UE Idle Mode Handling for Predicted NTN Coverage Gaps
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Solution Overview
Problem
Existing technologies struggle to effectively manage the Idle mode of user equipment (UE) when it moves out of the coverage area of a Non-Terrestrial Network (NTN), leading to inefficiencies and potential loss of connectivity.
Innovation Solution
The UE maintains an Access Stratum (AS) layer configuration without performing Idle mode tasks while out of coverage, using satellite information to anticipate disconnection and storing cell selection priorities for seamless reconnection, facilitated by UE-specific control signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs Idle mode tasks when moving out of NTN coverage area, then the UE follows standard Idle mode procedures, but connectivity is lost and reconnection delays occur
Solution Approach 1:
The network provides satellite movement information (ephemeris data, coverage area, service available/unavailable periods) to the UE in advance via RRC signaling. The UE uses this information to predict when it will exit coverage and maintains AS layer configuration proactively, performing necessary AS tasks before actual disconnection occurs, thus avoiding reconnection delays.
Solution Approach 2:
The UE dynamically adjusts its behavior based on the predicted service unavailable period. Instead of statically transitioning to Idle mode, the UE maintains AS layer configuration and performs AS tasks during the predicted outage period, adapting its operational state to the dynamic satellite coverage conditions.
2Reliability
If the UE maintains AS layer configuration while out of coverage, then connectivity is preserved, but additional power consumption occurs
Solution Approach 1:
The network provides satellite movement information in advance, allowing the UE to maintain AS layer configuration only during predicted service unavailable periods rather than continuously. This proactive approach limits power consumption to necessary time windows while ensuring connectivity continuity.
Solution Approach 2:
The UE maintains AS layer configuration periodically during predicted service unavailable periods rather than continuously. The network provides periodic satellite ephemeris information, and the UE synchronizes its configuration maintenance with these periodic coverage predictions, reducing overall power consumption.
3Ease of operation
If the UE transitions to Idle mode before disconnection, then standard procedures are followed, but AS layer configuration is lost
Solution Approach 1:
The network provides satellite coverage prediction information in advance, allowing the UE to maintain AS layer configuration proactively before disconnection. The UE performs necessary AS tasks during the predicted service unavailable period, preserving configuration information that would otherwise be lost during Idle mode transition.
Solution Approach 2:
The UE dynamically maintains AS layer configuration based on predicted satellite coverage conditions rather than statically transitioning to Idle mode. This dynamic approach preserves AS layer information while adapting to changing coverage conditions, eliminating the need for complete configuration re-establishment upon reconnection.
Data Source
AI summary
A method for a user equipment (UE) connected to a serving Radio Access Network (RAN) through a serving cell is provided. The serving RAN may include a Non-Terrestrial Network (NTN). The method receives, from the serving cell, satellite information regarding a coverage area of the serving RAN. After receiving the satellite information, the method determines, based on the satellite information, that the UE will be disconnected from the serving RAN by moving out of the coverage area of the serving RAN after a specific period of time. The method maintains an Access Stratum (AS) layer configuration of the UE without performing any task associated with an Idle mode of the UE while the UE is staying out of the coverage area of the serving RAN.