Conditional Handover Feedback Mechanism for Wireless Mobility
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Solution Overview
Problem
Current wireless communication systems face challenges in ensuring robustness and minimizing interruption time during handovers, particularly due to the uncertainty in selecting optimal target cells and timing, as well as potential failures in transmitting handover commands when radio conditions are poor.
Innovation Solution
The implementation of a conditional handover procedure that allows the network to provide early RRC signaling and adapt configurations based on measurement reports, enabling the UE to execute handovers when radio conditions improve, along with feedback mechanisms to refine future handover decisions and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the network sends handover commands when radio conditions are poor to enable timely handover, then handover timing is improved, but the reliability of command delivery deteriorates
Solution Approach 1:
The network prepares multiple candidate target cells and sends conditional handover commands in advance, before the source cell becomes unusable. The UE receives and stores these commands, executing them when trigger conditions are met, thus avoiding the need to send commands during poor radio conditions.
Solution Approach 2:
The system provides redundant handover commands for multiple potential target cells, creating a buffer against command delivery failures. If one command fails or its target cell becomes unavailable, the UE has alternative commands ready, cushioning against the unreliability of poor radio conditions.
2Reliability
If the network provides multiple potential target cells for conditional handover, then handover robustness is improved, but the complexity of configuration increases
Solution Approach 1:
The handover configuration is segmented into multiple independent conditional handover commands, each targeting a specific candidate cell with its own trigger condition. This allows the UE to process and execute commands independently, reducing the complexity of managing multiple targets compared to a single complex configuration.
Solution Approach 2:
The UE autonomously evaluates trigger conditions for multiple candidate cells and selects the appropriate target cell based on current radio measurements, without requiring continuous network control. This self-service approach reduces network configuration complexity while maintaining robustness through multiple candidates.
3Reliability
If the network waits for optimal radio conditions to send handover commands, then command delivery reliability is improved, but handover interruption time increases
Solution Approach 1:
The network sends conditional handover commands in advance when radio conditions are still good, storing them in the UE before the source cell becomes unusable. This preliminary action ensures reliable command delivery while enabling immediate execution when conditions deteriorate, avoiding both poor-condition transmission and excessive waiting.
4Speed
If dedicated random access resources are provided for each potential target cell, then handover execution speed is improved, but the quantity of resources required increases
Solution Approach 1:
The conditional handover configuration includes random access resources that can be universally applied across multiple candidate target cells. Instead of providing separate dedicated resources for each cell, the same resources serve multiple purposes, reducing the total quantity of resources required while maintaining fast execution capability.
Data Source
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AI summary
A method by a wireless device for handling conditional mobility procedures includes storing (910) information associated to a conditional mobility procedure to be performed by the wireless device, and transmitting (912) the information to a network node. A method by a network node for handling a conditional mobility procedure includes receiving (1000) feedback information from a wireless device (1300) generated from measurements relating to a trigger condition that triggers the conditional mobility procedure to be performed by the wireless device, and adapting (1002), based on the feedback information, how the wireless device is provided with a conditional mobility configuration. Related wireless devices and network nodes are disclosed.