Definizione, studio e progetto preliminare di una tecnica di geo-localizzazione di sorgenti interferenti per satelliti commerciali di telecomunicazioni

L’argomento del dottorato riguarda le telecomunicazioni satellitari commerciali. In particolare tratta della possibilità di poter definire, progettare e valutare mediante analisi e simulazioni, un sistema in grado di geo-localizzare sorgenti interferenti nell’area di copertura dell’antenna a bordo satellite per telecomunicazioni (area di servizio). Tale soluzione tecnologica rappresenta un valido supporto per intervenire a seguito di uno o più eventi interferenti. Tale intervento può essere o di tipo passivo, quanto il satellite non è provvisto di sotto-sistema di contromisura, oppure attivo quando il satellite è provvisto a bordo di sistema di contromisura

Investigation of the effects of cloud attenuation on satellite communication systems

The aim of this project is to investigate the attenuation due to clouds at 20- 50GHz; to develop an accurate long-term prediction model of cloud attenuation applicable to slant-path links and evaluate the impact of cloud attenuation dynamics on the design of future portable EHF earth-space systems. Higher frequencies offer several advantages, for example, greater bandwidth and immunity to ionospheric effects. The EHF band is being targeted for the launch of earth-space communication systems to provide global delivery of bandwidthintensive services (e.g. interactive HDTV, broadband internet access and multimedia services, television receive-only, etc.) to portable terminal units. Since spectrum shortage and terminal bulk currently preclude the realization of these breakthrough-broadband wireless communication services at lower frequencies, a better understanding is needed in order to optimize their usage. One major obstacle in the design of EHF earth-space communication systems is the large and variable signal attenuation in the lower atmosphere, due to a range of mechanisms including attenuation (and scattering) due to clouds and rain, tropospheric scintillation caused by atmospheric turbulence and variable attenuation by atmospheric gasses. In particular, cloud attenuation becomes very significant at EHF. In this thesis, we start with an overview of literature review in the first chapter. Followed next by the theory and description of accepted-up to date- cloud attenuation models in the field (chapter 2). Then followed up by a description of the pre-processing, validations, sources and assumptions made in order to conduct the analysis of the cloud attenuation in this work (chapter 3). Afterwards, a comprehensive analysis of Meteorological and local tropospheric degradation was carried out (chapter 4). That was followed by an overview of cloud fade statistics and suggested methods to counter their effects (chapter 5). And finally the improved cloud attenuation model and the enhancement of the currently accepted cloud attenuation model (ITU-R 840.4) by terms of validating the effective temperature concept and ways of acquiring it (chapter 6)

Satellite-Based Communications Security: A Survey of Threats, Solutions, and Research Challenges

Satellite-based Communication systems are gaining renewed momentum in Industry and Academia, thanks to innovative services introduced by leading tech companies and the promising impact they can deliver towards the global connectivity objective tackled by early 6G initiatives. On the one hand, the emergence of new manufacturing processes and radio technologies promises to reduce service costs while guaranteeing outstanding communication latency, available bandwidth, flexibility, and coverage range. On the other hand, cybersecurity techniques and solutions applied in SATCOM links should be updated to reflect the substantial advancements in attacker capabilities characterizing the last two decades. However, business urgency and opportunities are leading operators towards challenging system trade-offs, resulting in an increased attack surface and a general relaxation of the available security services. In this paper, we tackle the cited problems and present a comprehensive survey on the link-layer security threats, solutions, and challenges faced when deploying and operating SATCOM systems.Specifically, we classify the literature on security for SATCOM systems into two main branches, i.e., physical-layer security and cryptography schemes.Then, we further identify specific research domains for each of the identified branches, focusing on dedicated security issues, including, e.g., physical-layer confidentiality, anti-jamming schemes, anti-spoofing strategies, and quantum-based key distribution schemes. For each of the above domains, we highlight the most essential techniques, peculiarities, advantages, disadvantages, lessons learned, and future directions.Finally, we also identify emerging research topics whose additional investigation by Academia and Industry could further attract researchers and investors, ultimately unleashing the full potential behind ubiquitous satellite communications.Comment: 72 page

Cognitive satellite communications and representation learning for streaming and complex graphs.

This dissertation includes two topics. The first topic studies a promising dynamic spectrum access algorithm (DSA) that improves the throughput of satellite communication (SATCOM) under the uncertainty. The other topic investigates distributed representation learning for streaming and complex networks. DSA allows a secondary user to access the spectrum that are not occupied by primary users. However, uncertainty in SATCOM causes more spectrum sensing errors. In this dissertation, the uncertainty has been addressed by formulating a DSA decision-making process as a Partially Observable Markov Decision Process (POMDP) model to optimally determine which channels to sense and access. Large-scale networks have attracted many attentions to discover the hidden information from big data. Particularly, representation learning embeds the network into a lower vector space while maximally preserving the similarity among nodes. I propose a real-time distributed graph embedding algorithm (RTDGE) which is capable of distributively embedding the streaming graph by combining a novel edge partition approach and an incremental negative sample approach. Furthermore, a platform is prototyped based on Kafka and Storm. Real-time Twitter network data can be retrieved, partitioned and processed for state-of-art tasks. For knowledge graphs, existing works cannot capture the complex connection patterns and never consider the impacts from complicated relations, due to the unquantifiable relationships. A novel embedding algorithm is proposed to hierarchically measure the structural similarity and the impacts from relations by constructing a multi-layer graph. Then, an advanced representation learning model is designed based on an entity\u27s context generated by random walks on the multi-layer content graph

Routing UAVs to Co-Optimize Mission Effectiveness and Network Performance with Dynamic Programming

In support of the Air Force Research Laboratory\u27s (AFRL) vision of the layered sensing operations center, command and control intelligence surveillance and reconnaissance (C2ISR) more focus must be placed on architectures that support information systems, rather than just the information systems themselves. By extending the role of UAVs beyond simply intelligence, surveillance, and reconnaissance (ISR) operations and into a dual-role with networking operations we can better utilize our information assets. To achieve the goal of dual-role UAVs, a concrete approach to planning must be taken. This research defines a mathematical model and a non-trivial deterministic algorithmic approach to determining UAV placement to support ad-hoc network capability, while maintaining the valuable service of surveillance activities

Identification of Technologies for Provision of Future Aeronautical Communications

This report describes the process, findings, and recommendations of the second of three phases of the Future Communications Study (FCS) technology investigation conducted by NASA Glenn Research Center and ITT Advanced Engineering & Sciences Division for the Federal Aviation Administration (FAA). The FCS is a collaborative research effort between the FAA and Eurocontrol to address frequency congestion and spectrum depletion for safety critical airground communications. The goal of the technology investigation is to identify technologies that can support the longterm aeronautical mobile communication operating concept. A derived set of evaluation criteria traceable to the operating concept document is presented. An adaptation of the analytical hierarchy process is described and recommended for selecting candidates for detailed evaluation. Evaluations of a subset of technologies brought forward from the prescreening process are provided. Five of those are identified as candidates with the highest potential for continental airspace solutions in L-band (P-34, W-CDMA, LDL, B-VHF, and E-TDMA). Additional technologies are identified as best performers in the unique environments of remote/oceanic airspace in the satellite bands (Inmarsat SBB and a custom satellite solution) and the airport flight domain in C-band (802.16e). Details of the evaluation criteria, channel models, and the technology evaluations are provided in appendixes

FCS Technology Investigation Overview

This working paper provides an overview of the Future Communication Study (FCS) technology investigation progress. It includes a description of the methodology applied to technology evaluation; evaluation criteria; and technology screening (down select) results. A comparison of screening results with other similar technology screening activities is provided. Additional information included in this working paper is a description of in-depth studies (including characterization of the L-band aeronautical channel; L-band deployment cost assessment; and performance assessments of candidate technologies in the applicable aeronautical channel) that have been conducted to support technology evaluations. The paper concludes with a description on-going activities leading to conclusion of the technology investigation and the development of technology recommendations

Space-Air-Ground Integrated 6G Wireless Communication Networks: A Review of Antenna Technologies and Application Scenarios

A review of technological solutions and advances in the framework of a Vertical Heterogeneous Network (VHetNet) integrating satellite, airborne and terrestrial networks is presented. The disruptive features and challenges offered by a fruitful cooperation among these segments within a ubiquitous and seamless wireless connectivity are described. The available technologies and the key research directions for achieving global wireless coverage by considering all these layers are thoroughly discussed. Emphasis is placed on the available antenna systems in satellite, airborne and ground layers by highlighting strengths and weakness and by providing some interesting trends in research. A summary of the most suitable applicative scenarios for future 6G wireless communications are finally illustrated