Inside all-optical networks

Imagine a world where lightning speed Internet is as common as telephones today. Imagine when light, the fastest moving thing in the universe, is the signal-carrying transport medium. Imagine when bandwidth no more remains a constraint for any application. Imagine when imagination is the only limit! This all can be made possible with only one technology and that is optical communication. Optical networks have thus far provided a realization to a greater extent to the unlimited bandwidth dreams of this era, but as the demands are increasing, the electro-optic conversions seem to become bottlenecks in blended optical networks. The only answer to this is a complete migration to `All-Optical Networks\u27 (AONs) which promise an end-to-end optical transmission. This thesis will investigate various aspects of all-optical networks and prove that AONs perform better than currently existing electro-optical networks. In today\u27s\u27 electro-optical networks, routing and switching is performed in electronic domain. Performance analysis of electro-optical and all-optical networks would include node utilization, link utilization and percentage of traffic routed. It will be shown through Opnet Transport Planner simulations that AONs work better under various traffic conditions. The coming decade will see a great boom in demands on telecommunications networks. The development in bandwidth-hungry applications like real-time video transmission, telemedicine, distance learning and video on demand require both an unlimited amount of bandwidth and dependable QoS. It is well understood that electrically switched networks and copper cables will not be able to meet the future network demands effectively. The world has already agreed to move towards optical communication techniques through the introduction of fiber in access parts of the networks replacing copper. Now the race is to bring optics in higher layers of OSI reference model. Optical communication is on the horizon, and new discoveries are still underway to add to the value of available bandwidth through this technology. My research thesis will primarily focus on the design, architecture and network properties of AONs and challenges being faced by AONs in commercial deployment. Optical components required in AONs will be explored. A comparison between AONs and electro-optical networks will also be shown through optical transport planner simulations

A heuristic for placement of limited range wavelength converters in all-optical networks

Wavelength routed optical networks have emerged as a technology that can effectively utilize the enormous bandwidth of the optical fiber. Wavelength converters play an important role in enhancing the fiber utilization and reducing the overall call blocking probability of the network. As the distortion of the optical signal increases with the increase in the range of wavelength conversion in optical wavelength converters, limited range wavelength conversion assumes importance. Placement of wavelength converters is a NP complete problem [K.C. Lee, V.O.K. Li, IEEE J. Lightwave Technol. 11 (1993) 962-970] in an arbitrary mesh network. In this paper, we investigate heuristics for placing limited range wavelength converters in arbitrary mesh wavelength routed optical networks. The objective is to achieve near optimal placement of limited range wavelength converters resulting in reduced blocking probabilities and low distortion of the optical signal. The proposed heuristic is to place limited range wavelength converters at the most congested nodes, nodes which lie on the long lightpaths and nodes where conversion of optical signals is significantly high. We observe that limited range converters at few nodes can provide almost the entire improvement in the blocking probability as the full range wavelength converters placed at all the nodes. Congestion control in the network is brought about by dynamically adjusting the weights of the channels in the link thereby balancing the load and reducing the average delay of the traffic in the entire network. Simulations have been carried out on a 12-node ring network, 14-node NSFNET, 19-node European Optical Network (EON), 28-node US long haul network, hypothetical 30-node INET network and the results agree with the analysis. (C) 2001 Elsevier Science B.V, All rights reserved

An Optical Grooming Switch for High-Speed Traffic Aggregation in Time, Space and Wavelength

In this book a novel optical switch is designed, developed, and tested. The switch integrates optical switching, transparent traffic aggregation/grooming, and optical regener-ation. Innovative switch subsystems are developed that enable these functionalities, including all-optical OTDM-to-WDM converters. High capacity ring interconnection between metro-core rings, carrying 130 Gbit/s OTDM traffic, and metro-access rings carring 43 Gbit/s WDM traffic is experimentally demonstrated. The developed switch features flexibility in bandwidth provisioning, scalability to higher traffic volumes, and backward compatibility with existing network implementations in a future-proof way

Effective fiber bandwidth utilization in TDM WDM optical networks

Ph.DDOCTOR OF PHILOSOPH

Cost-effective Information and Communication Technology (ICT) infrastructure for Tanziania

The research conducted an Information and Communication Technology (ICT) field survey, the results revealed that Tanzania is still lagging behind in the ICT sector due to the lack of an internationally connected terrestrial ICT infrastructure; Internet connectivity to the rest of the world is via expensive satellite links, thus leaving the majority of the population unable to access the Internet services due to its high cost. Therefore, an ICT backbone infrastructure is designed that exploits optical DWDM network technology, which un-locks bandwidth bottlenecks and provides higher capacity which will provide ICT services such as Internet, voice, videos and other multimedia interactions at an affordable cost to the majority of the people who live in the urban and rural areas of Tanzania. The research analyses and compares the performance, and system impairments, in a DWDM system at data transmission rates of 2.5 Gb/s and 10 Gb/s per wavelength channel. The simulation results show that a data transmission rate of 2.5 Gb/s can be successfully transmitted over a greater distance than 10 Gb/s with minimum system impairments. Also operating at the lower data rate delivers a good system performance for the required ICT services. A forty-channel DWDM system will provide a bandwidth of 100 Gb/s. A cost analysis demonstrates the economic worth of incorporating existing optical fibre installations into an optical DWDM network for the creation of an affordable ICT backbone infrastructure; this approach is compared with building a completely new optical fibre DWDM network or a SONET/SDH network. The results show that the ICT backbone infrastructure built with existing SSMF DWDM network technology is a good investment, in terms of profitability, even if the Internet charges are reduced to half current rates. The case for building a completely new optical fibre DWDM network or a SONET/SDH network is difficult to justify using current financial data

Performance analysis on multi-dimensional optical routing networks.

Zhang Yu.Thesis (M.Phil.)--Chinese University of Hong Kong, 2002.Includes bibliographical references (leaves 67-72).Abstracts in English and Chinese.Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Overview of Optical Networking --- p.1Chapter 1.2 --- Mechanism in Optical Routing Networks --- p.3Chapter 1.3 --- Related Work on Optical Routing Networks --- p.4Chapter 1.4 --- The Motivation of This Thesis --- p.7Chapter 1.5 --- Thesis Structure --- p.8Chapter 2 --- Technologies for Multi-dimensional Optical Routing Networks --- p.10Chapter 2.1 --- Background --- p.10Chapter 2.2 --- Multi-fiber WDM Networks --- p.11Chapter 2.2.1 --- Phased-Array-Based WDM Device --- p.11Chapter 2.2.2 --- Wavelength-tunable lasers --- p.11Chapter 2.2.3 --- Tunable optical Filter --- p.12Chapter 2.2.4 --- Wavelength Converter --- p.13Chapter 2.3 --- OCDM/WDM --- p.16Chapter 2.3.1 --- Optical En/Decoder --- p.17Chapter 2.3.2 --- Optical Switch --- p.18Chapter 2.3.3 --- Optical Code Conversion --- p.18Chapter 2.4 --- OTDM/WDM --- p.21Chapter 2.4.1 --- Fast Optical Switch --- p.22Chapter 2.4.2 --- Optical Time Slot Interchanger (OTSI) --- p.22Chapter 2.5 --- Conclusion --- p.23Chapter 3 --- Performance of Code/Wavelength Routing Networks --- p.24Chapter 3.1 --- Background --- p.24Chapter 3.2 --- Reconfiguration Capability --- p.25Chapter 3.3 --- Analytic Models --- p.27Chapter 3.3.1 --- Trunk Switched Model --- p.27Chapter 3.3.2 --- Assumptions --- p.28Chapter 3.3.3 --- Blocking of the Paths with Various Configurations --- p.29Chapter 3.4 --- Numerical Results --- p.34Chapter 3.5 --- Conclusion --- p.35Chapter 4 --- Decomposition Schemes --- p.40Chapter 4.1 --- Introduction --- p.40Chapter 4.2 --- Inclusive Converted Networks --- p.41Chapter 4.3 --- Decompositions --- p.43Chapter 4.3.1 --- Spatial Decomposition (S.D.) --- p.43Chapter 4.3.2 --- Dimensional Decomposition (D.D.) --- p.44Chapter 4.3.3 --- Iterative Decompositions --- p.45Chapter 4.4 --- Conclusion --- p.46Chapter 5 --- Performance of Multi-Dimensional Optical Routing Networks --- p.48Chapter 5.1 --- Homogeneous Trunk Switched Networks --- p.48Chapter 5.2 --- Analytical Model --- p.49Chapter 5.3 --- Utilization Gain --- p.53Chapter 5.4 --- Conversion Gain --- p.54Chapter 5.5 --- Comparison on the Utilization Gain by Multiplexing and by Conversion --- p.56Chapter 5.6 --- Conclusion --- p.57Chapter 6 --- Conclusion --- p.65Chapter 6.1 --- Summary of the Thesis --- p.65Chapter 6.2 --- Future Work --- p.6