Wireless Cell Switching Fallback for L1/L2 Mobility Failures
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Solution Overview
Problem
Existing specifications for L1/L2-triggered mobility (LTM) in wireless communication systems lack clear methods for handling cell switch failures, particularly in terms of security measures during cell change procedures.
Innovation Solution
A system and method for cell switching in wireless communication systems that includes a receptor and switcher in the terminal device, and a transmitter and controller in the base station device, which handle cell change failures by executing a reestablishment procedure using alternative configurations when initial cell switching fails, ensuring seamless transition to a secondary cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If L1/L2-triggered mobility is implemented to reduce latency in cell switching, then mobility speed is improved, but reliability deteriorates due to lack of defined failure handling procedures
Solution Approach 1:
The base station pre-configures multiple candidate cells (first cell, second cell, third cell) and their associated configurations (first configuration, second configuration, third configuration) before mobility is needed. When cell switching is triggered, the terminal device can immediately execute the pre-prepared switching procedure without additional signaling, reducing latency while maintaining reliability through predefined fallback options.
Solution Approach 2:
The system prepares multiple candidate cells and configurations in advance as backup options. If the primary cell switching attempt fails, the terminal device has pre-configured alternative cells ready to switch to, cushioning against the failure and ensuring continuous connectivity without compromising reliability.
2Adaptability or versatility
If multiple candidate cells are configured for fast mobility switching, then adaptability is improved, but device complexity increases
Solution Approach 1:
The mobility management is segmented into distinct candidate cells (first cell, second cell, third cell), each with its own configuration. This segmentation allows the terminal device to handle cell switching in discrete, manageable steps rather than managing a complex unified switching process, reducing perceived complexity while maintaining adaptability.
Solution Approach 2:
All candidate cell configurations are pre-configured and stored in the terminal device before mobility events occur. This preliminary preparation eliminates the need for complex real-time configuration decisions during actual cell switching, simplifying the runtime operation while maintaining high adaptability to different mobility scenarios.
3Reliability
If reestablishment procedure with fallback configurations is implemented, then reliability is improved, but loss of time increases due to additional switching steps
Solution Approach 1:
The fallback configurations for candidate cells are pre-configured and stored in the terminal device before any cell switching attempt. When a switching failure occurs, the terminal device can immediately execute the fallback to a pre-configured candidate cell without additional signaling or configuration steps, minimizing time loss while ensuring reliability through the fallback mechanism.
Data Source
AI summary
A terminal device includes: a receptor that receives, from a base station device, a first signal including change destination information that designates first cell and second cell as cell change destination candidates; and a switcher that performs first processing of switching a serving cell from a third cell to the first cell according to information related to a cell change included in a second signal received from the base station device, and performs, in a case where the first processing fails, second processing of executing a reestablishment procedure by using a third configuration applied in the third cell; wherein in the second processing, in a case where the second cell is selected as a change destination, the switcher switches the serving cell to the second cell by using a second configuration applied in the second cell instead of the third configuration.