IRAT RRC Re-establishment with Timer Inheritance
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Solution Overview
Problem
Current wireless communication systems face challenges in handling radio link failures (RLFs) during Inter Radio Access Technology (IRAT) Radio Resource Control (RRC) re-establishment and IRAT resume procedures, especially in 5G communication systems with multiple radio access technologies.
Innovation Solution
The proposed solution involves a method for a User Equipment (UE) to detect RLFs and select a cell on a different Radio Access Technology (RAT) for RRC re-establishment, while ensuring that timers like T311 are inherited across RATs to facilitate seamless recovery. Additionally, the method allows for IRAT resume procedures to maintain the inactive state across different RATs connected to the same 5G Core (5GC).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs RRC re-establishment on a different RAT after detecting RLF on the original RAT, then service continuity can be maintained during inter-RAT transitions, but timer management becomes complex and may lead to RLF recovery failures
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with a second timer corresponding to the second RAT before RLF occurs. When RLF is detected on the first RAT, the UE can immediately start using the pre-configured second timer for the RRC re-establishment procedure on the second RAT, avoiding the complexity of timer conversion and ensuring timely recovery without waiting for timer calculations during the failure event.
2Ease of operation
If the UE inherits timer values from the first RAT to the second RAT, then RLF recovery can be facilitated across RATs, but timer value compatibility and accuracy may be compromised
Solution Approach 1:
The patent applies copying by creating a separate timer instance for the second RAT that is initialized with the appropriate value for that specific RAT. Instead of copying or converting timer values between different RAT systems which may have different timing characteristics, the UE maintains an independent timer for the second RAT, ensuring both ease of operation and timing accuracy specific to each RAT's requirements.
3Reliability
If the UE maintains inactive state across different RATs during IRAT resume procedure, then service continuity is improved, but state management complexity increases
Solution Approach 1:
The patent applies universality by implementing a unified state management mechanism that handles both RRC connected and inactive states across multiple RATs through a common framework. The UE maintains a single inactive state indicator that applies to both the first and second RATs, allowing the same state management logic to operate universally across different radio access technologies, thereby reducing complexity while maintaining service continuity.
Data Source
AI summary
Embodiments herein achieve a method for handling a RLF in a wireless communication system by a UE. The method includes detecting the RLF at the UE associated with a first cell that is associated with a first RAT. Further, the method includes selecting a second cell, associated with a second RAT, by performing a cell selection procedure. Further, the method includes detecting that a 5GC is connected. Further, the method includes determining whether a timer is running in the UE. Further, the method includes performing an IRAT RRC re-establishment procedure on the second cell when the RLF is occurred on the first cell associated with the first RAT in response to determining that the timer is running in the UE.