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Dissertations / Theses on the topic 'Optical communication network'
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Liu, Guanglei. "Management and Control of Scalable and Resilient Next-Generation Optical Networks." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/14610.
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Two research topics in next-generation optical networks with wavelength-division multiplexing (WDM) technologies were investigated: (1) scalability of network management and control, and (2) resilience/reliability of networks upon faults and attacks.
In scalable network management, the scalability of management information for inter-domain light-path assessment was studied. The light-path assessment was formulated as a decision problem based on decision theory and probabilistic graphical models. It was found that partial information available can provide the desired performance, i.e., a small percentage of erroneous decisions can be traded off to achieve a large saving in the amount of management information.
In network resilience under malicious attacks, the resilience of all-optical networks under in-band crosstalk attacks was investigated with probabilistic graphical models. Graphical models provide an explicit view of the spatial dependencies in attack propagation, as well as computationally efficient approaches, e.g., sum-product algorithm, for studying network resilience. With the proposed cross-layer model of attack propagation, key factors that affect the resilience of the network from the physical layer and the network layer were identified. In addition, analytical results on network resilience were obtained for typical topologies including ring, star, and mesh-torus networks.
In network performance upon failures, traffic-based network reliability was systematically studied. First a uniform deterministic traffic at the network layer was adopted to analyze the impacts of network topology, failure dependency, and failure protection on network reliability. Then a random network layer traffic model with Poisson arrivals was applied to further investigate the effect of network layer traffic distributions on network reliability. Finally, asymptotic results of network reliability metrics with respect to arrival rate were obtained for typical network topologies under heavy load regime.
The main contributions of the thesis include: (1) fundamental understandings of scalable management and resilience of next-generation optical networks with WDM technologies; and (2) the innovative application of probabilistic graphical models, an emerging approach in machine learning, to the research of communication networks.
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Angeh, Wolfgang Ondua. "Design and performance analysis of a survivable metropolitan area fiber optic communication network." Master's thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-02022010-020030/.
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Wong, Albert Kai-Sun. "Channel scheduling for optical communication network with frequency concurrency." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14536.
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Wang, Evan Y. (Ye-Wen). "Traffic control in a multichannel optical fiber communication network." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14716.
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Lim, Kok Seng. "Analysis of network management protocols in optical networks." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Mar%5FLim%5FK.pdf.
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Al-Ani, Layth. "Integrating IP Protocol Into Optical Networks by Using Software-defined Network (SDN)." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33010.
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The Internet, with cloud computing, offers amazing services that require a fast, intelligent, reliable network connection. Current networks, electrical or optical, need to work together to provide the user with a high-quality connection. The IP protocol as Layer 3 and an optical network as Layer 2 need to talk to each other and help each other instead of working separately. Therefore, this thesis proposes using software-defined network (SDN) technology for integrating the IP protocol into an optical network to fill the gap between the two layers and to give the network more intelligence and flexibility for new connection requests, choosing the best route, and monitoring the network. A two-layer SDN centralized controller design has been used. The Layer 1 SDN controller is the centralized controller that connects and updates all Layer 2 SDN controllers which control traffic in each domain. New connection requests are processed in the SDN controller and the traffic is forwarded by the optical network. SDN technology and the integration of IP into the optical network promise to enhance network connectivity.
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Ansari, Ashlaghi Aria. "100 GBPS Orthogonal Frequency Division Multiplexing optical fiber communication network." Thesis, California State University, Long Beach, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1604879.
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<p> Optical fiber communication has emerged as a high potential substitute for communication methods such as twisted pair and coaxial wire. The main advantage of optical fiber over previous methods is to have higher capacity of data rate transmission. The conventional types of modulation and demodulation technique, which have been used through optical fiber communication system are Wavelength Division Multiplexing (WDM) technique and Dense Wavelength Division Multiplexing (DWDM) technique so far. </p><p> In this thesis, the Orthogonal Frequency Division Multiplexing (OFDM) is applied through the modulation and demodulation parts due to some advantages over WDM and DWDM to reach to 100 Gbps data transmission. The main advantage of OFDM-optical fiber is that it only needs one optical source to modulate and one optical source to demodulate the signals at transmitter side and receiver side, which results in a reduction of the cost of the system. Also, by using the OFDM, the chromatic dispersion can be eliminated or decreased. </p>
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Abu, Almaalie Zina. "Free space optical wireless communication with physical layer network coding." Thesis, Northumbria University, 2016. http://nrl.northumbria.ac.uk/32546/.
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Terrestrial free-space optical (FSO) communications is an emerging low-cost, licensefree and high-bandwidth access solution for a number of applications including the “last mile” access network. However, for a transmission range from a few meter to longer than 1 km, a number of atmospheric phenomena, such as rain, haze, fog, snow, scintillation and pointing errors become a major performance limiting factors in FSO systems resulting in link deterioration and ultimately complete link failure. Relay-assisted technique is capable of mitigating the signal fading and maintain acceptable performance levels. In this thesis, a two-way relay (TWR) channel technique is adopted to increase system spectral efficiency, which in turn boosts the network throughput. This is achieved by using a physical layer network coding (PNC) technique, where network coding (NC) is applied at the physical layer. It takes advantage of the superimposition of the electromagnetic waves, and embraces the interference, which was typically deemed as harmful, by performing the exclusive-OR mapping of both users’ information at the relay. Therefore, the main contribution of this thesis is to study the design of the TWR-FSO communication system that embraces PNC technique for the full utilization of network resources based on the binary phase shift keying (BPSK) modulation. Moreover, error control coding (ECC) in conjunction with interleaving can be employed in FSO communications to combat turbulence-induced fading, which can enhance the performance of the proposed TWR-FSO PNC system. A comparative study between convolutional code (CC) and bit-interleave coded modulation with iterative decoding (BICM-ID) code are carried out. The result shows that the BICM-ID code outperforms the CC for TWR-FSO based PNC over strong turbulence regime by ~10dB of SNR to achieve a BER of 10-4 . However, the number of users that can be simultaneously transmitted to the relay is considered the main constraint in PNC system. Therefore, to overcome this challenge, a new scheme that integrates the iterative multiuser detection (I-MUD) technique with the PNC system over RF and FSO links are introduced as another achievement. The results show that the I-MUD offers improved performance about 8, and 22dB of SNR to get a BER of 10-4 over RF and FSO channels, respectively, for number of simultaneously users equal to 14 with respect to TWR-PNC system.
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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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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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Quintana, Joel. "Hybrid optical network using incoherent optical code division multiple access via optical delay lines." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Radziwilowicz, Robert. "Future Extensions to Passive Optical Access Networks." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/22811.
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Rapid changes in population distribution across Canada and the introduction of new telecommunication services to the consumer market have resulted in a number of significant challenges for existing network infrastructure. Fast growing populations in metropolitan regions require high density access networks to meet the growing need for bandwidth that results. Furthermore, new services such as high definition TV, online gaming and real-time video teleconferencing are becoming increasingly popular among consumers. These services require higher bandwidth to be available to end users. Changes in the Canadian economy will soon lead to a transition in Canadian industry from manufacturing to services and exploration of natural resources. This will create opportunities for new industrial development and growth in northern regions. Expanding industrialization towards northern Canada will require deployment of reliable telecommunication infrastructure. The combination of open source software, Linux operating system and Personal Computer (PC) based hardware platform is proposed to become the foundation for low cost and flexible technology that will provide transition towards all-optical infrastructures. An innovative prototype of a low-cost optical gigabit Ethernet switch is presented and its benchmark results are discussed. Scalability of the switch and its future applications in optical networks are studied. A prototype of a software based data encapsulation system was designed and implemented in a PC based platform, and its performance was evaluated using real data that was captured in commercial LAN. Semiconductor optical amplifiers (SOA) are studied as a building block in next generation switching devices for all-optical access networks. A prototype of an SOA-based low-cost optical switching device with implemented FPGA based controlling mechanism is presented and its characteristics are discussed. SOA is also studied as an energy efficient optical amplifier that can be deployed in end user facilities. The presented results provide proof of concept of a low cost flexible platform that can be used to design and build network devices to facilitate the transition of existing telecommunication networks towards next generation optical access infrastructure.
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Chen, Zhe. "Interference mitigation techniques for optical attocell networks." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/22868.
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The amount of wireless data traffic has been increasing exponentially. This results in the shortage of radio frequency (RF) spectrum. In order to alleviate the looming spectrum crisis, visible light communication (VLC) has emerged as a supplement to RF techniques. VLC uses light emitting diodes (LEDs) for transmission and employs photodiodes (PDs) for detection. With the advancement of the LED technology, LEDs can now fulfil two functions at the same time: illumination and high-speed wireless communication. In a typical indoor scenario, each single light fixture can act as an access point (AP), and multiple light fixtures in a room can form a cellular wireless network. We refer to this type of networks as ‘optical attocell network’. This thesis focuses on interference mitigation in optical attocell networks. Firstly, the downlink inter-cell interference (ICI) model in optical attocell networks is investigated. The conventional ray-tracing channel model for non-line-of-sight (NLOS) path is studied. Although this model is accurate, it leads to time-consuming computer simulations. In order to reduce the computational complexity, a simplified channel model is proposed to accurately characterise NLOS ICI in optical attocell networks. Using the simplified model, the received signal-to-interference-plus-noise ratio (SINR) distribution in optical attocell networks can be derived in closed-form. This signifies that no Monte Carlo simulation is required to evaluate the user performance in optical attocell networks. Then, with the knowledge of simplified channel model, interference mitigation techniques using angle diversity receivers (ADRs) are investigated in optical attocell networks. An ADR typically consists of multiple PDs with different orientations. By using proper signal combining schemes, ICI in optical attocell networks can be significantly mitigated. Also, a novel double-source cell configuration is proposed. This configuration can further mitigate ICI in optical attocell networks in conjunction with ADRs. Moreover, an analytical framework is proposed to evaluate the user performance in optical attocell networks with ADRs. Finally, optical space division multiple access (SDMA) using angle diversity transmitters is proposed and investigated in optical attocell networks. Optical SDMA can exploit the available bandwidth resource in spatial dimension and mitigate ICI in optical attocell networks. Compared with optical time division multiple access (TDMA), optical SDMA can significantly improve the throughput of optical attocell networks. This improvement scales with the number of LED elements on each angle diversity transmitter. In addition, the upper bound and the lower bound of optical SDMA performance are derived analytically. These bounds can precisely evaluate the performance of optical SDMA systems. Furthermore, optical SDMA is shown to be robust against user position errors, and this makes optical SDMA suitable for practical implementations.
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Shi, Lishen. "Coherent optical code division multiple access (CDMA) network employing CW semiconductor lasers." Thesis, University of Strathclyde, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273787.
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Rajbhandari, Sujan. "Application of wavelets and artificial neural network for indoor optical wireless communication systems." Thesis, Northumbria University, 2010. http://nrl.northumbria.ac.uk/1933/.
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This study investigates the use of error control code, discrete wavelet transform (DWT) and artificial neural network (ANN) to improve the link performance of an indoor optical wireless communication in a physical channel. The key constraints that barricade the realization of unlimited bandwidth in optical wavelengths are the eye-safety issue, the ambient light interference and the multipath induced intersymbol interference (ISI). Eye-safety limits the maximum average transmitted optical power. The rational solution is to use power efficient modulation techniques. Further reduction in transmitted power can be achieved using error control coding. A mathematical analysis of retransmission scheme is investigated for variable length modulation techniques and verified using computer simulations. Though the retransmission scheme is simple to implement, the shortfall in terms of reduced throughput will limit higher code gain. Due to practical limitation, the block code cannot be applied to the variable length modulation techniques and hence the convolutional code is the only possible option. The upper bound for slot error probability of the convolutional coded dual header pulse interval modulation (DH-PIM) and digital pulse interval modulation (DPIM) schemes are calculated and verified using simulations. The power penalty due to fluorescent light interference (FL I) is very high in indoor optical channel making the optical link practically infeasible. A denoising method based on a DWT to remove the FLI from the received signal is devised. The received signal is first decomposed into different DWT levels; the FLI is then removed from the signal before reconstructing the signal. A significant reduction in the power penalty is observed using DWT. Comparative study of DWT based denoising scheme with that of the high pass filter (HPF) show that DWT not only can match the best performance obtain using a HPF, but also offers a reduced complexity and design simplicity. The high power penalty due to multipath induced ISI makes a diffuse optical link practically infeasible at higher data rates. An ANN based linear and DF architectures are investigated to compensation the ISI. Unlike the unequalized cases, the equalized schemes don‘t show infinite power penalty and a significant performance improvement is observed for all modulation schemes. The comparative studies substantiate that ANN based equalizers match the performance of the traditional equalizers for all channel conditions with a reduced training data sequence. The study of the combined effect of the FLI and ISI shows that DWT-ANN based receiver perform equally well in the present of both interference. Adaptive decoding of error control code can offer flexibility of selecting the best possible encoder in a given environment. A suboptimal 'soft' sliding block convolutional decoder based on the ANN and a 1/2 rate convolutional code with a constraint length is investigated. Results show that the ANN decoder can match the performance of optimal Viterbi decoder for hard decision decoding but with slightly inferior performance compared to soft decision decoding. This provides a foundation for further investigation of the ANN decoder for convolutional code with higher constraint length values. Finally, the proposed DWT-ANN receiver is practically realized in digital signal processing (DSP) board. The output from the DSP board is compared with the computer simulations and found that the difference is marginal. However, the difference in results doesn‘t affect the overall error probability and identical error probability is obtained for DSP output and computer simulations.
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Dey, Sanjoy Namuduri Kameswara. "Performance analysis of CCR based distributed sensor network based on optical wireless communication." A link to full text of this thesis in SOAR, 2008. http://hdl.handle.net/10057/2007.
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Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical and Computer Engineering.<br>Copyright 2008 by Sanjoy Dey. All Rights Reserved. Includes bibliographical references (leaves 16-18).
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Manukulasuriya, Varuna. "Architecture and protocol for an infrared semi-permanent local network." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309515.
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Schrenk, Bernhard. "Characterization and design of multifunction photonic devices for next-generation fiber-to-the-home optical network units." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/22676.
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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.<br>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.
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Tsutsumi, Takuya. "Field Measurement and Analysis of Next-Generation Optical Access Network with Optical Amplifiers." Kyoto University, 2018. http://hdl.handle.net/2433/232417.
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Yin, Liang. "Design and performance analysis of optical attocell networks." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31390.
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The exponentially increasing demand for high-speed wireless communications will no longer be satisfied by the traditional radio frequency (RF) in the near future due to its limited spectrum and overutilization. To resolve this imminent issue, industrial and research communities have been looking into alternative technologies for communication. Among them, visible light communication (VLC) has attracted much attention because it utilizes the unlicensed, free and safe spectrum, whose bandwidth is thousand times larger than the entire RF spectrum. Moreover, VLC can be integrated into existing lighting systems to offer a dual-purpose, cost-effective and energy-efficient solution for next-generation small-cell networks (SCNs), giving birth to the concept of optical attocell networks. Most relevant works in the literature rely on system simulations to quantify the performance of attocell networks, which suffer from high computational complexity and provide limited insights about the network. Mathematical tools, on the other hand, are more tractable and scalable and are shown to closely approximate practical systems. The presented work utilizes stochastic geometry for downlink evaluation of optical attocell networks, where the co-channel interference (CCI) surpasses noise and becomes the limiting factor of the link throughput. By studying the moment generating function (MGF) of the aggregate interference, a theoretical framework for modeling the distribution of signal-to-interference-plus-noise ratio (SINR) is presented, which allows important performance metrics such as the coverage probability and link throughput to be derived. Depending on the source of interference, CCI can be classified into two categories: inter-cell interference (ICI) and intra-cell interference. In this work, both types of interference are characterized, based on which effective interference mitigation techniques such as the coordinated multipoint (CoMP), power-domain multiplexing and successive interference cancellation (SIC) are devised. The proposed mathematical framework is applicable to attocell networks with and without such interference mitigation techniques. Compared to RF networks, optical attocell networks are inherently more secure in the physical layer because visible light does not penetrate through opaque walls. This work analytically quantifies the physical-layer security of attocell networks from an information-theoretic point of view. Secrecy enhancement techniques such as AP cooperation and eavesdropper-free protected zones are also discussed. It is shown that compared to AP cooperation, implementing secrecy protected zones is more effective and it can contribute significantly to the network security.
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Brown, Trevor Junior. "Time division multiple access/code division multiple access for the optical local access network." Thesis, Manchester Metropolitan University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243716.
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Lee, Peng Joo. "Alternative high speed network access for the last mile /." Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02Dec%5FLee%5FPeng.pdf.
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Mahloo, Mozhgan. "Reliability versus Cost in Next Generation Optical Access Networks." Licentiate thesis, KTH, Optical Network Laboratory (ON Lab), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122380.
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The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place. Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements. Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism. First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential capacity, low cost and power consumption. So we continued our studies by investigating two WDM-based PON architectures regarding their cost and reliability performance. The study has also included a proposed fiber layout compatible with these two candidates aiming to minimize the required investment needed to offer protection. Our primary results confirmed that hybrid PON (HPON) is the best alternative for the NGOA networks. Therefore we further analyzed this candidate considering several variants of HPON. The most important components and sections of the HPON, which need to be protected to decrease the impact of each failure in the network have been identified. Based on these outcomes, two resilience architectures protecting the shared part of the HPON were proposed and their reliability performance parameters as well as cost of protection were evaluated. According to the results, using our proposed protection schemes a considerable improvement in reliability performance of the HPON variants can be provided at minor extra investment. We also introduced a cost efficient HPON architecture with different levels of protection for users with various reliability requirements, i.e. the protection of shared parts of the access network for all the connected users and end-to-end resilience scheme for some selected ones (e.g., business users). To gain an overall view on the cost efficiency of the proposed architecture, we evaluated the investment required for deploying these schemes considering several network upgrading paths towards a protected network. Moreover, a sensitivity analysis investigating the influence of network deployments time and the density of the users with higher availability requirements was presented. In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per-user, large coverage and client count. The work carried out in the thesis has proved that HPON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Moreover, low power consumption and high flexibility in resource allocation of this architecture, makes it a winning candidate for the NGOA networks. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market.<br><p>QC 20130530</p><br>FP7 EU project, Optical Access Seamless Evolution(OASE)
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Abdollahi, Seyedreza. "Fully-photonic digital radio over fibre for future super-broadband access network applications." Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/10121.
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In this thesis a Fully-Photonic DRoF (FP-DRoF) system is proposed for deploying of future super-broadband access networks. Digital Radio over Fibre (DRoF) is more independent of the fibre network impairments and the length of fibre than the ARoF link. In order for fully optical deployment of the signal conversion techniques in the FP-DRoF architecture, two key components an Analogue-to-Digital Converter (ADC) and a Digital-to-Analogue Converter (DAC)) for data conversion are designed and their performance are investigated whereas the physical functionality is evaluated. The system simulation results of the proposed pipelined Photonic ADC (PADC) show that the PADC has 10 GHz bandwidth around 60 GHz of sampling rate. Furthermore, by changing the bandwidth of the optical bandpass filter, switching to another band of sampling frequency provides optimised performance condition of the PADC. The PADC has low changes on the Effective Number of Bit (ENOB) response versus analogue RF input from 1 GHz up to 22 GHz for 60 GHz sampling frequency. The proposed 8-Bit pipelined PADC performance in terms of ENOB is evaluated at 60 Gigasample/s which is about 4.1. Recently, different methods have been reported by researchers to implement Photonic DACs (PDACs), but their aim was to convert digital electrical signals to the corresponding analogue signal by assisting the optical techniques. In this thesis, a Binary Weighted PDAC (BW-PDAC) is proposed. In this BW-PDAC, optical digital signals are fully optically converted to an analogue signal. The spurious free dynamic range at the output of the PDAC in a back-to-back deployment of the PADC and the PDAC was 26.6 dBc. For further improvement in the system performance, a 3R (Retiming, Reshaping and Reamplifying) regeneration system is proposed in this thesis. Simulation results show that for an ultrashort RZ pulse with a 5% duty cycle at 65 Gbit/s using the proposed 3R regeneration system on a link reduces rms timing jitter by 90% while the regenerated pulse eye opening height is improved by 65%. Finally, in this thesis the proposed FP-DRoF functionality is evaluated whereas its performance is investigated through a dedicated and shared fibre links. The simulation results show (in the case of low level signal to noise ratio, in comparison with ARoF through a dedicated fibre link) that the FP-DRoF has better BER performance than the ARoF in the order of 10-20. Furthermore, in order to realize a BER about 10-25 for the ARoF, the power penalty is about 4 dBm higher than the FP-DRoF link. The simulation results demonstrate that by considering 0.2 dB/km attenuation of a standard single mode fibre, the dedicated fibre length for the FP-DRoF link can be increased to about 20 km more than the ARoF link. Moreover, for performance assessment of the proposed FP-DRoF in a shared fibre link, the BER of the FP-DRoF link is about 10-10 magnitude less than the ARoF link for -19 dBm launched power into the fibre and the power penalty of the ARoF system is 10 dBm more than the FP-DRoF link. It is significant to increase the fibre link’s length of the FP-DRoF access network using common infrastructure. In addition, the simulation results are demonstrated that the FP-DRoF with non-uniform Wavelength Division Multiplexing (WDM) is more robust against four wave mixing impairment than the conventional WDM technique with uniform wavelength allocation and has better performance in terms of BER. It is clearly verified that the lunched power penalty at CS for DRoF link with uniform WDM techniques is about 2 dB higher than non-uniform WDM technique. Furthermore, uniform WDM method requires more bandwidth than non-uniform scheme which depends on the total number of channels and channels spacing.
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Shahpari, Ali. "Next generation optical access networks : technologies and economics." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14857.
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Doutoramento em Engenharia Eletrotécnica - Telecomunicações<br>The work presented herein, studies Next Generation Optical Access Networks (NG-OAN) economically (e.g. energy consumption) and technologically (e.g. rate, reach and dedicated/shared bandwidth). The work is divided into four main topics: energy efficiency in optical access architectures, novel spectrally efficient Long-Reach Passive Optical Networks (LR-PON), crosstalk impacts in heterogeneous and homogenous access networks and hybrid optical wireless transmissions.
We investigate the impact of user profiles, optical distribution network topologies and equipment characteristics on resource sharing and power consumption in LR-PON. To have a clear vision on the energy consumption evolution of each part of NG-OAN, a model is proposed to evaluate the energy efficiency of optical access technologies.
A spectrally efficient bidirectional Ultra-Dense Wavelength Division Multiplexing (UDWDM) PON architecture is developed using Nyquist shaped 16-ary quadrature amplitude modulation, offering up to 10 Gb/s service capabilities per user or wavelength. Performance of this system in terms of receiver sensitivity and nonlinear tolerance under different network transmission capacity conditions are experimentally optimized. In bi-directional transmis-sion, using frequency up/down-shifting of Nyquist pulse shaped signal from optical carrier, a full bandwidth allocation and easy maintenance of UDWDM networks as well as reduction of Rayleigh back-scattering are achieved. Moreover, self-homodyne detection is used to relax the laser linewidth requirement and digital signal processing complexity at the optical network unit.
Simplified numerical model to estimate the impact of Raman crosstalk of multi-system next generation PONs in video overlay is proposed. Coexistence of considered G.98X ITU-T series and coherent multi-wavelength systems is considered and assessed.
Additionally, the performances of bidirectional hybrid optical wireless coherent PONs over different optical distribution network power budgets and hybrid splitting ratios are evaluated.<br>O trabalho aqui apresentado estuda redes óticas de acesso de próxima geração (NG-OAN) nas vertentes económica (consumo de energia) e tecnológica (taxa, alcance e largura de banda dedicada/partilhada). O trabalho está dividido em quatro grandes temas de investigação: a eficiência energética em arquiteturas de acesso ótico, as redes óticas passivas de longo alcance (LR-PON) com nova eficiência espetral, o impacto da diafonia em redes de acesso heterogéneas e homogéneas e as transmissões ópticas híbridas com tecnologias sem fio.
Investiga-se o impacto dos perfis dos utilizadores, as tipologias da rede de distribuição ótica, as características do equipamento de partilha de recursos e o consumo de energia em LR-PON. Para se ter uma visão clara sobre o consumo de energia de cada parte das NG-OAN, é proposto um modelo para avaliar a eficiência energética das tecnologias de acesso óticas.
Desenvolve-se uma arquitetura PON bi-direcional com elevada eficiência espetral, recorrendo a multiplexagem por divisão de comprimento de onda ultra-densa (UDWDM), modulação de amplitude em quadratura com formato de impulso de Nyquist, oferecendo até 10 Gb/s por utilizador/comprimento de onda. O desempenho deste sistema em termos de sensibilidade do recetor e da tolerância à resposta não linear do canal de comunicação, sob diferentes condições de transmissão, é avaliado experimentalm-ente. Em transmissão bi-direcional, utilizando desvio de frequência (cima/baixo) do impulso com formato de Nyquist relativo à portadora ótica conseguiu-se uma alocação de largura de banda completa e uma manutenção mais simplificada de redes UDWDM, bem como a redução do espalhamento de Rayleigh. Além disso, a deteção auto-homodina é usada para relaxar o requisito de largura de linha do laser e a complexidade do processamento digital de sinal nas unidades da rede ótica.
Propõe-se um modelo numérico simplificado para estimar o impacto da diafonia de Raman em sistemas PON de próxima geração, com sobreposição do sinal de vídeo. É analisada a coexistência da série G.98X ITU-T e são considerados e avaliados sistemas coerentes multi-comprimento de onda.
Adicionalmente avaliam-se os desempenhos de PONs bi-direcionais híbridas, considerando tecnologia coerente e propagação por espaço livre, para diferentes balanços de potência e taxas de repartição na rede ótica de distribuição.
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Boiyo, Duncan Kiboi, and Romeo Gamatham. "Optimization of flexible spectrum in optical transport networks." Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/14609.
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The ever-increasing demand for broadband services by end-user devices utilising 3G/4G/LTE and the projected 5G in the last mile will require sustaining broadband supply from fibre-linked terminals. The eventual outcome of the high demand for broadband is strained optical and electronic devices. The backbone optical fibre transport systems and techniques such as dense wavelength division multiplexing (DWDM), higher modulation formats, coherent detection and signal amplification have increased both fibre capacity and spectrum efficiency. A major challenge to fibre capacity and spectrum efficiency is fibre-faults and optical impairments, network management, routing and wavelength assignment (RWA). In this study, DWDM and flexible spectrum techniques such as wavelength assignment and adjustment, wavelength conversion and switching, optical add and drop multiplexing (OADM) and bitrate variable transmission have been experimentally optimized in a laboratory testbed for short- and long-haul optical fibre networks. This work starts by experimentally optimising different transmitters, fibre-types and receivers suitable for implementing cost effective and energy efficient flexible spectrum networks. Vertical cavity surface-emitting lasers (VCSELs) and distributed feedback (DFB) lasers have been studied to provide up to 10 Gb/s per channel in 1310 nm and 1550 nm transmission windows. VCSELs provide wavelength assignment and adjustment. This work utilises the non-return-to-zero (NRZ) on-off keying (OOK) modulation technique and direct detection due to their cost and simplicity. By using positive intrinsic negative (PIN) photo-receivers with error-free BER sensitivity of -18±1 dBm at the acceptable 10-9-bit error rate (BER) threshold level, unamplified transmission distances between 6 km and 76 km have been demonstrated using G.652 and G.655 single mode fibres (SMFs). For the first time, an all optical VCSEL to VCSEL wavelength conversion, switching, transmission at the 1550 nm window and BER evaluation of a NRZ data signal is experimentally demonstrated. With VCSEL wavelength conversion and switching, wavelength adjustments to a spectrum width of 4.8 nm (600 GHz) can be achieved to provide alternative routes to signals when fibre-cuts and wavelength collision occurs therefore enhancing signal continuity. This work also demonstrates a technique of removing and adding a wavelength in a bundle of DWDM and flexible channels using an OADM. This has been implemented using a VCSEL and a fibre Bragg grating (FBG) providing a wavelength isolation ratio of 31.4 dB and ~0.3 𝑑𝐵 add/drop penalty of 8.5 Gb/s signal. As a result, an OADM improves spectrum efficiency by offering wavelength re-use. Optical impairments such as crosstalk, chromatic dispersion (CD) and effects of polarization mode dispersion (PMD) have been experimentally investigated and mitigated. This work showed that crosstalk penalty increased with fibre-length, bitrate, interfering signal power and reduced channel spacing and as a result, a crosstalk-penalty trade-off is required. Effects of CD on a transmitted 10 Gb/s signal were also investigated and its mitigation techniques used to increase the fibre-reach. This work uses the negative dispersion fibres to mitigate the accumulated dispersion over the distance of transmission. A 5 dB sensitivity improvement is reported for an unamplified 76 km using DFB transmitters and combination of NZDSF true-wave reduced slope (TW-RS) and submarine reduced slope (TW-SRS) with + and – dispersion coefficients respectively. We have also demonstrated up to 52 km 10 Gb/s per channel VCSEL-based transmission and reduced net dispersion. Experimental demonstration of forward Raman amplification has achieved a 4.7 dB on-off gain distributed over a 4.8 nm spectral width and a 1.7 dB improvement of receiver sensitivity in Raman-aided 10 Gb/s per wavelength VCSEL transmission. Finally, 4.25-10 Gb/s PON-based point to point (P2P) and point to multipoint (P2MP) broadcast transmission have been experimentally demonstrated. A 10 Gb/s with a 1:8 passive splitter incurred a 3.7 dB penalty for a 24.7 km fibre-link. In summary, this work has demonstrated cost effective and energy efficient potential flexible spectrum techniques for high speed signal transmission. With the optimized network parameters, flexible spectrum is therefore relevant in short-reach, metro-access and long-haul applications for national broadband networks and the Square Kilometre Array (SKA) fibre-based signal and data transmission.
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Vikrant, Nikam. "Design and Performance Evaluation of Resource Allocation Mechanisms in Optical Data Center Networks." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-198163.
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A datacenter hosts hundreds of thousands of servers and a huge amount of bandwidth is required to accommodate communication between thousands of servers. Several packet switched based datacenter architectures are proposed to cater the high bandwidth requirement using multilayer network topologies, however at the cost of increased network complexity and high power consumption. In recent years, the focus has shifted from packet switching to optical circuit switching to build the data center networks as it can support on demand connectivity and high bit rates with low power consumption. On the other hand, with the advent of Software Defined Networking (SDN) and Network Function Virtualization (NFV), the role of datacenters has become more crucial. It has increased the need of dynamicity and flexibility within a datacenter adding more complexity to datacenter networking. With NFV, service chaining can be achieved in a datacenter where virtualized network functions (VNFs) running on commodity servers in a datacenter are instantiated/terminated dynamically. A datacenter also needs to cater large capacity requirement as service chaining involves steering of large aggregated flows. Use of optical circuit switching in data center networks is quite promising to meet such dynamic and high capacity traffic requirements. In this thesis work, a novel and modular optical data center network (DCN) architecture that uses multi-directional wavelength switches (MD-WSS) is introduced. VNF service chaining use case is considered for evaluation of this DCN and the end-to-end service chaining problem is formulated as three inter-connected sub-problems: multiplexing of VNF service chains, VNFs placement in the datacenter and routing and wavelength assignment. This thesis presents integer linear programming (ILP) formulation and heuristics for solving these problems, and numerically evaluate them.<br>Ett datacenter inrymmer hundratusentals servrar och en stor mängd bandbredd krävs för att skicka data mellan tusentals servrar. Flera datacenter baserade på paketförmedlande arkitekturer föreslås för att tillgodose kravet på hög bandbredd med hjälp av flerskiktsnätverkstopologier, men på bekostnad av ökad komplexitet i nätverken och hög energiförbrukning. Under de senaste åren har fokus skiftat från paketförmedling till optisk kretsomkoppling for att bygga datacenternätverk som kan stödja på-begäran-anslutningar och höga bithastigheter med låg strömförbrukning. Å andra sidan, med tillkomsten av Software Defined Networking (SDN) och nätverksfunktionen Virtualisering (NFV), har betydelsen av datacenter blivit mer avgörande. Det har ökat behovet av dynamik och flexibilitet inom ett datacenter, vilket leder till storre komplexitet i datacenternätverken. Med NFV kan tjänstekedjor åstadkommas i ett datacenter, där virtualiserade nätverksfunktioner (VNFs) som körs på servrar i ett datacenter kan instansieras och avslutas dynamiskt. Ett datacenter måste också tillgodose kravet på stor kapacitet eftersom tjänstekedjan innebär styrning av stora aggregerade flöden. Användningen av optisk kretsomkoppling i datacenternätverk ser ganska lovande ut for att uppfylla sådana trafikkrav dynamik och hög kapacitet. I detta examensarbete, har en ny och modulär optisk datacenternätverksarkitektur (DCN) som använder flerriktningvåglängdsswitchar (MD-WSS) införs. Ett användningsfall av VNF-tjänstekedjor noga övervägd för utvärdering av denna DCN och end-to-end-servicekedjans problem formuleras som tre sammankopplade delproblem: multiplexering av VNF-servicekedjor, VNF placering i datacentret och routing och våglängd uppdrag. Denna avhandling presenterar heltalsprogrammering (ILP) formulering och heuristik för att lösa dessa problem och numeriskt utvärdera dem.
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Abbood, Abdul Nasser Abdul Jabbar. "Optimised radio over fibre links for next generation radio access networks." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17019.
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Optical fibre has become the dominant theme of transmission in long haul, high data rate communication systems due to its tremendous bandwidth and low loss. Radio over Fibre (RoF) technology facilitates the seamless integration between wireless and optical communication systems and found to be the most promising solution to meet the exponential bandwidth demands expected for the upcoming years. However, the main bit-rate/distance limitation in RoF systems is the chromatic dispersion. In this thesis, the two generations of RoF technologies, namely Analogue RoF (ARoF) and Digital RoF (DRoF) are investigated. The overall aim of this research is to optimise the optical bandwidth utilisation of these two approaches for a typical transmission of the fronthaul link proposed in the next generation Centralised Radio Access Network (C-RAN). Consequently, a number of physical layer design scenarios for the optimised transmission of the Radio Frequency (RF) signals over a Standards Single Mode Fibre (SSMF) are demonstrated. Firstly, for an ARoF transmission, where the analogue RF signals are transported over SSMF using an optical carrier, a bidirectional link transmitting four Downlink/Uplink channels in a chromatic dispersion limited scenario is designed. Simulation results have shown a clear constellation diagram of a 2.5 Gb/s RF signal transmission over 120 km fibre length. Secondly, a DRoF system with reduced optical bandwidth occupancy is proposed. This system employs an optical Duobinary transmission to the digitised RF signal at the transmitter side to reduce its spectrum and to address the chromatic dispersion effect, simultaneously. Simulation results demonstrate the capability of the proposed system to maintain high-quality transmission of the digitised signals over 70 km of fibre distance without dispersion compensation requirements. Finally, an advanced DRoF transmission link based on integrating digital Optical Single Sideband (OSSB) transmission with Duobinary encoding scheme is designed. Simulation results have clearly verified system's robustness against transmission impairments and have better performances in terms of the obtained BER and EVM with respect to the 3GPP standardised values. Moreover, the results show that both transmission distance and power budget are furtherly improved in comparison with two other digital transmission scenarios.
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Sousa, Ana Oliveira de Pratas e. "Técnicas de monitorização em redes ópticas de próxima geração." Doctoral thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12476.
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Doutoramento em Engenharia Física<br>In this work several techniques to monitor the performance of optical networks were developed. These techniques are dedicated either to the measurement of the data signal parameters (optical signal to noise ratio and dispersion) or to the detection of physical failures on the network infrastructure.
The optical signal to noise ratio of the transmitted signal was successfully monitored using methods based on the presence of Bragg gratings imprinted on high birefringent fibres that allowed the distinction of the signal from the noise due to its polarization properties.
The monitoring of the signal group-velocity dispersion was also possible. In this case, a method based on the analysis of the electric spectrum of the signal was applied. It was experimentally demonstrated that this technique is applicable on both amplitude and phase modulated signals.
It was also developed a technique to monitor the physical infrastructure of an optical access network. Once again, the application of Bragg gratings (this time imprinted on standard single mode fibres) was the basis of the developed method.<br>Neste trabalho foram desenvolvidas diversas técnicas que permitem a monitorização de desempenho das redes de comunicações ópticas. Estas técnicas dedicam-se quer à determinação de parâmetros do próprio sinal de dados (como a relação sinal ruído óptico e a dispersão), quer à detecção de eventuais falhas físicas na infra-estrutura da rede.
Relativamente à monitorização da relação sinal-ruído óptico foram desenvolvidos métodos baseados na aplicação de redes de Bragg gravadas em fibras birrefringentes que permitiram distinguir o sinal do ruído através das suas propriedades de polarização.
A monitorização da dispersão cromática sofrida pelo sinal durante a sua propagação também foi possível. Neste caso foi testada uma técnica baseada na análise do espectro eléctrico do sinal. Demonstrou-se que esta técnica pode ser aplicada quer em sinais modulados na amplitude quer em sinais modulados na fase.
Foi também desenvolvida uma técnica para a monitorização da infra-estrutura física de uma rede de acesso. Mais uma vez, aqui foi utilizado um método baseado na presença de redes de Bragg, desta vez gravadas em fibras monomodo que são utilizadas como pontos de monitorização em locais estratégicos da rede.
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Hsueh, Yu-Ting. "Frontiers of optical networking technologies: millimeter-wave radio-over-fiber and 100g transport system for next-generation high-data-rate applications." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43681.
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The enabling technologies and the issues of next-generation millimeter-wave wireless access network and 100G long-haul optical transport network were developed and identified. To develop a simple and cost-effective millimeter-wave optical-wireless system, all-round research on the technical challenges of optical millimeter-wave generation, transmission impairments compensation, and simple base station design were discussed. Several radio-over-fiber systems were designed to simultaneously deliver multi-band wireless services on a single optical infrastructure, enabling converged system control and quality maintenance in central office. For the 100G optical transport network, the issues related to successful implementations of transmitter, fiber link, and receiver of a 112-Gb/s polarization-division multiplexing-quadrature phase shift keying (PDM-QPSK) system were comprehensively explored. The experimental results based on the constructed 112-Gb/s testbed indicated that careful dispersion management can effectively increase nonlinearity tolerance. Furthermore, the special emphasis on the two impairments of the 100G network with reconfigurable optical add-drop multiplexers: passband narrowing and in-band crosstalk, was studied. The results demonstrated that these impairments can be readily predicted with proper experimental and simulation efforts.
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Mysore, Sudhesh M. "Advances in optical power budgets and bandwidth capacity of broadband networks /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9953885.
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West, Lamar. "Analysis and simulation of reverse path laser clipping in subcarrier multiplexed hybrid fiber coax networks." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/13301.
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Wu, Haitao. "Conception et analyse d’algorithmes d’approximation dans les réseaux de communication de nouvelle génération." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0231/document.
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Avec l’avènement de l’ère intellectuelle et de l’Internet of Everything (IoE), les besoins de la communication mondiale et des applications diverses ont explosé. Cette révolution exige que les futurs réseaux de communication soient plus efficaces, intellectuels, agiles et évolutifs. De nombreuses technologies réseau sont apparues pour répondre à la tendance des réseaux de communication de nouvelle génération tels que les réseaux optiques élastiques (EONs) et la virtualisation de réseau. De nombreux défis apparaissent avec les apparences de la nouvelle architecture et de la nouvelle technologie, telles que le routage et l’allocation de ressource spectrale (RSA) dans les EONs et l’intégration de réseaux virtuels (Virtual Network Embedding ou VNE) dans la virtualisation de réseau.Cette thèse traite la conception et l’analyse d’algorithmes d’approximation dans trois problèmes d’optimation du RSA et du VNE : les impacts de la distribution du trafic et de la topologie du réseau sur le routage tout optique, de l’allocation de ressource spectrale, et du VNE dans les topologies des chemins et cycles. Pour le routage tout optique, le premier sous-problème du RSA, il y a toujours un problème en suspens concernant l’impact de la distribution du trafic et de la topologie EON. Comme le routage tout optique joue un rôle essentiel pour la performance globale de la RSA, cette thèse fournit une analyse approfondi théorique sur ces impacts. Pour le deuxième sous-problème du RSA, l’allocation de ressource spectrale, deux chemins optiques quelconques partageant des fibres optiques communes pourraient devoir être isolés dans le domaine spectral avec une bande de garde appropriée pour empêcher la diaphonie et / ou réduire les menaces de sécurité de la couche physique. Cette thèse considère le scénario dans lequel les exigences de bandes de garde réelles optiques sont différentes pour différentes paires de chemins, et étudie comment affecter les ressources spectrales efficacement dans une telle situation. L’hétérogénéité de la topologie des demandes de réseau virtuel (VNR) est un facteur important qui entrave les performances de la VNE. Cependant, dans de nombreuses applications spécialisées, les VNR ont des caractéristiques structurelles communes par exemple, des chemins et des cycles. Pour obtenir de meilleurs résultats, il est donc essentiel de concevoir des algorithmes dédiés pour ces applications en tenant compte des caractéristiques topologiques. Dans cette thèse, nous prouvons que les problèmes VNE dans les topologies de chemin et de cycle sont NP-difficiles. Afin de les résoudre, nous proposons des algorithmes efficaces également analysons leurs ratios d’approximation<br>With the coming of intellectual era and Internet of Everything (IoE), the needs of worldwide communication and diverse applications have been explosively growing. This information revolution requires the future communication networks to be more efficient, intellectual, agile and scalable. Many technologies have emerged to meet the requirements of next generation communication networks such as Elastic Optical Networks (EONs) and networking virtualization. However, there are many challenges coming along with them, such as Routing and Spectrum Assignment (RSA) in EONs and Virtual Network Embedding (VNE) in network virtualization. This dissertation addresses the algorithm design and analysis for these challenging problems: the impacts of traffic distribution and network topology on lightpath routing, the distance spectrum assignment and the VNE problem for paths and cycles.For lightpath routing, the first subproblem of the RSA, there is always a pending issue that how the changes of the traffic distribution and EON topology affect it. As the lightpath routing plays a critical role in the overall performance of the RSA, this dissertation provides a thoroughly theoretical analysis on the impacts of the aforementioned two key factors. To this end, we propose two theoretical chains, and derive the optimal routing scheme taking into account two key factors. We then treat the second subproblem of RSA, namely spectrum assignment. Any two lightpaths sharing common fiber links might have to be isolated in the spectrum domain with a proper guard-band to prevent crosstalk and/or reduce physical-layer security threats. We consider the scenario with diverse guard-band sizes, and investigate how to assign the spectrum resources efficiently in such a situation. We provide the upper and lower bounds for the optimal solution of the DSA, and further devise an efficient algorithm which can guarantee approximation ratios in some graph classes.The topology heterogeneity of Virtual Network Requests (VNRs) is one important factor hampering the performance of the VNE. However, in many specialized applications, the VNRs are of some common structural features e.g., paths and cycles. To achieve better outcomes, it is thus critical to design dedicated algorithms for these applications by accounting for topology characteristics. We prove the NP-Harness of path and cycle embeddings. To solve them, we propose some efficient algorithms and analyze their approximation ratios
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Del, Portillo Barrios Iñigo. "Optimal locations for the ground segment of optical space communications networks." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/105609.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2016.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 123-126).<br>Optical communications are envisioned as a key technology for space communication in the near future. This transition to optical terminals is being pushed by the higher data volume demand of certain missions and by the spectrum encroachment in current RF bands. In addition, optical systems present multiple advantages with respect to RF terminals, such as their lower mass, size, and power, as well as the higher data-rate. However, one of the main issues of using optical systems is the space-to-ground link, as it is impossible for the laser beam to penetrate atmospheric clouds. Geographic diversity of ground stations has been proposed as an alternative to mitigate these effects. This thesis uses the systems architecture approach to analyze different architectures for the ground segment of an optical space communications network to serve low Earth orbit (LEO) missions. In particular, we analyze the tradespace characterized by three decisions: 1) number and location of optical ground stations, 2) use of geostationary relay satellites vs. the direct-to-Earth approach and 3) presence of crosslinks among relay satellites. Previous analyses studied the problem of mitigating cloud outage through site diversity both from a simulation perspective (working with point designs or a reduced tradespace composed of a fixed set of candidate locations), and from an analytical standpoint after assuming various simplifying hypotheses (independence of ground stations, uniform cloud conditions across the globe). This thesis expands those assumptions, presents a tool to analyze scenarios where no constraints are placed in the location and proposes a new cloud model to obtain first order approximations for the network availability. In order to analyze the availability of a network of optical ground stations, we use historical weather data from the National Oceanic and Atmospheric Administration (NOAA) and the cloud fraction dataset from Aqua's and Terra's MODIS instruments to characterize weather conditions across the globe. Next, we present the Optical Network Ground Segment Analyzer (ONGSA), a network simulator that incorporates the cloud models to simulate operations of the optical network. Finally we employ ONGSA to explore the aforementioned tradespace and analyze both cost and performance (in terms of availability) for each architecture. Results show that a maximum availability of 95.5 % can be achieved using an architecture similar to the actual system (the Tracking and Data Relay Satellite System) and 12 additional optical ground stations. Furthermore, an unconstrained optimization analysis identified the north of Mexico, southwest of Saudi Arabia, Morocco and central Australia as areas with high potential to construct new ground stations. Building new ground stations was identified to be a more cost-effective solution when the required level of availability is high, while using existing infrastructure is a better solution for systems when the required optical availability is low. Our analysis shows that inter-satellite links (ISL) are a cost-effective solution that adds an extra mitigation layer to combat the effects of cloud coverage. In particular, having ISL results in an increase in availability from 80% with six ground stations to 98.7% with the same number of ground stations.<br>by Iñigo del Portillo Barrios.<br>S.M.
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Santos, Alex Ferreira dos. "Algoritmos para alocação de banda em redes de acesso GPON." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/18/18155/tde-11032010-160905/.
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Neste trabalho propomos e analisamos algoritmos de alocação dinâmica de banda para rede óptica passiva (PON) de acesso padrão GPON (Gigabit PON). Estes algoritmos utilizam dados oriundos de SLA (service level agreement) para gerenciar a alocação de banda e classificar em 4 contêineres de tráfego (T-CONT) o tráfego gerado em 16 ONUs (optical network unit). Na transmissão upstream é utilizada a técnica de multiplexação por divisão de tempo (TDM) para gerenciar o acesso ao meio, evitando colisões. O primeiro algoritmo proposto aloca banda garantida para as ONUs e distribui a banda não utilizada de acordo com critério baseado em três SLAs. A taxa de bit upstream é 1,25 Gbps e o desempenho do algoritmo é analisado com base na variação do atraso de pacotes em função do tráfego gerado nas ONUs. O segundo algoritmo proposto utiliza ponderação de tráfego. Neste, analisamos o comportamento dos atrasos e a quantidade de banda solicitada e atendida por ONU quando as bandas garantida e extra são alteradas. Por fim, acrescentamos em nossa implementação um intervalo para o processamento do algoritmo de alocação dinâmica de banda (DBA) e resposta do hardware relacionado ao ciclo de interrogação. Então, analisamos o atraso de pacotes quando variamos o intervalo de processamento do DBA. Ao final, propomos uma solução preliminar para minimizar estes atrasos. Os resultados obtidos por meio de simulação computacional mostram a versatilidade dos algoritmos.<br>In this work we propose and analyze the performance of dynamic bandwidth allocation algorithms for optical passive networks (PON) in GPON standard (Gigabit PON). These algorithms use data from SLA (service level agreement) to manage bandwidth allocation and classify in 4 traffic containers (T-CONT) the traffic generated by 16 ONUs (optical network unit). In the upstream transmission the time division multiplexing (TDM) technique is used to manage the medium access, avoiding collisions. The first proposed algorithm allocates guaranteed bandwidth for the ONUs and distributes the bandwidth not used according to the criteria based on three SLAs. The upstream bit rate is 1.25 Gbps and the algorithm performance is analyzed based on the packets delay variation versus the traffic generated by ONUs. The second proposed algorithm uses weighted traffic. In this, we analyze the delay performance and the required bandwidth for each ONU and how much it is served when the guaranteed and extra bandwidth are changed. Finally, we added in our implementation an interval for the processing of the dynamic bandwidth allocation algorithm (DBA) and response of the hardware related to the interrogation cycle. In the end, we propose a preliminary solution to minimize these delays. The results obtained by means of computational simulation show the versatility of the algorithms.
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Li, Ji. "Design and analysis of survivable WDM mesh networks." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B38574846.
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Chapple, Rebecca Jane. "Communication problems in optical networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq37496.pdf.
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Al-Yatama, Anwar. "Quantization and routing in broadband networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/15374.
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Ahmadvand, Nima. "Wavelength division multiplexing cross connect networks." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30066.pdf.
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Haris, Muhammad. "Advanced modulation formats for high-bit-rate optical networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24811.
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Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.<br>Committee Chair: Chang, Gee-Kung; Committee Co-Chair: Yu, Jianjun; Committee Member: Altunbasak, Yucel; Committee Member: Ji, Chunayi; Committee Member: Ralph, Stephen; Committee Member: Xu, Jun.
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Bignell, Allan M. "Photonic bus and photonic mesh networks : design techniques in extremely high speed networks /." *McMaster only, 1997.
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Ware, Cédric. "On optical functionalities and high-capacity communication networks." Habilitation à diriger des recherches, Telecom ParisTech, 2013. http://tel.archives-ouvertes.fr/tel-00983948.
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The global communications network has become a pervasive and critical item of everyday life, spawning and enabling countless worldwide services that went from nonexistent to must-have in less than a decade. Its implementation makes considerable use of optical transmission systems, which are the physical medium of choice for most non-wireless links, being capable of high data rates over long distances. However, the potential of optics is still underexploited, and can help a smarter network meet the simultaneous challenges of ever-higher data rates, network switching, and the "last-mile" access network. <p> Very high data rates were achieved in optical transmissions in the late 1990s especially through wavelength-division multiplexing (WDM) over the C and later the L spectral bands. For some time, the way to increase data rates was forecast to be higher symbol rates per wavelength, for which optical-to-electronic (O-E) conversions are a speed bottleneck. This required all-optical functionalities, especially to process optical time-domain multiplexed signals. In that line, I contributed to ultrafast clock recovery using opto-electronic phase-locked loops. <p> However, the recent comeback of coherent optical communications points to easier ways to increase the data rate by pushing towards higher spectral efficiencies, closer to the optical channel's Shannon capacity in the presence of certain physical impairments. Notably, some of my recent results suggest that polarization-dependent loss can be handled close to the limit thanks to a combination of space-time codes and more conventional error-correcting codes. <p> Switching is another bottleneck: the Internet's great versatility results in part from its packet-switching paradigm, but current optical networks are essentially circuit-switched using wavelength granularity. Packet-switching functionality is implemented purely in electronics, incurring numerous energy-inefficient O-E conversions and ballooning energy costs. <p> My work on all-optical functionalities included an all-optical label-processing scheme for switching nodes, though this approach would be subject to scaling problems in practice. More recently, my concern has shifted to hybrid switching nodes using electronic buffers to supplement an optical switching matrix. My current studies show great improvements of their sustainable load compared to all-optical switches at a given packet-loss probability. <p> Access network is the last stronghold where optical transmissions are not quite dominant yet. The focus there is on cost effectiveness and resource sharing, especially in passive optical networks (PONs). In order to bring WDM to PONs, I contributed to a pulsed continuum optical source that could have provided optical channels to multiple users simultaneously. More recently, I also oversaw work on reflective semiconductor optical amplifiers designed for colorless optical network units. <p> Finally, the challenge goes on for a better match between network functionalities and the untapped potential of optics. My focus is currently shifting towards cross-layer optical networking, requiring novel network architectures to break free from the electronic-centric layered-network model, and finally meeting the energy consumption problem square-on.
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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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Tariq, Sana. "Inside all-optical networks /." Online version of thesis, 2009. http://hdl.handle.net/1850/10960.
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Dods, Sarah D. "Homodyne crosstalk in wavelength-division multiplexed ring and cus networks /." Connect to thesis, 2000. http://eprints.unimelb.edu.au/archive/00000597.
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Hwang, Yong Goo. "Optimal configuration of digital communication network." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA243041.
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Thesis (M.S. in Computer Science)--Naval Postgraduate School, December 1990.<br>Thesis Advisor(s): Suh, Myung W. Second Reader: Hamming, Richard W. "December 1990." Description based on title screen as viewed on March 30, 2010. DTIC Identifier(s): Program Listings, Lagrangian Relaxation. Author(s) subject terms: Network, Langrangian Relaxation, Subgradient Optimization. Includes bibliographical references (p. 66-67). Also available in print.
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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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Li, Ji, and 李季. "Design and analysis of survivable WDM mesh networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B38574846.
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Huang, Hong. "Hybrid and resilient WDM mesh optical networks." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15751.
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He, Jingyi. "Routing and channel assignment in optical and wireless networks /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202004%20HE.
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Chonbodeechalermroong, Yongyut School of Electrical Engineering UNSW. "Simple star multihop optical network." Awarded by:University of New South Wales. School of Electrical Engineering, 2001. http://handle.unsw.edu.au/1959.4/20328.
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A new multihop wavelength-division multiplexed (WDM) optical network designed for uniform traffic with two wavelengths per node that can give the maximum throughput and minimum delay is proposed. It is called a 'Simple Star' multihop optical network. This network has good characteristics in traffic balance and small average number of hops. Moreover, Simple Star can be used together with multiple star couplers to reduce the number of wavelength used. Furthermore, unlike most existing networks, this network does not impose an upper limit to the number of nodes. Another interesting pattern is Simple Star with Center Node (Simple Star CN) particularly for prime numbers of nodes. It can be shown that the average number of hops of Simple Star (normal plus CN) is in between those of Shufflenet and Kautz, but the throughput and delay are better. An associated network called Simple Star Shared Channel (Simple Star SC) for two transceivers per node is also presented and it can be used together with multiple star couplers to reduce the number of wavelengths. An example of a 16-node Simple Star SC shows that the number of wavelengths used can be 8 times less than that in the normal Simple Star network. The Shared Channel simulation model is based on the concept of CSMA/CD (Carrier Sense Multiple Access with Collision Detection).