Interference Cancellation in HAPS Feeder Links via Band Segmentation
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Solution Overview
Problem
Dynamic interference occurs in multi-feeder links of aerial-floating type communication relay apparatuses due to the movement of upper-air relay apparatuses, which affects the communication capacity and frequency utilization efficiency.
Innovation Solution
Implementing a system with time-synchronized gateway stations that transmit and receive relay signals on the same frequency, using an interference suppression section to separate pilot signals, estimate propagation path responses, calculate weights for interference cancellation, and subtract interference signals using directional beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple gateway stations transmit relay signals on the same frequency to improve frequency utilization efficiency, then frequency utilization efficiency is improved, but dynamic interference occurs between feeder links
Solution Approach 1:
The transmission signal band of the feeder link is divided into multiple divided frequency bands. For each divided frequency band, propagation path responses are estimated separately, and weights are calculated to suppress interference signals. This segmentation allows interference cancellation to be performed effectively across the entire frequency band while maintaining high frequency utilization efficiency.
Solution Approach 2:
The patent converts the harmful interference signals from other gateway stations into useful information by using them as input for interference cancellation. The interference suppression section utilizes the received signals containing interference, estimates propagation path responses, calculates appropriate weights, and subtracts the estimated interference components to recover the desired signal. This transforms the harmful interference into an opportunity for implementing advanced signal processing that improves overall system performance.
2Productivity
If multiple gateway stations transmit relay signals on the same frequency to improve communication capacity, then communication capacity is improved, but interference suppression becomes more difficult
Solution Approach 1:
The transmission signal band is segmented into multiple divided frequency bands, and interference suppression is performed independently for each band. This segmentation simplifies the interference suppression process by breaking down the complex multi-frequency interference problem into multiple simpler, narrower-band problems that can be solved more effectively with dedicated propagation path response estimation and weight calculation for each band.
Solution Approach 2:
The patent changes the parameter of frequency band width by dividing the overall transmission band into multiple narrower divided frequency bands. This parameter change makes interference suppression easier because the propagation path responses can be estimated more accurately for each narrow band, and the interference characteristics vary less within each band, improving the effectiveness of the weight calculation and interference cancellation.
3Adaptability or versatility
If the upper-air relay apparatus moves in predetermined airspace to provide coverage, then service coverage is improved, but dynamic interference occurs between feeder links and gateway stations
Solution Approach 1:
The patent implements a dynamic interference suppression system that adapts to the moving upper-air relay apparatus. The propagation path response estimation and weight calculation are performed continuously based on current channel conditions, allowing the interference suppression to track and counteract the dynamic interference caused by the apparatus's movement through predetermined airspace while maintaining service coverage.
Solution Approach 2:
The interference suppression section uses feedback from the received signals to continuously estimate propagation path responses and recalculate weights for interference cancellation. This feedback mechanism allows the system to adapt to the changing interference conditions caused by the moving relay apparatus, maintaining effective interference suppression despite the dynamic service coverage requirements.
Data Source
AI summary
Interference in multi-feeder links of a same frequency between an aerial-floating type communication relay apparatus and plural gateway (GW) stations is suppressed. A transmission signal band of a feeder link is divided into plural divided frequency bands, and plural propagation path responses between plural GW stations and an antenna for feeder link of the communication relay apparatus are respectively estimated with respect to each of plural divided frequency bands, by setting a center frequency of the divided frequency band as an estimation frequency, based on a reception result of the pilot signals respectively received from the plural GW stations and separated from each other. A weight for suppressing an interference signal that causes an interference by a transmission signal transmitted from the GW station and received with a directional beam corresponding to another GW station is calculated for each of the divided frequency bands based on the plural propagation path responses. A reception signal received with the directional beam corresponding to the other GW station is multiplied by the weight corresponding to the other GW station and subtracted from the reception signal received with the directional beam corresponding to the other GW station, for each of the divided frequency bands.