GNSS Spoofer Identification via CRPA Null Steering
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Solution Overview
Problem
GNSS receivers are vulnerable to spoofing attacks, where false signals trick the system into incorrect position, velocity, and time estimates, leading to potential accidents or errors in navigation and tracking.
Innovation Solution
A controlled reception pattern antenna (CRPA) system with a beamformer and processor that steers a main lobe to survey directions, identifies spoofer locations by detecting increased signal power, and nulls out signals from spoofers using null steering, thereby enhancing the receiver's resistance to spoofing attacks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the main lobe is steered to survey all directions in space, then the ability to detect spoofer signals is improved, but the time required to complete the survey increases
Solution Approach 1:
The beamformer performs periodic scanning of different spatial directions by steering the main lobe sequentially across predefined beam angles. This periodic action allows the system to survey the entire space over time while maintaining reasonable detection capability at each sampled direction.
Solution Approach 2:
The system pre-defines a set of discrete beam angles and survey patterns before actual spoofer detection begins. This preliminary configuration allows the main lobe to efficiently cover the survey space without requiring continuous or exhaustive scanning, reducing the overall survey time while maintaining detection effectiveness.
2Reliability
If null steering is applied to block spoofer signals, then the reliability of GNSS reception is improved, but the device complexity increases
Solution Approach 1:
The processor continuously monitors signal characteristics across different beam angles and uses this feedback to identify directions containing spoofer signals. Based on this feedback, the beamformer dynamically adjusts the null directions to block the identified spoofer signals, creating a closed-loop system that improves reliability through adaptive response.
Solution Approach 2:
The system extracts the harmful spoofer signals by steering nulls specifically toward the directions where spoofer signals are detected. This selective extraction approach blocks only the harmful signals while preserving legitimate GNSS signals from other directions, improving reliability without requiring complete signal rejection.
3Measurement precision
If signal power thresholds are set low to detect weak spoofer signals, then the detection sensitivity is improved, but false alarms from normal signal variations increase
Solution Approach 1:
The system evaluates signal power increases locally at each specific beam angle rather than using a single global threshold. By comparing signal power at each direction against local baseline conditions and considering the spatial distribution of signal increases, the system can detect weak spoofer signals while filtering out normal signal variations that do not exhibit the characteristic pattern of spoofing.
Solution Approach 2:
The beamformer serves multiple functions: it surveys space for spoofer detection, identifies spoofer directions, and simultaneously steers nulls to block detected spoofers. This multi-functionality allows the system to use the same signal processing chain for both detection and mitigation, reducing false alarms through consistent evaluation criteria across different operational phases.
Data Source
AI summary
Disclosed is a technique that can provide one or more countermeasures against spoofers. A direction from which a spoofing attack occurs is identified. A beamformer can control an antenna pattern of a CRPA to null out signals from that direction, which can assist a GNSS receiver to avoid error induced by the spoofing attack. Further, after two or more observations, the location of the spoofer can be identified.