Search

Position and time information provided by the satellite navigation system is important in many application fields. However, the satellite navigation signal is vulnerable to interference signals due to the low navigation signal strength. This interference signal for the satellite navigation signal is being advanced to the spoofing signal, which can adjust the position and time information of the satellite navigation receiver, beyond simple jamming signal. To ensure the safe use of satellite navigation signals in the future, it is necessary to prepare for attacks by such spoofing signals. It is possible to reduce the damage to users of satellite navigation by early detection of the spoofing signals. For spoofing signals, the detection method should be applied according to the attack method, and various detection methods should be applied because the impact of the attacker on the receiver may vary depending on the attack method and attack item. In this study, we propose a method to detect the spoofing signal when the signal is induced based on the satellite navigation correction data and measurement value. The proposed detection method is advantageous in that it can be applied to a receiver directly because the spoofing signal can be detected without being equipped with additional hardware in a conventional receiver. Additionally, this method can be applied to a mobile receiver as well as a fixed receiver. It is expected that the proposed technique will increase the usefulness and reliability of the satellite navigation system.

As the strength of global navigation satellite system (GNSS) signals is very low, they are vulnerable to interference and susceptible to attacks motivated by economic, military, and security reasons. These threats are gradually increasing. The most common attack is jamming, in which a strong signal is used to make a receiver miss the GNSS signal. As attacks become more sophisticated, they are expected to evolve to spoofing interference, in which the receiver is deceived. Spoofing interference is a larger threat because the receiver cannot recognize that they are being targeted by an attacker. For this reason, it is becoming more important to monitor GNSS signals so that they can be evaluated in terms of reliability. In this paper, we analyze spoofing detection methods with respect to the navigation solution, measurements, and navigation messages obtained by a receiver. We propose an advanced detection method for overcoming the limitations of each individual detection algorithm. The proposed methods enhance the performance of spoofing detection and reduce the false alarm rate. This research can be applied directly to GNSS signal monitoring systems and will be helpful for enhancing the stability of satellite navigation systems.

The Global Navigation Satellite System is vulnerable to interference signals that can potentially disable the system, because the signal strength tends to be very weak. Interference such as jamming, which disables the receiver via excessively high signal strength in the satellite navigation frequency band, and spoofing, which induces the receiver to output erroneous position and time data via signals similar to actual navigation signals, disrupt satellite navigation systems. As the threat of interference is increasing, considerable research effort has been expended in an attempt to deal with it in various ways. Spoofing attacks are especially difficult to detect. This paper deals with a technique to detect a spoofing signal and to mitigate attacks on satellite navigation systems. The satellite navigation signal is influenced by the navigation satellite itself and errors due to environmental factors, and spoofing signal detection should be well reflected in the navigation signal. Especially, in the case of mobile receivers, it is not easy to detect a spoofing signal because the exact position of the receiver cannot be known. To detect a spoofing signal, additional hardware may be required; in some cases, heterogeneous sensors, such as inertial sensors, may be used. The technique introduced in this paper effectively discriminates spoofing signals based only on receiver measurements, without the need for additional devices. It generates test statistics based on the pseudorange, which is the measured value of the receiver position, and detects spoofing signals by setting the monitoring interval according to a “sliding window”. Because the proposed method uses output data and measurements obtained from the receiver, it can be applied to general receivers at low cost.

As GNSS(Global Navigation Satellite System) is used in various filed, many countries establish GNSS system independently. But GNSS system has the limitation of accuracy and stability in stand-alone mode, because this system has error elements which are ionospheric delay, tropospheric delay, orbit ephemeris error, satellite clock error, and etc. For overcome of accuracy limitation, the DGPS(Differential GPS) and RTK(Real-Time Kinematic) systems are proposed. These systems perform relative positioning using the reference and user receivers. ETRI(Electronics and Telecommunications Research Institute) is developing precision navigation system in point of extension of GNSS usage. The precision navigation system is for providing the precision navigation solution to common users. If this technology is developed, GNSS system can be used in the fields which require precision positioning and control. In this paper, we introduce the precision navigation system and perform design and algorithm verification.

GNSS (Global Navigation Satellite System) Ground Station monitors navigation satellite signal, analyzes navigation result, and uploads correction information to satellite. GNSS Ground Station is considered as a main object for constructing GNSS infra-structure and applied in various fields. ETRI (Electronics and Telecommunications Research Institute) is developing Monitoring and Control subsystem, which is subsystem of GNSS Ground Station. Monitoring and Control subsystem acquires GPS and Galileo satellite signal and provides signal monitoring data to GNSS control center. In this paper, the configurations of GNSS Ground Station and Monitoring and Control subsystem are introduced and the preliminary design of Monitoring and Control subsystem is performed. Monitoring and Control subsystem consists of data acquisition module, data formatting and archiving module, data error correction module, navigation solution determination module, independent quality monitoring module, and system operation and maintenance module. The design process uses UML (Unified Modeling Language) method which is a standard for developing software and consists of use-case modeling, domain design, software structure design, and user interface structure design. The preliminary design of Monitoring and Control subsystem enhances operation capability of GNSS Ground Station and is used as basic material for detail design of Monitoring and Control subsystem.

Galileo is the Europe`s global navigation satellite system corresponding to the GPS. The GIOVE-A test experiment has been finished and the second test satellite GIOVE-B will be launched soon. The integration of GPS and Galileo lead an increase of visible satellite number. We can obtain an improved navigation performance in signal blocked area such as urban or forest. GPS and Galileo have each time-coordinate system and use the different error model to calculate the navigation solution. In this paper, we studied on GPS and Galileo channel error model and time-coordinate system. Using this result, we implement the integrated navigation algorithm. In simulation, we analyzed the navigation error caused by time and coordinate disagreement and verified performance of integrated navigation algorithm in terms of visible satellite number, DOP(Dilution of Pression) and position error.

Visibility of the satellite navigation is related to a environmental condition of a receiver. Obstacles like buildings and trees in urban areas can block signals and have effects on accuracy and reliability of positioning. This paper presents a method of creating 3D analysis model of urban canyon of Seoul using three-Dimensional digital map. Analysis techniques of visible satellites with Ray-Polygon Collision Detection and validation of algorithm through field tests are discussed. We have compared and analyzed the visibility of GPS and Galileo with respect to separate and simultaneous tracking in view of DOP (Dilution of Precision) using the 3D GIS digital map.

The Global Navigation Satellite System (GNSS) becomes more important and is applied to various systems. Recently, the Galileo navigation system is being developed in Europe. Also, other countries like China, Japan and India are developing the global/regional navigation satellite system. As various global/regional navigation satellite systems are used, the navigation ground system gets more important for using the navigation system reasonably and efficiently. According to this trend, the technology of GNSS Ground Station (GGS) is developing in many fields. The one of purposes for this study is to develop the high precision receiver for GNSS sensor station and to provide ground infrastructure for better performance services on navigation system. In this study, we consider the configuration of GNSS Ground Station and analyze function of Monitoring and Control subsystem which is a part of GNSS Ground Station. We propose Monitoring and Control subsystem which contains the navigation software for GNSS Ground System to monitor and control equipments in GNSS Ground Station, to spread the applied field of navigation system, and to provide improved navigation information to user.

GNSS(Global Navigation Satellite System) is used in various fields. Because the strength of GNSS signal is very weak on Earth surface, GNSS signal is easy to be disturbed by interference. For increasing the GNSS signal stability and availability, various mitigation methods and analysis of interference are studied. As these situation, it is necessary the standard platform to assist the interference mitigation studies and analyze receiver properties and interference effect. ETRI(Electronics and Telecommunications Research Institute) is developing GNSS Interference Signal Verification Platform. This platform generates interference signal and measures the receiver properties influenced by interference. Using the measurement result and signal propagation model, this platform analyzes the effect of interference. GNSS Interference Signal Verification Platform consists of GNSS Interference Signal Generation Equipment, GNSS Interference Signal Measurement Equipment, and GNSS Interference Propagation Model. This paper introduces GNSS Interference Signal Verification and describes the generation signal types which are jamming and spoofing interference. Finally we make the interference signal generation scenario for GNSS Interference Signal Generation Equipment. This scenario reflects the purpose and usage of GNSS Interference Signal Verification Platform.

The GNSS(Global Navigation Satellite System) is used widely and generally these days. The satellite navigation system provides navigation service globally and doesn"t need an extra cost to use. Thus this system is portrayed as public service. But this system has a weak point. The satellite signal strength is very weak on the ground so this system is vulnerable against interference signal. When the GNSS interference signal is induced, the receiver cannot operate normally. The interference is presented by jamming or spoofing about GNSS signal. The effect of the interference can be done in various field from car navigation to national infrastructure like mobile communication, power plant, etc. ETRI(Electronics and Telecommunications Research Institute) developed GPS Jamming monitoring system for monitoring interference of GNSS signal. The developed GPS Jamming monitoring system has the functions which are jamming & spoofing detection and jamming location with direction finders. Among the technologies of GPS Jamming monitoring system, this paper describes spoofing detection module. This module monitors GPS signal and detects the spoofing signal with measurement and message of receiver. ETRI performed the functional test of developed spoofing detection module through the spoofing signal generation equipment. In this test, we confirm that the spoofing signal is induced in GPS receiver and verify the performance of spoofing detection.

As the field of GNSS application is stretched, the stability of GNSS is concerned. GNSS is connected with the social infrastructure and economic problem. GNSS is used in communication system, military weapon, power station, satellite system, and so on. The information of position and time which is provided by GNSS is related with economy and military capabilities. Thus the threat of GNSS attack will increase in the future. For dealing with this request, ETRI is developing GNSS interference detection system. In this paper, we introduce the GNSS interference detection system and specially focus on the spoofing detection module. The algorithm for detecting the spoofing signal is implemented on the GNSS interference detection system. The result of implemented system is verified by the system test. The functions of spoofing detection module are verified by the spoofing environment which is generated by test-bed.