Global navigation satellite systems (GNSS) like GPS but also Galileo, GLONASS, and Beidou represent an important infrastructure to our society. They provide position and timing for numerous applications. A GNSS is a rather complex system consisting of around 30 satellites, a number of monitor stations, plus a control center. Billions of GNSS receivers represent the user segment. The receivers and the monitor stations receive a weak satellite radio signal and thus are susceptible to interference like jamming or spoofing. This paper outlines the core operation principles of satellite navigation to describe those kind of interference and to analyze the impacts. Different types of interference attacks result in different effects at the target receiver. The attack schemes are categorized within this paper. Reported incidents are summarized as well as the potential impact of GNSS vulnerability on critical infrastructure. Well known countermeasures at user receiver level or at system level are outlined and discussed for their suitability. The political and socioeconomic context of GNSS vulnerability is described emphasizing the large impact of a potential disruption of the GNSS service.

Known Vulnerabilities of Global Navigation Satellite Systems, Status, and Potential Mitigation Techniques

Critical government and industry sectors (such as law enforcement, transportation, communication, and finance) are growing increasingly dependent on Global Navigation Satellite Systems (GNSS) for positioning, navigation, and timing. At the same time, the availability of low-cost GNSS jamming devices are presenting a serious threat to GNSS and increasing the likelihood of outages to infrastructures relying on GNSS. The attacks range from malicious parties intentionally jamming GNSS signals within a targeted geographical region to uninformed users causing accidental interference. This paper is an overview of different approaches adopted to date to mitigate GNSS disruption caused by intentional and unintentional jamming. The first approach outlined in this paper is the use of inertial systems to aid GNSS. The second and third approaches are the filtering of jamming/interference in the spatial and time-frequency domains, respectively. The fourth approach is vector tracking of GNSS signals in the receiver.

Protecting GNSS Receivers From Jamming and Interference

Accurate and reliable vehicle localization is a key component of numerous automotive and Intelligent Transportation System (ITS) applications, including active vehicle safety systems, real time estimation of traffic conditions, and high occupancy tolling [1]. Various safety critical vehicle applications in particular, such as collision avoidance or mitigation, lane change management or emergency braking assistance systems, rely principally on the accurate and reliable knowledge of vehicles? positioning within given vicinity.

A New Decentralized Bayesian Approach for Cooperative Vehicle Localization Based on Fusion of GPS and VANET Based Inter-Vehicle Distance Measurement

Current and future wireless applications strongly rely on precise real-time localization. A number of applications, such as smart cities, Internet of Things (IoT), medical services, automotive industry, underwater exploration, public safety, and military systems require reliable and accurate localization techniques. Generally, the most popular localization/positioning system is the global positioning system (GPS). GPS works well for outdoor environments but fails in indoor and harsh environments. Therefore, a number of other wireless local localization techniques are developed based on terrestrial wireless networks, wireless sensor networks (WSNs), and wireless local area networks (WLANs). Also, there exist localization techniques which fuse two or more technologies to find out the location of the user, also called signal of opportunity-based localization. Most of the localization techniques require ranging measurements, such as time of arrival (ToA), time difference of arrival (TDoA), direction of arrival (DoA), and received signal strength (RSS). There are also range-free localization techniques which consider the proximity information and do not require the actual ranging measurements. Dimensionality reduction techniques are famous among the range free localization schemes. Multidimensional scaling (MDS) is one of the dimensionality reduction technique which has been used extensively in the recent past for wireless networks localization. In this paper, a comprehensive survey is presented for MDS and MDS-based localization techniques in WSNs, IoT, cognitive radio networks, and 5G networks.

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A State-of-the-Art Survey on Multidimensional Scaling-Based Localization Techniques

Cooperative localization of the connected vehicles is significant for many advanced intelligent transportation system (ITS) applications. Vehicle-to-vehicle communication using dedicated short-range communication (DSRC) has great potential to enhance global navigation satellite systems (GNSSs) for the capability of cooperative localization. In the integration of DSRC and GNSS, the tolerance against the unknown and time-varying observation conditions is a key factor to fulfill the requirements of several specific ITS applications. Under a GNSS/DSRC integrated architecture for cooperative localization, a novel robust cubature Kalman filter (CKF) is proposed in this paper to improve the performance of the data fusion under uncertain sensor observation environments. In the proposed solution, the structure of the standard CKF is enhanced using the Huber M-estimation technique, in which the original measurement update in the CKF is modified considering the probable anomalies in state estimation. Furthermore, based on the investigation of the adjustment effect from the constraint factor, an adaptive strategy for this parameter is introduced to optimize the performance comprehensively. The proposed method is validated using a specific simulation system. Results of experiment and simulations demonstrate the capability of improving the robustness and adaptive performance over the original filters under the unknown operation conditions.

Cooperative Localization of Connected Vehicles: Integrating GNSS With DSRC Using a Robust Cubature Kalman Filter

A new diagram for SBAS integrity validation is presented in this paper The proposed concept is a modification of the well known Stanford plot, where a 2D histogram shows the relationship of position errors against protection levels for a set of measurements using an all-in-view satellite selection The method consists of a new representation (known here as the Stanford-ESA Integrity Diagram) where, at each sample time and given location, the solutions from all possible combinations of satellites from four to all-in-view are displayed, instead of only the all-in-view one In the case of MIs, the geometries associated to each epoch are labeled with different symbols and colors The diagram allows for easy identification of the different clusters and assessment of the time correlation of the events Real measurement results are presented here showing that EGNOS integrity margins remain safe under this very exigent criterion, which is certainly a very positive result

The Stanford – ESA Integrity Diagram: A New Tool for The User Domain SBAS Integrity Assessment

To improve the performance of GNSS receivers in hostile environments, we consider a Cooperative Positioning approach, where receivers exchange data and information with their neighbors. We focus on unstructured P2P networks, without a control or fusion center. We show that a significant reduction of the acquisition time can indeed by achieved when GNSS aiding quantities like Doppler, satellite Carrierto-Noise ratio and secondary code delay are provided by some aiding peers. The approach is clearly similar to that of Assisted GNSS, but does not require a fixed infrastructure and may better take into account the local environment. Since, in the near future, multi-standard devices will be more and more inter-connected, GNSS Cooperative Positioning may soon become an alternative or a complement to fixed augmentation systems

Peer-to-Peer Cooperative Positioning Part I: GNSS Aided Acquisition

The present invention relates to a method for determining a position of an object having a Global Navigation Satellite System (GNSS) receiver. According to the invention, the method comprises the steps of: receiving signals by the GNSS receiver which are transmitted by GNSS transmitters positioned on board of satellites which are positioned in a view of the object; updating service data in the object, the service data including satellite clock data indicating internal clocks of the satellites, satellite orbit data indicating positions of the satellites, satellite delay code bias data relating to delay code biases of the GNSS transmitters and ionospheric model data indicating a state of an ionosphere; determining, based on the ionospheric model data, ionospheric delay data indicating corrections relating to delays of the signals, the delays of the signals resulting from a passage of the signals through the ionosphere between transmission of the signals from the GNSS transmitters and reception of the signals by the GNSS receiver; and determining a position of the object based on the signals, the satellite clock data, the satellite orbit data, the satellite delay code bias data and the determined ionospheric delay data.

Method, apparatus and system for determining a position of an object having a global navigation satellite system receiver by processing undifferenced data like carrier phase measurements and external products like ionosphere data

This paper focuses the attention on the problem of Radio Frequency Interference (RFI) mitigation in the framework of GNSS. The paper concentrates on interference mitigation algorithms to be applied within the digital part of a GNSS receiver. The first part of the paper focuses on the mitigation of RFI based on Wavelets. The theoretical fundamentals of the approach are presented, introducing the continuous and the discrete wavelet transformations, and its application to the mitigation of pulsed interferences is demonstrated. The mitigation of strong pulses as well as of low power Distance Measurement Equipment (DME) pulses is discussed and the results obtained for both the cases are presented. In the second part of the paper the mitigation of Continuous Wave Interference (CWI) by means of Notch Filtering is studied, presenting the fundamental steps of this method and presenting its benefits by means of simulation results.

Innovative interference mitigation approaches: Analytical analysis, implementation and validation

It is known that the Aeronautical Radio Navigation Systems sharing the Global Navigation Satellite Systems (GNSS) frequency band represent a threat to the satellite-based navigation services. Distance Measuring Equipment (DME) and Tactical Air Navigation (TACAN) systems broadcast strong pulsed ranging signals within the Global Positioning System L5 and Galileo E5a frequency bands where the aviation positioning aids services are allocated. This study provides an experimental assessment of the DME/TACAN interference effect on the GNSS receivers performance in scenarios where the presence of several transmitters in view generates radio-frequency interference hard to mitigate by means of the classical solutions. In detail, analysis in terms of the receiver performance will be presented by showing the effect of the non-ideal pulse blanking on the GNSS signal quality. The optimal set-up of the mitigation process, investigated by means of a software simulation, is provided.

Performance assessment of pulse blanking mitigation in presence of multiple Distance Measuring Equipment/Tactical Air Navigation interference on Global Navigation Satellite Systems signals

Jaron Samson

Papers

The Stanford – ESA Integrity Diagram: A New Tool for The User Domain SBAS Integrity Assessment

Peer-to-Peer Cooperative Positioning Part I: GNSS Aided Acquisition

Method, apparatus and system for determining a position of an object having a global navigation satellite system receiver by processing undifferenced data like carrier phase measurements and external products like ionosphere data

Innovative interference mitigation approaches: Analytical analysis, implementation and validation

Performance assessment of pulse blanking mitigation in presence of multiple Distance Measuring Equipment/Tactical Air Navigation interference on Global Navigation Satellite Systems signals