Calibration Earth Station Placement for Ground-Based Beam Forming
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Solution Overview
Problem
The Ground-Based Beam Forming (GBBF) system faces challenges in calibrating the payload antenna array due to improper placement of Calibration Earth Stations (CESs), leading to increased system cost and maintenance concerns, as well as potential deterioration of calibration performance.
Innovation Solution
A method using stochastic annealing to determine the optimal number and locations of CESs, ensuring each feed element and CES has strong secondary pattern connections, and employing a signal processor to estimate calibration parameters by linking channel coefficients and perturbations across CESs, with a bridging element providing a strong pilot signal for at least two CESs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple Calibration Earth Stations (CESs) are deployed to improve calibration performance, then calibration accuracy is improved, but system cost and complexity increase
Solution Approach 1:
The patent introduces a bridging feed element that acts as an intermediary to connect multiple CESs. This bridging element enables indirect calibration paths between CESs, allowing calibration information to be propagated across the network without requiring direct line-of-sight between all CES pairs. The bridging element serves as a mediator that facilitates calibration while reducing the total number of CESs needed.
Solution Approach 2:
The calibration network is segmented into multiple calibration paths involving different combinations of CESs and feed elements. Instead of requiring a single comprehensive calibration path, the system uses multiple smaller calibration segments that can be combined. This segmentation allows the calibration function to be distributed across fewer CESs while maintaining accuracy.
2Reliability
If more CESs are placed within satellite coverage to improve calibration coverage, then calibration performance is improved, but system cost increases
Solution Approach 1:
The patent merges multiple calibration functions into a smaller number of CESs by introducing bridging feed elements that enable indirect calibration paths. Instead of placing separate CESs for direct calibration of each feed element, the system combines calibration capabilities through shared bridging elements, reducing the total number of CESs required while maintaining comprehensive coverage.
Solution Approach 2:
The patent adds a temporal dimension to the calibration process by enabling multi-hop calibration paths that propagate calibration information through the network over time. Instead of requiring all CESs to simultaneously observe all feed elements, the calibration information flows through the network sequentially via bridging elements, achieving comprehensive calibration with fewer CESs.
3Adaptability or versatility
If FDM channels are used to separate feed element paths for flexibility, then beamforming adaptability is improved, but amplitude and phase imbalances increase requiring complex calibration
Solution Approach 1:
The bridging feed elements serve as intermediaries that provide reference paths for calibrating the FDM channels. By introducing these intermediate reference points, the system can measure and correct amplitude and phase imbalances in the FDM channels without requiring complex direct measurements between all CES and feed element pairs.
Data Source
AI summary
A system and method for estimating calibration parameters and locating a Calibration Earth Station (CES) is described. The method may be performed offline. The method includes: providing L×M pilot signal measurements in a matrix R from L CESs and the M feed elements, wherein the matrix R comprises a set of channel coefficients c={c1, c2, . . . , cM}, and k={k1, k2, . . . , kL} perturbations; linking a subset of channel coefficients {c1, c2, . . . , cM} using each of the L CESs; and estimating a relative estimate of the k={k1, k2, . . . , kL} pertubations across the L CESs by using each of the L CESs as a bridging element. In the method, the bridging element provides a strong pilot signal for at least two of the L CESs. A set of criteria for determining locations of CESs have been described. A set of desirable properties for the solution set of L CESs have been disclosed. A combination of inner loop and outer loop methods for determining the final set of optimal locations have been described.