Dissertations / Theses: 'Optical telecommunication networks'

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Mbah, Afamefuna Maduka. "Hybrid fibre and free-space optical solutions in optical access networks." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32572/.

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This thesis evaluates the potentials of hybrid fibre and free space optical (FSO) communications access networks in providing a possible solution to an all optical access network. In such network architectures, the FSO link can extend the system to areas where an optical fibre link is not feasible, and/or provide limited mobility for indoor coverage. The performance of hybrid fibre and FSO (HFFSO) networks based on digital pulse position modulation (DPPM), for both the indoor and outdoor environments of the optical access network, are compared with the performance of such a network that is based on conventional on-off keying non-return-to-zero (OOK NRZ) modulation using results obtained through computational and analytical modelling. Wavelength division multiplexing (WDM) and/or code division multiple access (CDMA) are incorporated into the network for high speed transmission and/or network scalability. The impacts of optical scintillation, beam spreading and coupling losses, multiple access interference (MAI), linear optical crosstalk and amplified spontaneous emission noise (ASE) on the performance of hybrid fibre and FSO (HFFSO) access networks are analysed, using performance evaluation methods based on simple Gaussian approximation (GA) and more complex techniques based on moment generating function (MGF), including the Chernoff bound (CB), modified Chernoff bound (MCB) and saddlepoint approximation (SPA). Results in the form of bit error rate (BER), power penalty, required optical power and outage probability are presented, and both the CB and MCB, which are upper bounds, are suggested as safer methods of assessing the performance of practical systems. The possibility of using a CDMA-based HFFSO network to provide high speed optical transmission coverage in an indoor environment is investigated. The results show a reduction in transmit power of mobile devices of about 9 – 20 dB (depending on number of active users) when an optical amplifier is used in the system compared to a non-amplified system, and up to 2.8 dB improvement over OOK NRZ receiver sensitivity is provided by a DPPM system using integrate and compare circuitry for maximum likelihood detection, and at coding level of two, for minimum bandwidth utilization. Outdoor HFFSO networks using only WDM, and incorporating CDMA with WDM, are also investigated. In the presence of atmospheric scintillations, an OOK system is required (for optimum performance) to continuously adapt its decision threshold to the fluctuating instantaneous irradiance. This challenge is overcome by using the maximum likelihood detection DPPM system, and necessitated the derivation of an interchannel crosstalk model for WDM DPPM systems. It is found that optical scintillation worsens the effect of interchannel crosstalk in outdoor HFFSO WDM systems, and results in error floors particularly in the upstream transmission, which are raised when CDMA is incorporated into the system, because of MAI. In both outdoor HFFSO networks (with WDM only and with WDM incorporating CDMA), the optical amplifier is found necessary in achieving acceptable BER, and with a feeder fibre of 20 km and distributive FSO link length of 1500 m, high speed broadband services can be provided to users at safe transmit power at all turbulence levels in clear air atmosphere.

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Jabar, Sakena Abdul. "The efficient deployment of passive optical networks within the telecommunication access network." Thesis, University of Hertfordshire, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440171.

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Yu, Wing Wa. "Routing and time-slot assignment in photonic circuit switching networks /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202002%20YUW.

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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002.
Includes bibliographical references (leaves 68-70). Also available in electronic version. Access restricted to campus users.

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Subramaniam, Suresh. "All-optical networks with sparse wavelength conversion /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6032.

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Al-Fuqaha, Ala Isam Chaudhry Ghulam M. "Routing and wavelength assignment in all-optical DWDM networks with sparse wavelength conversion capabilities." Diss., UMK access, 2004.

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Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2004.
"A dissertation in engineering and computer networking." Advisor: Ghulam Chaudhry. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed Feb. 22, 2006. Includes bibliographical references (leaves 135-157). Online version of the print edition.

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Ding, Zhemin. "Resource allocation and management in optical networks using the blocking island paradigm /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?COMP%202004%20DING.

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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.
Includes bibliographical references (leaves 123-127). Also available in electronic version. Access restricted to campus users.

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Øverby, Harald. "Quality of service differentiation, teletraffic analysis and network layer packet redundancy in optical packet switched networks." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-563.

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Optical Packet Switching (OPS) has emerged as a promising candidate for the next-generation Wavelength Division Multiplexed (WDM) based alloptical network. By enabling packet switching in the optical domain, OPS networks can provide cost-efficient and transparent transport services to higher layers. However, a commercial deployment of OPS requires not only a maturation of several key enabling technologies, but also a thorough investigation of a number of networking challenges related to OPS, since OPS networks are fundamentally different from today’s store-and-forward networks. This thesis addresses the latter issue by considering the following three OPS networking issues:

· Quality of Service (QoS) differentiation at the WDM layer, with focus on packet loss rate (PLR) and delay-jitter differentiation.

· Teletraffic analysis of OPS networks.

· How to combat packet loss in OPS networks by using network layer packet redundancy.

First, a crucial issue in OPS networks is packet loss at the network layer due to contention. Contention occurs when a packet is destined for a wavelength currently occupied by another packet. Several approaches to combat such packet loss have been proposed in recent literature, e.g. by utilizing wavelength conversion, buffering, deflection routing or traffic shaping.

This thesis considers a novel approach to combat packet loss in OPS: The proposed Network Layer Packet Redundancy Scheme (NLPRS) allows redundancy packets to be injected into the OPS network, thus enabling reconstruction of lost data packets at the OPS egress node. Results show that the NLPRS is able to reduce the end-to-end data PLR several orders of magnitude in an asynchronous OPS ring network with and without wavelength conversion.

Another crucial issue in OPS networks is QoS differentiation at the WDM layer. Due to the lack of optical random access memory, existing QoS differentiation schemes suitable for today’s WDM point-to-point architecture are not feasible to use in OPS networks. Hence, new schemes that utilize the WDM layer to provide QoS differentiation are needed.

A preemption based QoS differentiation scheme, the Preemptive Drop Policy (PDP), has been proposed for asynchronous bufferless OPS. With the PDP, high priority arrivals are allowed to preempt and take over a busy wavelength currently occupied by a low priority packet in the case of contention. This results in a lower PLR for high priority traffic compared to low priority traffic. The PDP has been extended into the Adaptive PDP (APDP), which provides absolute guarantees to the PLR for high priority ivtraffic in OPS by using a measurement based preemption probability parameter adjustment.

An access-restriction based QoS differentiation scheme, the Wavelength Allocation algorithm (WA), has been studied. In the WA, which provides QoS differentiation in asynchronous bufferless OPS networks with full range output wavelength converters, a certain number of wavelengths at an output fibre are exclusively reserved for high priority traffic.

When QoS differentiation (with respect to the PLR) is introduced in asynchronous OPS, it has been shown that the average throughput decreases, often referred to as the throughput penalty of introducing QoS differentiation. The main cause for this throughput penalty is because network resources must be used in a non-optimal manner when employing QoS differentiation schemes that utilize the WDM layer to isolate the service classes. However, as shown in this thesis, the throughput penalty is only found in asynchronous OPS. For slotted OPS, the average throughput stays the same after the introduction of QoS differentiation.

An evaluation framework suitable for quantifying the throughput penalty when introducing QoS differentiation has been proposed. Using this framework, three fundamental different QoS differentiation schemes for asynchronous OPS, including the PDP and the WA, have been evaluated. It has been shown that preemptive techniques result in the lowest throughput penalty, followed by access-restriction and dropping based techniques. This is because, when using preemption, packets are dropped only when the output port is congested. With access-restriction, packets are dropped when the output port is highly strained, and with statistically packet dropping, packets are dropped independently of the state of the output port.

A QoS differentiation scheme for slotted OPS has been proposed and evaluated. The scheme isolates the service classes by ensuring that a certain number of high priority packets can be transmitted at an output port in a time-slot in the case of contention. Using the proposed scheme does not result in a reduced throughput when the service classes are isolated.

QoS differentiation schemes for asynchronous OPS with a share pernode (SPN) contention resolution pool architecture consisting of Tunable Wavelength Converters (TWCs) and Fibre Delay Lines (FDLs) have been proposed. In particular, it has been shown that the PLR and delay-jitter may be independently differentiated in this switch architecture.

Analytical models of some of the proposed QoS differentiation schemes have been derived, providing explicit results of the PLR. In addition, an analytical framework regarding packet arrivals to an output port in an optical packet switch has been derived for both asynchronous and slotted OPS. This framework is particularly useful for studying the effects of nonuniform traffic. Furthermore, it has been shown that both the Erlang and Engset traffic models are suitable to model packet arrivals to an output port in an asynchronous optical packet switch. Regarding the Engset traffic model, it has been shown how the blocking probability can be evaluated vusing either the Engset lost calls cleared (LCC) traffic model or the Engset overflow (OFL) traffic model. For all Engset based traffic models, the time-, call- and traffic congestion have been derived. A numerical evaluation of the presented traffic models reveals that there is a small, but non-negligible, deviation between the observed blocking probabilities, which depends on the number of input/output fibres and the system load.

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Mustafa, Haithem A. "Opto-VLSI-based adaptive optical power splitter/combiner for next generation dynamic optical telecommunication networks." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2013. https://ro.ecu.edu.au/theses/923.

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The demand for optical power splitters is growing globally, due to the rapid deployment of fibre-to-the-premises, optical metropolitan area network (MAN), and active optical cables for TV/Video signal transport. Optical splitters play an important role in passive optical network (PON) technology by enabling several hundred users to share one optical line terminal. However, current PONs, which use fixed optical power splitters, have limited reconfigurability particularly in adding/dropping users to/from an optical network unit. An adaptive optical power splitter (OPS) can dynamically reallocate the opticalpower in the entire network according to the real-time distribution of users and services, thus providing numerous advantages such as improve an optical network efficiency, scalability, and reliability. An adaptive OPS is also important for realizing self-healing ring-to-ring optical MAN, thus offering automatic communication recovery when line break occurs. In addition, future optical line protection systems will require adaptive optical splitters to switch optical signals from faulty lines to active power lines, avoid the use of optical attenuators and/or amplifiers, and achieve real time line monitoring. An adaptive OPS can also be incorporated in tunable optical dispersion compensators, optical attenuator and optical gain equalizer, and reconfigurable optical switches. This thesis proposes and demonstrates the principle of a novel Opto-VLSI-based adaptive optical splitter/combiner for next generation dynamic optical telecommunication networks. The proposed splitter structure enables an input optical power to be split adaptively into a larger number of output fibre ports, through optimized phase holograms driving the Opto-VLSI processor. The new adaptive optical splitter has additional advantages including lossless operation, adequate inter-port crosstalk, compressed hardware and simple user interface. This thesis demonstrates, in particular, the concept of an adaptive optical power splitter employing an Opto-VLSI processor and a 4-f imaging system experimentally in three stages as follow: (i) a 1×2 adaptive optical power splitter based on an Opto-VLSI processor, a fibre collimator array and 4-f imaging systems (single lens), (ii) a 1×4 adaptive optical power splitter based on an Opto-VLSI processor, a fibre array and 4-f imaging systems (single lens), and (iii) a 1×N lossless adaptive optical power splitter structure integrating an Opto-VLSI processor, optical amplifiers, a fibre array, and an array of 4-f imaging systems (lens array). The thesis also demonstrates the concept of an adaptive optical signal combiner which enables multiple signals to be combined with user-defined weight profiles into a single fibre port. Experimental results demonstrate that an input optical signal can arbitrarily be split into N signals and coupled into optical fibre ports by uploading optimized multicasting phase holograms onto the Opto-VLSI processor. They also demonstrate that N input optical signals can be dynamically combined with arbitrary weights into a single optical fibre port. Excellent agreement between theoretical and experimental results is demonstrated. The total insertion loss of the optical power splitter is only 5 dB. Results also show that the optical amplifiers can compensate for the insertion and splitting losses, thus enabling lossless splitter operation. A crosstalk level around -25 dB and a wavelength spectral range exceeding 40 nm is experimentally realized. In addition, a novel broadband adaptive RF power splitter/combiner based on Opto-VLSI processor is proposed and experimentally demonstrated. By uploading optimized multicasting phase holograms onto the software-driven Opto-VLSI processor, the input RF signal is dynamically split and directed to different output ports, with userdefined splitting ratios. Also, multiple input RF signals can be dynamically combined with arbitrary user-defined weights. As a proof-of-concept demonstration, two input RF signals are dynamically combined with different user-defined weight profiles. We also propose and demonstrate a photonic microwave filter based on the use of an Opto-VLSI-based adaptive optical combiner. The experimental results demonstrate that the developed Opto-VLSI-based adaptive optical combiner can dynamically route multiple input optical signals to a single output, with user-defined weight profiles, thus realising a tunable microwave filter. Overall this Opto-VLSI-based adaptive optical power splitter should allow as many as 32 output ports to be supported while achieving high splitting resolution and dynamic range. This will greatly enhance the efficiency of optical communication networks.

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Da, Rosa Marcelo Zannin. "Optical gain clamping in erbium doped fibre amplifier : investigation in optical burst switching networks." Thesis, Swansea University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678524.

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Chowdhury, Arshad M. "Optical Label Switching Technologies for Optical Packet Switched Networks." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14047.

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Optical packet switching (OPS) is the most prominent candidate transport solution that can seamlessly integrate electrical and optical layers by transferring certain switching functionality from electronics to optics, thus alleviating unnecessarily slow and expensive optical-electrical-optical conversions and signal processing at the switching node. Optical Label Switching (OLS) is an important aspect of the optical packet switched network that enables very low-latency forwarding of ultra-high bit-rate, protocol-independent packets entirely in the optical domain. The objective of the proposed research is to develop novel, efficient techniques to realize several key enabling technologies such as optical label generation and encoding, optical label swapping, all-optical buffering, and spectral efficient transmission system for optical label switched based OPS networks. A novel scheme of generating optical label at the ingress node using optical carrier suppression and separation (OCSS) technique is proposed. This scheme does not suffer from any unavoidable interference, limited extinction ratio or strict synchronization requirements between payload and label as observed by the currently available other label generation methods. One of the primary challenges to realize optical label swapping at the core node of scalable OLS network is the insertion of new optical labels without any wavelength conversion for same wavelength packet routing. A novel mechanism to realize same wavelength packet switching without using any conventional wavelength converter in the OLS network carrying differential phase-shift keying (DPSK) modulated payload and on-off keying (OOK) modulated optical label is demonstrated. Also a new dense wavelength division multiplexing (DWDM) optical buffer architecture using optical fiber delay lines that can provide wavelength selective reconfigurable variable delays is proposed. Optical packet switching provides automated, reconfigurable, and faster provision of both wavelength and bandwidth with finer granularity in the optical layer. However, a newer, cost-effective, and spectrally efficient optical transmission technology is essential to support the explosive bandwidth demand expected by the future optical packet switched networks. To meet this challenge, a spectrally efficient solution for transporting 40 Gbps per channel data over 50 GHz spaced DWDM system is developed by exploiting optical carrier suppression and separation technique and optical duobinary modulation.

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Lim, Wee Shoong. "An evaluation of management techniques for SONET/SDH Telecommunication networks." Thesis, Monterey California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1389.

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Approved for public release; distribution is unlimited
A study of SONET network management applications and the load they impart to the network is conducted to provide a better understanding of the capability of various management approaches. In this study, a SONET network is set up in the Advanced Networking Laboratory of the Naval Postgraduate School using four Cisco ONS 15454s. Next, two Element Management Systems, the Cisco Transport Controller and the Cisco Transport Manager, are deployed onto the SONET network. Subsequently, the network traffic of the Element Management Systems is captured and analyzed using a packet analyzer. Link utilization of the two tools is computed using the first-order statistics of the captured traffic distributions. In addition, the Hurst parameter is estimated using the variance-index plot technique (which uses higher-orders statistics of the modeled distributions) to determine the captured traffic's degree of self-similarity. Finally, the calculated utilization is extrapolated to obtain the link utilization for 2500 network elements (the maximum number supported by the Cisco Transport Manager). The result obtained is useful in determining the maximum number of network elements (Cisco ONS 15454s) that the Cisco Transport Manager can support from a network loading point of view.
Civilian, Ministry of Defense, Singapore

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Li, Jonathan Chi Fai. "Eye closure penalty based signal quality metric for intelligent all-optical networks /." Connect to thesis, 2009. http://repository.unimelb.edu.au/10187/7047.

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Paul, Harald. "Passive optical network planning in the local access network - an optimisation based approach utilising genetic algorithms." Thesis, University of Sunderland, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.310010.

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Yuen, Siu Yu. "Routing and time-slot assignment algorithms and connection management in photonic circuit switched networks /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202005%20YUEN.

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Sau, Ignasi. "Optimization in Graphs under Degree Constraints. Application to Telecommunication Networks." Phd thesis, Université de Nice Sophia-Antipolis, 2009. http://tel.archives-ouvertes.fr/tel-00429092.

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La première partie de cette thèse s'intéresse au groupage de trafic dans les réseaux de télécommunications. La notion de groupage de trafic correspond à l'agrégation de flux de faible débit dans des conduits de plus gros débit. Cependant, à chaque insertion ou extraction de trafic sur une longueur d'onde il faut placer dans le noeud du réseau un multiplexeur à insertion/extraction (ADM). De plus il faut un ADM pour chaque longueur d'onde utilisée dans le noeud, ce qui représente un coût d'équipements important. Les objectifs du groupage de trafic sont d'une part le partage efficace de la bande passante et d'autre part la réduction du coût des équipements de routage. Nous présentons des résultats d'inapproximabilité, des algorithmes d'approximation, un nouveau modèle qui permet au réseau de pouvoir router n'importe quel graphe de requêtes de degré borné, ainsi que des solutions optimales pour deux scénarios avec trafic all-to-all: l'anneau bidirectionnel et l'anneau unidirectionnel avec un facteur de groupage qui change de manière dynamique. La deuxième partie de la thèse s'intéresse aux problèmes consistant à trouver des sous-graphes avec contraintes sur le degré. Cette classe de problèmes est plus générale que le groupage de trafic, qui est un cas particulier. Il s'agit de trouver des sous-graphes d'un graphe donné avec contraintes sur le degré, tout en optimisant un paramètre du graphe (très souvent, le nombre de sommets ou d'arêtes). Nous présentons des algorithmes d'approximation, des résultats d'inapproximabilité, des études sur la complexité paramétrique, des algorithmes exacts pour les graphes planaires, ainsi qu'une méthodologie générale qui permet de résoudre efficacement cette classe de problèmes (et de manière plus générale, la classe de problèmes tels qu'une solution peut être codé avec une partition d'un sous-ensemble des sommets) pour les graphes plongés dans une surface. Finalement, plusieurs annexes présentent des résultats sur des problèmes connexes.

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Bozek, Matthew Peter. "Express lanes modification to the data vortex photonic all-optical path interconnection network." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24680.

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Thesis (M. S.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.
Committee Chair: Wills, D. Scott; Committee Member: Keezer, David; Committee Member: Yalamanchili, Sudhakar

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Puris, Dmitriy [Verfasser], and Klaus [Akademischer Betreuer] Petermann. "Modeling of Quantum Dot Semiconductor Optical Amplifiers for Telecommunication Networks / Dmitriy Puris. Betreuer: Klaus Petermann." Berlin : Universitätsbibliothek der Technischen Universität Berlin, 2013. http://d-nb.info/1035276380/34.

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Jordan, Wayne George. "New zirconium fluoride-based halide glasses for 1.3 #mu#m optical fibre amplifiers in telecommunication networks." Thesis, Brunel University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239091.

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Ng, Hwee Ping. "Performance analysis of management techniques for SONET/SDH telecommunications networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2005. http://library.nps.navy.mil/uhtbin/hyperion/05Mar%5FNg.pdf.

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Sharma, Ameeth. "Performance comparison of two dynamic shared-path protection algorithms for WDM optical mesh networks." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-141918/.

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Jia, Zhensheng. "Optical millimeter-wave signal generation, transmission and processing for symmetric super-broadband optical-wireless access networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24640.

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Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Gee-Kung Chang; Committee Co-Chair: Jianjun Yu; Committee Member: John A. Buck; Committee Member: Joy Laskar; Committee Member: Umakishore Ramachandran; Committee Member: Ye Li

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Chen, Jiajia. "Design, analysis and simultion for optical access and wide-area networks." Doctoral thesis, KTH, Mikroelektronik och tillämpad fysik, MAP, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10348.

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Due to the tremendous growth of traffic volume caused by both exponential increase of number of Internet users and continual emergence of new bandwidth demanding applications, high capacity networks are required in order to satisfactorily handle the extremely large amount of traffic. Hence, optical fiber communication is the key technology for the network infrastructure. This thesis addresses design, analysis and simulation of access and core networks targeting important research problems, which need to be tackled for the effective realization of next generation optical networks. Among different fiber access architectures, passive optical network (PON) is considered as the most promising alternative for the last mile connection due to its relatively low cost and resource efficiency. The inherent bursty nature of the user generated traffic results in dynamically changing bandwidth demand on per subscriber basis. In addition, access networks are required to support differentiated quality of service and accommodate multiple service providers. To address these problems we proposed three novel scheduling algorithms to efficiently realize dynamic bandwidth allocation in PON, along with guaranteeing both the priority and fairness of the differentiated services among multiple users and/or service providers. Meanwhile, because of the increasing significance of reliable access to network services, an efficient fault management mechanism needs to be provided in PON. In addition, access networks are very cost sensitive and the cost of protection should be kept as low as possible. Therefore, we proposed three novel cost-effective protection architectures keeping in mind that reliability requirement in access networks should be satisfied at the minimal cost. Regarding the optical core networks, replacing electronic routers with all-optical switching nodes can offer significant advantages in realizing high capacity networks. Because of the technological limitations for realizing all-optical nodes, the focus is put on the ingenious architecture design. Therefore, we contributed on novel switching node architectures for optical circuit and packet switching networks. Furthermore, we addressed different aspects of routing and wavelength assignment (RWA) problem, which is an important and hard task to be solved in wavelength routed networks. First, we proposed an approach based on the information summary protocol to reduce the large amount of control overhead needed for dissemination of the link state information in the case of adaptive routing. In addition, transparency in optical networks may cause vulnerability to physical layer attacks. To target this critical security related issue, we proposed an RWA solution to minimize the possible reachability of a jamming attack. Finally, in order to evaluate our ideas we developed two tailor-made simulators based on discrete event driven system for the detailed studies of PON and switched optical networks. Moreover, the proposed tabu search heuristic for our RWA solution was implemented in C++.
QC 20100707

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Hawkins, William Cory. "Evaluation of the data vortex photonic all-optical path interconnection network for next-generation supercomputers." Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-12182006-155304/.

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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2007.
Dr. Henry L. Owen III, Committee Member ; Dr. David Keezer, Committee Member ; Dr. D. Scott Wills, Committee Chair.

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Woeste, Christian C. "Passive-optical-network planning based on Tabu Search : an investigation of zero-base Brownfield planning for passive optical telecommunication networks based on the modern heuristic optimisation method Tabu Search." Thesis, University of Sunderland, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267750.

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Savasini, Marcio Saenz. "Esquemas de proteção e conversão de comprimento de onda em redes opticas WDM." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/261764.

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Orientador: Helio Waldman
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-05T14:57:27Z (GMT). No. of bitstreams: 1 Savasini_MarcioSaenz_M.pdf: 1495771 bytes, checksum: 8580ad17c20a8326cbb9cee63471d096 (MD5) Previous issue date: 2005
Resumo: Este trabalho tem como objetivo analisar a redução na probabilidade de bloqueio com o uso de conversores de comprimento de onda e esquemas de proteção em redes ópticas. É apresentada a proteção por roteamento em sub-grafos, um método de criar caminhos de proteção dependentes a falha para cada conexão. Alguns esquemas para eliminar realocações desnecessárias de conexões no caso de falha, sem penalizar fortemente a aceitação de novas conexões, foram sugeridos e comparados. Outro tema abordado no trabalho foi o ganho do uso de conversores de comprimento de onda em redes em malha em um ambiente dinâmico de tráfego. Foi utilizado nas simulações um número limitado de conversores plenos espalhados pela rede. Foi analisada a quantidade suficiente de conversores para se ter uma probabilidade de bloqueio satisfatória, pensando em minimizar os investimentos a serem feitos no momento de uma expansão da rede. Para um melhor entendimento dos problemas estudados há uma descrição do funcionamento da rede óptica e seus elementos principais e dos algoritmos de roteamento e alocação de comprimento de onda utilizados e descritos na literatura
Abstract: This work examines the blocking reduction with the use of wavelength converters and some protection schemes in optical networks. Sub-Graph Routing Protection, a protection method that creates different failure-dependent protection paths for each connection is presented. Some schemes were proposed and compared, aiming at eliminating unnecessary connection reallocations on a failure occurrence, without compromising the acceptance of new connections. Another topic studied for this work is the conversion gain, when wavelength converters are used in mesh topology networks under dynamic traffic. A limited number of total converters were used in the simulations. The sufficient amount of converters for a satisfactory blocking probability was analyzed, for minimizing investments in a network upgrade. For a better problem formulation understanding the optical network and its elements were explained. The routing and wavelength allocation algorithms proposed in the literature are also detailed.
Mestrado
Telecomunicações e Telemática
Mestre em Engenharia Elétrica

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De, Vega Rodrigo Miguel. "Modeling future all-optical networks without buffering capabilities." Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210455.

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In this thesis we provide a model for a bufferless optical burst switching (OBS) and an optical packet switching (OPS) network. The thesis is divided in three parts.

In the first part we introduce the basic functionality and structure of OBS and OPS networks. We identify the blocking probability as the main performance parameter of interest.

In the second part we study the statistical properties of the traffic that will likely run through these networks. We use for this purpose a set of traffic traces obtained from the Universidad Politécnica de Catalunya. Our conclusion is that traffic entering the optical domain in future OBS/OPS networks will be long-range dependent (LRD).

In the third part we present the model for bufferless OBS/OPS networks. This model takes into account the results from the second part of the thesis concerning the LRD nature of traffic. It also takes into account specific issues concerning the functionality of a typical bufferless packet-switching network. The resulting model presents scalability problems, so we propose an approximative method to compute the blocking probability from it. We empirically evaluate the accuracy of this method, as well as its scalability.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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Pereira, Flavio de Melo. "Modelagem, policiamento e escalonamento em redes Ethernet PON." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260703.

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Orientadores: Dalton Soares Arantes, Nelson Luis Saldanha da Fonseca
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-08-07T07:59:05Z (GMT). No. of bitstreams: 1 Pereira_FlaviodeMelo_D.pdf: 3025086 bytes, checksum: 2baf4e2cf83a53c366092610c84e1bdc (MD5) Previous issue date: 2006
Resumo: Neste trabalho, apresentamos uma nova proposta de modelagem, policiamento e escalonamento de tráfego em redes Ethernet com elementos ápticos passivos. Esta proposta visa ao suporte a garantias de desempenho individuais para os fluxos. Propomos um processo envelope denominado Processo de Chegada com Limitante Fracionário para a representação de tráfego multimidia com características fractais. Com base neste modelo, propomos o uso do algoritmo do balde furado para o policiamento do tráfego. Para o escalonamento de tráfego, propomos uma nova política em que a rede reserva uma parcela minima de banda para cada fluxo, sendo que os fluxos com demanda reprimida recebem uma parcela justa dos recursos ociosos. Para esta política, denominada Compartilhamento Proporcional com Reserva de Carga, estabelecemos as condições de estabilidade da rede e apresentamos expressões limitantes para a justiça e para o atraso dos fluxos
Abstract: We propose new framework for traffic modelling, policing and scheduling in Ethernet Passive Optical Networks. This framework aims at providing performance guarantees to individual flows in access networks. We propose a new envelope process called Fractional Bounded Arrival Process for selfsimilar 'multimedia traffic representation. The policing of such a kind of traffic by using the leaky bucket algorithm is also proposed. We present a novel discipline for scheduling the upstream flows in EPON networks. In such a discipline, which is calle4 Proportional Sharing with Load Reservation, each flow is guaranteed a minimum share of bandwidth and the unused bandwidth is fairly distributed among them in proportion to their own demands and priorities. We analyze the performance of the proposed discipline and provide fairness and delay bounds on a per-flow basis
Doutorado
Telecomunicações e Telemática
Doutor em Engenharia Elétrica

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28

Walker, Graham Richard. "Optical amplifiers for future telecommunications networks." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241118.

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Evans, T. "Active optical waveguide devices for telecommunications networks." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.598865.

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Two active optical waveguide devices were investigated using a variety of theoretical techniques for their potential application to telecommunications networks. A reconfigurable transverse waveguide grating was numerically modelled and shown to offer switching up to 1x16 with high refractive index modulating materials or 1x4 with much faster, but lower refractive index modulating materials. Furthermore, a method was shown for combining the grating with a finer fixed grating to select a wavelength multiplexed signal. A previously devised dynamic gain flattening filter device was also numerically analysed to determine its general characteristics and the limitations of its configuration. Its effects on attenuation control and data signal distortion were analysed under a range of conditions and guidelines for keeping that distortion limited determined. A simplified model of the filter operation was used to form a control algorithm allowing immediate jumps in the attenuation levels to be accomodated. Finally, an experimental implementation of the filter with an arrayed waveguide grating and free space imaged liquid crystal phase modulating array was demonstrated. Unfortunately errors in the construction of this filter prevented typical attenuation profiles from being illustrated, but the resulting measurements were found consistent with the filter modelling. It was judged that the gain flattening filter could potentially be used for both generating a set of data modulated wavelength channels as a source and for correcting the relative levels of those channels after different transmission paths had modified them. Both of these features would be particularly desirable in an optically routed system. The wide switching capabilities of the transverse grating (1x16) could be useful for initial network configuration or recovery from link failure, but unfortunately it does not offer sufficient advantages over an array of simpler junctions to make its development clearly worthwhile. Electrically selecting a single wavelength channel from many using the fixed and reconfigurable grating combination would potentially be useful in an add/drop multiplexer component.

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AMORIM, RAFAEL FREITAS DE. "INTEGER PROGRAMMING PROBLEMS ON TELECOMMUNICATIONS OPTICAL NETWORKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8796@1.

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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
Impulsionadas pelo crescimento do mercado corporativo e pela prestação de serviços para grandes clientes, as operadoras de serviços de telecomunicação estão buscando processos automatizados e redução de custo no desenvolvimento de novos projetos de redes de telecomunicações. Nesse cenário, dois modelos de Programação Inteira são apresentados buscando uma minimização de custos. O primeiro para o problema de planejamento de novas redes. E segundo para o problema de configuração de trails nas redes SDH. Uma introdução sobre meios de transmissão, redes de telecomunicações, topologias mais utilizadas e sistemas de proteção são apresentados. Por fim, em ambos problemas, são apresentados estudos comparativos com situações reais, com o intuito de validar os modelos.
Stimulated by the growth of the corporate market and by the services dedicated to big customers, providers are searching for, even more nowadays, automated process and cost reduction on the development of new telecommunications networks projects. In that setting, two models of Integer Programming will be presented, seeking a minimization of costs. At first, for the problem of planning of new networks, and second for the problem of configuration of trails in the SDH networks. Beyond that, an introduction about transmission lines, networks of communication, topology more utilized and systems of protection will be presented. In both problems, comparing real situations, with the purpose of validate the models.

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31

Gilfedder, Timothy Hugh. "Physical layer modelling of optical telecommunications architecutures." Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366806.

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Rotich, Enoch Kirwa. "Fibre optic network supporting high speed transmission in the square kilometre array, South Africa." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/6552.

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This thesis provides in-depth information on the high speed optical transport requirements for the Square Kilometre Array. The stringent data rates as well as timing and synchronization requirements are dealt with respect to the optical fibre technology. Regarding the data transport, we draw a clear comparison between a typical telecommunication access network and a telescope network. Invoking simulations and experiments on the field and laboratory test bed, we successfully implement a suitable telescope network using vertical cavity surface emitting laser (VCSEL) technology. Polarization effects on the KAT-7 telescope network, an operational prototype for the SKA is studied so as to estimate the expected effect in the MeerKAT telescope with transmission distances _ 12 km. The study further relates the obtained values to the expected impact on the distribution of the time and frequency reference in the MeerKAT array. Clock stability depends on the differential group delay (DGD) and polarization stability. On a 10:25 km link that includes the riser cable a DGD of 62:1 fs was attained. This corresponds to a polarization mode dispersion (PMD) coefficient of 19:4 fs=km1=2. This is a low PMD value considering telecommunication network. The PMD value is within the allowed budget in the telescope network. However, this may not be the case at longer baselines extending to over 1000 km as expected in SKA 2. The fibre's deployment contribution to the DGD is measured by comparing the deployed fibre to the undeployed of equal lengths. On the 10:25 km deployed single mode fibre, the maximum and mean DGDs measured were 217:7 fs and 84:8 fs respectively. The undeployed fibre of similar type and equal length, gave a maximum and minimum DGDs of 58:6 fs and 36:3 fs respectively. The deployment is seen to increase the maximum and minimum DGDs by factors of 3.7 and 2.3 respectively. This implies that fibre deployment is very critical in ensuring the birefringence is minimized. Polarization fluctuation recorded a maximum of 180o during the 15 hour real time astronomer use of the antenna. To ascertain the contribution of the riser cable, state of polarization (SOP) of the buried section of the single mode fibre in the link was established. A maximum SOP change of 14o over 15 hour monitoring was measured. From the stability realized on the buried section of the fibre, the change in polarization is contributed by the riser cable. The fluctuation in polarization can cause the phase of a clock signal to drift between the birefringent axes by an equal amount corresponding to DGD. We experimentally demonstrate how polarization stabilization can be attained using the polarization maintaining fibre. We also demonstrate the applicability of VCSEL technology in the SKA unidirectional data flow especially for shorter baselines < 100 km. The VCSEL is a low cost light source with attractive advantages such as low power consumption, high speed capabilities and wavelength tuneability. This work entails the use of traditional amplitude modulation commonly known as non-return-to-zero (NRZ) on-off keying (OOK) because of its simplicity and cost. For the MeerKAT typical distances, we show that even in a worst case scenario, the use of VCSEL on different fibres in MeerKAT distance is achievable. Using the impairment reduction approach, we successfully manage to achieve transmission distance beyond MeerKAT. Several in-line dispersion compensation mechanisms in telecommunication have been successfully employed. The work focused on the use of negative dispersion fibre to mitigate the chromatic dispersion effects in the optical fibre. The inverse dispersion fibre (IDF) is proposed for compensation in the conventional zero dispersion wavelength fibres, G.652 that are used at the third window. Similarly, the chromatic dispersion compensation of non-zero dispersion shifted fibre (NZDSF) is experimentally demonstrated using negative dispersion submarine reduced slope (SRS), G. 655 (-). With dispersion management, we demonstrate how transmissions beyond MeerKAT baselines can be achieved error free. A systematic investigation of the use of distributed Raman amplification to overcome the attenuation losses is provided. High on-off gains of up to 15 dB, 8 dB and 5 dB for bidirectional, forward and backward pumping respectively is achieved on a 25 km Raman optimized NZDSF-Reach fibre. Combined dispersion mitigation technique and low noise distributed Raman amplification, up to about 80 km transmission was achieved on a 4:25 Gbps modulated VCSEL using a single pump. Using bidirectional pumping, more than 100 km of transmission was achieved error free. The high gains enhance the VCSEL transmission distance. We further suggest a novel way of using the Raman pump to distribute the clock signal while amplifying the data signal streaming the astronomical data from the remote placed telescope receivers. In summary, the work presented in this thesis has demonstrated the potential use of VCSEL technology for data collection in the telescope array. We have studied the optical effects and mitigation so as to improve the clock and data transmission. This work is relevant and valuable in providing SKA with VCSELs, an option for extremely high network performance at reasonable costs.

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Stanojević, Daliborka. "Optimization of contemporary telecommunications networks : generalized spanning trees and WDM optical networks." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/3194.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Business and Management. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Brown, Deborah Robyn. "Optimal design, dimensioning and tariffing of telecommunications networks /." Title page, contents and abstract only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phb8774.pdf.

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Lowe, Ewart D. "Performance and dimensioning of optical transport networks." Thesis, University of Essex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295647.

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36

Antoniu, Nikolaos H. "Optimal admission policies for small star networks." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5665/.

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In this thesis admission stationary policies for small Symmetric Star telecommunication networks in which there are two types of calls requesting access are considered. Arrivals form independent Poisson streams on each route. We consider the routing to be fixed. The holding times of the calls are exponentially distributed periods of time. Rewards are earned for carrying calls and future returns are discounted at a fixed rate. The operation of the network is viewed as a Markov Decision Process and we solve the optimality equation for this network model numerically for a range of small examples by using the policy improvement algorithm of Dynamic Programming. The optimal policies we study involve acceptance or rejection of traffic requests in order to maximise the Total Expected Discounted Reward. Our Star networks are in some respect the simplest networks more complex than single links in isolation but even so only very small examples can be treated numerically. From those examples we find evidence that suggests that despite their complexity, optimal policies have some interesting properties. Admission Price policies are also investigated in this thesis. These policies are not optimal but they are believed to be asymptotically optimal for large networks. In this thesis we investigate if such policies are any good for small networks; we suggest that they are. A reduced state-space model is also considered in which a call on a 2-link route, once accepted, is split into two independent calls on the links involved. This greatly reduces the size of the state-space. We present properties of the optimal policies and the Admission Price policies and conclude that they are very good for the examples considered. Finally we look at Asymmetric Star networks with different number of circuits per link and different exponential holding times. Properties of the optimal policies as well as Admission Price policies are investigated for such networks.

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Agarwal, Shweta S. "Search for an optimal network reporting threshold." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1091451063.

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Sampson, David Douglas. "High bandwidth temporal correlators using optical fibre networks." Thesis, University of Kent, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293712.

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39

Stark, Andrew Joseph. "16QAM for next-generation optical transport networks." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47732.

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Fiber-optic networks are continually evolving to accommodate ever-increasing data transport rates demanded by modern applications, devices, and services. Network operators are now beginning to deploy systems with 100 Gb/s per-wavelength data rates while maintaining the 50 GHz dense wavelength division multiplexing grid that is (generally) standard for 10 Gb/s systems. Advanced modulation formats incorporating both amplitude- and phase-based data symbols are necessary to meet the spectral efficiency requirements of fiber-optic data transport. These modulation formats require coherent detection, enabling future networks to take advantage of advances in silicon CMOS via digital signal processing algorithms and techniques. The primary challenge for future networks is the fiber nonlinear response; changes in the intensity of the propagating optical signal induce changes in the optical fiber refractive index. Limiting the allowed propagation intensity will reduce these nonlinear effects and correspondingly limit the total available signal-to-noise ratio (SNR) within the channel. Predicting the nonlinear SNR limits of fiber-optic transport for data rates 100 Gb/s and beyond is a primary purpose of this research. This dissertation expressly matches several novel expressions for nonlinear interference accumulation to experimental data and demonstrates robust theoretical prediction of nonlinear transmission penalties. The experiments were performed to isolate the transmission performance of the fiber medium in the highly dispersive regime -- no dispersion compensation or Raman amplification was employed and all other hardware was kept static. These results are the first experimental validation of the nonlinear interference expressions on a fiber-type basis. Second, this dissertation moves to data transport beyond per-wavelength rates of 100 Gb/s by employing 16QAM at baud rates as high as 32 GHz. It examines signal processing strategies for 16QAM transport and extends the nonlinear interference prediction techniques to 16QAM. The results reveal that the SNR requirements of 16QAM as limited by nonlinear interference will likely limit deployments to high-density regional and metro networks.

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Boldrini, Leonardo. "Camera Based Localization for Indoor Optical Wireless Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20240/.

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The main focus of this work is to implement device localization in an indoor communication network which employs short range Optical Wireless Communication (OWC) using pencil beams. OWC is becoming increasingly important as a solution to the shortage of available radio spectrum. In order to counter this problem, a radical new approach is proposed by performing wireless communication using optical rather than radio techniques, by deploying optical pencil beam technologies to provide users with access to an indoor optical fiber infrastructure. An architecture based on free-space optics has been adopted. The narrow infrared beam is considered a good solution because of its ability to optimally carry all the information which the optical fiber can transport, in an energy-efficient way. Beam Steered - Infrared Light Communication (BS-ILC) brings the light only where is needed. Multiple beams may independently serve user devices within a room, hence each device can get a non-shared capacity without conflicts with other devices. Infrared light beams, additionally, are allowed to be operated at a higher power than visible light beams, due to a higher eye safety threshold for infrared light. Together with the directivity of a beam, this implies that the received signal-to-noise ratio with BS-ILC can be substantially higher than with Visible Light Communication (VLC), enabling a higher data rate and longer reach at better power efficiency. Current BS-ILC prototypes allow multiple beams with over 100 Gbit/s per beam. This high performance can only be achieved with small footprints, hence the system needs to know the exact location of user devices. In this thesis, an accurate and fast localization/tracking technique using a low-cost camera and simple image processing is presented.

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O'Farrell, Timothy. "Code-division multiple-access (CDMA) techniques in optical fibre local area networks." Thesis, University of Manchester, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.257164.

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42

Wosinska, Lena. "A study of the reliability of optical switching nodes for high capacity telecommunications networks /." Stockholm, 1999. http://www.lib.kth.se/abs99/wosi0617.pdf.

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Zhang, Jihui. "On the optimal formulation of resource management in wireless networks /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?COMP%202005%20ZHANG.

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Rhee, Seung Hyong. "Optimal flow control and bandwidth allocation in multiservice networks : decentralized approaches /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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45

Diab, Wassim. "Converging Fronthaul and Backhaul Traffic in Edge Optical Networks." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.

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Centralized Radio Access Network(C-RAN) has great potentials and is able to benefit the networks in many levels. In a C-RAN architecture, the BBU Is placed in a centralized position away from the RRU, this will provide many advantages to the network that will be shown in the following chapters. In this thesis, it has been considered the advantages of utilizing Ethernet in C-RAN, as a way to improve the network. Inorder to achieve this, encapsulation of the Common Packet Radio Interface(CPRI) has been introduced in the Fronthaul(FH), taking into consideration the different restrictions that are described later in the thesis. Then an analytical model is described and introduced, followed by a list of experiments inorder to guarantee a full successful transmission of the different classes of traffic. Finally, the results of the studies are analyzed and achieved.

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46

Thiessen, Christian. "Resilient routing and spectrum assignment in Elastic Optical Networks under Dynamic Traffic." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-155684.

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Transparent Elastic Optical Networks (EON) are seen as a promising solution for future optical transport networks to keep up with internet traffic growth, as they allow provisioning connections with different bandwidth requirements in an efficient way. To achieve high spectrum efficiency in these networks, making good Routing, Modulation and Spectrum Assignment (RMLSA) decisions is essential. Since fiber cuts are common, resiliency against single-link failures is another important topic. This can be provided efficiently through shared-path protection (SPP), which in turn complicates the RMLSA problem. Existing routing, modulation and spectrum assignment algorithms for SPP focus on the two-step approach, where primary paths are selected independently of their backup path options. However, selecting a different primary path can allow for a better backup path with higher shareability of backup resources if primary and backup path pairs are considered together. Previous studies on SPP in EONs mostly consider the static traffic scenario. Under a dynamic traffic scenario, where unpredictable connection re-quests arrive and terminate over time, fragmentation of spectral resources has a significant impact on the network performance. In this thesis, a new algorithm is proposed for SPP in EONs against single-link failures where primary and backup path pairs are selected jointly, thereby minimizing fragmentation and maximizing shareability which leads to better network performance in terms of blocking probability. Unlike existing algorithms, the primary and backup path and spectrum are decided simultaneously from a set of candidate path pairs and the spectrum assignment is done using a hybrid cost metric. The metric is a weighted combination of existing metrics that integrates fragmentation and shareability into a multi-objective function. Using network traffic simulations in two reference networks, the effect of the different cost functions on the algorithm’s behavior is explored and an optimal set of weights is determined. With this parameterization, traffic simulations in a scaled-down sample US network topology with load values of 190-240 Erlang, corresponding to blocking probabilities of 0.1% to 1%, show an average improvement over the reference algorithm of 79% in blocking probability, 6.9% in shareability and 5.9% in spectrum fragmentation. It is also shown that most of this improvement is caused by joint primary-backup path assignments. The hybrid cost function reduces blocking by a further 10%.
Transparenta Elastiska Optiska Nätverk (EON) ses som en lovande lösning för framtida optiska transportnät för att hänga med Internettrafikens tillväxt, eftersom de möjliggör att tillhandahålla förbindelser med olika krav på bandbredd på ett effektivt sätt. För att uppnå hög spektrumeffektivitet i dessa nätverk är det viktigt att fatta bra beslut vad avser routing, modulering och spektrumtilldelning (Routing, Modulation Level and Spectrum Assignment, RMLSA). Eftersom fiberavbrott är vanliga, så är tåligheten mot enstaka länkfel et annat viktigt ämne. Detta kan ske effektivt genom att skydda gemensamma reservvägar (Shared Path Protection, SPP), vilket dock försvårar RMLSA-problemet. Befintliga routing, modulering och spektrumtilldelningsalgoritmer för SPP fokuserar på strategier i två steg, där först de primära vägarna väljs oberoende av deras backupalternativ. Att välja en annan primär väg, kan dock möjliggöra en bättre reservväg med bättre delning av backupresurser om i stället par av primära och sekundära vägar bedöms tillsammans. Tidigare studier på SPP i EONs anser främst statiska trafikscenarier. I ett dynamiskt trafikscenario, där oförutsägbara anslutningsbegäranden inkommer och avslutas över tiden, så kommer fragmenteringen av spektrala resurser ha en betydande inverkan på nätverkets prestanda. I denna avhandling föreslås en ny algoritm för SPP i EONs för hantering av enskilda länkfel, där par av primära och sekundära vägar väljs gemensamt, vilket minimerar fragmentering och maximerar delning vilket leder till bättre nätverksprestanda i form av minskat blockering. Till skillnad från befintliga algoritmer beslutas den primära och sekundära vägen och spektrum samtidigt från en uppsättning av par av kandidatvägar och spektrumtilldelningen görs med en hybrid-kostnadsfunktion. Funktionen är en viktad kombination av befintliga mått som integrerar fragmentering och delning till en multi-objektiv målfunktion. Med användning av nätverkstrafiksimuleringar i två referensnätverk studeras effekten av olika kostnadsfunktioner på algoritmens beteende och en optimal uppsättning av vikter bestäms. Med dessa parametrar, trafiksimuleringar i en reducerad US-nätverkstopologi med belastningsvärden på 190-240 Erlang, motsvarande blockeringssannolikheter på 0,1 - 1%, visar en genomsnittlig förbättring under referensalgoritmen på 79% i blockeringens sannolikhet, 6.9% i delning och 5,9% i fragmentering. Det visas också att det mesta av denna förbättring beror på det samtidiga tilldelning av primära och reservlänkar. Hybridkostnadsfunktionen minskar blockeringen med ytterligare 10%.

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47

Ni, Wenlong. "Optimal call admission control policies in wireless cellular networks using Semi Markov Decision Process /." Connect to full text in OhioLINK ETD Center, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=toledo1227028023.

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48

Ozcelik, Fatih Mehmet. "Optimal And Implementable Transmission Schemes For Energy Harvesting Networks." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614636/index.pdf.

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Progress in energy harvesting technology and the increasing need for the energy efficient and environmentally friendly applications have called for reconsideration of communication systems. This reconsideration results in new problem formulations regarding the recent developments on energy harvesting systems. Recently, optimal strategies for various types of energy harvesting networks have been developed based on different harvesting models. This thesis reports the results of our research to develop the optimal scheduling structures on an energy harvesting broadcast and fading channels, and to devise online implementable algorithms for a point-to-point communication system. Particularly, structural properties of an optimal offline schedule in, (1) an energy harvesting broadcast channel with one transmitter two receivers, (2) a single user communication system under fading conditions, are investigated. Moreover, an online algorithm is proposed for a single-user energy harvesting communication system considering the physical constraints and necessities regarding implementation. The proposed scheme is implemented through GNU Radio framework on a USRP device.

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Dantas, Joana Sócrates. "Priority realloc: um mecanismo para alocação de rotas e recursos em redes EON." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3141/tde-12072016-080408/.

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Abstract:

Backbone networks are responsible for long-haul data transport serving many clients with a large volume of data. Since long-haul data transport service must rely on a robust high capacity network the current technology broadly adopted by the industry is Wavelength Division Multiplexing (WDM). WDM networks enable one single ber to operate with multiple high capacity channels, drastically increasing the ber capacity. In WDM networks each channel is associated with an individual wavelength. Therefore a whole wavelength capacity is assigned to a connection, causing waste of bandwidth in case the connection bandwidth requirement is less than the channel total capacity. In the last half decade, Elastic Optical Networks (EON) have been proposed and developed based on the fexible use of the optical spectrum known as the exigrid. EONs are adaptable to clients requirements and may enhance optical networks performance. For these reasons, research community and data transport providers have been demonstrating increasingly high interest in EONs which are likely to replace WDM as the universally adopted technology in backbone networks in the near future. EONs have two characteristics that may limit its ecient resources use. The spectrum fragmentation, inherent to the dynamic EON operation, decrease the network capacity to assign resources to connection requests increasing network blocking probability. The spectrum fragmentation also intensifides the denial of service to higher rate request inducing service unfairness. Due to the fact EONs were just recently developed and proposed, the aforementioned issues were not yet extensively studied and solutions are still being proposed. Furthermore, EONs do not yet provide specific features as differentiated service mechanisms. Differentiated service strategies are important in backbone networks to guarantee client\'s diverse requirements in case of a network failure or the natural congestion and resources contention that may occur at some periods of time in a network. Impelled by the foregoing facts, this thesis objective is three-fold. By means of developing and proposing a mechanism for routing and resources assignment in EONs, we intend to provide differentiated service while decreasing fragmentation level and increasing service fairness. The mechanism proposed and explained in this thesis was tested in a EON simulation environment and performance results indicated that it promotes beneficial performance enhancements when compared to benchmark algorithms.
Redes backbone s~ao responsáveis pelo transporte de dados à longa distância que atendem a uma grande quantidade de clientes com um grande volume de dados. Como redes backbone devem basear-se em uma rede robusta e de alta capacidade, a tecnologia atual amplamente adotada pela indústria é Wavelength Division Multiplexing (WDM). Redes WDM permitem que uma única fibra opere com múltiplos canais de alta largura de banda, aumentando drasticamente a capacidade da fibra. Em redes WDMcada canal está associado a um comprimento de onda particular. Por conseguinte, toda capacidade do comprimento de onda é atribuída a uma única conexão, fazendo com que parte da largura de banda seja desperdiçada no caso em que a requisição de largura de banda da conexão seja menor do que a capacidade total do canal. A partir da metade da última década, as Redes Ópticas Elásticas (Elastic Optical Networks - EON) têm sido propostas e desenvolvidas com base no uso flexível do espectro óptico conhecido como flexigrid. EONs s~ao adaptáveis às requisições por banda dos clientes e podem, portanto, melhorar o desempenho das redes ópticas. Por estas razões, EONs têm recebido cada vez mais interesse dos meios de pesquisa e provedores de serviço e provavelmente substituirão WDM como a tecnologia universalmente adotada pela indústria em redes backbone. EONs têm duas características que podem limitar a utilização eficiente de recursos. A fragmentação do espectro, inerente à operação dinâmica das EONs, pode diminuir a capacidade da rede em distribuir recursos ao atender às solicitações por conexões aumentando a probabilidade de bloqueio na rede. A fragmentação do espectro também intensifica a negação de serviço a solicitações por taxa de transmissão mais elevada, gerando injustiça no serviço prestado. Como EONs foram desenvolvidas recentemente, respostas às questões acima mencionadas ainda estão sob estudo e soluções continuam sendo propostas na literatura. Além disso, EONs ainda não fornecem funções específicas como um mecanismo que proveja diferenciação de serviço. Estratégias de diferenciação de serviço são importantes em redes backbone para garantir os diversos requisitos dos clientes em caso de uma falha na rede ou do congestionamento e disputa por recursos que podem ocorrer em alguns períodos em uma rede. Impulsionada pelos fatos anteriormente mencionados, esta tese possui três objetivos. Através do desenvolvimento e proposta de um mecanismo de roteamento e atribuição de recursos para EONs, temos a intenção de disponibilizar diferenciação de serviço, diminuir o nível de fragmentação de espectro e aumentar a justiça na distribuição de serviços. O mecanismo proposto nesta tese foi testado em simulações de EONs. Resultados indicaram que o mecanismo proposto promove benefícios através do aprimoramento da performance de uma rede EON quando comparado com algoritmos de referência.

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50

Liu, Cheng. "Advanced system design and signal processing techniques for converged high-speed optical and wireless applications." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49058.

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Abstract:

The ever-increasing data traffic demand drives the evolution of telecommunication networks, including the last-mile access networks as well as the long-haul backbone networks. This Ph.D. dissertation focuses on system design and signal processing techniques for next-generation converged optical-wireless access systems and the high-speed long-haul coherent optical communication systems. The convergence of high-speed millimeter-wave wireless communications and high-capacity fiber-optic backhaul networks provides tremendous potential to meet the capacity requirements of future access networks. In this work, a cloud-radio-over-fiber access architecture is proposed. The proposed architecture enables a large-scale small-cell system to be deployed in a cost-effective, power-efficient, and flexible way. Based on the proposed architecture, a multi-service reconfigurable small-cell backhaul network is developed and demonstrated experimentally. Additionally, the combination of high-speed millimeter-wave radio and fiber-optic backhaul is investigated. Several novel methods that enable high-spectral-efficient vector signal transmission in millimeter-wave radio-over-fiber systems are proposed and demonstrated through both theoretical analysis and experimental verification. For long-haul core networks, ultra-high-speed optical communication systems which can support 1Terabit/s per channel transmission will soon be required to meet the increasing capacity demand in the core networks. Grouping a number of tightly spaced optical subcarriers to form a terabit superchannel has been considered as a promising solution to increases channel capacity while minimizing the need for high-level modulation formats and high baud rate. Conventionally, precise spectral control at transmitter side is required to avoid strong inter-channel interference (ICI) at tight channel spacing. In this work, a novel receiver-side approach based on “super receiver” architecture is proposed and demonstrated. By jointly detecting and demodulating multiple channels simultaneously, the penalties associated with the limitations of generating ideal spectra can be mitigated. Several joint DSP algorithms are developed for linear ICI cancellation and joint carrier-phase recovery. Performance analysis under different system configurations is conducted to demonstrate the feasibility and robustness of the proposed joint DSP algorithms, and improved system performance is observed with both experimental and simulation data.

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Dissertations / Theses on the topic 'Optical telecommunication networks'

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