Same-Channel Satellite-Terrestrial Repeater Feedback Cancellation
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Solution Overview
Problem
Satellite communications face poor signal penetration through natural and artificial blockages due to low link margins, limiting their use in urban areas and under foliage, and existing repeater systems require additional radiofrequency spectrum and cannot support UE mobility without modification.
Innovation Solution
A same-channel satellite-terrestrial repeater system that amplifies and retransmits satellite signals terrestrially using the same frequency, employing feedback cancellation and adaptive nulling techniques to reduce self-interference, allowing for improved signal coverage without the need for bandpass filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If satellite communications use low link margins to maintain system operation, then system continuity is preserved, but signal penetration through blockages deteriorates
Solution Approach 1:
A terrestrial repeater is introduced as an intermediary device between the satellite and user equipment in cluttered areas. The repeater receives satellite signals through its satellite antenna, processes them, and retransmits via terrestrial antennas positioned to provide coverage in areas with natural or artificial blockages, thereby improving signal penetration without requiring the satellite system to increase its link margin
2Object-generated harmful factors
If conventional repeaters use frequency separation to reduce self-interference, then self-interference is reduced, but additional spectrum requirements increase system complexity
Solution Approach 1:
The patent converts the harmful self-interference effect into a measurable signal by using feedback cancellation techniques. The repeater captures its own transmitted signal through the feedback path, estimates the interference, and subtracts it from the received satellite signal. This allows the system to operate on the same frequency for both satellite and terrestrial links without requiring additional spectrum, as the self-interference is actively cancelled rather than avoided through frequency separation
3Object-affected harmful factors
If satellite communications operate with high link margins to improve signal penetration, then coverage in cluttered areas improves, but system efficiency deteriorates
Solution Approach 1:
The communication system is segmented into two parts: the satellite portion maintains its original low link margin operation for efficiency, while the terrestrial repeater portion provides the additional coverage in cluttered areas. This segmentation allows each part to operate optimally - the satellite efficiently and the repeater effectively in areas requiring enhanced coverage - without compromising overall system efficiency
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 reliable satellite signal coverage in cluttered areas with increased link margins, reducing self-interference and maintaining UE mobility without additional spectrum requirements.
Implementation Method 1
A satellite signal is received by a satellite antenna of the repeater and is amplified and retransmitted terrestrially by the repeater using the same channel
Implementation Method 2
A feedback canceller of the repeater reduces self-interference by canceling an estimated feedback amount from an input signal
Implementation Method 3
An adaptive nulling system of the repeater reduces self-interference by creating nulls in an antenna radiation pattern toward the repeater
Data Source
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AI summary
Systems and methods for same frequency /band repeaters for satellite and terrestrial links. One system includes a satellite antenna, a terrestrial antenna, a satellite transceiver coupled to the satellite antenna, a terrestrial transceiver coupled to the terrestrial antenna, and a controller communicatively coupled to transceivers. The controller is configured to receive a satellite downlink signal having a first frequency. The controller is configured to receive a plurality of terrestrial return link signals from a plurality of user terminals, the plurality of uplink signals having a second frequency. The controller is configured to generate a repeated, terrestrial downlink signal based on the satellite downlink signal. The controller is configured to generate a repeated satellite uplink signal that is a linearly amplified version of the combined terrestrial uplink signals. The controller is configured to transmit the repeated downlink signal at the first frequency. The controller is configured to transmit the combined uplink signal at the second frequency.