1. Αποθετήριο Παραδοτέων Υποτρόφων Δράσεων ΕΣΠΑ Τριτοβάθμιας Εκπαίδευσης 2017-2023
2. Όλο το Αποθετήριο
3. Μεταδιδακτορικοί ερευνητές

Τύπος:	Κείμενο εργασίας
Τίτλος:	Δορυφορικά και στρατοσφαιρικά συστήματα ευρυζωνικών επικοινωνιών επόμενης γενιάς
Συγγραφέας:	[EL] Μιχαηλίδης, Εμμανουήλ[EN] Michailidis, Emmanouel
Επιβλέπων διατριβής:	[EL] Κανάτας, Αθανάσιος[EN] Kanatas, Athanasios
Ημερομηνία:	2018
Περίληψη:	As the aerospace systems are expected to be an essential part of the Fifth-Generation (5G) communication infrastructure, the post-doctoral research provides a convenient framework and guidelines for the analysis, test, and design of 5G aerospace-based systems. The core of this research deals with advanced techniques and methods that intend to increase the data rate, extend the radio coverage, and improve the link reliability. Since the 5G vision will bring new unique network and service capabilities towards the evolution of Internet of Things (IoT), the report of this research initially justifies why the aerospace communications is a key technology that will bring the IoT vision closer to reality and underlines the potential IoT applications. In this report, Multi-User (MU) Multiple-Input Multiple-Output (MIMO) relay-based satellite and stratospheric systems are also studied. To model the satellite and terrestrial channel, the Loo and Rician statistical distributions are utilized, respectively. Numerical results are provided in terms of the bit-error rate and the channel capacity and the linear Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) signal detection techniques are employed. Moreover, a MU-MIMO aerial relay aided system with orthogonal Space-Time Block Coding (OSTBC) transmission and rate-adaptive modulation is presented and a novel three-dimensional (3-D) geometry-based optimization method for the location of an aerial relay is proposed. Expressions for the outage probability and the spectral efficiency are presented. The results highlight the impact of the relay position, power allocation, fading severity, and number of antennas on the overall system performance. Moreover, this report presents a triple-hop mixed Radio-Frequency/Free-Space-Optical/Radio-Frequency (RF/FSO/RF) communication system, which intends to support wireless long-range links between two terrestrial stations via multiple stratospheric relays. It is considered that these terrestrial stations communicate with the relays over Single-Input Single-Output (SISO) or MIMO RF links, whereas the relays communicate with each other over an FSO link. The RF channels experience Rician fading due to the Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) signal components. Besides, the optical channel is affected by atmospheric attenuation, atmospheric turbulence, and pointing errors. Mathematical expressions for the outage probability are derived, considering the beam wander effect. The results demonstrate the theoretical derivations. Finally, this report proposes a novel theoretical non-stationary 3-D model for wideband massive MIMO stratospheric channels. This model considers nearfield effects instead of farfield effects, since the dimension of massive MIMO antenna arrays cannot be ignored. To model the non-stationary properties of clusters, a birth-death process is presented corresponding to cluster appearance and disappearance on both the array and time axes. The statistical properties of the proposed model are investigated in terms of the space-time correlation function (STCF) and the Doppler power spectral density (PSD). The numerical results demonstrate the theoretical derivations.
Γλώσσα:	Αγγλικά
Τόπος δημοσίευσης:	Ελλάδα
Σελίδες:	113
Θεματική κατηγορία:	[EL] Μηχανική και συστήματα επικοινωνιών, Τηλεπικοινωνίες[EN] Communication engineering and systems, Telecommunications
Λέξεις-κλειδιά:	Atmospheric turbulence; birth-death process; Free-Space-Optical (FSO) communications; High-Altitude Platforms (HAPs); Internet of Things (IoT); massive Multiple-Input Multiple-Output (MIMO) systems; multi-user (MU) systems; nonstationarity; relays; satellite networks; Unmanned Aerial Vehicles (UAVs)
Κάτοχος πνευματικών δικαιωμάτων:	Εμμανουήλ Μιχαηλίδης
Σημειώσεις:	«Η Μεταδιδακτορική Έρευνα υλοποιήθηκε με υποτροφία του ΙΚΥ η οποία χρηματοδοτήθηκε από την Πράξη «Ενίσχυση Μεταδιδακτόρων Ερευνητών/Ερευνητριών» από τους πόρους του ΕΠ «Ανάπτυξη Ανθρώπινου Δυναμικού, Εκπαίδευση και Διά Βίου Μάθηση» με άξονες προτεραιότητας 6,8,9 και συγχρηματοδοτείται από το Ευρωπαϊκό Κοινωνικό Ταμείο – ΕΚΤ και το ελληνικό δημόσιο».
Εμφανίζεται στις συλλογές:	Μεταδιδακτορικοί ερευνητές