Hybrid Satellite Forward-Link Multiplexing for LEO Traffic Offload
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Solution Overview
Problem
Integrating multiple types of satellite constellations into a single system to provide uninterrupted service is challenging, especially when user terminals configured for one type of constellation need to be deployed in a system with different types of constellations, due to differences in orbital patterns, propagation delays, and modulation schemes.
Innovation Solution
A method for switching forward link communications between different types of satellites, such as LEO, MEO, and GSO satellites, using time-division multiplexing (TDM) configuration information and concatenated coding, allowing user terminals to dynamically switch between satellites while maintaining a return link connection with one satellite, thereby increasing overall data throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple types of satellite constellations (LEO, MEO, GSO) are integrated into a single system, then coverage area and service continuity are improved, but system complexity and difficulty of coordination increase
Solution Approach 1:
The patent segments the satellite communication system into distinct functional layers: a mobility management entity (MME) that handles signaling and satellite selection, and eNodeBs that handle data transmission. This segmentation allows different satellite types to be integrated without overwhelming complexity in any single component.
Solution Approach 2:
The patent introduces a mobility management entity (MME) as an intermediary that coordinates between user equipment and multiple satellite constellations. The MME receives satellite selection information from satellites, determines optimal satellite selections, and provides handover commands, thereby simplifying the integration complexity of hybrid constellations.
2Reliability
If user terminals switch between different satellite constellations, then service continuity is improved, but timing synchronization and frequency alignment become more difficult
Solution Approach 1:
The patent implements feedback mechanisms where the mobility management entity receives satellite selection information from satellites, evaluates timing and frequency parameters, and provides handover commands with specific timing advance values and frequency adjustments. This feedback loop ensures synchronized operation across different satellite constellations.
Solution Approach 2:
The patent performs preliminary timing and frequency adjustments before handover execution. The MME calculates required timing advance values and frequency offsets in advance based on satellite orbital parameters and propagation delays, then provides these adjustments in handover commands to ensure seamless synchronization.
3Power
If hybrid satellite constellations are used, then bandwidth and signal-to-noise ratio are improved, but propagation delay and transmission power requirements increase
Solution Approach 1:
The patent dynamically selects between LEO, MEO, and GSO satellites based on real-time conditions including propagation delay, bandwidth requirements, and signal-to-noise ratio needs. The mobility management entity adjusts satellite selection and handover parameters dynamically, allowing the system to exploit the high bandwidth of GSO satellites when needed while minimizing propagation delay by selecting LEO satellites for time-sensitive communications.
Data Source
AI summary
A method and apparatus for operating a satellite system including different satellites that may belong to different types of satellite constellations. In some implementations, the satellite system may include a LEO satellite constellation and one or more non-LEO satellite constellations that can be used to increase the forward link capacity of the LEO satellite constellation, for example, by allowing an LEO satellite to offload at least some of its forward link traffic to one of the non-LEO satellites. The user terminals can dynamically switch forward link communications between a LEO satellite and a non-LEO satellite while maintaining a return link connection with the LEO satellite.