Αντικείμενο της παρούσας διπλωματικής εργασίας είναι η ολοκληρωμένη παρουσίαση του προτύπου IEEE 802.16, που χρησιμοποιείται από το σύγχρονο ασύρματο ευρυζωνικό δίκτυο με την εμπορική ονομασία WiMAX και η εκπόνηση μίας μελέτης ράδιο-κάλυψης για τον προσδιορισμό των τεχνικών παραμέτρων, ώστε η εφαρμογή ενός τέτοιου δικτύου να προσφέρει τη βέλτιστη ράδιο-κάλυψη. Αρχικά γίνεται μια εισαγωγική παρουσίαση των ασύρματων τεχνολογιών, που χρησιμοποιούνται στην Ελλάδα για την πρόσβαση στις ευρυζωνικές υπηρεσίες και παρατίθενται στατιστικά στοιχεία, που απεικονίζουν την κατάσταση που επικρατή στον ελλαδικό χώρο. Στη συνέχεια καταγράφεται η ανάπτυξη και η εξέλιξη του προτύπου IEEE 802.16 και γίνεται αναφορά στο ρόλο που διαδραματίζουν το WiMAX Forum και οι επίσημοι κατασκευαστές. Προχωρώντας, εμβαθύνουμε περισσότερο με την παρουσίαση της αρχιτεκτονικής των δικτύων WiMAX, αλλά και των τεχνικών χαρακτηριστικών και των προδιαγραφών, που αυτά προσφέρουν και τα έχουν καταστήσει πρωτοπόρα στην εμπορική αγορά των ασύρματων επικοινωνιών. Τέλος, εκπονούμε μία λεπτομερή μελέτη για τη βέλτιστη ράδιο-κάλυψη σε μία συγκεκριμένη γεωγραφική περιοχή, σύμφωνα με τις προδιαγραφές της τεχνολογίας WiMAX και προσδιορίζουμε την ποιότητα των υπηρεσιών που θα μπορεί να προσφέρει το δικτύου WiMAX, στηριζόμενοι στα αποτελέσματα της μελέτης. / The subject of this thesis is the complete presentation of the standard IEEE 802.16, which is used by the modern wireless broadband network under the trade name WiMAX and the conduction of a radio coverage study to determine the technical parameters, so that the implementation of such a network can offer the optimal radio coverage. First, we make an introduction of wireless technologies used for access to broadband services and we present statistics that reflect the real market condition in Greece. Then we record the development and the progress of the IEEE 802.16 standard and we also make a small reference to the role of the WiMAX Forum and the official manufacturers. In depth, we analyze the architecture of WiMAX networks and all the technical features and specifications, which make the WiMAX technology a pioneer and have consolidate it in the market of wireless communications. Finally, we work out a detailed study on the optimal radio coverage in a specific geographic area, in accordance with the requirements of WiMAX technology and furthermore we estimate the quality of services that can be provided by the WiMAX network, relying on the results of the simulation.

Τα τελευταία χρόνια έχει παρουσιαστεί μία τηλεπικοινωνιακή τεχνολογία υλοποίησης δικτύων η οποία μας επιτρέπει την μεταφορά τηλεπικοινωνιακού σήματος προς και από τους συνδρομητές χρησιμοποιώντας το υφιστάμενο δίκτυο διανομής της ηλεκτρικής ισχύος. Η τεχνολογία αυτή είναι η “BPL” ή “Broadband over Power line” και είναι το κύριο θέμα της εργασίας αυτής. Αρχικά θα παρουσιάσουμε τις τηλεπικοινωνιακές υπηρεσίες που μπορούν να προσφέρονται μέσω των “BPL” δικτύων τόσο για τους καταναλωτές/συνδρομητές, αλλά και προς του ίδιους τους παρόχους και διαχειριστές του δικτύου. Μία νέα γενιά έξυπνων δικτύων γεννιέται και είναι πολλά υποσχόμενη σε ποικίλους τομείς. Στη συνέχεια θα μελετήσουμε τα δίκτυα αυτά από πλευράς τοπολογίας υλοποίησης τους αναφέροντας τρείς τρόπους με τους οποίους αυτό μπορεί να γίνει εφικτό. Θα παρουσιάσουμε επίσης τα βασικά στοιχεία του εξοπλισμού, τις προδιαγραφές αυτών των δικτύων καθώς επίσης και τις παρεμβολές που μπορεί να παρουσιαστούν μαζί με την ηλεκτρομαγνητική συμβατότητα των συστημάτων αυτών. Συνεχίζοντας θα μελετήσουμε με περισσότερη λεπτομέρεια την υλοποίηση των “BPL” δικτύων, αναφέροντας τις τεχνικές διαμόρφωσης σήματος, την διαχείριση σφαλμάτων, την λειτουργία του “BPL” “MAC” στρώματος, αλλά την οικογένεια ασύρματης διαμόρφωσης τηλεπικοινωνιακών σημάτων 802.11x. Λόγω του ότι η τεχνολογία “BPL” προορίζεται για χρήση σε ηλεκτρικά δίκτυα ανά το παγκόσμιο στην εργασία αυτή θα παρουσιάσουμε επίσης τα διεθνής πρότυπα και τα κριτήρια περί ηλεκτρομαγνητικής συμβατότητας αυτού του τύπου τηλεπικοινωνιακών δικτύων. Προχωρώντας παρουσιάζεται η συμπεριφορά των βασικών διατάξεων ενός δικτύου διανομής ηλεκτρικής ενέργειας όταν λειτουργούν σε υψηλές συχνότητες. Μελετώνται βασικές διατάξεις ηλεκτρικών κινητήρων, αντιστροφείς, πυκνωτές, διατάξεις γειωτών πλέγματος και μετασχηματιστών ισχύος. Η αναφορά αυτή κρίνεται απαραίτητη αφού τα “BPL” δίκτυα τα οποία μελετούμε λειτουργούν σε τέτοιες υψηλές συχνότητες. Στο “Κεφάλαιο 6” θα δούμε το “BPL” δίκτυο στο μέλλον παρουσιάζοντας στατιστικά δεδομένα τα οποία επιβεβαιώνουν την όλο και αυξανόμενη ανάγκη των σύγχρονων ανθρώπων για πρόσβαση στο διαδίκτυο, αλλά και το γεγονός ότι η αξιοποίηση των υφιστάμενων ηλεκτρικών δικτύων αποτελεί ίσως την πλέον συμφέρουσα λύση. Τελειώνοντας την εργασία θα παρουσιάσουμε την υλοποίηση “GPON-BPL” με στοιχεία και εξοπλισμό από την εταιρία “Corinex” και θα παρουσιάσουμε την θεωρητική υλοποίηση των τριών τοπολογιών “BPL” δικτύου που έχουμε αναφέρει σε προηγούμενο κεφάλαιο. Η υλοποίηση γίνεται με βάση τον σταθμό Υψηλής/Μέσης τάσης της Κοκκινοτριμιθιάς της επαρχίας Λευκωσίας στην Κύπρο και γίνεται σύγκριση των τριών αρχιτεκτονικών από πλευράς κόστους υλοποίησης και ταχύτητας δικτύου που παρέχεται στους συνδρομητές του. Τελικά γίνεται μια σύγκριση των δικών μας αποτελεσμάτων με παρόμοια εργασία που έγινε για το νομό της Λακωνίας στην Ελλάδα / In recent years has presented a telecommunication network implementation technology which allows us to transfer telecommunication signals to and from subscribers using the existing distribution network of electric power. This technology is the "BPL" or "Broadband over Power line" and is the main topic of this work. Initially we present the telecommunications services may be offered through the "BPL" networks to consumers / subscribers, but also to the same providers and network administrators. A new generation of intelligent networks is born and is promising in various fields. Then we will study these networks in terms of their implementation topology indicating three ways in which this can be feasible. We also present the basics of the equipment, the specifications of these networks as well as the interference that can occur with the electromagnetic compatibility of these systems. Continuing we will study in more detail the implementation of "BPL" networks, indicating the signal modulation techniques, management errors, the function of "BPL" "MAC" layer, but the family configuration wireless telecommunications signals 802.11x. Because the technology "BPL" intended for use on electrical networks worldwide in this paper will also present the international standards and criteria EMC this type of telecommunication networks. Moving shows the behavior of the main provisions of a power distribution network when operating at high frequencies. Discuss basic provisions of electric motors, inverters, capacitors, earthing grid devices and power transformers. This reference is necessary as the "BPL" networks that we study operate at such high frequencies. In "Chapter 6" will see the "BPL" network in the future by presenting statistical data confirm the ever growing need of modern people to access the internet, but the fact that the use of existing electrical networks is perhaps the most advantageous solution . Finishing the job will present the implementation "GPON-BPL" to data and equipment from the company "Corinex" and will present the theoretical implementation of the three topologies "BPL" network we have mentioned in the previous chapter. The implementation is based on the station high / medium voltage Kokkinotrimithia of Nicosia in Cyprus and compares the three architectures in terms of implementation cost and speed network provided to its subscribers. Finally a comparison of our results with similar work done for the county of Laconia in Greece

In this thesis, three broadband low-noise mixing circuits which use CMOS 130 nm technology are presented. As one of the first few stages in a receiving front-end, stringent requirements are posted on mixer performance. The Gilbert cell mixers have presented excellent properties and achieved wide applications. However, the noise of a conventional active Gilbert cell mixer is high. This thesis demonstrates both passive and active mixing circuits with improved noise performance while maintaining the advantages of the Gilbert cell-based mixing core. Furthermore, wide bandwidth and variable gain are implemented, making the designed mixers multi-functional, yet with compact sizes and low power consumptions. The first circuit is a passive 2x subharmonic mixer that works from 4.5 GHz to 8.5 GHz. The subharmonic mixing core is a two-stage passive Gilbert cell driven by a quadrature LO signal. Together with a noise-cancelling transconductor and an inverter-based TIA, this subharmonic mixer possesses an excellent broadband conversion gain and a low noise figure. Measurement results show a high conversion gain of 16 dB and a low average DSB NF of 9 dB. The second design is a broadband low-noise variable gain mixer which operates between 1 and 6 GHz. The transconductor stage is implemented with noise cancellation and current bleeding techniques. Series inductive peaking is used to extend the bandwidth. Gain variation is achieved by a current-steering IF stage. Measurements show a wide gain control range of 13 dB and a low noise performance over the entire frequency and gain range. The lowest DSB NF is 3.8 dB and the highest DSB NF is 14.2 dB. The Third design is a broadband low-noise mixer with linear-in-dB gain control scheme. Using the same transconductance stage with the second circuit, this design also works from 1 to 6 GHz. A 10 dB linear-in-dB gain control range is achieved using an R-r load network with a linear-in-dB error less than $\pm$ 0.5 dB. Low noise performance is achieved. For different frequencies and conversion gains, the lowest DSB NF is 3.8 dB and the highest DSB NF is 12 dB. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-10-02 04:37:31.606

M.Phil. (Electrical & Electronic Engineering) / Without any doubt, the entire range of voice and TV signals will migrate to the packet network. The universal addressable mode of Internet protocol (IP) and the interfacing framing structure of Ethernet are the main reasons behind the success of TCP/IP and Ethernet as a packet network and network access scheme mechanisms. Unfortunately, the success of the Internet has been the problem for real-time traffic such as voice, leading to more studies in the domain of Teletraffic Engineering; and the lack of a resource reservation mechanism in Ethernet, which constitutes a huge problem as switching system mechanism, have raised enough challenges for such a migration. In that context, ITU-T has released a series of Recommendation under the umbrella of H.323 to guarantee the required Quality of Service (QoS) for such services. Although the “utilisation” is not a good parameter in terms of traffic and QoS, we are here in proposing a multiplexing scheme with a queuing solution that takes into account the positive correlations of the packet arrival process experienced at the multiplexer input with the aim to optimize the utilisation of the buffer and bandwidth on the one hand; and the ITU-T H.323 Endpoints and Terminals configuration that can sustain such a multiplexing scheme on the other hand. We take into account the solution of the models from the M/M/1 up to G/G/1 queues based on Kolmogorov’s analysis as our solution to provide a better justification of our approach. This solution, the Diffusion approximation, is the limit of the Fluid process that has not been used enough as queuing solution in the domain of networking. Driven by the results of the Fluid method, and the resulting Gaussian distribution from the Diffusion approximation, the application of the asymptotic properties of the Maximum Likelihood Estimation (MLE) as the central limit theorem allowed capturing the fluctuations and therefore filtering out the positive correlations in the queue system. This has resulted in a queue system able to serve 1 erlang (100% of transmission link capacity) of traffic intensity without any extra delay and a queue length which is 60% of buffer utilization when compared to the ordinary Poisson queue length.

The work in this thesis is divided in three parts. In part one we developed electrodeposition method of Nickel Nanowire in commercial AAO template in constant current (Galvanostatic) mode, further we tried to estimate the growth rate from theory, from saturation magnetization and direct measurement from SEM image. In part two we focused on using the Vector Network Analyzer (VNA) to measure the Ferromagnetic Resonance (FMR))of various magnetic Nanowire arrays. We employed different measurement geometries using microstripline and coplanar waveguide as microwave transmission lines. In part three our aim was to study the magnetic properties of complex ferromagnetic system, especially the effect of interactions on dynamic properties of magnetic nanostructures (nanowire arrays and exchange biased ferromagnetic-antiferromagnetic multilayers). Our effort was centered on using ferromagnetic resonance to understand the dynamic response of these systems.

The liberalization of the telecommunications sector in South Africa has brought about vast improvement in the take-up and use of mobile telephony, however the opposite can be said of broadband penetration. As recently as 2012, there has been some degree of stagnation in fixed telephony and broadband access. This research report explores the evolution of broadband policy and regulation over the past decade, 2003-2012. Several themes from international trends are used, as guidelines of what an integrated, efficient broadband policy should address what governance and policy leadership is necessary for driving broadband policy initiatives across all spheres of government. The study proposes a conceptual framework that informs the analysis in comparing and contrasting the national broadband policy and plans, as well as provincial and local government’s policies and plans against desirable characteristics, such coordinated planning and implementation of broadband across government. The research analyses the current state of the country’s national broadband policy and plans across the three spheres of government. The analysis considers the contextual differences between the trends studied and the local data collected in the formal research phase, for the benefit of identifying the strengths and weaknesses of the South African broadband plans. The conclusion focuses on the incentive structure needed to extend the development of the broadband ecosystem in terms of infrastructure, services, applications and user involvement in the country.

Leung, Yiu-Wing. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 150-157). / Acknowledgments / Abstract / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Broadband Video Services --- p.1 / Chapter 1.3 --- Videoconference Services --- p.7 / Chapter 1.4 --- Videoconference Systems --- p.8 / Chapter 1.5 --- Chapter Summary and Thesis Organization --- p.18 / Chapter Chapter 2 --- Efficient Algorithms for Multiple Destinations Routing --- p.20 / Chapter 2.1 --- Background --- p.20 / Chapter 2.2 --- Integer Programming Formulation of the MDR Problem --- p.26 / Chapter 2.3 --- Heuristics for Multiple Destinations Routing --- p.27 / Chapter 2.4 --- Performance Comparisons --- p.40 / Chapter 2.5 --- Chapter Summary --- p.50 / Chapter Chapter 3 --- Connection Optimization for Two Types of Videoconferences --- p.51 / Chapter 3.1 --- Background --- p.51 / Chapter 3.2 --- The Videoconference Services --- p.52 / Chapter 3.3 --- Connection Optimization --- p.54 / Chapter 3.4 --- Performance Analysis --- p.62 / Chapter 3.5 --- Chapter Summary --- p.80 / Chapter Chapter 4 --- A TDM-based Multibus Packet Switch --- p.81 / Chapter 4.1 --- Background --- p.81 / Chapter 4.2 --- Architecture of the Multibus Switch --- p.89 / Chapter 4.3 --- Operation of the Multibus Switch --- p.93 / Chapter 4.4 --- Performance Analysis --- p.95 / Chapter 4.5 --- Numerical Results --- p.106 / Chapter 4.6 --- Discussions --- p.109 / Chapter 4.7 --- Chapter Summary --- p.113 / Chapter Chapter 5 --- A Modular Shared Media Video Switch --- p.114 / Chapter 5.1 --- System Architecture and Operation --- p.114 / Chapter 5.2 --- Slot Assignment for Point-to-Point Transmissions --- p.129 / Chapter 5.3 --- Slot Assignment for Point-to-Multipoint Transmissions --- p.132 / Chapter 5.4 --- Network Design Example --- p.136 / Chapter 5.5 --- Chapter Summary --- p.143 / Appendix --- p.144 / Chapter Chapter 6 --- Conclusions --- p.147 / References --- p.150

An Zhuo. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 62-65). / Abstracts in English and Chinese. / Acknowledgments --- p.i / 摘要 --- p.ii / Abstract --- p.iii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Circuit switching and Packet switching --- p.2 / Chapter 1.2 --- Virtual paths in high-speed networks --- p.6 / Chapter 1.3 --- BEF in cross-path switch --- p.8 / Chapter 1.4 --- Organization --- p.11 / Chapter Chapter 2 --- Analysis models --- p.12 / Chapter 2.1 --- Routing schemes in Clos network --- p.12 / Chapter 2.2 --- Path Switching --- p.15 / Chapter 2.3 --- Traffic Model of Input Modules --- p.17 / Chapter 2.4 --- Traffic Model of Output Modules --- p.19 / Chapter 2.5 --- Summary --- p.23 / Chapter Chapter 3 --- Throughput Performance of Input Modules in Path Switching --- p.24 / Chapter 3.1 --- Throughput performance vs. BEF --- p.24 / Chapter 3.2 --- Throughput performance vs. number of virtual paths --- p.30 / Chapter 3.2.1 --- Throughput performance vs. integer group size m/k --- p.33 / Chapter 3.2.2 --- Throughput performance vs. group size 0<R<2 --- p.39 / Chapter 3.2.3 --- Throughput performance vs. look-ahead scheme window size ω --- p.46 / Chapter 3.3 --- Summary --- p.48 / Chapter Chapter 4 --- Traffic Balancing Control in Path Switching --- p.50 / Chapter 4.1 --- Loss Probability in Output Modules --- p.50 / Chapter 4.1.1 --- Loss probability vs. number of central modules m --- p.51 / Chapter 4.1.2 --- Loss probability vs. knockout group size R and cluster size g --- p.52 / Chapter 4.2 --- Simulation Comparison of look-ahead scheme --- p.53 / Chapter 4.3 --- Simulation result of throughput vs. BEF --- p.55 / Chapter 4.4 --- Traffic Balancing Control --- p.55 / Chapter 4.5 --- Summary --- p.53 / Chapter Chapter 5 --- Conclusion --- p.60 / Bibliography --- p.62

No description available.

by Vincent Wing-Shing Tse. / Thesis submitted in: December 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 62-[64]). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- Principles of Multirate Circuit Switching in Quantized Clos Network --- p.10 / Chapter 2.1 --- Formulation of Multirate Circuit Switching --- p.11 / Chapter 2.2 --- Call Level Routing in Quantized Clos Network --- p.12 / Chapter 2.3 --- Cell Level Routing in Quantized Clos Network --- p.16 / Chapter 2.3.1 --- Traffic Behavior in ATM Network --- p.17 / Chapter 2.3.2 --- Time Division Multiplexing in Multirate Circuit Switching and Cell-level Switching in ATM Network --- p.19 / Chapter 2.3.3 --- Cell Transmission Scheduling --- p.20 / Chapter 2.3.4 --- Capacity Allocation and Route Assignment at Cell-level --- p.29 / Chapter 3 --- Performance Evaluation of Different Implementation Schemes --- p.31 / Chapter 3.1 --- Global Control and Distributed Switching --- p.32 / Chapter 3.2 --- Implementation Schemes of Quantized Clos Network --- p.33 / Chapter 3.2.1 --- Classification of Switch Modules --- p.33 / Chapter 3.2.2 --- Bufferless Switch Modules Construction Scheme --- p.38 / Chapter 3.2.3 --- Buffered Switch Modules Construction Scheme --- p.42 / Chapter 3.3 --- Complexity Comparison --- p.44 / Chapter 3.4 --- Delay Performance of The Two Implementation Schemes --- p.47 / Chapter 3.4.1 --- Assumption --- p.47 / Chapter 3.4.2 --- Simulation Result --- p.50 / Chapter 4 --- Conclusions --- p.59 / Bibliography --- p.62