Radio Frequency Interference Impact Assessment on Global Navigation Satellite Systems

The Institute for the Protection and Security of the Citizen of the EC Joint Research Centre (IPSC-JRC) has been mandated to perform a study on the Radio Frequency (RF) threat against telecommunications and ICT control systems. This study is divided into two parts. The rst part concerns the assessment of high energy radio frequency (HERF) threats, where the focus is on the generation of electromagnetic pulses (EMP), the development of corresponding devices and the possible impact on ICT and power distribution systems. The second part of the study concerns radio frequency interference (RFI) with regard to global navigation satellite systems (GNSS). This document contributes to the second part and contains a detailed literature study disclosing the weaknesses of GNSS systems. Whereas the HERF analysis only concerns intentional interference issues, this study on GNSS also takes into account unintentional interference, enlarging the spectrum of plausible interference scenarios.JRC.DG.G.6-Security technology assessmen

Impact Study of Unintentional Interference on GNSS Receivers

This work has been performed in the context of an Administrative Arrangement for DG HOME. The overall scope is to perform an impact assessment of radio frequency (RF) interference on critical infrastructures relying on GNSS-services for timing and synchronization purposes. In WP3, the analysis has been divided into the impact of intentional interference on critical infrastructures presented in WP3.1 and the analysis of unintentional interference, covered in this report. DVB-T has been identied as the most important source of unintentional interference in the GNSS frequency bands and therefore a special attention is paid to this interference source. The main motivation to assess the performance reduction of receivers due to unintentional interference, is related to the high probability of these events. Unintentional interference stems from out-of-band emissions or spurious transmissions. Four different scenarios have been considered in this work, covering (i) additive white Gaussian noise, (ii) continuous wave interference, (iii) pulsed continuous wave nterference and (iv) interference that stems from the third harmonic of DVB-T transmissions. All these scenarios are highly relevant and are frequently observed in realistic signal conditions. The scenario of DVB-T interference receives most of the attention in this work, since DVB-T has become the most widely adopted digital terrestrial television broadcasting standard in the world. Harmonics of the DVB-T signal could possibly fall together with the GPS L1 or Galileo E1 bands and as such become a threat. DVB-T services are operational in more than 40 countries, with more than 75% of the deployment in Europe. In the coming years, DVB-T is expected to be deployed in more than 100 countries. In the frame of this work, different tools have been developed to quantify the impact of unintentional interference. First, a laboratory testbed has been set up, that allows to take real GPS L1 signals, combine them with synthetic interfering signals and test the robustness of different commercial and professional receivers. Further, in order to have a full control of the signal characteristics and the implementation details of the receiver, a simulation platform has been developed. This simulation tool generates GNSS as well as interfering signals, and observes consequently the impact on the acquisition or tracking performance for different receiver implementations. Finally, since it is difcult to reach statistical signicance for the acquisition performance, an analytical tool has been developed allowing to evaluate the effects of interference. This report summarises the relevant results for the four considered scenarios. For the assessment of the acquisition performance the analytical tool and the simulation platform have been used. In order to evaluate the tracking performance, experimental work has been conducted with real receivers and simulations have been performed. For the acquisition, the report quanties how much the probability of detection and the probability of false alarm are affected by the presence of interference. For the tracking, the main result of this report is the quantication of the signal degradation in terms of C=N0 and in terms of the variance of the position solution. In the scenario of DVB-T Page 2 of 94 WP3.2 interference, the degradation of the signal quality has been determined as a function of the DVB-T third harmonic power and the distance between the victim receiver and the DVB-T base station.JRC.DG.G.6-Security technology assessmen

Characterization and Control of Conservative and Non-conservative Network Dynamics

Diffusion processes are instrumental to describe the movement of a continuous quantity in a network of interacting agents. Here, we present a framework for diffusion in networks and study in particular two classes of agent interactions depending on whether the total network quantity follows a conservation law. Focusing on probabilistic, asymmetric interactions between agents, we define how the dynamics of conservative and non-conservative networks relate to the weighted in-degree and out-degree Laplacians. For uncontrolled networks, we compare the convergence behavior of both types of networks as a function of the eigenvectors of the weighted graph Laplacians. For networks with exogenous controls, we also analyze convergence and provide a method to measure the difference between conservative and non-conservative network dynamics based on the comparison of their respective reachable sets. The presented network control framework enables the comparative study of the dynamic and asymptotic network behavior for conservative and non-conservative networks

Statistical modeling and analysis of interference in wireless networks

In current wireless networks, interference is the main performance-limiting\ud factor. The quality of a wireless link depends on the signal and interference\ud power, which is strongly related to the spatial distribution of the concurrently\ud transmitting network nodes, shortly denominated as the network geometry.\ud Motivated by the ongoing revision of wireless network design, this\ud dissertation aims to describe the relation between geometry and network\ud performance.\ud Given the exponential growth of wireless devices, it is meaningful to evaluate how network interference affects signal detection. We propose a unified statistical approach based on the characteristic function of the decision variable to describe the detection performance, accounting for single and multiple interference, as well as different detection schemes and architectures. The proposed framework is able to capture the deployment density of the interferers, transmission power, and fading distribution of the interferers and the signal of interest. In addition, we establish a fundamental\ud limit of the interferer node density beyond which robust energy detection is\ud impossible. This work highlights the crucial role of spatial statistics in the\ud evaluation of signal detection.\ud The capacity gain obtained through the densification of the network\ud architecture comes at the expense of an increase in energy consumption.\ud Although small cell access points consume little energy in comparison with\ud the macrocell base stations, the massive deployment of these additional small\ud cell base stations entails a significant increase in energy consumption. We\ud extend the capacity analysis of small cell networks to include the energy\ud consumption of the small cell tier. Considering a distributed sleep mode\ud strategy for the small cell access points, we cast the trade-off between energy\ud consumption and capacity as a set of optimization problems. We develop an\ud analytical framework, which can be used in practice to correctly set sensing\ud time and sensing probability whilst guaranteeing user quality of service.\ud Furthermore, the analytical tool accounts for the network load and predicts\ud the achievable energy reduction of the small cell tier by means of distributed\ud sleep mode strategies as a function of the user density.\ud Finally, given that current networks are interference-limited, we study how signal processing can improve the signal quality. We present a probabilistic framework to describe the performance gain of successive interference cancellation and show that the benefit is modest when users connect to the base station that provides the highest average signal-to-interference ratio. We extend the analysis to include novel ways to associate users to their access points and demonstrate that the benefits of successive interference cancellation are substantial for these operational scenarios.\ud By systematically incorporating the spatial statistics in the performance\ud analysis, this dissertation presents a methodology and analytical toolset\ud useful to enhance the understanding of the design, operation, and evaluation\ud of future wireless networks

Acquisition of GNSS signals in urban interference environment

In urban environment Global Navigation Satellite System (GNSS) signals are impaired by strong fading and by the presence of several potential sources of interference that can severely affect the acquisition. The work presented here evaluates the acquisition performance for the most common acquisition strategies in terms of receiver operating characteristics (ROC) and studies the impact of fading and interference on the acquisition performance. Two different interference scenarios are considered: a single interferer and a network of interferers. We present a framework to evaluate the GNSS acquisition performance with respect to all relevant system parameters that jointly considers the acquisition method, the effect of radio signal propagation conditions, and the spatial distribution of the interfering nodes

GNSS signal acquisition in harsh urban environments

In urban environment, Global Navigation Satellite System (GNSS) signals are impaired by non-line-of-sight fading conditions and by the presence of potential sources of electromagnetic disturbance. This paper analyzes the impact of the wireless propagation medium and aggregate network interference by measuring the degradation of the acquisition performance expressed in terms of receiver operating characteristics (ROC). The presented framework allows to realistically evaluate the GNSS acquisition performance by jointly considering the effect of radio signal propagation conditions, interfering nodes spatial distribution, and other relevant environment dependent parameters. By means of numerical examples we elucidate the need for alternative positioning techniques in harsh urban environments

Effectiveness of successive interference cancellation and association policies for heterogeneous wireless networks

The densification of the network infrastructure is a possible solution to meet the explosive growth of mobile data demand. In the resulting interference-limited networks, interference management techniques are of interest to increase the spectral efficiency. Successive interference cancellation (SIC) provides modest gains when users are connected to the access point (AP) which provides the maximum average received signal power. In this paper, we focus on alternative association policies where SIC gives rise to a substantial performance gain. Specifically, we present a probabilistic framework to evaluate the performance of heterogeneous networks with SIC capabilities considering the minimum load association policy and range expansion. Numerical results show the effectiveness of SIC for these association policies