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This article presents a new strategy to assign wavelengths in an optical link considering the four wave mixing effect in the optical fiber, for different sizes of wavelength grids. The four wave mixing effect is taken into account by using a formulation that calculates the fiber noise figure for each wavelength. We obtain the distributions of wavelengths from a genetic algorithm, which considers the...
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A new interpretation for the wavelet analysis is reported, which can is viewed as an information processing technique. It was recently proposed that every basic wavelet could be associated with a proper probability density, allowing defining the entropy of a wavelet. Introducing now the concept of wavelet mutual information between a signal and an analysing wavelet fulfils the foundations of a wavelet...
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In this paper, we investigate the switching process in triangular symmetric and planar symmetric three-core nonlinear fiber coupler (TNLDC) and we have numerically shown, via the coupled nonlinear Schrodinger equations (NLSEs), that logic gates AND, OR and NXOR can be constructed from a triangular TNLDC while the planar TNLDC produced logical gates AND, NAND, OR, and XOR. We consider two basic models...
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We have investigated the performance of various optical packet switched network (OPSN) architectures comprising optical bufferless nodes and fully connected mesh topologies, under uniform traffic distribution, i.e., all nodes generate the same traffic. We demonstrate that increasing the number of nodes in OSPNs does not necessarily increase performance, or even capacity. By establishing an efficiency...
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This paper introduces a complete family of trigonometric transforms over prime finite fields (FFTTs). Eight cosine transforms and eight sine transforms are defined, denoted FFCT and FFST, respectively. The property of symmetric convolution for these new tools is introduced. It is shown that the use of this operation, together with the development of fast algorithms, allows efficient computation of...
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One of the major challenges nowadays when managing IP networks is to guarantee proper quality of service by using network infrastructure in an optimized way. One of the recently proposed solutions is the so called traffic engineering with MPLS. In this paper, we propose a novel approach for adaptive fuzzy model-based flow control in MPLS networks. Current research treats MPLS as the Internet's solution...
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In cellular planning, it is important to guarantee the system capacity in order to ensure the minimum power necessary to provide acceptable levels of the received signal at the mobile terminals. The transmission effects in adjacent areas must be estimated, to identify the limiting zones, where the signal level is minimum and the ones where there is a possibility of signal interference. Therefore,...
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In this paper, an exact new closed formula for the multivariate alpha-mu joint probability density function (PDF) is derived allowing for an arbitrary correlation matrix. In addition, the bit error rate (BER) and the outage probability for the selection combining (SC) technique in a correlated alpha-mu fading channel is obtained.
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Circulant graphs are homogeneous graphs with special properties which have been used to build interconnection networks for parallel computing. The association of circulant graphs to a spherical code in dimension 2k is presented here via the construction of an isomorphic graph supported by a lattice in Rk.
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In this paper we present a method to obtain a set of orthogonal pulses to be used in pulse shape modulation (PSM) for ultra-wide band (UWB) communications. The pulses are built as linear combinations of Hermite functions which are shown to have unique advantageous features. Mathematical restrictions of orthogonality and spectral efficiency are introduced as guidelines to a fully explained search procedure...
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We propose to modify the MODEX algorithm for estimating direction of arrival (DOA) of plane waves using array of sensors. The MODEX algorithm is a method of direction estimation (MODE) based estimator that conveniently increases the number of MODE estimates, increasing the order of the polynomial, whose roots (candidates) estimate the DOA parameters. To select the better set of candidates, MODEX employs...
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Return channel interactivity is a digital TV feature that leads to a bidirectional information flow. This article presents an analysis of four technological alternatives for the digital terrestrial TV platform return channel subsystem, to be deployed in Brazil. Major aspects taken into account for choosing the most suitable alternative are highlighted, such as the performance and cost factors, in...
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Impedance measurements of an encapsulated semiconductor optical amplifier (SOA) were used to obtain the SOA equivalent circuit parameters. The effect of decreasing the packaging inductances and stray capacitances are then analyzed aiming the SOA enhancement as a high-speed electro-optical switch.
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Numerical investigation of the propagation of ultrashort pulses in the region of 1.55 mum and the conversion efficiency for the FWM and modulation instability of ordinary and different dispersion decreasing fibers for WDM systems was studied.
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Transporting voice over IP, instead of traditional CS voice, is a necessary prerequisite for an all IP network. Among the hurdles that need to be overcome are the QoS demands of VoIP, which comprise timely and error free delivery of comparatively low rate packet streams. One way to provide the necessary QoS for VoIP is some admission control strategy, where an incoming connection that cannot have...
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The growth in the number of voice over IP (VoIP) users on the Internet makes it the service with the highest interest to be provided by cellular operators. On the other hand, it demands very strict QoS control, which becomes even more complicated in wireless networks, because packets can be lost due to radio link transmission errors, as well as network congestion. Within this paradigm, scheduling...
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By means of dynamic system-level simulations, this work evaluates whether the studied Packet Scheduling (PS) algorithms are capable of guaranteeing the quality of service (QoS) of the voice over IP (VoIP) on a scenario where the VoIP and Web browsing services will compete for the same resources and there is a maximum allowed end-to-end delay for VoIP packets. Two sets of algorithms were considered:...
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Several applications are using the matching pursuit algorithm for signal and video compression. The matching pursuit approximates signals iteratively using linear combinations of pre-defined atoms of a dictionary. In compression applications matching pursuits coefficients, which multiply the atoms in the linear combination, need to be quantized. The Lloyd-Max quantizer is known to be the best quantizer...
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In this paper we present a new methodology based on the stochastic gradient descent to optimizing parameters of the biased distribution along importance sampling simulations. A particular aspect of the new technique is that of use of multiple parameters for the simulation of each codeword. An example of application estimating the performance of a encoded system is given.
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2006 International Telecommunications Symposium > 100 - 102
In this paper, the EDFA transient behavior was experimentally characterized in terms of the Q factor following severe amplifier input power variations. The performance was observed for a conventional EDFA and for optically and electronically (feedforward and feedback modes) gain-controlled EDFAs. Estimations of the Q factor were obtained by an error analyzer in burst mode after the delay of a gate...
