A key aspect to be considered in the design of new generations of global navigation satellite system (GNSS) signals and receivers is a proper partition between system and receiver contribution to the robustness against spoofing attacks. This article maps the current threats and vulnerabilities of GNSS receivers and presents a survey of recent defenses, focusing on cryptographic solutions suitable to authenticate civil signals. Future perspectives and trends are analyzed, with particular emphasis on spreading code authentication techniques, considered as a key innovation for the next generation of civil GNSS signals. An assessment of the robustness and feasibility of the various presented solutions is also provided, analyzing in particular the impact on both current and future receivers.

The definition of new families of curves named interference error envelope (IEE) and interference running average (IRA) is presented. Such tools are able to assess the impact of RF interference on different GNSS receivers, taking into account the features of the in-band interference source. In fact the actual impact on the final performance is strictly related to the specific receiver architectures. Continuous wave (CW) and wide band (WB) interference signals are considered in order to assess by means of IEE and IRA the robustness of new modulations based on the multiplexed binary offset carrier (MBOC) scheme for several receiver configurations, by varying the discriminator spacing, type, and the front-end filter bandwidth. Interference robustness is evaluated and compared with those of the well-known binary phase shift keying (BPSK) and binary offset carrier BOC(1,1) modulations. Simulation and theoretical results are validated by means of laboratory tests, proving the reliability of IEE curves for interference impact assessment.

This paper proposes a novel concept of “local integrity” suitable to Global Navigation Satellite System (GNSS) receivers in urban vehicular scenarios. The idea is to take into account not only the system, but also the environment nearby the receiver in its nominal conditions, exploiting the potentialities offered by a Vehicular Ad-hoc Network (VANET) infrastructure. In detail, the potential availability of multiple observations of GNSS signals, taken by different vehicles participating to a VANET, can be shared and combined in order to implement a collaborative spatial/temporal characterization and prediction of the local degradations of the GNSS signals. These concepts are intended to pave the way for the reconsideration/redefinition of the classic GNSS integrity concept, in order to overcome the major problems and limitations to its applicability in urban vehicular scenarios. The analytical development of the proposed methodology and the suitable network architecture for its implementation, as well as some validation results, are presented and discussed in the paper.

Global Navigation Satellite Systems (GNSS) with the ability to provide accurate positioning and timing information have become very important for many essential applications of both military and civil purposes. The upcoming European GNSS, Galileo system, foresees providing new advanced signals aiming to improve the receiver sensitivity. Towards the objective of a high sensitivity Galileo receiver architecture capable of operating anywhere at any time, the authors introduce possible joint data/pilot acquisition strategies to adapt with the problem of low received signal power in indoor environments. Analytical expressions as well as Monte Carlo simulations in indoor scenarios are presented to describe and prove the strategies improvement with respect to the conventional one currently operating inside GPS receivers. Additionally, based on the performance comparison among all the strategies, some applicable suggestions with respect to different operation modes are provided as the main contribution here.

The design of a solution for the authentication of both navigation data bits and spreading code chips, referred to as SNAP and suitable for the evolution of the Galileo E1 OS signal, is presented in the paper. Though the technique is innovative and able to achieve predefined authentication performance, it exploits the structure of the legacy Galileo signal and the characteristics of the OS NMA. A detailed overview of the open choices for the design of signal components dedicated to authentication is provided, together with an analysis of signal parameters definition. A possible implementation option of the SNAP solution is also presented.

In recent years, research activities in the field of Satellite Navigation have boosted worldwide. At the same time, it has become evident that few educational opportunities in the field were available for students and there was a need to develop dedicated tools for hands-on sessions. To partially answer this need, the NavSAS Group has developed N-FUELS and SOPRANO. N-FUELS, a MATLAB ^® -based signal simulator, allows students to understand the physical layer of the Global Navigation Satellite Systems (GNSS) signals and to learn how to manipulate them via software. SOPRANO, a collection of ANSI C language routines, implements the whole chain of GNSS signal elaboration in post-processing and enables testing and validation of new GNSS signal processing algorithms and architectures. Both tools are used in post-graduate courses at Politecnico di Torino with a high degree of internationalization, which opens interesting points of discussion concerning the introduction of novel educational tools able to meet the demand and the learning styles of students with different educational backgrounds and cultures.