Optical networks based on Wavelength Division Multiplexing (WDM) technology show many clear benefits in terms of high capacity, flexibility and low power consumption. All these benefits make WDM networks the preferred choice for today’s and future transports solutions which are strongly driven by a plethora of emerging online services. In such a scenario, capability to provide high capacity during the service provisioning phase is of course very important, but it is not the only requirement that plays a central role. Traffic dynamicity is another essential aspect to consider because in many scenarios, e.g., in the case of real time multimedia services, the connections are expected to be provisioned and torn down quickly and relatively frequently. High traffic dynamicity may put a strain on the network control and management operations (i.e., the overhead due to control message exchange can grow rapidly) that coordinate any provisioning mechanisms. Furthermore, survivability, in the presence of new failure scenarios that goes beyond the single failure assumption, is still of the utmost importance to minimize the network disruptions and data losses. In other words, protection against any possible future failure scenario where multiple faults may struck simultaneously, asks for highly reliable provisioning solutions. The above consideration have a general validity i.e., can be equally applied to any network segment and not just limited to the core part. So, we also address the problem of service provisioning in the access paradigm. Long reach Passive Optical Networks (PONs) are gaining popularity due to their cost, reach, and bandwidth advantages in the access region. In PON, the design of an efficient bandwidth sharing mechanism between multiple subscribers in the upstream direction is crucial. In addition, Long Reach PONs (LR-PONs) introduces additional challenges in terms of packet delay and network throughput, due to their extended reach. It becomes apparent that effective solutions to the connection provisioning problem in both the core and access optical networks with respect to the considerations made above can ensure a truly optimal end-to-end connectivity while making an efficient usage of resources. The first part of this thesis focuses on a control and management framework specifically designed for concurrent resource optimization in WDM-based optical networks in a highly dynamic traffic scenario. The framework and the proposed provisioning strategies are specifically designed with the objective of: (i) allowing for a reduction of the blocking probability and the control overhead in a Path Computation Element (PCE)-based network architecture, (ii)  optimizing resource utilization for a traffic scenario that require services with diverse survivability requirements which are achieved by means of  dedicated and shared path-protection, and (iii) designing provisioning mechanism that guarantees high connection availability levels in Double Link Failures (DLF) scenarios. The presented results show that the proposed dynamic provisioning approach can significantly improve the network blocking performance while making an efficient use of primary/backup resources whenever protection is required by the provisioned services. Furthermore, the proposed DLF schemes show good performance in terms of minimizing disruption periods, and allowing for enhanced network robustness when specific services require high connection availability levels. In the second part of this thesis, we propose efficient resource provisioning strategies for LR-PON. The objective is to optimize the bandwidth allocation in LR-PONs, in particular to: (i) identify the performance limitations associated with traditional (short reach) TDM-PON based Dynamic Bandwidth Allocation (DBA) algorithms when employed in long reach scenarios, and (ii) devise efficient DBA algorithms that can mitigate the performance limitations imposed by an extended reach. Our proposed schemes show noticeable performance gains when compared with conventional DBA algorithms for short-reach PON as well as specifically devised approaches for long reach. / <p>QC 20130520</p>

Passive optical networks (PONs) are point-to-multipoint networks where a single Central Office (CO) is connected to a number of downstream Optical Network Units (ONUs) via a single optical fiber by splitting the optical signal with passive splitters. Due to technology advances and increasing bandwidth requirements, these networks have moved to last mile deployment, also known as fiber-to-the-home (FTTH). The planning of these PONs are traditionally done by hand, but automated methods can be used to decrease deployment costs and planning time. Even though a number of methods have been proposed to address this problem through the solving of integer linear programming (ILP) models, they suffer from limited availability, inaccuracies and limited scalability due to the problem complexity. This dissertation focusses on improving the accuracy of these models as well as improving scalability to a point where large-scale problems can be solved feasibly. To address this, a basic model is implemented to capture the network structure and verified accordingly. Results show this model can be solved quickly, but has large discrepancies with real-world plans. Refinements in the form of fiber duct sharing, network constraints, multiple splitter types and economies of scale among others are then incorporated into a refined model and solved. Analysis of the experimental results indicates improved accuracy and lower deployment costs, at the expense of increasing computation effort considerably. Heuristic techniques are then examined to improve computational performance, including an elementary heuristic (ELEM), the Branch Contracting Algorithm (BCA) and problem decomposition. It is demonstrated that through the use of k-means clustering, the refined model can be solved in a fraction of the time while keeping deployment costs comparably low. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

Passive optical networks (PONs) are point-to-multipoint networks where a single Central Office (CO) is connected to a number of downstream Optical Network Units (ONUs) via a single optical fiber by splitting the optical signal with passive splitters. Due to technology advances and increasing bandwidth requirements, these networks have moved to last mile deployment, also known as fiber-to-the-home (FTTH). The planning of these PONs are traditionally done by hand, but automated methods can be used to decrease deployment costs and planning time. Even though a number of methods have been proposed to address this problem through the solving of integer linear programming (ILP) models, they suffer from limited availability, inaccuracies and limited scalability due to the problem complexity. This dissertation focusses on improving the accuracy of these models as well as improving scalability to a point where large-scale problems can be solved feasibly. To address this, a basic model is implemented to capture the network structure and verified accordingly. Results show this model can be solved quickly, but has large discrepancies with real-world plans. Refinements in the form of fiber duct sharing, network constraints, multiple splitter types and economies of scale among others are then incorporated into a refined model and solved. Analysis of the experimental results indicates improved accuracy and lower deployment costs, at the expense of increasing computation effort considerably. Heuristic techniques are then examined to improve computational performance, including an elementary heuristic (ELEM), the Branch Contracting Algorithm (BCA) and problem decomposition. It is demonstrated that through the use of k-means clustering, the refined model can be solved in a fraction of the time while keeping deployment costs comparably low. / Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013

Orientador: Rangel Arthur / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-22T06:36:42Z (GMT). No. of bitstreams: 1 Hoshino_FelipeKojiGodinho_M.pdf: 3730881 bytes, checksum: d6cd57d6d8286fe95b3166c35de77d73 (MD5) Previous issue date: 2013 / Resumo: O aumento exponencial no tráfego mundial de dados tem imposto inúmeros desafios para os sistemas de telecomunicações. Há um compromisso entre o interesse das operadoras de telecomunicações, de aumentar a receita líquida, e dos clientes, de aumentar a taxa de transmissão de dados. Com isso, diversas soluções têm sido discutidas no âmbito das comunicações ópticas. Uma das propostas estudadas é a aplicação mais intensa do processamento digital de sinais. Dessa forma, neste trabalho foi estudado e simulado o uso da modulação OFDM (Orthogonal Frequency Division Multiplexing) nas redes ópticas de nova geração. Também foi simulado um modem OFDM em linguagem VHDL (Very High Speed Integrated Circuit Hardware Description Language) sendo esta uma etapa do projeto de novos equipamentos. Como prova de conceito, analisou-se o desempenho de redes ópticas por meio do software OptiSystem. De maneira geral, os resultados obtidos foram satisfatórios para demonstrar a viabilidade da modulação OFDM em redes ópticas de nova geração / Abstract: The exponential increase in global data traffic has imposed many challenges for telecommunication systems. There is a trade-off between the interest of telecom operators to increase the net revenue and the customers to increase the transmission data rate. Several solutions have been discussed in optical communications field. One approach is the more intense application of the digital signal processing. Thus, in this work is presented a review and simulations of OFDM modulation (Orthogonal Frequency Division Multiplexing) in the next generation networks. It was also simulated a OFDM modem in VHDL (Very High Speed Integrated Circuit Hardware Description Language) which for a new equipment design. The performance of optical networks has been examinated with OptiSystem software as o proof of concept. In general, the results obtained were satisfactory to show the feasibility of OFDM modulation in the next generation networks / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

In this study, a review of research literature has been carried out to investigate Hybrid Time and wavelength Division Multiplexing techniques with respect to reach, split ratio, and speed of the network. This was done to overcome challenges presented by Passive Optical Networks, such as the reach and the high split ratio. A comparison of different methods clarifies that Hybrid PassiveOptical Networks have a high power-budget that ensure efficient signal transmission. The Optisys software has been used to analyze the performance of the different techniques.

Centralized light source (CLS) at the central office is an attractive solution for low-cost implementation of WDM-PON, as it eliminates the need of wavelength-specific transmitters and wavelength management at the optical network units (ONU). CLS can be realized by either a carrier-distributed scheme or a remodulation scheme. In both schemes, however, the upstream signal is susceptible to the interferometric crosstalk induced by the beating between the upstream signal and the back-reflected light due to the intrinsic Rayleigh Backscattering (RB), both of which are of the same wavelength. We propose and demonstrate a simple and novel scheme to suppress the RB noise in the carrier-distributed WDM-PON. Differential phase-shift keying (DPSK) is used as the upstream modulation format and the destructive port of the delay-interferometer (DI) is employed to demodulate the upstream DPSK signal. As the spectrum of RB towards the OLT is narrow due to the very narrow spectrum of the distributed carrier, the RB noise can be considerably rejected by the notch filter-like destructive port of the DI at the OLT, which is used simultaneously to demodulate the upstream DPSK signal. The scheme can also be extended to the application in the remodulation-based WDM-PON, as long as the downstream signal has a narrow spectrum (i.e. via reducing downstream modulation depth). A unique feature of the DPSK signal with reduced modulation depth (RMD-DPSK) is that it can be demodulated by DI's destructive port without extinction ratio (ER) degradation, whereas the demodulated signal from DI's destructive port has a very low ER and can be used as the source for upstream remodulation. We also proposed a novel offset-Manchester coding to suppress Rayleigh noise in electrical domain via a postdetection high-pass filter. / Foreseeing the rapidly growing demand for multimedia services and the trend of service convergence, the penetration of optical fiber in access network is an ultimate solution to break the last-mile bottleneck imposed by the 100-year-old copper network. One of the most promising solutions to realize optical access is the passive optical network (PON), in which the network infrastructure is shared by many subscribers and has no active elements between the central office and the customer. Thus a PON requires neither electrical power nor active management, leading to effective reduction in operational expenses. Time-division-multiplexed passive optical networks (TDM-PONs) such as Ethernet PON (EPON) and Gigabit PON (GPON) are being widely deployed in current fiber-based access networks for providing broadband access, offering triple-play services including video, data and voice. In the near future, wavelength-division-multiplexed passive optical network (WDM-PON) can be the enabler of the next-generation optical broadband access that requires large dedicated and symmetric bandwidth, data privacy, and upgrade flexibility. TDM-PONs also can benefit from WDM technologies for capacity upgrade. / With more diverse multimedia and data services available for broadband access, the access network has to be flexible enough to cope with various data or video delivery such as broadcast/multicast services, in addition to the point-to-point traffic. Multicast is more attractive, compared to broadcast, as it allows selective control of the connection for each subscriber individually. Multicast can be easily realized in TDM-PONs as it employs power-splitting at the remote node (RN). However, it is more challenging in WDM-PONs, due to the dedicated connection between the optical line terminal (OLT) and each ONU. Many studies have been carried out to solve this problem. The prior schemes either need relatively complicated multicast control and/or cannot support future proof 10-Gb/s symmetric point-to-point (PtP) transmission. We proposed a novel multicast control scheme for a WDM-PON with 10-Gb/s symmetric bit rate. The multicast data encoded in DPSK format is superimposed onto all PtP channels modulated in inverse return-to-zero format. With an athermal Dr being used at the ONU to demodulate the DPSK signal, the multicast data can be effectively disabled by slight detuning the laser wavelength at OLT, which has negligible effect on the PtP data. The proposed scheme differs from all the previous schemes in that, the multicast control is realized via the inherent wavelength management of WDM systems, rather than via any other additional adjustment such as ER, synchronization, and polarization. v / Xu, Jing. / Adviser: Lian-Kuan Chen. / Source: Dissertation Abstracts International, Volume: 73-06, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Besides colorless ONUs, we investigate potentially low cost, high speed vertical-cavity-surface-emitting lasers (VCSELs) for use in future access networks. VCSELs are attractive because they may meet the stringent size, power dissipation and cost constraints of access network components. We carry out experiments to demonstrate that up to 20 Gb/s direct modulation of long wavelength VCSEL is possible and evaluate their performance as high-speed transceivers. / In order to reduce the complexity and costs of ONU transceiver, we propose a scheme based on a nonreciprocal optical modulator and a linear loop mirror for receiving downstream and sending upstream data We show that the nonreciprocity of traveling wave electrodes can selectively impress signal modulation onto the reflected upstream signals only. Monolithic integrated transceivers may thus remodulate downstream signals for upstream data transmission without needing integrated optical circulators. The proposed ONU is thus compatible with monolithic integration. / In this thesis, we describe our research on photonic devices and subsystems for future access networks. Since optical network units (ONUs) are the most cost-sensitive parts, we first investigate the use of advanced modulation format in colorless ONU structure. We implement a scheme which uses dark return-to-zero (DRZ) for downstream transmission and remodulation of it using a differential-phase-shift-keying (DPSK) for upstream both at 10 Gb/s. We also experimentally demonstrate silicon microring based optical frequency discriminators for use in demodulating DPSK and differential-quadrature-phase-shift-keying (DQPSK) signals. We show that the scheme is robust to variations in bit-rates in contrast with conventional Mach-Zehnder delay interferometer scheme. / Internet traffic has undergone tremendous growth in the past decades and has already penetrated into the daily lives of the general population. Demand for new high bandwidth services is beginning to drive the deployment of optical fiber-based access networks to solve the so-called last mile bottleneck around the world. Passive optical networks (PON) are attractive because there are no active components in the transmission line, thus reducing operational and deployment costs. Time-division-multiplexing (TDM) used in currently deployed PON, in which the bandwidth is shared among the users by time domain multiplexing, does not fully utilize the bandwidth potential of optical fibers and will not be able to satisfy the bandwidth demand in access networks in the near future. Among the advanced multiplexing techniques, wavelength-division-multiplexing (WDM) PON is a good candidate technology for providing sustained bit-rates beyond 10 Gb/s in access networks. However, reduction of costs in WDM PON remains a key challenge for their practical deployment. / Wired and wireless hybrid optical access networks are also investigated. Radio-over-fiber is one low-cost approach to deliver broadband wireless services, in which radio signals at the carrier frequency are delivered over optical networks from a central office to remote antenna base stations. Generation of high frequency carrier and radio frequency fading are the main research challenges. We propose and demonstrate frequency upconversion based on frequency doubling and quadrupling. Novel wired and wireless hybrid subsystems that mitigate millimeter-wave signal distortion are also demonstrated. / Xu, Lin. / Adviser: H. K. Tsang. / Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

El estudio e investigación en el campo de las redes ópticas de acceso han sido fomentadas en años recientes debido a la continua migración de Servicios multimedia que son ofrecidos a través de Internet. Aunque los dispositivos utilizados para implementar Fiber-to-the-Home (fibra a casa), que reemplazan las soluciones tradicionales basadas en cable de cobre, están basadas aún en micro-óptica, se puede prever una evolución hacia integración fotónica. Todavía queda la pregunta acerca de los diseños necesarios para este paso importante de integración, que debe ser optimizado en términos del desempeño de transmisión, eficiencia energética y costo con el fin de lograr todos los requerimientos de las redes fotónicas de siguiente generación. Como elemento más crítico en las redes de acceso ópticas es el equipo en los clientes, este trabajo se centra en éste. Los temes cubiertos abarcan una gama amplia e incluyen: el reciclado de longitudes de onda para transmisión de datos en full-dúplex a través de una sola frecuencia óptica; la generación de formatos de modulación avanzados con moduladores semiconductores de bajo costo y factor pequeño de integración; soporte de amplificación óptica a través de técnicas de sembrado y el soporte de funcionalidades de capes superiores en la capa física. Después de la prueba principal de las técnicas propuestas, se resaltan los beneficios, impedimentos y caminos de reemplazo hacia sistemas fotónicos multifuncionales a través de casos de estudio. Por su parte, los diseños más representativos se profundizan más sobre todo por su posibilidad de ser integrados fotónicamente. / Optical access technology has experienced a boost in the last years, thanks to the continuously migrating multimedia services that are offered over the internet. Though the devices used for deploying Fiber-to-the-Home instead of traditional copper-based solutions are still based on micro-optics, an evolution towards photonic integration can be foreseen. What remains is the question about the exact designs for this important step of integration, which should be optimized in terms of transmission performance, energy efficiency and cost to address all requirements of next-generation photonic networks. As the most critical element in optical access, the customer premises equipment is in primary focus of this discussion. The covered topics span over a wide range and include wavelength recycling for full-duplex data transmission on a single optical frequency, the generation of advanced modulation formats with low-cost semiconductor modulators with small form factor, support for optical amplification by means of seeding techniques and the support of higher layer functionality at the physical layer. Next to the principal proof of the proposed techniques, the benefits, impediments and upgrade paths towards multifunctional photonic systems are highlighted in different case studies, while the most representative designs are further discussed in their capability of being photonically integrated.

Τα σύγχρονα παθητικά οπτικά δίκτυα (PONs) αποτελούν ίσως την πιο σημαντική επιλογή για την ανάπτυξη των μελλοντικών δικτύων ευρυζωνικής πρόσβασης στο παρόν και το μέλλον. Κύριοι λόγοι είναι το χαμηλό κόστος εφαρμογής τους, η απλή λειτουργία τους και υψηλά ποσοστά-ρυθμού μετάδοσης. Τα σύγχρονα Ethernet Passive Optical Networks (EPONs) και η εξέλιξή τους τα Gigabit PON (XGPON) έχουν τυποποιηθεί σε ταχύτητες της τάξεως των 10 Gb/s, ενώ τα επερχόμενα πρότυπα αναμένεται να αυξήσουν τη διαθέσιμη δυναμικότητα τους. Τα EPONs, ειδικότερα, καθιστούν δυνατή τη σύγκλιση των Ethernet δικτύων μεταξύ τους, η οποία βρίσκει ευρεία εφαρμογή σε τοπικά (local) και μέτρo (metro) δίκτυα περιοχής, και την υποδομή οπτικών ινών που εγκαθίσταται εντός του πεδίου εφαρμογής σε fiber-to-the-home (FTTH), την fiber-to-the-building (FTTB) και fiber-to-the-curb (FTTC) δίκτυα. Ακόμα όμως και για πρόσβαση μέχρι τους τελικούς χρήστες. Προτείνουμε ,μέσα από την παρούσα εργασία, μια νέα μέθοδο πρόβλεψης της κυκλοφορίας με σκοπό την ελαχιστοποίηση της καθυστέρησης πακέτων σε Ethernet Passive Optical Networks (EPON). Η μέθοδος βασίζεται στην παρακολούθηση της κυκλοφορίας στο Μονάδων Οπτικού Δικτύου (ONUs) και χρησιμοποιεί τις άμεσα διαθέσιμες πληροφορίες για την κυκλοφορία του δικτύου ώστε να προβλέψει τα δεδομένα που πρόκειται να συσσωρευτούν σε κάθε ONU στον επόμενο κύκλο. Έπειτα από σχετική έρευνα υλοποιήθηκε ο κατάλληλος αλγόριθμος και εξετάστηκε πειραματικά. Τα αποτελέσματα της προσομοίωσης δείχνουν ότι η βελτίωση της καθυστέρησης διάδοσης πακέτων (delay) μειώθηκε πάνω από 25% , χωρίς τροποποίηση του υπάρχοντος αλγορίθμου ανάθεσης εύρους ζώνης. Τέλος αποδείχθηκε η δικαιοσύνη (fairness) του αλγορίθμου στην παροχή πόρων του συστήματος ανάμεσα στις μονάδες ONU. / Modern passive optical networks (PONs) are perhaps the most important choice for the development of future broadband network in the present and the future . Main reason is the low cost of implementation, simple operation and high - transmission rate . Modern Ethernet Passive Optical Networks (EPONs) and the evolution of the Gigabit PON (XGPON) have standardized speeds of 10 Gb / s, while the upcoming standards expected to increase the available capacity . The EPONs, in particular , enable the convergence of Ethernet networks , which finds wide application in locally (local) and metro (metro) area networks , and fiber optic infrastructure installed within the scope of a fiber-to-the -home (FTTH), the fiber-to-the-building (FTTB) and fiber-to-the-curb (FTTC) networks . But even for access to the end users . We propose , through this work , a new prediction method of traffic in order to minimize the delay packets in Ethernet Passive Optical Networks (EPON). The method is based on monitoring the traffic on the Optical Network Units (ONUs) and uses readily available information about network traffic to provide the data to be accumulated at each ONU in the next cycle . After investigation, the appropriate algorithm was implemented and tested experimentally. Simulation results show that the improvement of packet propagation delay (delay) fell over 25 % , without modifying the existing bandwidth assignment algorithm . Finally turned justice (fairness) algorithm in providing system resources between units ONU.

Με την ανάπτυξη της τεχνολογίας οπτικών ινών κατά την τελευταία δεκαετία, η υποδομή των τηλεπικοινωνιών έχει παρουσιάσει μία τρομερή ανάπτυξη στη χωρητικότητα εύρους ζώνης των δικτύων κορμού. Η ανάπτυξη αυτή ξεκίνησε με τα δίκτυα ευρείας περιοχής (WANs) που παρέχουν συνδεσιμότητα μεταξύ πόλεων μέσω των δικτύων μητροπολιτικής περιοχής (MANs), τα οποία συνδέουν τα τηλεπικοινωνιακά κέντρα των παρόχων υπηρεσιών. Ωστόσο, τα δίκτυα πρόσβασης, που εξυπηρετούν πολυάριθμους οικιακούς χρήστες, μικρές επιχειρήσεις και οργανισμούς, δεν έχουν αναπτυχθεί ανάλογα. Παρόλο που η πρόσφατη ανάπτυξη των πρωτοποριακών τεχνολογιών xDSL και CaTV έχει αναβαθμίσει σημαντικά το τμήμα αυτό, οι τεχνολογίες αυτές είναι ακόμη ανεπαρκείς για να καλύψουν την ολοένα και αυξανόμενη ζήτηση εύρους ζώνης των χρηστών. Για την αντιμετώπιση αυτού του προβλήματος, οι τεχνολογίες της οπτικής ίνας μέχρι το σπίτι/το πεζοδρόμιο/το κτίριο (Fiber To The Home/Curb/Building – FTTH/FTTC/FTTB) έχουν θεωρηθεί από καιρό ως μια προτιμώμενη λύση και τα παθητικά οπτικά δίκτυα (PONs) θεωρούνται ευρέως ως μία πολλά υποσχόμενη τεχνολογία για την εφαρμογή διάφορων λύσεων FTTx. Η παρούσα διπλωματική εργασία αρχικά εισάγει το πρόβλημα σχετικά με την ανάγκη εφαρμογής οπτικών δικτύων πρόσβασης. Στη συνέχεια, εξετάζει πιθανές λύσεις στο πρόβλημα αυτό και αναδεικνύει τα παθητικά οπτικά δίκτυα (PONs) ως την καλύτερη επιλογή. Επιπλέον, γίνεται αναφορά στις διάφορες τεχνολογίες πολλαπλής πρόσβασης στα PONs (TDMA, OCDMA και WDMA). Η εφαρμογή της TDMA τεχνολογίας στα PONs αποδεικνύεται η πιο οικονομικά αποδοτική. Για τη χρήση της TDMA τεχνολογίας στα PONs αναπτύχθηκαν τα πρότυπα ATM PON (BPON), Ethernet PON (EPON) και Gigabit PON (GPON). Μετά από σχετική σύγκριση των προτύπων αυτών, το EPON θεωρείται η καλύτερη επιλογή για την εφαρμογή της TDMA τεχνολογίας στα PONs. Αυτή η διπλωματική εργασία στη συνέχεια εισάγει τις θεμελιώδεις έννοιες σχετικά με τα EPONs, εξετάζει τα κύρια ζητήματα που σχετίζονται με τη διάθεση εύρους ζώνης του ανοδικού καναλιού (από τον τελικό χρήστη προς το τηλεπικοινωνιακό κέντρο) στα συστήματα EPONs και παρουσιάζει μία επισκόπηση των πιο πρόσφατων αλγορίθμων δυναμικής διάθεσης εύρους ζώνης (Dynamic Bandwidth Allocation – DBA) για ανοδικές μεταδόσεις στα EPONs. Τέλος, γίνεται περιγραφή και υλοποίηση ενός εκ των πρώτων DBA αλγορίθμων που προτάθηκαν για τη διάθεση του ανοδικού εύρους ζώνης στα EPONs, του αλγορίθμου IPACT (Interleave Polling with Adaptive Cycle Time – IPACT). Κατά την περιγραφή, η limited service του αλγορίθμου IPACT προκύπτει ως η καλύτερη, με βάση διάφορα κριτήρια, μεταξύ των διάφορων υπηρεσιών αυτού του DBA αλγορίθμου και αποτελεί σημείο αναφοράς για μεταγενέστερες δημοσιευμένες εργασίες που υπάρχουν στη βιβλιογραφία. Η υλοποίηση περιλαμβάνει προσομοίωση της limited service του αλγορίθμου IPACT με χρήση της γλώσσας προσομοίωσης SIMSCRIPT II.5 και εξαγωγή αναλυτικών αποτελεσμάτων από εξισώσεις που μοντελοποιούν τη συμπεριφορά του αλγορίθμου, με χρήση της γλώσσας προγραμματισμού C. Τα αποτελέσματα της ανάλυσης και της προσομοίωσης συγκρίνονται και προκύπτουν τα κατάλληλα συμπεράσματα. / With the development of fiber-optic technology over the last decade, the telecommunications infrastructure has shown a tremendous growth in the bandwidth capacity of backbone networks. This development began with the wide area networks (WANs) that provide connectivity between cities through the metropolitan area networks (MANs), which connect service providers’ central offices. However, access networks that serve numerous residential users, small businesses and organizations have not been developed accordingly. Although the recent development of innovative xDSL and CaTV technologies has significantly upgraded this segment, these technologies are still inadequate to meet the ever-increasing bandwidth demand of users. To address this problem, fiber to the home / curb / building (FTTH / FTTC / FTTB) technologies have long been regarded as a preferred solution, and passive optical networks (PONs) are widely regarded as a promising technology for implementing various FTTx solutions. This thesis first introduces the problem concerning the need for optical access networks. Then, examines possible solutions to this problem and highlights the passive optical networks (PONs) as the best option. Furthermore, a reference is made to the various multiple access technologies in PONs (TDMA, OCDMA and WDMA). The implementation of the TDMA technology in PONs proved the most cost-effective. The ATM PON (BPON), Ethernet PON (EPON) and Gigabit PON (GPON) standards have been developed for the use of the TDMA technology in PONs. Upon comparison of these standards, the EPON is considered the best option for the implementation of the TDMA technology in PONs. This thesis then introduces the fundamental concepts on EPONs, examines the major issues related to bandwidth allocation of the upstream channel (from the end user to the central office) in EPONs systems and presents a survey of the most recent dynamic bandwidth allocation (DBA) algorithms for upstream transmissions in EPONs. Finally, a description and an implementation are made of one of the first DBA algorithms proposed for upstream bandwidth allocation in EPONs, the IPACT (Interleave Polling with Adaptive Cycle Time - IPACT) algorithm. In the description, the limited service of the IPACT algorithm emerges as the best among the different services of this DBA algorithm according to various criteria and is a benchmark for subsequent published papers in the literature. The implementation includes the simulation of the limited service of the IPACT algorithm, using the SIMSCRIPT II.5 simulation language and extraction of analytical results from equations modeling the behavior of the algorithm, using the C programming language. The analysis and simulation results are compared and the appropriate conclusions arise.