Conditional Handover Cell Configuration Retention in NTN Terminals
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Solution Overview
Problem
In non-terrestrial networks (NTN), the efficient management of candidate cell configurations during conditional handover is hindered by the constant movement of cells, leading to unnecessary deletion of configurations and reduced handover efficiency.
Innovation Solution
A terminal apparatus and base station apparatus system that manages candidate cell configurations by receiving and transmitting information about event conditions and order of candidate cells, allowing the terminal to selectively delete configurations based on fulfillment of event conditions and order, optimizing handover processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the terminal apparatus autonomously deletes candidate cell configurations after successful conditional handover, then the device complexity is reduced, but in NTN environments where cells constantly move, this leads to loss of information about potentially useful candidate cells
Solution Approach 1:
The invention changes the deletion parameter from unconditional (automatic deletion after handover) to conditional (deletion only when event conditions are not fulfilled). This allows the system to maintain candidate cell configurations when movement patterns suggest they may still be useful, while still reducing complexity when conditions warrant deletion.
Solution Approach 2:
The base station performs preliminary evaluation of candidate cell configurations and event conditions before handover execution. By pre-configuring event conditions that predict future cell viability, the system prepares in advance for potential handover scenarios, avoiding both premature deletion and unnecessary retention of configurations.
2Reliability
If the terminal apparatus retains all candidate cell configurations after handover, then the reliability of future handovers is improved, but the loss of energy increases due to maintaining unnecessary configurations
Solution Approach 1:
The invention dynamically changes the retention parameter of candidate cell configurations based on event condition fulfillment. Configurations are retained when event conditions indicate potential future utility, and deleted when conditions indicate obsolescence, thereby optimizing the balance between reliability and energy consumption.
Solution Approach 2:
Instead of retaining all configurations or deleting all configurations, the invention applies partial retention based on event condition evaluation. Only the necessary subset of candidate cell configurations is maintained, avoiding excessive energy consumption while preserving sufficient reliability.
3Productivity
If the terminal apparatus evaluates multiple event conditions for each candidate cell, then the productivity of handover decision-making is improved, but the device complexity increases due to multiple condition evaluations
Solution Approach 1:
The invention segments the evaluation process by associating specific event conditions with specific candidate cell configurations. Each configuration has its own set of relevant conditions, allowing independent evaluation without requiring comprehensive assessment of all conditions for all cells, thus improving efficiency while managing complexity.
Solution Approach 2:
The base station pre-configures event conditions and associations before handover execution. This preliminary setup organizes the evaluation framework in advance, reducing the computational burden during actual handover decisions and improving decision-making productivity without proportionally increasing operational complexity.
Data Source
AI summary
A terminal apparatus includes: a receiver configured to receive information related to a plurality of candidate cell configurations respectively corresponding to a plurality of candidate cells to be target cell, and first information indicating one or more second candidate cell configurations that are applicable next to a first candidate cell configuration included in the plurality of candidate cell configurations; and processor circuitry configured to determine, when a reconfiguration process is performed for a first cell which correspond to the first candidate cell configuration, one or more candidate cell configurations which are deleted form the plurality of candidate cell configurations according to the first information.