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Data Communications (data + communication)
Selected AbstractsAutomation of the East Bench irrigation main canal,IRRIGATION AND DRAINAGE, Issue 4 2006Blair L. Stringam automation; écluses; algorithme de contrôle; irrigation Abstract Canal automation equipment in the East Bench Irrigation District in Dillon, Montana, was over 30 years old and needed to be replaced. Portions of the old automation system were salvaged in an attempt to reduce rehabilitation costs. Because wiring diagrams were not available for the old control system, time would have been saved if the old control system were completely removed and replaced with a completely new system. Data communication via radio and bubbler water level sensors proved to be troublesome. After three seasons of operation, problems with the new automation system were corrected, but it became evident that a technician was needed to maintain the system. Copyright © 2006 John Wiley & Sons, Ltd. Les equipements de fonctionnement automatique des canaux âgés plus de trente ans qui se trouve dans le East Bench Irrigation District à Dillon, Montana, avait besoin de remplacement. Une partie de l'outillage ancien avait été récupérée dans l'espoir de diminuer les frais de réhabilitation. Au fait que diagrammes schématiques du système ancien n'éxistaient plus, on aurait gagné du temps par l'abandon complet de l'ancien système et son remplacement par un nouveau système. La communication d'information scientifique par radio et par instruments d'eau bouillonant, dans le nouveau système, s'est révélée problématique. A la fin de trois années d'opération, les problèmes du nouveau système ont été corrigés, mais on a realisé la nécessité d'un technicien pour maintenir le système. Copyright © 2006 John Wiley & Sons, Ltd. [source] Optical CDMA codes for use in a lightwave communication network with multiple data rates,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2002Jian-Guo Zhang This paper presents a new kind of optical code-division multiple-access (CDMA) codes, called unequal-length optical orthogonal codes (UL-OOC's), for multirate data communications. The autocorrelation and cross-correlation functions of UL-OOC's are dependent only on each individual codeword, in spite of either an aperiodic or a periodic pulse-sequence pattern at the input of optical CDMA decoders. This property can be thus used to support multirate data communications in a lightwave network, without any violation of the minimum correlation constraint (i.e., "1") for incoherent optical processing. Theory and simple design of UL-OOC's are presented. Applications of the proposed codes to multirate optical CDMA is also explained in detail. [source] Satellite rural communications: telephony and narrowband networksINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2005Roberto Conte Abstract Rural communications are important for large and developing countries, and telecommunications systems have been implemented depending upon the available technology at the time. Rural users do not generate the same amount of revenue as urban users do, thus lowering incentives for rural telecommunications investment with service to those regions delayed as long as possible. Voice and data communications are essential to the economic development of a region, and it has been shown that traffic increases rapidly as soon as the service is available. Satellite-based digital networks provide efficient long-distance service to rural communities at lower cost than similar land-based wired networks with acceptable quality. Small earth stations along with Wireless Local Loops can provide both local and long-distance service efficiently and at low cost, offering digital multimedia services on a global scale. This paper focuses on the description of different narrowband technologies used to service rural communities, namely basic telephone and low-bit-rate data (<64 kbps) applications through the use of satellite and terrestrial wireless systems. A basic network economic planning description is presented, and important parameters such as satellite network size, topology and multiple access are identified in order to improve the process of effective and cost-efficient rural communications network design. Copyright © 2005 John Wiley & Sons, Ltd. [source] Fast, scalable, and distributed restoration in general mesh optical networksBELL LABS TECHNICAL JOURNAL, Issue 1 2001Gary P. Austin Service providers are demanding transport network solutions that can accommodate exponential traffic growth and, at the same time, provide novel services such as point-and-click provisioning of very high bandwidth circuits, optical bandwidth service management, fast protection and restoration, and bandwidth on demand. It is becoming increasingly clear that the required scalability (terabits/s to petabits/s) and cost structure can only be provided by transparent optical cross connects (OXCs). The challenge, then, is to make the optical network consisting of OXCs, dense wavelength division multiplexers (DWDMs), and optical add/drop multiplexers (OADMs) dynamic and intelligent. A major aspect of this intelligence is fast provisioning and restoration. In this paper, we present a fast, scalable, and distributed solution for optical layer restoration in general mesh-type optical networks, which is being implemented as part of the Optical Navigator System (ONS) residing in Lucent's LambdaRouter product. The key ingredients to our solution are a fast and scalable restoration strategy, a fast and scalable connection setup strategy, a contention-free wavelength assignment strategy, and a fast and reliable data communications network to exchange signaling messages. We also introduce novel concepts of demand bundling and optical virtual paths that ensure that restoration performance scales with network and traffic volumes. Together these components provide an intelligent optical networking solution that not only guarantees restoration times within few hundreds of milliseconds, but also achieves scalability. [source] | ||||||||||