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The threat of signal spoofing attacks against global navigation satellite system (GNSS) has grown in recent years and has motivated the study of anti-spoofing techniques. However, defense methods have been designed only against specific attacks. This paper introduces a general model of the spoofing attack framework in GNSS, from which optimal attack and defense strategies are derived. We consider a scenario with a legitimate receiver (Bob) testing if the received signals come from multiple legitimate space vehicles (Alice) or from an attack device (Eve). We first derive the optimal attack strategy against a Gaussian transmission from Alice, by minimizing an outer bound on the achievable error probability region of the spoofing detection test. Then, framing the spoofing and its detection as an adversarial game, we show that the Gaussian transmission and the corresponding optimal attack constitute a Nash equilibrium. Lastly, we consider the case of practical modulation schemes for Alice and derive the generalized likelihood ratio test. Numerical results validate the analytical derivations and show that the bound on the achievable error region is representative of the actual performance.
Global navigation satellite systems (GNSSs) may transmit data to provide additional services. Since the resources reserved for these data are typically fixed and the message rate is low, we propose to split long messages into shorter packets and properly schedule their transmission from the entire constellation of satellites. Considering an efficient data transmission (useful for example for search and rescue messages), we aim at the scheduling of packets on the satellites on multiple rounds with two objectives: 1) the minimization of the maximum latency among all receivers or 2) the maximization of the average received packets per round. We first derive bounds on the performance of any GNSS single or multiround scheduling solution, on which the proposed scheduling solutions are based. Then, we introduce the scheduling problems that turn out to be integer linear programming problems. Lastly, we assess their performance, showing that our solution minimizes the maximum latency, while the scheduling targeting the average latency outperforms existing literature solutions.
The students will learn principles and methodologies for data transmission and communication networks.In particular, they will get to know techniques for digital encoding of information, characterization of physical channels and noise phenomena, digital modulation, error control techniques, as well as basic principles of medium access protocols and error management. The students will also acquire the capabilities to perform quantitative analysis of a communication systems evaluating its performance and necessary resources; design a communication system in its basic components, under specific application contexts, target requirements and constraints on resources and performance; place network problems in the context of the general architecture and evaluate the resulting trade-offs in terms of reliability, performance, and scalability.
In modern computer communication systems, securing against malicious behavior has become a primary issue, that must be part of the design since its earliest phases rather than a patch added as a belated measure. The class aims at introducing the students to the fundamental notions and tools in information security, with a focus on the solutions, attacks and countermeasures that can be deployed at the different layers in modern communication networks. Topics include: basic security notions and definitions; unconditional vs computational security; cryptographic and non cryptographic security mechanisms; network security protocols at different layers; further security issues for wireless, ad hoc and mobile networks.
If you are interested in carrying out a (Bachelor or Master) thesis on the topics of Information Security, please visit the thesis proposals page or contact me at the address below
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