Ground-Based Beamforming for Satellite Bandwidth Constraints
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Solution Overview
Problem
Conventional ground-based beamforming techniques face challenges in high-capacity satellite systems due to bandwidth expansion issues, increased complexity, and cost, particularly when trying to provide high-throughput communications, as they require significant feeder link bandwidth proportional to the number of antenna elements in the user link array.
Innovation Solution
The implementation of mutually synchronized spatially multiplexed feeder links (MSSMFL) that phase-synchronize and beam-weight feeder-link signals, allowing for frequency reuse and reducing bandwidth requirements by focusing feeder beams onto different regions, thereby avoiding the bandwidth expansion problem.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ground-based beamforming is implemented with conventional methods, then beamforming capability is achieved, but feeder link bandwidth requirements expand proportionally with the number of antenna elements
Solution Approach 1:
The patent merges multiple feeder links carrying the same frequency band into a single aggregated link, allowing bandwidth reuse across multiple antenna elements. This combining approach enables the system to achieve beamforming capability without requiring proportional feeder bandwidth expansion, as the same bandwidth resource is shared across multiple links through coordinated combining at the satellite receiver.
Solution Approach 2:
The patent makes the feeder link bandwidth resource universal by enabling the same frequency band to serve multiple antenna elements simultaneously. Through spatial multiplexing and coherent combining, a single bandwidth resource performs the function of supporting multiple beamforming channels, eliminating the traditional one-to-one mapping between antenna elements and feeder bandwidth.
2Productivity
If the number of beams is increased to increase capacity, then bandwidth reuse is improved, but beam sizes decrease requiring increased antenna pointing accuracy
Solution Approach 1:
The patent uses coherent copying of the same frequency band across multiple feeder links to create multiple beams. Instead of requiring each beam to have dedicated bandwidth, the system copies the same frequency resource across multiple spatial paths and combines them coherently at the satellite, achieving high capacity with relaxed pointing accuracy requirements.
Solution Approach 2:
The patent transitions from a two-dimensional problem (beam count vs. beam width in the sky) to a three-dimensional solution by adding the temporal/coherent dimension. Through coherent combining in the time domain and spatial processing, the system achieves capacity increase without sacrificing beam width or requiring excessive pointing precision.
3Adaptability or versatility
If on-board beamforming arrays are used to address beam size and capacity issues, then beamforming performance is improved, but satellite size, weight, cost, and complexity increase
Solution Approach 1:
The patent extracts the beamforming complexity from the satellite platform and relocates it to the ground-based feeder link network. By performing coherent combining and spatial processing in the ground segment rather than on-board, the satellite maintains simple receive functionality while achieving sophisticated beamforming performance through external processing.
Solution Approach 2:
The patent introduces the ground-based feeder link network as an intermediary between the antenna array and the satellite payload. This intermediary performs the complex beamforming operations externally, allowing the satellite to achieve advanced beamforming capability without incorporating complex on-board processing 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 implementation of high-throughput satellite communications systems, such as those providing 1 Terabit-per-second or more, by efficiently managing bandwidth and reducing the complexity and cost associated with conventional methods.
Implementation Method 1
mutually phase-synchronizing and beam-weighting spatially multiplexed feeder-link signals
Implementation Method 2
focused feeder beams are used to receive the mutually phase-synchronized and beam-weighted, spatially multiplexed forward uplink signals
Data Source
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AI summary
Embodiments provide ground-based beamforming with mutually synchronized spatially multiplexed gateways in a wireless communications system. Some embodiments operate in context of a satellite having a focused-beam feeder antenna that communicates with multiple, geographically distributed gateway terminals (e.g., single gateway per beam), and a user antenna that provides communications with user terminals via formed user beams. The gateway terminals can communicate feeder signals that are beam-weighted and mutually phase-synchronized (e.g., according to satellite and/or loopback beacons). For example, the synchronization can enable forward uplink signals to be phase-synchronously received by the satellite, and the beam weighting can enable the forward downlink signals to spatially combine to form forward user beams. Embodiments can achieve extensive bandwidth reuse through mutually synchronized spatial multiplexing of the feeder-link communications.