• 한국통신학회논문지
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• 제38C권11호
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• pp.1044-1050
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• 2013

본 논문은 ETRI에서 개발한 GPS RF 신호생성기와 상용수신기인 U-Blox 수신기를 이용하여 기만신호의 공격을 완화하는 방법에 대하여 분석하였다. 기만신호는 대상 수신기의 코드 및 반송파 성분의 변이를 이용하여 대상수신기가 비정상적인 위치를 생성하도록 하는 것이다. 우리는 이러한 기만신호 공격에 따른 수신기에서의 신호세기 및 항법해 영향을 분석하였다. 또한 기만신호를 제거하기 위하여 기만신호와 역위상 코드를 가지는 신호를 고려하였다. GPS RF 신호생성기를 이용하여 정상적인 GPS 신호, 기만신호, 기만신호와 역위상을 가지는 항기만신호를 생성하였고 기만신호와 항기만신호간의 코드 위상차이에 따른 기만신호 공격의 영향을 수신기를 통하여 확인하였다. 기만 신호의 코드 지연과 동일한 코드지연의 신호를 생성할 경우 기만신호가 상쇄되는 것을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제4권4호
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• pp.173-180
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• 2015

In this study, an algorithm that detects a spoofing signal for a GPS L1 signal was proposed, and the performance was verified through RF spoofing signal simulation. The proposed algorithm determines the reception of a spoofing signal by detecting a correlation distortion of GPS L1 C/A code caused by the spoofing signal. To detect the correlation distortion, a detection criterion of a spoofing signal was derived from the relationship among the Early, Prompt, and Late tap correlation values of a receiver correlator; and a detection threshold was calculated from the false alarm probability of spoofing signal detection. In this study, an RF spoofing environment was built using the GSS 8000 simulator (Spirent). For the RF spoofing signal generated from the simulator, the RF spoofing environment was verified using the commercial receiver DL-V3 (Novatel Inc.). To verify the performance of the proposed algorithm, the RF signal was stored as IF band data using a USRP signal collector (NI) so that the data could be processed by a CNU software receiver (software defined radio). For the performance of the proposed algorithm, results were obtained using the correlation value of the software receiver, and the performance was verified through the detection of a spoofing signal and the detection time of a spoofing signal.

• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.173-179
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• 2022

The satellite navigation deception technology disturbs the navigation solution of the receiver by generating a deceptive signal simulating the actual satellite for the satellite navigation receiver mounted on the unmanned aerial vehicle, which is the target of deception. A single spoofing technique that creates a single deceptive position and velocity can be divided into a synchronized spoofing signal that matches the code delay, Doppler frequency, and navigation message with the real satellite and an unsynchronized spoofing signal that does not match. In order to generate a signal synchronized with a satellite signal, a very sophisticated and high precision signal generation technology is required. In addition, the current position and speed of the UAV equipped with the receiver must be accurately detected in real time. Considering the detection accuracy of the current radar technology that detects small UAVs, it is difficult to detect UAVs with an accuracy of less than one chip. In this paper, we assume the asynchrony of a single spoofing signal and propose a region defense technique using multiple spoofing signals.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.793-800
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• 2010

GPS spoofing is an intentional interference which uses the mimic GPS signals to fake the receivers. The generic GPS receiver is hard to recognize the spoofing signal because the spoofer generates the fake signals as close as possible to the GPS signal. So the spoofer can do critical damage to public operations. This paper introduces a basic concept of spoofing and analyzes the effect of the spoofing signal to the GPS receiver. Also for stand-alone GPS receivers, two anti-spoofing methods are implemented : RAIM based method and the SQM based method. To evaluate the performance of anti-spoofing method, the software based spoofing signal generator and GPS signal generator are implemented. The performance of the anti-spoofing methods obtained using the output of the software based GPS receiver shows that SQM based method is more effective when multiple spoofing signals exist.

• 제어로봇시스템학회논문지
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• 제19권2호
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• pp.113-118
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• 2013

In this paper, spoofing effects on a GNSS receiver were analyzed. The spoofer (spoofing device) was classified to two categories. One is an active spoofer and the other is a passive spoofer. The active spoofer was considered for analysis. For the analysis of spoofing effects on a GNSS receiver, a real-time GNSS spoofing simulator was developed. The simulator was consisted with two parts which are a baseband signal generation part and a RF up-conversion part. The first GNSS baseband signal was generated according to spoofing parameters such as range, range rate, GNSS navigation data, spoofing to GNSS signal ratio, and etc. The generated baseband signal was up-converted to GNSS L1 band. Then the signal transmitted to a GNSS signal. For a perfect spoofing, a spoofer knew an accurate position and velocity of a spoofing target. But, in real world, that is not nearly possible. Although uncertainty of position and velocity of the target was existed, the spoofer was operated as an efficient jammer.

• 한국위성정보통신학회논문지
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• 제8권2호
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• pp.29-35
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• 2013

본 논문에서는 GPS L1 신호에 대한 기만의 종류 및 이를 검출하기 위한 방법에 대한 연구를 수행하고 GPS L1 신호에 대한 기만신호 검출 및 판단 알고리즘을 구현한 후 시뮬레이션을 통하여 성능을 분석하였다. 수신기의 동작 여부에 따라 기만과 재밍신호가 차이가 있으며 기만신호는 재밍신호와 달리 GPS 신호와 유사한 신호로 수신기를 공격하므로 기만 대상 수신기에서는 정상동작하는 것처럼 판단하게 되며 따라서 수신기에서 기만공격을 판단하기란 매우 어렵다. 기만신호 검출 및 판단 알고리즘의 성능을 검증하기 위하여 소프트웨어 기반의 기만신호/정상 GPS 신호생성기와 소프트웨어 기반의 수신기를 구현하였다. 본 논문에서 기만신호의 코드지연 및 도플러 주파수 변이에 따른 수신기의 DLL/PLL의 출력 오차를 확인하였다. 또한 수신기의 출력값인 의사거리, 신호세기, 항법해를 이용하여 기만신호 검출 및 판단 알고리즘을 구현하였으며 기만신호를 효율적으로 검출 및 판단할 수 있었다.

• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.181-189
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• 2022

The public open signals from Global Navigation Satellite System (GNSS) including Global positioning system (GPS) are used widely by many peoples in the world except for the public regulated restriction signals which are encrypted. Nowadays there are growing concerns about GNSS signal spoofing which can deceive the GNSS receivers by abusing these open services. To counter these spoofing threats, many researches have been studied including array antenna techniques which can detect the direction of arrival by means of Multiple Signal Classification (MUSIC) algorithm. Originally the array antenna techniques were developed to countermeasure the jamming signal in electronic warfare by using the nulling or beamforming algorithm toward a certain direction. In this paper, we study the anti-spoofing techniques using array antenna to overcome the jamming and spoofing issues simultaneously. First, we will present the theoretical analysis results of spoofing signal response of Minimum Variance Distortionless Response (MVDR) algorithm in array antenna. Then the eigenvector algorithm of covariance matrix is suggested and verified to work with the existing anti-jamming method. The modeling and simulation are used to verify the effectiveness of the anti-spoofing algorithm. Also, the field test results show that the array antenna system with the proposed algorithms can perform the anti-spoofing function. This anti-spoofing method using array antenna is very effective in the view point of solving both the jamming and spoofing problems using the same array antenna hardware.

• 한국항행학회논문지
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• 제18권1호
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• pp.7-13
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• 2014

본 논문에서는 GPS 전파 간섭 신호의 한 종류인 기만 신호를 검출하는 기법을 제안한다. 본 논문에서 기만의 대상이 되는 신호에는 민간에 구조가 공개된 GPS L1 C/A 신호로 선정하였으며 GPS L1 C/A 기만 신호의 영향을 분석하고 이를 통해서 기만 신호 검출 기법을 제안한다. 제안하는 기만 신호 검출 기법은 상관함수가 왜곡된 정도로 기만 신호의 인가를 판단한다. 기만 신호의 판단기준은 수신기 열잡음의 통계적 특성으로부터 정량적인 수치로 계산된 임계값을 이용하였다. 제안하는 기법을 검증하기 위한 시뮬레이션은 MATLAB을 기반으로 구성하였으며 기만 신호에 의한 상관함수 왜곡 및 코드 위상 오차를 확인하였다. 그리고 본 논문에서 제안하는 기만 신호 검출 기법을 적용하여 기만 신호의 검출 시뮬레이션을 수행하여 제안하는 기법에 의한 기만 신호 검출성능을 확인하였다.

• 한국위성정보통신학회논문지
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• 제7권1호
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• pp.128-133
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• 2012

본 논문에서는 기만신호의 영향을 분석하기 위하여 기만신호의 코드지연에 따른 코드 및 반송파 추적에 대한 결과를 분석하였다. 기만신호의 특성 및 방어 방법에 대한 조사를 통하여 현재 GPS 신호와 동기를 유지할 수 있는 중급기만을 고려하여 기만신호생성기를 이용하여 시뮬레이션을 수행하였다. 기만신호생성기에서 생성한 정상신호 및 기만신호가 합성된 신호를 소프트웨어 수신기를 통하여 신호처리를 수행하였다. 본 논문에서는 코드추적루프(DLL) 및 위상추적루프(PLL)의 출력값을 비교분석하여 기만신호의 영향을 파악하였으며 또한 기만신호 인가 시 잘못된 의사거리에 따른 항법해의 영향을 분석하였다. 결과적으로 기만신호의 영향은 신호추적 단계에서는 1칩 이내의 코드지연을 갖는 기만신호의 영향을 받으며 신호획득에서는 코드 지연에 상관없이 영향을 받는 것을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제10권3호
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• pp.169-177
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• 2021

In this paper, we propose a novel global navigation satellite system (GNSS) spoofing detection technique through an array antenna-based direction of arrival (DoA) estimation of satellite and spoofer. Specifically, we consider a sophisticated GNSS spoofing attack scenario where the spoofer can accurately mimic the multiple pseudo-random number (PRN) signals since the spoofer has its own GNSS receiver and knows the location of the target receiver in advance. The target GNSS receiver precisely estimates the DoA of all PRN signals using compressed sensing-based orthogonal matching pursuit (OMP) even with a small number of samples, and it performs spoofing detection from the DoA estimation results of all PRN signals. In addition, considering the initial situation of a sophisticated spoofing attack scenario, we designed the algorithm to have high spoofing detection performance regardless of the relative spoofing signal power. Therefore, we do not consider the assumption in which the power of the spoofing signal is about 3 dB greater than that of the authentic signal. Then, we introduce design parameters to get high true detection probability and low false alarm probability in tandem by considering the condition for the presence of signal sources and the proximity of the DoA between authentic signals. Through computer simulations, we compare the DoA estimation performance between the conventional signal direction estimation method and the OMP algorithm in few samples. Finally, we show in the sophisticated spoofing attack scenario that the proposed spoofing detection technique using OMP-based estimated DoA of all PRN signals outperforms the conventional spoofing detection scheme in terms of true detection and false alarm probability.