NTN UE Distance Thresholds for PSM Coverage Alignment
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Solution Overview
Problem
UEs in non-terrestrial networks experience time-discontinuous coverage and power-saving mode (PSM) leading to premature deregistration or detachment due to misalignment between UE active times and satellite coverage periods, especially when power-constrained and operating with limited network connectivity.
Innovation Solution
The UE initiates a procedure to report location information when exceeding a distance threshold, aligning its active time with satellite coverage by transmitting a tracking area update request, and delaying the transmission until entering a radio access network coverage area, thereby optimizing PSM configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the UE operates in power saving mode (PSM) for extended periods to conserve energy, then power consumption is reduced, but the UE may miss satellite coverage opportunities and experience premature deregistration or detachment
Solution Approach 1:
The UE performs preliminary actions by determining satellite coverage periods in advance and proactively scheduling wake-up times to coincide with these coverage periods. The UE calculates when satellite beams will pass over its location and schedules communications accordingly, ensuring it is awake and ready to communicate before the actual coverage window begins, thus preventing missed opportunities while maintaining PSM for power savings.
2Reliability
If the UE frequently wakes up to check for network connectivity and report location, then connection reliability is improved, but power consumption increases
Solution Approach 1:
Instead of frequent random wake-ups, the UE implements periodic wake-up actions synchronized with satellite pass schedules. The UE wakes up at predetermined intervals that align with expected satellite coverage windows, performs necessary communications (connectivity checks, location reporting), and then returns to sleep mode. This periodic scheduling ensures reliable network contact while minimizing unnecessary wake-ups that would consume power.
3Use of energy by moving object
If the UE waits for satellite coverage to wake up and communicate, then power consumption is reduced, but location information accuracy deteriorates due to outdated data
Solution Approach 1:
The UE implements a feedback mechanism where it continuously tracks its own location changes during PSM and compares them against predefined distance thresholds. When the UE detects that it has moved beyond the threshold distance from its last reported location, it triggers a wake-up event to report updated location information to the network, even if this means slightly increased power consumption. This feedback loop ensures location accuracy is maintained dynamically rather than relying on static periodic reporting.
Data Source
AI summary
While at a first location, a user equipment (UE) connected to a core network via a non-terrestrial network (NTN) receives a distance threshold, before the UE enters a power saving mode, PSM. While in the PSM, the UE initiates the procedure for reporting a current UE location information when a current UE location has exceeded the distance threshold relative to the first location.