Conditional Mobility Configuration Update Mechanism
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Solution Overview
Problem
The handover process in LTE and NR wireless communication networks faces challenges related to robustness, particularly when the radio conditions for a UE are poor, leading to potential failures in delivering the HO command to the UE before the connection with the target node is dropped.
Innovation Solution
Implementing conditional mobility operations, such as conditional handovers, where the HO command is associated with conditions like improved radio conditions, allowing for earlier preparation and execution of handovers when the UE's serving cell quality degrades, using techniques like resource reservation timers and delta signaling for updating configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If handover preparation is delayed until radio conditions are poor, then the handover execution is timely, but the HO command may fail to reach the UE before connection is dropped
Solution Approach 1:
The patent applies preliminary action by preparing the handover configuration in advance when radio conditions are still good, rather than waiting until conditions deteriorate. The source gNB generates and transmits the handover configuration to the target gNB before the radio link quality degrades below critical thresholds, ensuring the command reaches the UE reliably even as conditions worsen.
2Reliability
If handover configuration is sent early when radio conditions are good, then the command reaches UE reliably, but the handover may not be executed at the optimal time
Solution Approach 1:
The patent implements dynamics by making the handover configuration conditional and updateable. The configuration includes conditional execution criteria that allow the UE to execute the handover only when specific radio condition thresholds are met. Additionally, the source gNB can send updates or cancellations to adapt the configuration based on changing radio conditions, ensuring both reliable delivery and optimal timing.
3Reliability
If resources are reserved for conditional handover, then handover execution is supported, but network resources are consumed until handover completes or cancels
Solution Approach 1:
The patent applies periodic action through the use of a validity timer that periodically checks whether the conditional handover should still be supported. The timer is started when the handover configuration is sent and can be extended by update messages. When the timer expires without handover execution, the target gNB automatically releases the reserved resources, ensuring periodic resource validation and automatic cleanup to prevent permanent resource consumption.
Data Source
AI summary
Methods performed by a first node in a radio access network (RAN) for mobility of a user equipment (UE) served by a second node in the RAN. Such methods include receiving (1310), from the second node, a request for a mobility procedure for the UE towards at least one candidate target cell associated with the first node. Such methods include determining (1320) if the UE can be accepted for the requested mobility procedure and, if so, allocating resources to support mobility of the UE. Such methods include transmitting (1330), to the second node, a response that includes a configuration for the mobility procedure and indicates the UE can be accepted unless a cancelling message is subsequently received from the second node. Such methods include determining (1350) that the configuration is no longer valid, and transmitting (1360), to the second node, an indication that the configuration is no longer valid.