Satellite Terrestrial Frequency Overlap Interference Mitigation
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Solution Overview
Problem
Satellite radiotelephone systems face challenges in reliably serving densely populated areas due to signal blocking by high-rise structures and poor penetration into buildings, leading to underutilization of satellite spectrum, and existing dual mode radiotelephones are costly and bulky due to duplicate components for satellite and terrestrial communication.
Innovation Solution
A communications system combining a space-based network with an ancillary terrestrial network, using overlapping frequencies, spatial beam nulling, and adaptive power control to enhance link margins and reduce interference, while supporting terminal mobility and frequency reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If satellite radiotelephone systems use single antenna pattern covering entire service region, then system complexity is reduced, but service reliability in densely populated areas deteriorates due to signal blocking by high-rise structures
Solution Approach 1:
The patent divides the service region into multiple distinct service regions, each served by a separate satellite antenna pattern (beam or cell). This segmentation allows the system to provide targeted coverage to densely populated areas while maintaining broader coverage in other regions, resolving the contradiction between system simplicity and service reliability.
2Reliability
If terrestrial networks reuse satellite frequencies in densely populated areas, then service reliability improves, but spectrum interference increases between satellite and terrestrial systems
Solution Approach 1:
The patent implements frequency reuse with different quality characteristics in different locations. Satellite frequencies are reused by terrestrial networks in densely populated areas where satellite signals are blocked, while maintaining separate frequency usage in open areas. This local differentiation allows reliability improvement without causing widespread interference.
3Reliability
If dual mode radiotelephones with duplicate components are used, then communication reliability in both satellite and terrestrial modes improves, but device cost and size increase
Solution Approach 1:
The patent enables radiotelephones to operate in both satellite and terrestrial modes using shared communication components and protocols. By making the radiotelephone universal and capable of multi-functionality across different network types, the system achieves reliable communication in both modes without requiring separate duplicate components, thereby reducing device weight and cost.
4Device complexity
If satellite spectrum is used exclusively for satellite communications, then spectrum allocation simplicity is maintained, but spectrum utilization efficiency deteriorates in densely populated areas
Solution Approach 1:
The patent implements dynamic spectrum allocation where the same satellite frequencies are reused by terrestrial networks in densely populated areas where satellite coverage is poor, while satellite frequencies continue to serve open areas. This dynamic, location-dependent frequency assignment maximizes spectrum utilization efficiency without requiring complex centralized spectrum management.
Data Source
AI summary
A communications system includes a space-based network (SBN) including a plurality of spotbeams using a first set of frequencies and an ancillary terrestrial network (ATN) including a plurality of base stations using a second set of radio frequencies. In a coverage zone of a given spot beam wherein the SBN and the ATN use at least one frequency from the first and second sets of frequencies in common, the SBN uses a narrower bandwidth than the ATN on both forward and return links, the ATN employs frequency spreading on at least its return link communications, the SBN employs spatial beam nulling directed toward at least one ancillary terrestrial component (ATC) of the ATN, the SBN employs forward link margin control, the ATN employs return link power control, the SBN employs return link power control and base stations of the ATN provide isolation in the direction of at least one satellite of the SBN. Using such a combination of measures, the ATN and the SBN may support completely or partially overlapping use of the first and second sets of radio frequencies.