5G Terminal Cell Search State Management
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Solution Overview
Problem
In a 5G network environment, User Equipment (UE) in an RRC_INACTIVE state may struggle to find a suitable cell when the cell signal is poor, leading to unmanageable and uncontrollable behavior, as existing technologies lack effective methods for controlling the state and context of the UE during cell selection and reselection.
Innovation Solution
A cell search method where the terminal device enters an arbitrary cell search state to find either an acceptable cell for restricted service or a suitable cell for normal service, with the option to start timers for managing the search process and context information, ensuring the UE's behavior is manageable and controllable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device follows cell selection and reselection principle in RRC_IDLE state when moving out of paging area, then the UE can resume RRC connection and re-obtain paging area, but when cell signal is not good, the UE may be unable to find a suitable cell to reside in and may enter an arbitrary cell search state
Solution Approach 1:
The patent applies dynamics by making the terminal device's cell search behavior adaptive and controllable through timer mechanisms. The device dynamically transitions between different search states (arbitrary cell search state with timers vs. conventional cell selection) based on whether a suitable cell is found within the timer period, allowing flexible adjustment of search persistence and enabling network-controlled behavior management in poor signal conditions
Solution Approach 2:
The patent changes the parameter of cell search behavior by introducing timer-based control mechanisms. The terminal device uses timers to limit the duration of arbitrary cell search, transforming the uncontrolled search process into a time-bounded, manageable operation. This parameter change enables the network to control UE behavior through timer configuration while maintaining the ability to find cells in poor signal conditions
2Adaptability or versatility
If the terminal device enters arbitrary cell search state to search for acceptable cell and/or suitable cell, then the UE can potentially find a cell to reside in even with poor signal, but the UE behavior becomes unmanageable and uncontrollable
Solution Approach 1:
The patent applies preliminary action by configuring timers before the terminal device enters arbitrary cell search state. The network pre-configures timer values that control the duration and behavior of the cell search process, establishing control mechanisms in advance. This preliminary timer configuration enables the device to execute controlled arbitrary cell search without real-time complex state management, reducing operational complexity while maintaining adaptability
Solution Approach 2:
The patent implements feedback through timer expiration events that provide information about cell search outcomes. When timers expire without finding a suitable cell, the terminal device receives feedback that triggers state transitions (e.g., returning to RRC_IDLE or adjusting search parameters). This feedback mechanism allows the network to manage UE behavior indirectly through timer configurations and expiration responses, simplifying state management while maintaining control
Data Source
AI summary
Provided are a cell search method and a terminal device. The method includes that a terminal device searches a cell to camp on, wherein the terminal device is in an inactive state, and searches for an acceptable cell and/or a suitable cell when the terminal device does not find any suitable cell to camp on, wherein the acceptable cell is a cell on which the terminal device is capable of camping and only obtaining a limited service, and the suitable cell is a cell on which the terminal device is capable of camping and obtaining a normal service, and when searching for an acceptable cell and/or a suitable cell, continues to maintain the inactive state and a timer, wherein the timer is a location update timer.