Conditional Handover Validity Time Mechanism
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Solution Overview
Problem
In wireless communications systems with numerous small cells, the inefficiency of existing methods in managing conditional handover leads to high overhead signaling and resource wastage, as multiple target base stations are prepared for potential handovers without knowing which one the UE will actually use, resulting in unnecessary resource allocation and cleanup processes.
Innovation Solution
Incorporating a validity time in handoff messages that allows target base stations to allocate resources conditionally, with the option to release them automatically upon expiration, reducing the need for multiple release messages and optimizing resource allocation based on UE priority, traffic type, and base station load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple target base stations are prepared for conditional handover, then handover reliability is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts the essential handover preparation signaling from the complete handover process. Instead of requiring full handover request/response sequences with all associated signaling for every potential target base station, the system prepares only the necessary handover parameters and configurations in advance, reducing the signaling overhead while maintaining multiple target preparations for reliability.
Solution Approach 2:
The patent applies preliminary action by pre-configuring handover parameters, target base station information, and resource allocations before the actual handover event. This allows multiple target base stations to be prepared in advance with minimal signaling, and the actual handover can proceed quickly by simply selecting from the pre-prepared options, thus reducing overall signaling overhead while maintaining reliability.
2Reliability
If resources are allocated to multiple target base stations for conditional handover, then handover reliability is improved, but resource wastage increases
Solution Approach 1:
The patent applies preliminary action by pre-allocating resource configurations and parameters for multiple target base stations without actually reserving full resources at each target. The actual resource allocation only occurs at the selected target base station after handover decision, eliminating resource wastage while maintaining the ability to handover to multiple potential targets for reliability.
Solution Approach 2:
The patent applies local quality by allocating full resources only at the specific target base station that is actually selected for handover, rather than pre-allocating resources at all potential target base stations. The pre-prepared information includes only essential parameters and configurations, not actual resource reservations, thus avoiding resource wastage while maintaining handover reliability through multiple prepared options.
3Productivity
If context cleanup is performed at target base stations, then resource efficiency is improved, but additional signaling messages are required
Solution Approach 1:
The patent applies self-service by enabling target base stations to automatically clean up their context information and resource allocations based on pre-configured validity timers or handover completion notifications. The target base station autonomously determines when to release resources without requiring explicit cleanup signaling from the source base station, thus improving resource efficiency while minimizing additional signaling messages.
Data Source
AI summary
Methods and apparatus used to facilitate preparation of one or more target base stations for possible UE handoffs, e.g., conditional handoffs, which may or may not occur depending on whether or not various handoff conditions are satisfied are described. A handoff message, e.g., a conditional handoff message, including a validity time is generated and sent to each selected target base stations to which a UE may be handed off. The validity time indicates to the target base station a time window, e.g., a time duration for which the handoff target message is to be considered valid. In response to the handoff message, the target base station, receiving the handoff message, allocates resources to the UE and starts a countdown validity timer based on the indicated length of the validity time. When the validity timer expires without handoff to the target base station, the target base station releases the allocated resources.