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Publications

Publications by CTM

2012

Interference Study Between Wireless Microphone Systems and TV White Space Devices

Authors
Dionisio, R; Marques, P; Rodriguez, J;

Publication
2012 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC)

Abstract
This work focus on a coexistence study between wireless microphone systems and secondary users of the TV White Spaces, using a Monte-Carlo methodology. Exclusion areas around wireless microphone receivers, for co-channel and adjacent channel interference, are computed, considering indoor and outdoor scenarios. Using this methodology, impact and tendencies of several parameters over the probability of interference are analyzed, like spectral channel spacing, separation distance and propagation scenario. As an example, for outdoor scenarios, the spectral spacing between primary system and secondary users, ranging from 0 MHz (co-channel operation) to 16 MHz (2 DVB-T channels) results in a protection distance of 13.9 km and 2.2 km, respectively.

2012

Evolution of all-optical flip-flops and their applications in optical communications networks

Authors
Reis, C; Costa, L; Bogoni, A; Maziotis, A; Teixeira, A; Kouloumentas, C; Apostolopoulos, D; Erasme, D; Berrettini, G; Meloni, G; Parca, G; Brahmi, H; Tomkos, I; Poti, L; Bougioukos, M; Andre, PS; Zakynthinos, P; Dionisio, R; Chattopadhyay, T; Avramoupoulos, H;

Publication
IET OPTOELECTRONICS

Abstract
This study provides a review of all-optical flip-flops (AOFFs) technologies, and their possible experimental implementation solutions, for a variety of applications in optical communication networks. A description of the state-of-the-art experimental implementations and validation testing of the technologies used in different AOFFs schemes is made, presenting to the interested reader an overview of the up to date AOFFs design schemes. Some of the research results presented in this study were performed under the EU NoE EURO-FOS project consortium. This study also provides researchers working on this topic with interesting trends that are worth considering in their own research studies.

2012

Enhancing the real-time capabilities of the Linux kernel

Authors
Sousa, PB; Pereira, N; Tovar, E;

Publication
SIGBED Review

Abstract

2012

Building a Microscope for the Data Center

Authors
Pereira, N; Tennina, S; Tovar, E;

Publication
WIRELESS ALGORITHMS, SYSTEMS, AND APPLICATIONS, WASA 2012

Abstract
Managing the physical and compute infrastructure of a large data center is an embodiment of a Cyber-Physical System (CPS). The physical parameters of the data center (such as power, temperature, pressure, humidity) are tightly coupled with computations, even more so in upcoming data centers, where the location of workloads can vary substantially due, for example, to workloads being moved in a cloud infrastructure hosted in the data center. In this paper, we describe a data collection and distribution architecture that enables gathering physical parameters of a large data center at a very high temporal and spatial resolution of the sensor measurements. We think this is an important characteristic to enable more accurate heat-flow models of the data center and with them, find opportunities to optimize energy consumption. Having a high resolution picture of the data center conditions, also enables minimizing local hotspots, perform more accurate predictive maintenance (pending failures in cooling and other infrastructure equipment can be more promptly detected) and more accurate billing. We detail this architecture and define the structure of the underlying messaging system that is used to collect and distribute the data. Finally, we show the results of a preliminary study of a typical data center radio environment.

2012

Optical characterization of muscle

Authors
Oliveira, L; Lage, A; Clemente, MP; Tuchin, VV;

Publication
SARATOV FALL MEETING 2011: OPTICAL TECHNOLOGIES IN BIOPHYSICS AND MEDICINE XIII

Abstract
Optical characterization and internal structure of biological tissues is highly important for biomedical optics. In particular for optical clearing processes, such information is of vital importance to understand the mechanisms involved through the variation of the refractive indices of tissue components. The skeletal muscle presents a fibrous structure with an internal arrangement of muscle fiber cords surrounded by interstitial fluid that is responsible for strong light scattering. To determine the refractive index of muscle components we have used a simple method of measuring tissue mass and refractive index during dehydration. After performing measurements for natural and ten dehydration states of the muscle samples, we have determined the dependence between the refractive index of the muscle and its water content. Also, we have joined our measurements with some values reported in literature to perform some calculations that have permitted to determine the refractive index of the dried muscle fibers and their corresponding volume percentage inside the natural muscle.

2011

Network infrastructure extension using 802.1D-based wireless mesh networks

Authors
Campos, R; Duarte, R; Sousa, F; Ricardo, M; Ruela, J;

Publication
WIRELESS COMMUNICATIONS & MOBILE COMPUTING

Abstract
Ubiquitous Internet access is becoming a major requirement for end-users due to the increasing number of services and applications supported over the Internet. Extending the coverage of current Wi-Fi infrastructures installed in companies, universities and cities, has been considered a solution to help in fulfilling this requirement, namely when it comes to wireless and nomadic Internet access. This paper describes and analyses a new and simple solution, called Wi-Fi network Infrastructure eXtension (WiFIX), aimed at extending current Wi-Fi infrastructures. WiFIX is based on standard IEEE 802.1D bridges and a single-message protocol that is able to self-organize the network, and it only requires software changes in IEEE 802.11 access points (APs); no changes to IEEE 802.11 stations are needed. Overhead analysis and experimental results show both the higher efficiency of the solution compared to the IEEE 802.11s draft standard and its good performance as far as data throughput, delay and packet loss are concerned. Copyright (C) 2010 John Wiley & Sons, Ltd.

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