Optical ISL Satellite Feeder Link with Ground Beamforming
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Solution Overview
Problem
Current satellite communication systems face challenges in efficiently routing large amounts of bandwidth between ground-based gateways and space-based satellites, as well as between satellites, due to limitations in existing RF and optical communication technologies.
Innovation Solution
The implementation of a satellite communication system that uses analog-over-free-space optical signals for feeder links, eliminating the need for onboard demodulation and remodulation, and employing ground-based beamforming to simplify the satellite payload design and reduce mass, power, and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If RF signals are used for feeder links between gateway and satellite, then communication bandwidth can be routed, but the system requires onboard demodulation and remodulation hardware which increases device complexity
Solution Approach 1:
The patent replaces the mechanical/electronic demodulation and remodulation system with an optical communication system. Instead of using RF signals that require complex onboard processing, the system uses optical signals transmitted from ground-based gateways to satellites, eliminating the need for demodulation and remodulation hardware on the satellite payload.
Solution Approach 2:
The patent extracts the demodulation and remodulation functions from the satellite payload and relocates them to ground-based gateway equipment. This extraction simplifies the satellite design by removing complex processing hardware while maintaining the bandwidth routing capability through optical signal transmission.
2Productivity
If optical signals are used for inter-satellite links, then bandwidth capacity increases, but the system requires precise alignment and pointing which increases operational complexity
Solution Approach 1:
The patent implements self-service through automatic tracking and acquisition systems that enable the optical communication system to automatically maintain precise alignment between satellites. The system includes automated feedback mechanisms that continuously adjust the pointing of optical antennas to maintain optimal signal transmission without requiring manual intervention.
Solution Approach 2:
The patent employs feedback systems where receivers detect the quality and strength of optical signals and provide real-time information to transmitters. This feedback enables automatic adjustment of beam pointing and focusing, ensuring continuous optimal alignment between moving satellites while maintaining high bandwidth capacity.
3Quantity of substance
If ground-based beamforming is used to aggregate multiple user links, then bandwidth aggregation is achieved without extra hardware, but the beamforming complexity increases on the ground
Solution Approach 1:
The patent segments the beamforming function into multiple independent ground-based antenna elements that can be individually controlled. Each antenna element processes and transmits optical signals independently, and their combined effect creates the desired aggregated beam pattern. This segmentation allows bandwidth aggregation from multiple user links to be achieved through software control rather than additional hardware.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the aggregation of multiple user links without extra hardware, simplifies the satellite design, and increases bandwidth capacity, allowing for more efficient data transmission and reduced interference, thereby addressing the bandwidth requirements of satellite communication systems.
Implementation Method 1
an optical transceiver adapted to receive an optical feeder uplink beam transmitted from a ground based optical gateway
Implementation Method 2
an optical amplifier adapted to amplify an optical signal
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A system described herein includes a ground based gateway subsystem configured to transmit an RF feeder uplink beam to a satellite, and a space based subsystem of the satellite configured to receive the RF feeder uplink beam (602) and produce in dependence thereon an optical ISL beam that is transmitted to another satellite (618). The ground based gateway subsystem can include a ground based beamformer used to produce the RF feeder uplink beam. The optical ISL beam, produced by the space based subsystem and transmitted to the other satellite, can comprise a wavelength division multiplexed optical signal (614) having RF frequencies within a same specified RF frequency range within which the other satellite is configured to transmit a plurality of RF service downlink beams, thereby eliminating any need for the other satellite to perform any frequency conversions when producing the plurality of RF service downlink beams in dependence on the optical ISL beam.