Cell Reselection Feedback for Terrestrial to Non-Terrestrial Switching
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Solution Overview
Problem
In non-terrestrial network systems, there is a challenge in seamlessly switching client devices from terrestrial cells to non-terrestrial cells, particularly in locations with poor coverage, leading to potential loss of connectivity and energy inefficiencies, as existing methods do not allow for adequate preparation or testing of the target non-terrestrial cell before switching.
Innovation Solution
A network node device determines the switch-off time for a terrestrial cell and transmits cell reselection information to client devices, which are required to initiate a cell reselection to a target cell, allowing for feedback on accessibility and communication service expectations, thereby determining whether to proceed with the switch-off based on the received feedback, ensuring continuous connectivity and energy savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the terrestrial cell is switched off to save energy, then energy consumption is reduced, but client devices may lose connectivity if they cannot switch to a non-terrestrial cell
Solution Approach 1:
The network node provides advance notification to client devices about the upcoming cell switch-off, allowing devices to perform measurements and prepare for handover to non-terrestrial cells before the terrestrial cell is actually switched off. This preliminary action ensures connectivity is maintained while enabling energy savings.
Solution Approach 2:
The system implements a feedback mechanism where client devices report their ability to access non-terrestrial target cells back to the network node. Based on this feedback, the network node decides whether to proceed with the switch-off, modify it to exclude certain beams, or cancel it entirely, thus balancing energy savings with connectivity reliability.
2Reliability
If client devices are given time to prepare for cell reselection, then connectivity reliability is improved, but the switch-off process becomes more complex and time-consuming
Solution Approach 1:
The network node sends cell reselection information in advance, including switch-off time and target cell details, allowing client devices to perform measurements and prepare for handover before the actual switch-off. This structured preliminary action simplifies the overall process while ensuring reliability.
Solution Approach 2:
The system manages complexity by controlling the time parameter - providing a defined preparation window between the notification of switch-off and the actual switch-off time. This time parameter allows devices to complete measurements and preparations without extending the overall process excessively.
3Reliability
If client devices perform accessibility tests for non-terrestrial cells, then connectivity reliability is improved, but the time required for cell switching increases
Solution Approach 1:
Client devices perform accessibility measurements and tests in advance, during the preparation period before the terrestrial cell switch-off. By conducting these tests preliminarily rather than during the actual switching moment, the system ensures reliability while minimizing the time loss during the critical handover transition.
Data Source
AI summary
Devices, methods and computer programs for switching from a terrestrial cell to a non-terrestrial cell are disclosed. At least some example embodiments may allow switching a client device from a terrestrial cell to a non-terrestrial cell in such a way that the client device has time to prepare for the switch, and optionally perform tests related to a coverage of the non-terrestrial cell and inform a network node proposing the switch if the coverage is not sufficient. As a result, significant energy savings may be achieved on the network side, for example.