Optical communications applications of ultra-long Raman fiber lasers

Recent work on ultra-long Raman fiber lasers has shown that it is possible to create quasi-lossless transmission conditions in fiber spans long enough to be considered for high speed optical communications. This paper reviews how quasi-lossless transmission conditions are reached and presents experimental results of 40Gb/s transmission in a quasi lossless system. The performance is compared with a conventional EDFA based system.

Optical communications applications of ultra-long Raman fiber lasers

Recent work on ultra-long Raman fiber lasers has shown that it is possible to create quasi-lossless transmission conditions in fiber spans long enough to be considered for high speed optical communications. This paper reviews how quasi-lossless transmission conditions are reached and presents experimental results of 40Gb/s transmission in a quasi lossless system. The performance is compared with a conventional EDFA based system.

Synchronization of Discrete-Time Chaotic Systems in Bandlimited Channels

Over the last couple of decades, many methods for synchronizing chaotic systems have been proposed with communications applications in view. Yet their performance has proved disappointing in face of the nonideal character of usual channels linking transmitter and receiver, that is, due to both noise and signal propagation distortion. Here we consider a discrete-time master-slave system that synchronizes despite channel bandwidth limitations and an allied communication system. Synchronization is achieved introducing a digital filter that limits the spectral content of the feedback loop responsible for producing the transmitted signal. Copyright (C) 2009 Marcio Eisencraft et al.

Optical demultiplexer device operating in the visible spectrum

In this paper, we present results on the use of multilayered a-SiC:H heterostructures as a device for wavelength-division demultiplexing of optical signals. These devices are useful in optical communications applications that use the wavelength division multiplexing technique to encode multiple signals into the same transmission medium. The device is composed of two stacked p-i-n photodiodes, both optimized for the selective collection of photo generated carriers. Band gap engineering was used to adjust the photogeneration and recombination rate profiles of the intrinsic absorber regions of each photodiode to short and long wavelength absorption in the visible spectrum. The photocurrent signal using different input optical channels was analyzed at reverse and forward bias and under steady state illumination. A demux algorithm based on the voltage controlled sensitivity of the device was proposed and tested. An electrical model of the WDM device is presented and supported by the solution of the respective circuit equations.

Space–Time Block Codes and the Complexity of Sphere Decoding

In wireless communications the transmitted signals may be affected by noise. The receiver must decode the received message, which can be mathematically modelled as a search for the closest lattice point to a given vector. This problem is known to be NP-hard in general, but for communications applications there exist algorithms that, for a certain range of system parameters, offer polynomial expected complexity. The purpose of the thesis is to study the sphere decoding algorithm introduced in the article On Maximum-Likelihood Detection and the Search for the Closest Lattice Point, which was published by M.O. Damen, H. El Gamal and G. Caire in 2003. We concentrate especially on its computational complexity when used in space–time coding. Computer simulations are used to study how different system parameters affect the computational complexity of the algorithm. The aim is to find ways to improve the algorithm from the complexity point of view. The main contribution of the thesis is the construction of two new modifications to the sphere decoding algorithm, which are shown to perform faster than the original algorithm within a range of system parameters.

Unterstützung der Zusammenarbeit auf dem Vorfeld von Verkehrsflughäfen

Abstract. Auf Grund der steigenden Nachfrage nach Transportleistungen im Luftverkehr ist es dringend notwendig, die Kapazität der Flughäfen zu erhöhen. Neben der Anzahl der pro Zeiteinheit möglichen Starts und Landungen spielt dabei der Durchsatz auf dem Vorfeld eine entscheidende Rolle. Bewegungen von Boden- und Luftfahrzeugen, die Flüsse von Passagieren, Gepäck und Transportgütern und das Zusammenspiel der Dienstleister auf dem Vorfeld werden von der Verkehrszentrale überwacht und koordiniert. Aufgabenanalysen haben gezeigt, dass die Verkehrszentrale einen wichtigen Knotenpunkt der Informationsflüsse auf dem Flughafen darstellt. Zur Unterstützung der Arbeit der Verkehrszentrale wurde deshalb ein Kommunikationswerkzeug entwickelt, das die unterschiedlichen Medien und Verfahren der Kommunikation vereinheitlicht.

Supporting co-operative work in apron control and resource management offices on airports

A high demand exists to increase the efficiency of present airport ground facilities and the co-ordination of traffic and services. The Traffic Office plays a crucial role in managing the airport. The main tasks of the Traffic Office is management of equipment, services, and ressources based on the flight schedule and resolving conflicts arising from deviations from the schedule. A new tool will support information exchange between Traffic Office and other facilities on the airport.

Room temperature photoluminescence of InGaAs Surface Quantum Dots

Self-assembled InGaAs quantum dots show unique physical properties such as three dimensional confinement, high size homogeneity, high density and low number of dislocations. They have been extensively used in the active regions of laser devices for optical communications applications [1]. Therefore, buried quantum dots (BQDs) embedded in wider band gap materials have been normally studied. The wave confinement in all directions and the stress field around the dot affect both optical and electrical properties [2, 3]. However, surface quantum dots (SQDs) are less affected by stress, although their optical and electrical characteristics have a strong dependence on surface fluctuation. Thus, they can play an important role in sensor applications

Training Complex for Remote Study of Microcontrollers

This paper describes the use of technology of satellite and mobile communication for remote study of mictocontrollers.

Spectral properties of chaotic signals with applications in communications

This paper investigates the characteristics of the Power Spectral Density (PSD) of chaotic signals generated by skew tent maps. The influence of the Lyapunov exponent on the autocorrelation sequence and on the PSD is evaluated via computational simulations. We conclude that the essential bandwidth of these signals is strongly related to this exponent and they can be low-pass or high-pass depending on the family`s parameter. This way, the PSD of a chaotic signal is a function of the generating map although this is not a one-to-one relationship. (C) 2009 Elsevier Ltd. All rights reserved.

Some applications of FISST to wireless communications

This paper aims at illustrating some applications of Finite Random Set (FRS) theory to the design and analysis of wireless communication receivers, and at pointing out similarities and differences between this scenario and that pertaining to multi-target tracking, where the use of FRS has been traditionally advocated. Two case studies are considered, l.e., multiuser detection in a dynamic environment, and multicarrier (OFDM) transmission on a frequency-selective channel. Detector designand performance evaluation are discussed, along with the advantages of importing FRS-based estimation techniques to the context of wireless communications.

A new microstrip patch antenna for mobile communications and bluetooth applications

compact multihand planar octagonal-shaped microstrip antenna simultaneously suitable for mobile communication and blue tooth application is presented. The antenna provides sufficient isolation benveen the two operating bands and an area reduction of -29 % with respect to a circular patch operating in the same band

Interference and communications among active network applications

This paper focuses on active networks applications and in particular on the possible interactions among these applications. Active networking is a very promising research field which has been developed recently, and which poses several interesting challenges to network designers. A number of proposals for e±cient active network architectures are already to be found in the literature. However, how two or more active network applications may interact has not being investigated so far. In this work, we consider a number of applications that have been designed to exploit the main features of active networks and we discuss what are the main benefits that these applications may derive from them. Then, we introduce some forms of interaction including interference and communications among applications, and identify the components of an active network architecture that are needed to support these forms of interaction. We conclude by presenting a brief example of an active network application exploiting the concept of interaction.