Non-NTN Device Cell Selection Avoidance
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Solution Overview
Problem
Devices that do not support non-terrestrial networks (NTNs) face challenges in avoiding cell selection or reselection to an NTN cell, leading to potential connection failures due to invalid tracking areas, resulting in inefficient power consumption and latency, as well as interference with other uplink transmissions.
Innovation Solution
Implementing a method to differentiate NTN cells from terrestrial cells by using unique sync rasters and indicating cell barring information, allowing UEs to quickly identify unsuitable cells for camping, thereby preventing unnecessary system information acquisition and reducing network resource interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If devices perform cell selection/reselection without NTN awareness, then they can camp on any available cell, but they may select NTN cells leading to connection failures and wasted power
Solution Approach 1:
The network performs preliminary action by broadcasting NTN indication information in system information messages before UE devices attempt to camp on cells. This advance notification allows devices to identify and avoid NTN cells during cell selection, preventing connection failures and unnecessary power consumption that would result from attempting to camp on incompatible cells
Solution Approach 2:
The system introduces an intermediary indication mechanism (NTN indication information broadcast by the network) that mediates between NTN and non-NTN cells. This intermediary signal enables non-NTN devices to distinguish NTN cells without requiring complex device-side NTN detection capabilities, thus avoiding connection failures and reducing power waste
2Ease of operation
If devices acquire system information from all candidate cells, then they ensure complete information for cell selection, but they waste time and resources on NTN cells they cannot support
Solution Approach 1:
The system extracts NTN indication information from system information messages and presents it as a separate, easily detectable indicator to UE devices. This extraction allows devices to quickly identify and exclude NTN cells from consideration without having to fully acquire and process all system information, thereby reducing cell selection latency while maintaining operational simplicity
Solution Approach 2:
The network broadcasts NTN indication information as part of the system information in advance, allowing devices to perform preliminary filtering of candidate cells before committing resources to full system information acquisition. This preliminary action saves time and resources by preventing devices from thoroughly processing information from cells they cannot support
3Adaptability or versatility
If non-NTN devices camp on NTN cells, then they maximize available camping options, but they cause interference with uplink transmissions
Solution Approach 1:
The system implements feedback by broadcasting NTN indication information from the network to UE devices. This feedback mechanism informs devices about the NTN status of cells, enabling them to make informed camping decisions. By providing this feedback, the system prevents non-NTN devices from camping on NTN cells, thereby eliminating uplink interference while still allowing devices to camp on suitable non-NTN cells
Data Source
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AI summary
According to certain embodiments, a method is performed by a wireless device that does not support non-terrestrial network (NTN) communication. The method comprises receiving, from a network node, information configured to cause wireless devices that do not support NTN communication to avoid cell selection or re-selection to a candidate cell in the NTN. In response to receiving the information, the method comprises avoiding cell selection or re-selection to the candidate cell in the NTN.