Idle Mode NTN-TN Mobility Using Cell Suitability and Wake-Up Signaling
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing mobility between non-terrestrial networks (NTN) and terrestrial networks (TN) during idle mode, leading to inefficiencies in network energy consumption and user device power management.
Innovation Solution
A wireless transmit/receive unit (WTRU) is configured to receive and analyze configuration information for candidate NTN cells, perform suitability determinations, and manage cell reselection based on power sharing status, orbit type, and measurement thresholds, while also receiving wake-up signals to transition between NTN and TN cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the WTRU continuously monitors and measures all candidate cells for mobility during idle mode, then mobility reliability is improved, but device power consumption increases
Solution Approach 1:
The network pre-configures the WTRU with suitability conditions (power sharing thresholds, orbit types, measurement thresholds) before idle mode mobility. During idle mode, the WTRU only needs to check whether measured parameters satisfy these pre-configured conditions rather than performing full measurements on all cells, significantly reducing power consumption while maintaining mobility reliability
Solution Approach 2:
The WTRU performs partial measurements only on cells that potentially satisfy the pre-configured suitability conditions (e.g., cells with appropriate orbit types and power sharing status), rather than measuring all candidate cells. This selective measurement approach reduces power consumption while ensuring mobility to suitable cells
2Reliability
If the network maintains all TN cells in active state to ensure coverage, then service availability is improved, but network energy consumption increases
Solution Approach 1:
The network pre-configures wake-up signal parameters (time windows, frequency resources, signal patterns) in TN cells before they enter sleep mode. When a WTRU needs to access a sleeping cell, it transmits a wake-up signal that activates the cell temporarily for the configured time window, enabling on-demand service availability while reducing overall network energy consumption
Solution Approach 2:
TN cells operate in periodic sleep and active cycles rather than remaining continuously active. The cells are activated periodically or on-demand based on WTRU wake-up signals, creating a periodic operation pattern that reduces network energy consumption while maintaining service availability when needed
3Measurement precision
If the WTRU performs full cell reselection procedures for every cell change, then mobility accuracy is improved, but mobility speed decreases
Solution Approach 1:
The network pre-configures suitability conditions (power sharing status thresholds, orbit type preferences, measurement thresholds) that define suitable cells before mobility events. During idle mode mobility, the WTRU quickly checks whether target cells satisfy these pre-configured conditions without performing full reselection procedures, significantly speeding up mobility while maintaining accuracy through the pre-defined suitability criteria
Solution Approach 2:
The WTRU performs partial cell evaluation by checking only the pre-configured suitability conditions (power sharing status, orbit type, basic measurement thresholds) rather than executing complete reselection procedures. This partial evaluation approach enables faster mobility decisions while maintaining sufficient accuracy for idle mode scenarios
Data Source
AI summary
Systems, methods, and instrumentalities are configured for NTN-TN idle mode mobility for network energy savings. A WTRU may receive configuration information for a first and second candidate NTN cell, each associated with different orbit types and power sharing statuses. The WTRU may receive a message to perform suitability determinations for these cells, conduct measurements, and determine if the first cell satisfies suitability conditions based on its power sharing status, orbit type, and measurement. Additionally, the WTRU may receive a second message from a TN cell indicating a shutdown, prompting the exclusion of these TN cells from re-selection.