Current Trends in Multiwavelength Optical Networking in Software Printing qrcode in Software Current Trends in Multiwavelength Optical Networking

Current Trends in Multiwavelength Optical Networking generate, create quick response code none for software projects Codabar Co-authored by Neophytos Antoniades The City University of New York/College of Staten Island Despite the qr codes for None fact that optical ber communications has been an active area of research since the early 1970s and optical transmission facilities have been widely deployed since the 1980s, serious activity in optical networking did not reach beyond the laboratory until the 1990s. It was in the early 1990s that a number of ambitious optical network testbed projects were initiated in the United States, Europe, and Japan. Although the testbeds were largely government nanced, they planted the seeds for subsequent commercial developments, many of which were spin-offs of the testbed activities.

The commercial ventures bene ted from the knowledge accumulated from the testbeds as well as from the burgeoning worldwide demand for bandwidth. As a result, multiwavelength optical networks are deployed today in metropolitan area as well as wide area applications with increasing current activity in local access as well. In this chapter we give an overview of current developments in metropolitan and wide area networks.

Recent developments in access networks were discussed in detail in 5. The chapter begins with a brief discussion of the role of business drivers and relative costs in creating the current trends. This is followed by a summary of the early testbed projects in the United States and Europe, which provides the context for a description of current commercial activity in multiwavelength metro and long-haul networks.

We continue with a discussion of new applications and services made possible by the unique features of intelligent optical networks, and conclude with some thoughts for the future.. Business Drivers and Economics Traf c grow Quick Response Code for None th in the Internet and other new data communications services and deregulation of the telecommunications industry have resulted in new business opportunities and challenges for telecommunications network operators. Deregulation across the industry is currently resulting in the destruction of regulatory boundaries separating different markets, with each carrier trying to provide end-to-end network services under a single brand name. The increased demand and the competitive pressures of deregulation are the main driving forces behind the need for low-cost increased bandwidth.

WDM is a proven method of increasing bandwidth by a factor of 30 at 50% of the cost of alternate methods. These cost advantages are particularly signi cant in cases in which new ber builds are avoided by using WDM equipment. The saturation of ber capacity, known as ber exhaust, is a serious problem for network operators.

A study of some major. Current Trends intercity r QR Code 2d barcode for None outes in the United States in 2001 showed that 70% of the lit ber is in use, which means that the network operators are reaching a point where increased capacity is required. The decreasing number of spare bers available in the cables of the longdistance network carriers and the local exchange carriers (LECs) exacerbates the ber exhaust problem and has brought about a mass deployment of WDM into the network. In particular, WDM optical networks allow for the following: r r r r Duct, ber, and cable exhaust relief Reduction in the number of regenerators/optical ampli ers Equipment savings with advanced architectures Reduced network deployment cost achieved by introducing exibility and con gurability into the optical layer of the network.

Several stu dies have addressed the economics of multiwavelength optical networking [Arijs+00a, Bala+96, Bala+97, Cardwell+00, Chen97, Melle+95, Parys+00, Sasaki+99]. On the transmission level, not surprisingly, there is a clear advantage with WDM, which has been shown to be a more cost-effective solution than laying more ber in the ground [Melle+95]. By replacing a single optical carrier on a ber with 80 or more signals on distinct -channels, the inherent bandwidth of the ber is utilized much more ef ciently, and additional advantages are obtained through the use of optical rather than electronic ampli cation on long transmission links (see Section 4.

4). However, WDM networking1 also requires routing (switching) that is implemented by optical cross-connects of various types. Some have suggested that WDM switching should be opaque [Bala+95], and others have recommended that WDM routing should be performed using transparent optical approaches [Coathup+95].

In addition to the obvious capacity expansion advantages of WDM transmission, the advantages of all-optical approaches going beyond transmission include transparency to signal formats, upgradeability, and the ability to provide high-bandwidth clear channels directly to the users end systems. As studied quantitatively in Section 4.9, a signi cant disadvantage of transparency is the accumulation of transmission and switching impairments, such as noise, dispersion, nonlinear distortion, and switch cross-talk.

Among WDM equipment that is commercially available at this time, there are varying degrees of transparency. Some examples, in decreasing order of transparency are r Purely optical cross-connects r Optical transmission line-terminating equipment performing WDM multiplexing/ demultiplexing functions as well as partial to full (electronic) regeneration (see Section 2.5) r Fully regenerative terminal and switching equipment, with regeneration and switching performed electronically In this section, we study some evolutionary trends and economic trade-offs for a range of commercial products, applications, and architectures from point-to-point connections to rings to cross-connected mesh networks using optical networking elements for.

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