Antenna Array Beamforming With Nonlinear Filtering for Interference Nulling

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Solution Overview

Problem

Antenna arrays face challenges in accurately recovering weak desired signals in noisy environments with multiple interfering signals, as traditional signal processing methods fail to effectively suppress interference without degrading signal quality and noise ratio.

Innovation Solution

An antenna array system with an interferer-nulling beam forming network (IN-BFN) and non-linear filters is used to generate null signals, which are then filtered to suppress interfering signals, allowing for the recovery of desired signals even when they overlap with interference in time and frequency domains.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If traditional linear spatial filtering or conventional excision algorithms are used to attenuate interfering signals, then the structure remains simple, but the desired signal quality and signal to noise ratio deteriorate significantly

Engineering Contradiction:

Improveinterference signal attenuationVSAvoiddesired signal quality

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent segments the interference suppression task into multiple independent null BFNs, each responsible for nulling a specific interference signal from a particular direction. This segmentation allows each BFN to focus on suppressing one interference source without affecting others, thereby maintaining desired signal quality while achieving effective interference attenuation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces non-linear filters as intermediary components between the null BFNs and the final signal output. These non-linear filters act as mediators that further suppress residual interference components while preserving the desired signal characteristics, thus resolving the contradiction between interference attenuation and signal quality maintenance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If multiple nulling beam weight sets are applied to suppress N interfering signals, then interference attenuation improves, but the device complexity increases with N non-linear filters and multiple BFNs

Engineering Contradiction:

Improvemultiple interference signal suppressionVSAvoidnumber of beam forming networks and filters

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Each null BFN is designed to be multi-functional, capable of suppressing one specific interference signal while allowing the system to handle multiple interference sources through coordinated operation of multiple BFNs. This universality reduces the need for completely separate processing chains for each interference source, thereby managing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system dynamically allocates and activates specific null BFNs based on the number and characteristics of detected interference signals. When N interfering signals are present, the system activates N null BFNs with corresponding non-linear filters, rather than maintaining a fixed complex structure for all possible interference scenarios, thus adapting complexity to actual needs.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If conventional excision algorithms are used to remove interfering signals, then the processing remains simple, but the signal to noise ratio of the desired signal deteriorates

Engineering Contradiction:

Improveinterference signal removalVSAvoidsignal to noise ratio

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent replaces conventional excision algorithms with a beam forming-based approach using null BFNs and non-linear filters. This substitution transitions from simple signal excision to a more sophisticated spatial filtering mechanism that maintains better signal to noise ratio by exploiting spatial information and directional characteristics of interference signals.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250023231A1Antenna array system with disparate beam forming networks and non-linear filtering to mitigate interference

Publication Date: 2025.01.16 VIASAT INC

AI summary

Disclosed is an antenna array system including an antenna array of N≥2 antenna elements that output N antenna signals; an interferer-nulling beam forming network (IN-BFN) coupled to the antenna array, N non-linear filters coupled to the IN-BFN, and a desired signal BFN. The IN-BFN may include N “null BFNs” to generate N null signals, each null BFN applying a respective nulling beam weight set to the N antenna signals to generate a respective one of the N null signals. Each respective nulling beam weight set corresponds to a different respective set of (N−1) independent nulls. Each of the N non-linear filters may filter a respective one of the N null signals to provide a respective one of N filtered signals. The desired signal BFN may apply a desired signal beam weight set to the N filtered signals to generate an output signal.