RRC Connection Cell Selection Handling in LTE
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Solution Overview
Problem
Current LTE system specifications do not clearly define how mobile devices in RRC_Connected mode should handle cell selection when a cell is barred or reserved, leading to issues such as handover failures, radio link failures, and unnecessary power consumption.
Innovation Solution
A method for mobile devices to ignore access barring information when in RRC connection with a cell, and to perform RRC connection re-establishment procedures when a cell is determined to be barred, thereby avoiding handover and connection failures and maintaining data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE in RRC_Connected mode follows the cell barring status indication, then the cell selection behavior is standardized, but handover and connection re-establishment procedures fail
Solution Approach 1:
The patent applies different cell selection behaviors based on the UE's RRC state. In RRC_Connected mode, the UE ignores cell barring status for handover and re-establishment purposes, while in RRC_Idle mode, the UE follows the standard cell barring behavior. This local differentiation resolves the contradiction by allowing reliable handovers in connected mode without affecting idle mode cell selection.
Solution Approach 2:
The patent introduces dynamic behavior adjustment based on RRC state transitions. The UE dynamically changes its cell selection strategy depending on whether it is in RRC_Connected or RRC_Idle mode, allowing the system to adapt cell selection behavior to current operational requirements and avoid handover failures.
2Reliability
If the UE continuously monitors cell status in RRC_Connected mode, then connection reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic cell status monitoring only when necessary for RRC connection maintenance, rather than continuous monitoring. The UE monitors cell status at intervals appropriate for connection re-establishment needs, reducing power consumption while maintaining connection reliability through periodic assessments rather than constant monitoring.
3Adaptability or versatility
If the E-UTRAN bars a cell for resource management, then idle mode UEs avoid the cell, but connected mode UEs cannot be handed over to the cell
Solution Approach 1:
The patent applies different interpretations of cell barring status based on the target UE's current mode. For idle mode UEs, the cell barring status is respected and they avoid the cell. For connected mode UEs, the barring status is ignored for handover purposes, allowing the E-UTRAN to maintain resource management flexibility while ensuring handover reliability.
Data Source
AI summary
A method of handling cell selection for a mobile device in a wireless communication system is disclosed. The method includes when the mobile device has a radio resource control (RRC) connection with a cell and receives access barring information corresponding to a barred state of another cell, ignoring the access barring information.