Optical Transport Network

About: Optical Transport Network is a research topic. Over the lifetime, 6055 publications have been published within this topic receiving 85783 citations.

Optical transmission system and method using an optical carrier drop/add transceiver

Abstract: An optical carrier drop/add transmission system and method using a same optical carrier to both drop traffic from an optical network and to add traffic to the optical network. An optical carrier signal is received by a transceiver and is subsequently split into a first and second optical signal. The first optical signal can be converted into an electrical signal for processing by the subscriber (i.e., data out). The electrical signal corresponding to the first optical signal is additionally inverted by the transceiver. The inverted electrical signal is subsequently modulated with the second optical signal in order to create a nominally flat signal (“optical chalkboard”). The subscriber's data is then modulated onto the flat signal and sent across the optical network. As a consequence, the network subscriber controls the format and protocols of the data traffic on the optical network, while the optical network service provider controls the optical carrier wavelengths, which are of primary concern to maintain organization and efficiency on the optical network.

A cost-effective approach to introduce an optical WDM network in the metropolitan environment

Abstract: A case study shows that an optical wavelength division multiplexing (WDM) network can be employed in a metropolitan network in a cost effective way. In part, cost savings are realized due to the total number of line terminals required and the fact that the dimensions of the electrical nodes decrease when exploiting optical cross connects (OXCs) to a large extent. Optical WDM rings are also an important building element when designing a metropolitan network. A number of the properties of WDM rings are classified, resulting in eight different ring architectures. Additional requirements arise when considering ring-to-ring connections. The extent of the rings chosen for the case study is validated from the transmission point of view by a simple model. Finally, as an alternative to an all-optical approach, an opto-electrical approach is presented.

Investigation of Spectrum Granularity for Performance Optimization of Flexible Nyquist-WDM-Based Optical Networks

Abstract: The idea behind flexible optical transmission is to optimize the use of fiber capacity by flexibly assigning spectrum and data rate adapted to the needs of end-to-end connection requests. Several techniques have been proposed to this end. One such technique is based on the utilization of Nyquist-shaping filters with the aim of reducing the required channel spacing in flexible single-carrier and super-channel optical transmission systems. Nonetheless, the imperfect shape of the filters used at the bandwidth-variable transceivers and wavelength-selective switches compels the necessity to allocate a certain spectral guard band between (sub-)channels. Bearing this is mind, in this paper, we focus on the evaluation of the network-level performance, in terms of the filter characteristics and the WDM frequency-grid granularity, of flexible Nyquist-WDM-based transmission. We demonstrate that a granularity of 6.25 GHz offers a good compromise between network performance and filter requirements for spectrum assignment to single-carrier and super-channel signals. However, for subchannel allocation within a super-channel, granularities as fine as 3.125 GHz are required to take advantage of filters with resolutions in the region of 1–1.2 GHz. Finer filter resolutions and frequency slot granularities provide negligible performance improvement.

Minimizing energy and cost in fixed-grid and flex-grid networks

Abstract: Core networks offer high capacities, thanks mainly to the optical technologies they utilize, but they consume a non-negligible amount of energy. The traffic volume in metro and core networks is forecast to grow at very high rates, exceeding 30% per year for the next five years, and if the corresponding energy requirements grow analogously, they will sooner rather than later form a bottleneck for network communications. Thus, energy efficiency in optical networks is mandatory for the sustainability of the future Internet. The objectives of the current work are to identify the main causes of energy consumption for current fixed-grid wavelength division multiplexing and future flex-grid optical networks, and to propose and compare techniques for improving their energy efficiency. Toward this end, we carried out a comparative study of energy efficiency of flex-grid networks and fixed-grid single-line-rate and mixed-line-rate networks. Under realistic network scenarios, we calculated the energy consumption of the different components of the optical layer and demonstrated that by using energy-aware techniques in planning such networks, we can achieve significant power savings. Since energy prices are location dependent, especially in large networks, e.g., over continents, we show that accounting for such information can increase the cost savings.

All-optical time-domain multiplexing-demultiplexing scheme with nonlinear material

Abstract: Optics is a candidate for digital communication and data processing where tremendous operational speed is the basic requirement. Conventional electronic systems cannot compete in this arena. Nonlinear optical materials may find important uses in optical switches. In this paper, a new idea for all-optical time-domain multiplexing and demultiplexing with the massive use of nonlinear optical materials is reported. The scheme exploits some special characteristics of such materials.