The Experts below are selected from a list of 37473 Experts worldwide ranked by ideXlab platform

Maziar Nekovee - One of the best experts on this subject based on the ideXlab platform.

  • Worldwide trends in regulation of secondary access to white spaces using cognitive Radio
    IEEE Wireless Communications, 2012
    Co-Authors: Maziar Nekovee, Tim Irnich, Jörgen Karlsson
    Abstract:

    We review the state of the art in worldwide regulation of cognitive Radio-based secondary access to Radio spectrum. Emerging regulatory trends with regards to incumbent protection and detection, Operation parameters of cognitive Radio, and secondary licensing models in the United States, United Kingdom, Europe, and elsewhere are reviewed and compared. Particular emphasis is given to cognitive Radio Operation in unused portions of TV bands, the so-called TV white spaces. Initial views on regulatory feasibility of secondary access to civilian radar and military bands are presented.

  • GLOBECOM - Current Trends in Regulation of Secondary Access to TV White Spaces Using Cognitive Radio
    2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011
    Co-Authors: Maziar Nekovee
    Abstract:

    we review the state-of-the-art in worldwide regulation of cognitive Radio-based secondary access to Radio spectrum. Emerging regulatory trends with regards to incumbent protection and detection, Operation parameters of cognitive Radio and secondary licensing models in the United States, UK, Europe and the Asia Pacific region are reviewed and compared. Particular emphasis is given to cognitive Radio Operation in spatially unused portions of TV bands, the so-called TV White Spaces. Initial views on regulatory feasibility of secondary access to civilian radar and military bands are presented.

  • Quantifying the Availability of TV White Spaces for Cognitive Radio Operation in the UK
    2009 IEEE International Conference on Communications Workshops, 2009
    Co-Authors: Maziar Nekovee
    Abstract:

    Cognitive Radio is being intensively researched for opportunistic access to the so-called TV White Spaces (TVWS): large portions of the VHF/UHF TV bands which become available on a geographical basis after the digital switchover. Using accurate digital TV (DTV) coverage maps together with a database of DTV transmitters, we develop a methodology for identifying TVWS frequencies at any given location in the United Kingdom. We use our methodology to investigate variations in TVWS as a function of the location and transmit power of cognitive Radios, and examine how constraints on adjacent channel interference imposed by regulators may affect the results. Our analysis provides a realistic view on the spectrum opportunity associated with cognitive devices, and presents the first quantitative study of the availability and frequency composition of TWVS outside the United States.

Yung-tao Liu - One of the best experts on this subject based on the ideXlab platform.

  • realization of dual dipole antenna system for concurrent dual Radio Operation using polarization diversity
    Microwave and Optical Technology Letters, 2009
    Co-Authors: Jui-hung Chou, Yung-tao Liu
    Abstract:

    The study of the mutual coupling between the two simple strip dipole antennas is first carried out and investigated. The results show that the coupling or the antenna port isolation is almost separation distance independent when the two dipole antennas are arranged to be of orthogonal polarization. Following this characteristic, a novel dual-dipole-antenna system aimed for concurrent 2.4 and 5 GHz band Operation and at the same time, to achieve very compact integration of two individual antennas with separate feeds is proposed. The two dipole antennas are etched on a two-layered dielectric substrate with dimensions 30 mm × 30 mm. On the front layer is put the 2.4 GHz dipole, which is perpendicular to the 5 GHz dipole located on the bottom layer. Though the two dipoles are stacked up with a distance of 0.8 mm only, port isolation can still be below −15 dB. The proposed dual-dipole-antenna system is a promising candidate for the antenna solution that enables simultaneous dual-Radio Operation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1725–1729, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24421

  • Realization of dual‐dipole‐antenna system for concurrent dual‐Radio Operation using polarization diversity
    Microwave and Optical Technology Letters, 2009
    Co-Authors: Jui-hung Chou, Yung-tao Liu
    Abstract:

    The study of the mutual coupling between the two simple strip dipole antennas is first carried out and investigated. The results show that the coupling or the antenna port isolation is almost separation distance independent when the two dipole antennas are arranged to be of orthogonal polarization. Following this characteristic, a novel dual-dipole-antenna system aimed for concurrent 2.4 and 5 GHz band Operation and at the same time, to achieve very compact integration of two individual antennas with separate feeds is proposed. The two dipole antennas are etched on a two-layered dielectric substrate with dimensions 30 mm × 30 mm. On the front layer is put the 2.4 GHz dipole, which is perpendicular to the 5 GHz dipole located on the bottom layer. Though the two dipoles are stacked up with a distance of 0.8 mm only, port isolation can still be below −15 dB. The proposed dual-dipole-antenna system is a promising candidate for the antenna solution that enables simultaneous dual-Radio Operation. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1725–1729, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24421

Narjes Nabipour - One of the best experts on this subject based on the ideXlab platform.

  • Energy-Efficient Method for Wireless Sensor Networks Low-Power Radio Operation in Internet of Things
    Electronics, 2020
    Co-Authors: Mehdi Amirinasab Nasab, Shahaboddin Shamshirband, Anthony T. Chronopoulos, Amir Mosavi, Narjes Nabipour
    Abstract:

    The Radio Operation in wireless sensor networks (WSN) in Internet of Things (IoT) applications is the most common source for power consumption. Consequently, recognizing and controlling the factors affecting Radio Operation can be valuable for managing the node power consumption. Among essential factors affecting Radio Operation, the time spent for checking the Radio is of utmost importance for monitoring power consumption. It can lead to false WakeUp or idle listening in Radio duty cycles and ContikiMAC. ContikiMAC is a low-power Radio duty-cycle protocol in Contiki OS used in WakeUp mode, as a clear channel assessment (CCA) for checking Radio status periodically. This paper presents a detailed analysis of Radio WakeUp time factors of ContikiMAC. Furthermore, we propose a lightweight CCA (LW-CCA) as an extension to ContikiMAC to reduce the Radio Duty-Cycles in false WakeUps and idle listening though using dynamic received signal strength indicator (RSSI) status check time. The simulation results in the Cooja simulator show that LW-CCA reduces about 8% energy consumption in nodes while maintaining up to 99% of the packet delivery rate (PDR).

  • LW-CCA: A New Energy Efficient Method for Low-Power Radio Operation in Wireless Sensor Networks for IoT Applications
    2019
    Co-Authors: Mehdi Amirinasab Nasab, Shahaboddin Shamshirband, Anthony T. Chronopoulos, Amir Mosavi, Narjes Nabipour
    Abstract:

    The Radio activity in Wireless Sensor Networks (WSN) and Internet of Things (IoT) applications are the most common reason for power consumption. However, recognizing and controlling the factors affecting Radio activity can be valuable for managing node power. ContikiMAC is a low-power Radio Duty-Cycle protocol in Contiki OS that uses Clear Channel Assessments (CCA) to check Radio status periodically. The time taken to check the Radio in receive mode WakeUp, is one of the most important reasons for power consumption which in most the cases can lead to negative WakeUp in Radio Duty-Cycles and ContikiMAC especially. Here, we present a detailed analysis of idle listening time factors on the ContikiMAC. Then, we propose Light Weight CCA(LW-CCA) as an extension to ContikiMAC to reduce power consumption by reducing the Radio check time in receive mode WakeUp’s, while maintaining up to 99% the Packet Delivery Rate (PDR). The simulation results show that the proposed method reduces significantly energy consumption in nodes compared to ContikiMAC and thus it helps maintain a high network performance.

P.f. Marshall - One of the best experts on this subject based on the ideXlab platform.

  • Cognitive Radio as a mechanism to manage front-end linearity and dynamic range
    IEEE Communications Magazine, 2009
    Co-Authors: P.f. Marshall
    Abstract:

    Most of the consideration of the benefits and applicability of dynamic spectrum access has been focused on opportunities associated with spectrum availability. This article describes the use of DSA to resolve challenges in achieving wireless and cognitive Radio Operation in dense or energetic spectrum. It also demonstrates that the use of DSA can significantly reduce requirements for linearity and dynamic range in the Radio front-end, and reduce the intermodulation induced noise floor through integration of DSA with the selection of front-end filter settings. This approach could enable DSA and cognitive Radios to be more affordable than conventional Radios, and addresses spectrum issues that are not practically manageable through manual approaches.

  • Dynamic Spectrum Management of Front End Linearity and Dynamic Range
    2008 3rd IEEE Symposium on New Frontiers in Dynamic Spectrum Access Networks, 2008
    Co-Authors: P.f. Marshall
    Abstract:

    Most of the consideration of the benefits and applicability of Dynamic Spectrum Access (DSA) has been focused on issues associated with spectrum availability. This paper describes the use of DSA to resolve challenges in achieving wireless and cognitive Radio Operation in dense or energetic spectrum. It also demonstrates that the use of DSA can significantly reduce requirements for linearity and dynamic range in the Radio front end, and reduce the intermodulation- induced noise floor through integration of DSA with the selection of front end filter settings. This approach could enable DSA and cognitive Radios to be more affordable than conventional Radios, and addresses spectrum issues that are not practically manageable through manual approaches.

M A Ribot - One of the best experts on this subject based on the ideXlab platform.

  • energy consumption savings in zigbee based wsn adjusting power transmission at application layer
    Power and Timing Modeling Optimization and Simulation, 2014
    Co-Authors: C Carmona, B Alorda, M A Ribot
    Abstract:

    This paper proposes a transmission power management algorithm based on link quality parameter to obtain savings in node energy consumption. The Radio Operation is the most power consuming task in a wireless node network; therefore the proposed algorithm tries to determine the optimum transmission power level to use only the required energy. A new decision index is defined based on link quality information to determine the optimum transmission power level. Experimental data of node consumption and link quality is used to evaluate the energy efficiency of the proposed algorithm. In addition, the energy efficiency of the algorithm is also estimated using a proposed mathematical model, independent of the hardware platform used. Furthermore, the proposed power savings algorithm is implemented at application layer without requiring any physical or MAC layers modifications.

  • PATMOS - Energy consumption savings in ZigBee-based WSN adjusting power transmission at application layer
    2014 24th International Workshop on Power and Timing Modeling Optimization and Simulation (PATMOS), 2014
    Co-Authors: C Carmona, B Alorda, M A Ribot
    Abstract:

    This paper proposes a transmission power management algorithm based on link quality parameter to obtain savings in node energy consumption. The Radio Operation is the most power consuming task in a wireless node network; therefore the proposed algorithm tries to determine the optimum transmission power level to use only the required energy. A new decision index is defined based on link quality information to determine the optimum transmission power level. Experimental data of node consumption and link quality is used to evaluate the energy efficiency of the proposed algorithm. In addition, the energy efficiency of the algorithm is also estimated using a proposed mathematical model, independent of the hardware platform used. Furthermore, the proposed power savings algorithm is implemented at application layer without requiring any physical or MAC layers modifications.