Ground-Based Beamforming for Satellite Communications
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Solution Overview
Problem
Current satellite communications systems face challenges in performing beamforming on satellites due to the need for precise amplitude and phase settings of feed elements, which is technically difficult and limited by space-based constraints, and ground-based beamforming techniques struggle to compensate for temperature changes, pointing errors, and signal dispersion effects, especially when dealing with frequency division multiplexed signals.
Innovation Solution
Implementing a ground-based beamforming system that measures and corrects amplitude and phase errors for both forward and return path signals, using a distributed control system with elements on the ground and satellite, including a calibration network, payload beacon, payload pilot, and tracking master reference oscillator to manage beamforming coefficients and compensate for errors such as Doppler shifts and pointing errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If beamforming is performed on the satellite using space-based BFN's, then beamforming capability is achieved, but system reliability degrades and hardware mass increases
Solution Approach 1:
The beamforming network functions are extracted from the satellite and relocated to ground-based equipment. This removes the complex BFN hardware from the space environment, eliminating the associated reliability degradation and hardware mass increases while preserving beamforming capability through ground-based signal processing
Solution Approach 2:
A ground-based beamforming network acts as an intermediary between the satellite transponder and the feed array. This intermediary performs the beamforming processing on the ground, allowing the satellite to maintain a simpler architecture while still achieving the desired beamforming effects through coordinated ground-based signal manipulation
2Weight of stationary object
If ground-based beamforming is implemented, then hardware mass and cost are reduced, but the system must compensate for temperature changes, pointing errors, and signal dispersion
Solution Approach 1:
The system employs feedback mechanisms where the ground-based beamforming network continuously monitors and measures signal characteristics, including temperature variations, pointing errors, and dispersion effects. This feedback information is used to dynamically adjust beamforming coefficients and compensate for environmental changes, maintaining performance despite the added complexity
Solution Approach 2:
The ground-based beamforming network dynamically changes signal parameters including amplitude and phase of individual feed elements based on measured conditions. By adjusting these parameters in response to temperature changes, pointing errors, and dispersion effects, the system compensates for environmental variations without requiring additional hardware mass
3Measurement precision
If conventional space-based beamforming is used, then precise amplitude and phase control is achieved, but the system lacks flexibility to adapt to changing market demand
Solution Approach 1:
The ground-based beamforming network provides dynamic reconfigurability that was impossible with fixed satellite hardware. Beamforming coefficients can be updated in real-time based on changing traffic patterns and market demand, allowing the system to adapt flexibly while maintaining precise amplitude and phase control through digital signal processing
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
Enables flexible and efficient beamforming for satellite communications systems, allowing for adaptive beam configuration without hardware changes, improving system reliability and cost-effectiveness by moving beamforming functions to the ground, and supporting frequency division multiplexed signals.
Implementation Method 1
signal propagation amplitude and phase dispersion effects, including Doppler shifts
Data Source
AI summary
Methods, systems and apparatus for ground-based beamforming of a satellite communications payload (200) within a satellite communications network (100). An embodiment of the invention comprises a satellite (11) communicatively coupled to at least one gateway (12) via a feeder link (13) and a plurality of user terminals (16), each communicatively coupled with the satellite by a user link (17) where a ground based beam forming system (400) receives, via feeder link (13), return path signals (452) traveling from the user terminals (16) via the satellite (11) to the at least one gateway (12) and forward path signals (457) traveling from the at least one gateway (12) via the satellite (11) to the user terminals (16), and measures and corrects amplitude and phase errors of the return path signals (452) and the forward path signals (457).