Cell Selection for Satellite-Terrestrial Mobility
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Solution Overview
Problem
The mobility management solution for terrestrial cellular systems is ineffective when transitioning between satellite and terrestrial communication systems due to the large size difference between satellite and terrestrial cells, leading to difficulties in accurately redirecting terminals to appropriate cells, especially with low-orbit satellite movement speeds exceeding several kilometers per second.
Innovation Solution
A cell selection method that triggers terminals in idle or inactive states to move between satellite and terrestrial cells based on preset conditions, such as geographic distance thresholds or the availability of frequency band signals, using messages like connection rejection, connection release, or paging short messages to instruct the terminal to search for cells in either frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the terrestrial cellular communication system uses traditional mobility management solutions, then it can effectively manage terminal mobility within the terrestrial system, but it fails to accurately redirect terminals when transitioning between satellite and terrestrial systems due to the large size difference between satellite and terrestrial cells
Solution Approach 1:
The patent changes the parameter of cell selection criteria by introducing satellite-specific parameters (satellite cell ID, orbital parameters, beam coverage areas) alongside traditional terrestrial cell parameters. This allows the mobility management system to adapt to both terrestrial and satellite environments by dynamically adjusting selection parameters based on the current system context.
Solution Approach 2:
The patent segments the mobility management process into distinct phases: satellite cell detection, satellite cell evaluation, and conditional redirection to terrestrial cells. This segmentation allows each phase to be optimized independently, with specific algorithms for satellite beam identification and separate decision logic for inter-system handover.
2Measurement precision
If the network side stores large amounts of base station distribution information to redirect terminals to terrestrial cells, then terminal redirection accuracy improves, but system complexity and information storage requirements increase significantly
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing only essential satellite orbital parameters and beam coverage patterns, rather than storing detailed information about all possible terrestrial base stations. When a terminal needs redirection, the system uses these pre-stored parameters to identify the appropriate terrestrial cell area, reducing the need for extensive real-time information storage.
Solution Approach 2:
The patent introduces satellite cell identification information as an intermediary that bridges the gap between satellite and terrestrial systems. Instead of directly mapping satellite positions to specific terrestrial base stations, the system uses satellite cell IDs and coverage areas as intermediate parameters to guide terminal redirection, simplifying the information storage requirements on the network side.
3Area of stationary object
If the satellite beam sweeps over multiple terrestrial cells at high speed, then satellite coverage area increases, but the duration for which a terminal remains in a single satellite cell decreases, making accurate cell selection more difficult
Solution Approach 1:
The patent applies preliminary action by implementing proactive cell selection and pre-fetching of terrestrial cell information before the satellite beam moves away. The system predicts the terminal's next likely terrestrial cell based on satellite movement trajectories and prepares redirection information in advance, ensuring continuous connectivity despite the brief residence time in each satellite cell.
Solution Approach 2:
The patent ensures continuity of useful action by implementing overlapping satellite beam coverage and continuous cell reevaluation. As the satellite beam sweeps across terrestrial cells, the system maintains multiple active cell evaluations simultaneously, ensuring that terminal redirection can occur seamlessly without interruption, even though the terminal quickly transitions between satellite cells.
Data Source
AI summary
The present disclosure provides a cell selection method, a network device and a terminal. The method includes triggering a terminal in an idle state or in an inactive state to move between a satellite cell and a terrestrial cell when a first preset condition is met.