SHDC Device for Satellite Hand-off and Diversity Combining
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Solution Overview
Problem
Non-geostationary satellite hand-off and diversity-combining systems face challenges in maintaining seamless communication and achieving optimal signal-to-noise ratio (SNR) gains due to frequent hand-offs in LEO satellite constellations, interference from GEO satellites, and antenna failures, which affect the duty cycle and SNR gains in MEO and LEO satellite tracking.
Innovation Solution
The use of multiple satellite antennas with N−1 SHDC devices for collective hand-off and diversity combining, where each SHDC device includes a satellite hand-off device and a diversity combiner, allowing for seamless transitions and increased SNR gains by pointing multiple antennas to descending satellites while acquiring ascending satellites, and utilizing diversity selection instead of combining in cases of large antenna spacing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple antennas are used for make-before-break communications with non-geostationary satellites, then communication continuity is maintained during hand-off, but device complexity increases due to the need for multiple SHDC devices
Solution Approach 1:
The system divides the antenna array into multiple pairs, with each pair managed by a separate SHDC device. This segmentation allows independent operation of each SHDC device while maintaining overall system reliability through diversity combining of signals from multiple antenna pairs.
Solution Approach 2:
The system merges signals from multiple antennas through diversity combining at the SHDC device level. By combining signals from multiple antenna pairs that are simultaneously tracking the same satellite, the system achieves improved reliability without requiring a single complex centralized controller.
2Reliability
If N satellite antennas collectively utilize N−1 SHDC devices, then diversity SNR gains are increased, but the duty cycle of each individual SHDC device decreases due to frequent hand-offs in LEO constellations
Solution Approach 1:
The system utilizes periodic satellite passes and structured hand-off sequences where antennas alternately track descending and ascending satellites. This periodic operation allows SHDC devices to enter low-power states during certain phases while maintaining overall communication continuity through diversity combining.
Solution Approach 2:
The system performs preliminary acquisition and tracking setup before hand-off events occur. By pre-positioning antennas and establishing tracking sequences in advance, the system reduces the active processing time required during actual hand-off transitions, effectively increasing the duty cycle efficiency.
3Object-affected harmful factors
If antennas are spaced far apart for diversity combining, then interference mitigation from GEO satellites is improved, but combining signals becomes difficult due to large antenna spacing
Solution Approach 1:
The system replaces complex mechanical signal combining approaches with electronic signal processing methods. By using digital signal processing and adaptive combining algorithms in the SHDC device, the system can effectively combine signals from widely spaced antennas without requiring precise mechanical alignment or complex physical coupling structures.
Data Source
AI summary
At least two antennas are used for make-before-break communications over non-geostationary satellites. An SHDC device provides physical layer seamless hand-off and obtain diversity signal-to-noise ratio (SNR) gain. When additional antennas are available for standby or other reasons, it may be beneficial for a number of satellite antennas to collectively utilize additional SHDC devices to achieve higher diversity SNR gains under normal operational considerations. The asymptotic SNR gains are those obtained when receiver antenna noise dominates transponder and sky noises. According to exemplary embodiment of the present invention, N satellite antennas may collectively utilize N−1 SHDC devices. For example, 3 satellite antennas may collectively utilize 2 SHDC devices.