Mônica de Lacerda Rocha

ZigBee for building control wireless sensor networks

ZigBee and IEEE 802.15.4 are standard-based protocols that provide the network infrastructure required for wireless network applications. The IEEE defines the physical (PHY) and medium access protocol (MAC) layers in its standards. For ZigBee, an alliance of companies worked to develop specifications for stack profiles, which define network, application services and security parameters for the entire network. The stack profile is selected by the ZigBee coordinator and is chosen on the basis of application areas, such as home control, building automation or plant control. Aiming the development of a commercial ZigBee product for home control, in this paper we describe some important aspects of those standards and the main directives of the stack profile and network topology that have been selected for assembling first development kits, which are also presented.

Optical frequency comb generator for coherent WDM system in Tb/s applications

This paper presents a theoretical analysis and an experimental demonstration of an optical comb generator. Based on the recirculating frequency shifting technique, it targets high capacity applications that require high spectral efficiency and dispersion resilient transmission, such as optical orthogonal frequency division multiplexing (OFDM). The generator relies on the use of coherent and orthogonal multi-carrier (Coherent WDM) that makes use of a single laser source (seed). As far as we know, the theoretical model described here is presented for the first time. We experimentally demonstrate the generation of 26 comb lines with optical signal to noise ratio from 25 to 35 dB, in a spectral window of ~ 4 nm. The theoretical analysis prediction has shown excellent agreement with the experimental results.

Design of Passive Optical Networks using Genetic algorithm

In this paper a genetic algorithm is used as a tool for topology searching and splitter placement in Passive Optical Networks. In order to apply such approach, a graph representation scheme, associated to a street map, is proposed. The formulation has been applied to minimize the amount of optical cabling, number of splitters and power budget, based on standards for the ITU-T GPON parameters.

Transmission of a 1.12 Tb/s superchannel over 452 km fiber

This paper describes the transmission of a non-guard interval 1.12 Tb/s 10-carrier superchannel, launched into a 226 km recirculating loop. After two round trips (452 km) a BER below the FEC limit (3.8 x 10-3) was still obtained. To evaluate the superchannel generation technique, up to 72 comb lines (OSNRmin = 12.7 dB) were generated and modulated (DP-QPSK) at 112.5 Gb/s and, in a back-to-back configuration, such an 8.06 Tb/s signal was detected by a coherent receiver with offline processing, resulting in a maximum BER of 2.4 x 10-3.

A Cost-Benefit Analysis on Modulation Formats for 40-Gb/s Optical Communication Systems

Abstract This article discusses possible approaches for optical network capacity upgrade by considering the use of different modulation formats at 40 Gb/s. First, a performance evaluation is carried out regarding tolerance to three impairments: spectral narrowing due to filter cascading, chromatic dispersion, and self-phase modulation. Next, a cost-benefit analysis is conducted, considering the specific optoelectronic components required for the optical transmitter/receiver configuration of each format.

Project GIGA-high-speed experimental IP/WDM network

This paper describes Project GIGA-high-speed Experimental Network, a multiinstitutional, multidisciplinary, national project funded by the Brazilian government. The main goal of Project GIGA is to promote research, development and experimentation of technology at all layers, aiming at generating knowledge, products and services that will make it possible for Brazilian individuals and companies to play a role in the converged telecom sector. The project centres on the high-speed Network Testbed, a platform for experimentation and validation of technology, equipment, protocols, services and applications, whether they be developed in the project or not. The paper explains the objectives, the expected impact and the organisation of the project. It also describes the architecture of the network testbed, the ongoing research and development activities and some of the results obtained.

Cascade of amplitude- and phase-modulator in four different configurations of superchannel generation

We present a study aiming to improve the spectral purity and stability of optical superchannels for transmission above 1 Tb/s. After validating our simulation pallets with experimental data, we investigate the cascade of amplitude and phase modulators in different configurations, both in serial and in a recirculating frequency shift loop. The BER performance for a 23-subcarrier superchannel, DP-QPSK modulated at 1.15 Tb/s, has been evaluated in a 226 km long recirculating loop with a coherent receiver setup.

Design of a Comb Generator for High Capacity Coherent-WDM Systems

This paper presents a theoretical model developed for estimating the power, the optical signal to noise ratio and the number of generated carriers in a comb generator, having as a reference the minimum optical signal do noise ratio at the receiver input, for a given fiber link. Based on the recirculating frequency shifting technique, the generator relies on the use of coherent and orthogonal multi-carriers (Coherent-WDM) that makes use of a single laser source (seed) for feeding high capacity (above 100 Gb/s) systems. The theoretical model has been validated by an experimental demonstration, where 23 comb lines with an optical signal to noise ratio ranging from 25 to 33 dB, in a spectral window of ~ 3.5 nm, are obtained.

Effective penalty reduction in an L-Band WDM system using hybrid amplifier with a dispersion-compensating module

We demonstrate the combined use of a single laser diode and a fiber ring laser for pumping a Raman-amplified dispersion compensating fiber (DCF) to upgrade an L-Band WDM transmission system at 10 Gbit/s. The broadband DCF module is placed at the output of an L-Band Erbium-doped fiber pre-amplifier, to reduce the power penalties associated to chromatic dispersion. The hybrid DCF-Raman amplifier, provided by two pump-wavelengths originated from a single pump source, permits the L-band channel allocation with efficient transmission performance through a metro-scaled (100 km) standard single mode fiber (SSMF). The performance of eight WDM channels in the L-Band is presented with nearly penalty free operation at 10 Gbit/s, which are corroborated by numerical simulation analysis. The residual power penalties obtained were either close to 1 dB or less for all channels in the L-band. The L-band hybrid pre-amplifier, composed by a single-stage EDFA and a Raman-pumped DCF module, is proposed as an alternative solution for the capacity upgrade of metropolitan WDM transmission systems.

Q-factor penalty evaluation in a cascade of all-, optical nodes using a re-circulating loop

The impact of all-optical node concatenation effects on the performance of a WDM transmission through 350 km of standard fiber is investigated with re-circulating loop experiments. A node of the OMEGA test bed is used to simulate a chain of fourteen nodes. Each link comprises a combination between one node (mux/demux, thermal optical switch and erbium-doped fiber optical amplifier) and 25 km of standard single mode fiber. Amplifier noise accumulation has been found to be the most detrimental effect.