRmax, preparing mobility state information in advance. This preliminary action allows the system to determine mobility state and trigger reselection only when necessary, improving reliability by having measurements ready while minimizing time loss by avoiding premature or unnecessary reselection operations
Data Source
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AI summary
The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. Specifically, the present disclosure relates to a method performed by a user equipment (UE) in a wireless communication system, and the method may comprise the steps of: receiving, from a base station, configuration information for cell reselection, the configuration information including information for determining a mobility state of the UE; determining the mobility state on the basis of the configuration information for the cell reselection; and performing the cell reselection on the basis of the determined mobility state, wherein the information for determining the mobility state of the UE includes at least one of information on a cell reselection count-based threshold value for determining the mobility state on the basis of size information indicating sizes of count values for respective one or more times of cell reselection performed by the UE during a predetermined time interval and a sum of the count values, and information on a traveling distance-based threshold value for determining the mobility state on the basis of a distance travelled by the UE for the predetermined time interval, and the mobility state is determined on the basis of the cell reselection count-based threshold value and the sum of the count values for the respective one or more times of cell reselection, the count values having sizes indicated by the size information, or is determined on the basis of the distance travelled by the UE for the predetermined time interval and the traveling distance-based threshold value.