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Wu J.,Communications Research Center Canada
Computer Networks | Year: 2011

We survey the state-of-the-art technologies in Wavelength Division Multiplexing (WDM) network reconfiguration. Our focus is the strategies and triggering methods. We compare the proposed technologies in the literature from different perspectives: traffic-changes triggered vs. other events triggered, centrally-managed strategies vs. distributed strategies, new lightpath demands known vs. future user traffic unknown, adaptive/reactive approaches vs. proactive approaches, traffic prediction based vs. traffic uncertainty proof approaches. We outline the entire landscape of the strategies and triggering methods of WDM network reconfiguration from WDM network operators' point of view. There are gaps in research and in field trials, which must be addressed, so that the great potentials of WDM network reconfiguration may be realized to add significant flexibility in network operations. © 2011 Elsevier B.V. All rights reserved. Source


Petosa A.,Communications Research Center Canada
IEEE Antennas and Propagation Magazine | Year: 2012

Frequency-agile antennas can be designed to switch between a set of discrete frequencies, or to be tuned over a continuous range of frequencies. Methods for achieving discrete or continuous frequency tuning can be grouped into three categories: mechanical actuation, tunable materials, and integrated electronic devices. Example tuning techniques in each class are presented, highlighting strengths and weaknesses of each method. © 1990-2011 IEEE. Source


Mihailov S.J.,Communications Research Center Canada
Sensors | Year: 2012

Because of their small size, passive nature, immunity to electromagnetic interference, and capability to directly measure physical parameters such as temperature and strain, fiber Bragg grating sensors have developed beyond a laboratory curiosity and are becoming a mainstream sensing technology. Recently, high temperature stable gratings based on regeneration techniques and femtosecond infrared laser processing have shown promise for use in extreme environments such as high temperature, pressure or ionizing radiation. Such gratings are ideally suited for energy production applications where there is a requirement for advanced energy system instrumentation and controls that are operable in harsh environments. This paper will present a review of some of the more recent developments. © 2012 by the authors; licensee MDPI, Basel, Switzerland. Source


Dumais P.,Communications Research Center Canada
IEEE Journal of Quantum Electronics | Year: 2011

Thermal stress birefringence in buried-core waveguides is studied analytically and numerically to determine the role of cladding and core composition, core aspect ratio and over-etch depth. An analytical expression is derived for the over-etch depth required for stress birefringence compensation. Analytical expressions for the core stress are given for over-etched rectangular buried-core waveguides. The range of upper cladding thermal expansion coefficient over which stress birefringence compensation can be obtained through over-etching is established. © 2011 IEEE. Source


Omar H.A.,University of Waterloo | Zhuang W.,University of Waterloo | Li L.,Communications Research Center Canada
IEEE Transactions on Mobile Computing | Year: 2013

The need of a medium access control (MAC) protocol for an efficient broadcast service is of great importance to support the high-priority safety applications in vehicular ad hoc networks (VANETs). This paper introduces VeMAC, a novel multichannel TDMA MAC protocol proposed specifically for a VANET scenario. The VeMAC supports efficient one-hop and multihop broadcast services on the control channel by using implicit acknowledgments and eliminating the hidden terminal problem. The protocol reduces transmission collisions due to node mobility on the control channel by assigning disjoint sets of time slots to vehicles moving in opposite directions and to road side units. Analysis and simulation results in highway and city scenarios are presented to evaluate the performance of VeMAC and compare it with ADHOC MAC, an existing TDMA MAC protocol for VANETs. It is shown that, due to its ability to decrease the rate of transmission collisions, the VeMAC protocol can provide significantly higher throughput on the control channel than ADHOC MAC. © 2002-2012 IEEE. Source

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