Conditional Mobility Procedure for Wireless Device Handover
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Solution Overview
Problem
Current mobility procedures in LTE and NR face challenges with handover robustness and interruption time, particularly due to the timing of handover commands when radio conditions are poor, leading to potential message failures and unnecessary UE transitions to IDLE mode.
Innovation Solution
Implementing a conditional mobility procedure that allows the UE to trigger handover based on predefined radio conditions, using a timer that starts upon condition fulfillment and stops upon successful completion, enabling predictable failure detection and minimizing unnecessary transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If handover command is sent when radio conditions are poor, then network can prepare target cell in advance, but handover reliability deteriorates due to potential message failures
Solution Approach 1:
The network performs preliminary actions by preparing the target cell configuration and sending the handover command before the actual handover execution. The UE stores this command and executes it when the triggering condition is met, separating the preparation phase from the execution phase to ensure both readiness and reliability.
2Productivity
If handover command is sent when radio conditions are poor, then network can optimize resource allocation, but interruption time increases due to potential retransmissions and failures
Solution Approach 1:
The network prepares the handover command in advance when radio conditions permit, optimizing resource allocation. The UE then executes the stored command immediately when the triggering condition is met, minimizing interruption time by avoiding retransmissions and ensuring seamless handover execution.
3Speed
If UE executes handover immediately upon receiving command, then handover speed increases, but robustness deteriorates when radio conditions are poor
Solution Approach 1:
The network prepares and sends the handover command in advance when radio conditions are acceptable. The UE stores the command and executes it only when the triggering condition is met, ensuring both quick execution and robustness by avoiding execution during poor radio conditions.
Solution Approach 2:
The UE continuously monitors radio conditions and compares them against the triggering condition. When the condition is met, the UE executes the stored handover command. This feedback mechanism ensures the handover occurs at the optimal moment, balancing speed and robustness.
4Ease of operation
If network provides detailed target cell configuration, then ease of operation improves, but device complexity increases due to additional processing requirements
Solution Approach 1:
The network performs preliminary preparation by creating the complete target cell configuration and sending it to the UE in advance. The UE simply stores and executes this pre-prepared command when the triggering condition is met, reducing UE processing complexity while maintaining ease of operation.
Data Source
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AI summary
A method performed by a wireless device is disclosed, the method comprising determining that a condition to trigger a mobility procedure for the wireless device has been met, starting a timer, and determining a failure of the mobility procedure upon expiry of the timer before completion of at least part of the mobility procedure.