Satellite Handoff via Transition Tables
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Solution Overview
Problem
Non-geosynchronous satellite communication systems, such as low-earth orbit (LEO) systems, face challenges in seamless handoff of user terminals between satellites due to the relative motion of satellites and user terminals, leading to disruptions and inefficiencies in communication.
Innovation Solution
A satellite and cell transition table is generated and used to determine optimal handoff timing, with user terminals sending capability and location information to a satellite network portal, which selects a handoff procedure and updates the table based on measurement messages, ensuring smooth transitions between satellites and cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If non-geosynchronous satellites are used to provide Earth-wide coverage, then coverage area is improved, but handoff complexity increases due to relative motion between satellites and user terminals
Solution Approach 1:
The system performs preliminary actions by generating satellite and cell transition tables in advance that predict optimal handoff timing and target satellites. The network portal pre-calculates transition information based on satellite ephemeris data and user terminal locations, so that when handoff is needed, the terminal already has prepared transition instructions, eliminating the need for complex real-time handoff decisions during satellite relative motion.
Solution Approach 2:
The network portal acts as an intermediary that centralizes handoff control. Instead of requiring the user terminal to independently determine handoff timing and target satellites (which would be complex), the network portal receives satellite position data, calculates optimal transition points, and provides handoff instructions to the terminal. This mediator approach simplifies the terminal's role while maintaining seamless handoffs across the satellite constellation.
2Reliability
If traditional handoff procedures are used in LEO satellite systems, then communication continuity is maintained, but signaling overhead increases during handoff transitions
Solution Approach 1:
The system reduces signaling overhead by performing preliminary action through pre-generation of handoff instruction tables. The network portal calculates and stores optimal handoff timing and target satellite information in advance based on predicted satellite positions and user terminal trajectories. During actual handoff, the terminal simply retrieves pre-calculated instructions from the table rather than engaging in extensive real-time signaling exchanges, thus maintaining communication continuity while minimizing signaling overhead.
3Reliability
If real-time handoff decisions are made during satellite transitions, then communication quality is maintained, but handoff timing precision decreases
Solution Approach 1:
The system achieves precise handoff timing by performing preliminary calculation of transition points. The network portal uses satellite ephemeris data and user terminal location information to pre-determine exact handoff timing and generate transition tables in advance. This allows the system to maintain communication quality through accurately timed handoffs while avoiding the delays and imprecision that would result from making handoff decisions in real-time during satellite transitions.
Data Source
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AI summary
Various aspects of the disclosure relate to handoff of a user terminal in communication with a satellite network portal through a satellite. In some aspects, a satellite network portal and a user terminal use a satellite handoff information to determine when to handoff the user terminal from one cell to another and/or from one satellite to another. In some aspects, a user terminal sends capability information, location information, or other information to a satellite network portal whereby, based on this information, the satellite network portal generates the satellite handoff information and/or selects a handoff procedure for the user terminal. In some aspects, handoff of a user terminal to a different satellite involves the user terminal conducting satellite signal measurements and sending a measurement message to the satellite network portal. In some aspects, the satellite network portal generates new satellite handoff information as a result of receiving a measurement message.