Adaptive Antenna Spatial Nulls for Inter-System Interference

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Solution Overview

Problem

Inter-system interference occurs due to the terrestrial reuse of satellite frequencies by ancillary terrestrial networks, leading to interference between terrestrial cellular systems and independent satellite communications systems operating in adjacent frequency bands, which affects signal quality and system performance.

Innovation Solution

An adaptive antenna system is employed at the base transceiver station to receive vectors of signals from both terrestrial and satellite communications systems, generating complex transmitting weights that form spatial nulls directed at independent communications system transceivers, thereby reducing interference by forming a composite covariance matrix and using pseudo uplink beamforming weights for downlink communications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If terrestrial networks reuse satellite frequencies in densely populated areas, then system capacity and coverage are improved, but inter-system interference between terrestrial and satellite communications deteriorates

Engineering Contradiction:

Improvesystem capacityVSAvoidinter-system interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating spatially selective signal transmission characteristics. The adaptive antenna system forms directional beams toward satellite terminals and spatial nulls toward independent satellite systems in specific geographic directions, allowing frequency reuse in densely populated areas while locally suppressing interference in targeted directions through position-dependent signal weighting

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements parameter changes by dynamically adjusting antenna radiation pattern parameters based on detected interference conditions. The system modifies beamforming weights and spatial null depths in response to measured signal levels from independent satellite systems, enabling adaptive control of interference suppression while maintaining service to legitimate satellite terminals

Inventive Principle:

Principle #35Parameter changes

2Reliability

If adaptive beam forming is used to reduce interference, then signal quality is improved, but device complexity increases

Engineering Contradiction:

Improvesignal qualityVSAvoidantenna system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial action by implementing interference suppression only in specific spatial directions where independent satellite systems are detected, rather than applying uniform processing to all signals. The adaptive antenna system selectively forms spatial nulls toward identified interference sources while maintaining normal beamforming for other directions, reducing computational complexity compared to omnidirectional adaptive processing

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent uses an intermediary approach by introducing a detection and control system that mediates between the antenna array and signal processing functions. The system detects signals from independent satellite systems, determines their spatial locations, and controls the formation of spatial nulls accordingly, separating the complex adaptive processing into manageable detection and execution stages

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The adaptive antenna system effectively minimizes inter-system interference by creating spatial nulls towards independent satellite communications systems, improving signal quality and reducing overload and intermodulation interference, while maintaining high antenna discrimination and gain towards desired users.

Implementation Method 1

generating complex transmitting weights that form spatial nulls directed at independent communications system transceivers

Methodology Applied

Scientific EffectBeamforming:

Implementation Method 2

forming spatial nulls directed at the transceivers of the independent communications system

Methodology Applied

Scientific EffectSpatial filtering:

Data Source

PatentUS8412126B2Communications systems including adaptive antenna systems and methods for inter-system and intra-system interference reduction

Publication Date: 2013.04.02 ATC TECHNOLOGIES LLC

AI summary

Methods of forming a downlink beam in an adaptive antenna system of a communications system that may reduce inter-system and/or intra-system interference include receiving vectors of signals including signals transmitted by user terminals of the communications system and signals transmitted by transceivers of an independent communications system, obtaining spatial information for the user terminals of the communications system and the transceivers of the independent communications system, generating complex transmitting weights that form spatial nulls directed at the transceivers of the independent communications system, and transmitting a downlink communications signal using the complex transmitting weights. Related systems are also disclosed.