UE Waiting Timer Control for Handover-Aware Radio Link Failure
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Solution Overview
Problem
Existing methods for managing Radio Link Failure (RLF) and handover in wireless communication systems, particularly in heterogeneous networks, are inefficient and lead to increased service disconnection times due to premature RLF declaration without considering channel recovery possibilities.
Innovation Solution
A method and apparatus for efficiently controlling the waiting timer T312, allowing the UE to monitor channel conditions and delay RLF declaration until multiple handover attempts are made, based on signal strengths of detected target cells and reception of handover-related messages, while ensuring a minimum RLF timer duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE immediately performs RRC connection reconfiguration upon detecting handover event, then the service disconnection time is reduced, but the reliability of handover is worsened due to premature RLF declaration
Solution Approach 1:
The patent applies preliminary action by starting the waiting timer T312 in advance when the handover timer TTT expires, before the RLF timer T310 can complete its full duration. This allows the UE to prepare for potential handover while still maintaining the possibility of RLF recovery, thereby reducing service disconnection time without prematurely declaring RLF.
Solution Approach 2:
The patent implements dynamics by making the RLF determination process adaptive through the waiting timer mechanism. The system dynamically adjusts the RLF declaration timing based on whether handover attempts are still possible, allowing the UE to wait for handover opportunities while still progressing toward RLF declaration if needed, thus balancing speed and reliability.
2Reliability
If the UE waits for the RLF timer to complete before declaring RLF, then the reliability of RLF determination is improved, but the service disconnection time is increased
Solution Approach 1:
The patent applies segmentation by dividing the RLF determination process into distinct phases: the handover timer TTT phase, the waiting timer T312 phase, and the RLF timer T310 phase. This segmentation allows the UE to separately optimize for handover opportunities and RLF determination, enabling earlier RLF declaration without sacrificing determination accuracy.
Solution Approach 2:
The waiting timer T312 is started in advance when the handover timer TTT expires, creating a preliminary waiting period before final RLF determination. This preliminary action allows the UE to attempt handover while still within the RLF determination window, reducing overall service disconnection time while maintaining reliable RLF determination.
3Adaptability or versatility
If the UE performs multiple handover attempts, then the adaptability to channel conditions is improved, but the service disconnection time is increased
Solution Approach 1:
The patent implements dynamics by making the handover attempt process adaptive through the waiting timer mechanism. The system dynamically adjusts the timing and conditions for handover attempts based on real-time channel conditions, allowing the UE to perform multiple attempts when beneficial while limiting the total time through the coordinated expiration of timers T312 and T310.
Solution Approach 2:
The patent applies feedback by continuously monitoring channel conditions and using this information to determine whether to proceed with handover or declare RLF. The waiting timer T312 provides a feedback mechanism that allows the UE to wait for improved channel conditions while still progressing toward RLF declaration if handover fails, thus balancing adaptability with time efficiency.
Data Source
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AI summary
A method and an apparatus for controlling a waiting time related to determination of a radio link failure in a wireless communication system are provided. The method includes receiving a message from a network, if a first timer for determination of the radio link failure is running and the message includes timer information related to the waiting time, starting a second timer related to the waiting time based on the timer information, and if the second timer expires before expiration of the first timer, determining a channel situation of a serving cell as a situation of the radio link failure.