Optical Networks and the Future of Broadband Services

The evolution of broadband services will depend on the widespread deployment of optical networks. The deployment of such networks will, in turn, help drive increased demand for additional capacity. In this world, service providers will have a growing need to be able to flexibly adjust capacity to accommodate uncertain and growing demand. In this article, we present a cost model that highlights the advantages of new optical networking technologies such as Dense Wavelength Division Multiplexing (DWDM) over traditional architectures for optical networks. This analysis highlights the increased flexibility and scalability of DWDM networks, which lowers the deployment costs of such networks in light of growing and uncertain demand. The DWDM architecture holds the promise of allowing the emergence of wavelength markets, where traffic could be switched between service provider networks at the optical layer (without the need for multiple costly and wasteful electronic/optical conversions). While the DWDM and Optical Cross-Connect (OxC) technologies provide a technical infrastructure for supporting wavelength markets, additional developments are also likely to be required. This paper also considers some of the impediments to the growth of wavelength markets, namely the need for secondary markets and standardized contracts

Optimized Hybrid Optical Communication System for First Mile and Last Mile Problem Solution of Today's Optical Network

AbstractWe have proposed an optimized hybrid optical communication system for bit-rates of 160Gbps/channel, 100Gbps/channel and 40Gbps/channel. The system composed of 8-channel dense wavelength division multiplexing (DWDM) fiber optic link for longhaul, and wireless optical diffused link for short-haul, multicasting applications. The use of wireless optical diffused links at either end, solve the today's first mile and last mile problem of optical communication network. The wireless optical diffused link uses the optimized coherent optical quadrature phase shift keying modulation technique, as it offers the best performance in the presence of atmospheric turbulence effect. However, the fiber based DWDM system uses symmetrical dispersion compensation technique, with optimized modified duo-binary return-to-zero modulation format as it performs the best, in the presence of fiber non-linearity and dispersion. The system operates with the centre frequency of 193.1THz. The system performance is analyzed in terms of quality-factor, bit error rate, eye opening etc. For the bit rate of 160Gbps, the optimized coverage distance found is 126m of wireless optical diffused link and 450km of fiber optic link. The proposed system will be highly useful for present and next generation long distance optical communication systems and computer networks

Optical CMDA in light of current IT challenges

Optical code division multiple access (OCDMA) can provide very high spectral utilization, flexible data rates while delivering simplified network control and management. Higher channel count per the number of used wavelengths (compare to WDM) makes OCDMA a technology to be considered for the use in the number of targeted applications. By examining challenges the telecom faces today, we will discuss and show how Optical CDMA can help to overcome some of these challenges, fulfil our needs and requirements

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

An assembly and offset assignment scheme for self-similar traffic in optical burst switching

Includes bibliographical references.Optical Burst Switching (OBS) is a viable technology for the next generation core network. We propose an FEC-assembly scheme that efficiently assembles self-similar traffic and a Pareto-offset assignment rather than a constant offset assignment. Two buffers, a packet buffer and a burst buffer, are implemented at the Label Edge Router (LER), buffering traffic in the electronic domain. The assembler, between the packet and burst buffers, is served by the packet queue while the assembler serves the burst queue. We outline advantages of why burst assembly cannot be implemented independent of offset assignment. The two schemes must be implemented in a complementary way if QoS is to be realized in an OBS network. We show that there is a direct relation between OBS network performance with burst assembly and offset assignment. We present simulation results of the assembly and offset assignment proposals using the ns2 network simulator. Our results show that the combination of the proposed FEC-Based assembly scheme with the proposed Pareto-offset assignment scheme give better network performance in terms of burst drop, resource contention and delay. Key to any traffic shaping is the nature traffic being shaped. This work also compares performance of both traditional exponential traffic with realistic Self-Similar traffic of Internet traffic on the proposed assembly and offset assignment schemes. In our simulations, we assume that all Label Switch Routers (LSR) have wavelength converters and are without optical buffers. We use Latest Available Unused Channel with Void Filling (LAUC-VF) scheduling scheme and use Just Enough Time (JET) reservation scheme

Has silicon reached its limit?

In light of the rapidly increasing demand for ultra-high speed data transmission, data centres are under pressure to provide ever increasing data transmission through their networks and at the same time improve the quality of data handling in terms of reduced latency, increased scalability and improved channel speed for users. However as data rates increase, present electronic switching technology using current data centre architecture is becoming increasingly difficult to scale despite improvements in data management. In this paper the tremendous bandwidth potential of optical fibre based networks will be explored alongside the issues of electronic scalability and switching speed. A resulting need for alternative optical solutions for all-optical signal processing systems will be discussed. With this in mind, progress in the form of a novel and highly scalable optical interconnect will be reviewed

Physical Layer Aware Optical Networks

This thesis describes novel contributions in the field of physical layer aware optical networks. IP traffic increase and revenue compression in the Telecom industry is putting a lot of pressure on the optical community to develop novel solutions that must both increase total capacity while being cost effective. This requirement is pushing operators towards network disaggregation, where optical network infrastructure is built by mix and match different physical layer technologies from different vendors. In such a novel context, every equipment and transmission technique at the physical layer impacts the overall network behavior. Hence, methods giving quantitative evaluations of individual merit of physical layer equipment at network level are a firm request during network design phases as well as during network lifetime. Therefore, physical layer awareness in network design and operation is fundamental to fairly assess the potentialities, and exploit the capabilities of different technologies. From this perspective, propagation impairments modeling is essential. In this work propagation impairments in transparent optical networks are summarized, with a special focus on nonlinear effects. The Gaussian Noise model is reviewed, then extended for wideband scenarios. To do so, the impact of polarization mode dispersion on nonlinear interference (NLI) generation is assessed for the first time through simulation, showing its negligible impact on NLI generation. Thanks to this result, the Gaussian Noise model is generalized to assess the impact of space and frequency amplitude variations along the fiber, mainly due to stimulated Raman scattering, on NLI generation. The proposed Generalized GN (GGN) model is experimentally validated on a setup with commercial linecards, compared with other modeling options, and an example of application is shown. Then, network-level power optimization strategies are discussed, and the Locally Optimization Global Optimization (LOGO) approach reviewed. After that, a novel framework of analysis for optical networks that leverages detailed propagation impairment modeling called the Statistical Network Assessment Process (SNAP) is presented. SNAP is motivated by the need of having a general framework to assess the impact of different physical layer technologies on network performance, without relying on rigid optimization approaches, that are not well-suited for technology comparison. Several examples of applications of SNAP are given, including comparisons of transceivers, amplifiers and node technologies. SNAP is also used to highlight topological bottlenecks in progressively loaded network scenarios and to derive possible solutions for them. The final work presented in this thesis is related to the implementation of a vendor agnostic quality of transmission estimator for multi-vendor optical networks developed in the context of the Physical Simulation Environment group of the Telecom Infra Project. The implementation of a module based on the GN model is briefly described, then results of a multi-vendor experimental validation performed in collaboration with Microsoft are shown