The Experts below are selected from a list of 279 Experts worldwide ranked by ideXlab platform

Jaafar M H Elmirghani - One of the best experts on this subject based on the ideXlab platform.

  • Hologram selection in realistic indoor optical wireless systems with Angle diversity receivers
    IEEE OSA Journal of Optical Communications and Networking, 2015
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we introduce a new adaptive optical wireless system that employs a finite vocabulary of stored holograms. We propose a fast Delay, Angle, and power adaptive holograms (FDAPA-Holograms) approach based on a divide and conquer (D&C) methodology and evaluate it with Angle diversity receivers in a mobile optical wireless system. The ultimate goal is to increase the signal-to-noise ratio (SNR), reduce the effect of intersymbol interference, and eliminate the need to calculate the hologram at each transmitter and receiver location. A significant improvement is achieved in the presence of demanding background illumination noise, receiver noise, multipath propagation, mobility, and shadowing typical in a realistic indoor environment. The combination of beam Delay, Angle, and power adaptation offers additional degrees of freedom in the link design, resulting in a system that is able to achieve higher data rates (5 Gb/s). At a higher data rate of 5 Gb/s and under eye safety regulations, the proposed FDAPA-Holograms system offers around 13 dB SNR with full mobility in a realistic environment where shadowing exists. The fast search algorithm introduced that is based on a D&C algorithm reduces the computation time required to identify the optimum hologram. Simulation results show that the proposed system, FDAPA-Holograms, can reduce the time required to identify the optimum hologram position from 64 ms taken by a classic adaptive hologram to about 14 ms.

  • 10 gb s indoor optical wireless systems employing beam Delay power and Angle adaptation methods with imaging detection
    Journal of Lightwave Technology, 2012
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a mobile optical wireless system that employs beam Delay adaptation, and makes use of our previously introduced beam Angle and power adaptation multi-beam spot diffusing configuration in conjunction with an imaging receiver. Our ultimate goal is to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility. A significant reduction in the Delay spread can be achieved compared to a conventional diffuse system (CDS) when an imaging receiver replaces a nonimaging receiver at the room's corner, where the Delay spread is reduced from 2.4 ns to about 0.35 ns. Our proposed system, beam Delay, Angle, and power adaptation in a line strip multibeam spot diffusing configuration (BDAPA- LSMS), offers a reduction in Delay spread by a factor of more than 10 compared with only the beam Angle and power adaptation LSMS. An increase in channel bandwidth from 36 MHz (CDS) to about 9.8 GHz can be achieved when our methods of beam Delay, Angle, and power adaptation coupled with an imaging receiver are employed. These improvements enhance our system and enable it to operate at a higher data rate of 10 Gb/s. At a bit rate of 30 Mb/s, our proposed BDAPA-LSMS achieves about 50 dB SNR gain over conventional diffuse systems that employ a nonimaging receiver (CDS). Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gb/s achieves about 32.3 dB SNR at the worst communication path under the presence of background noise and mobility while achieving a bit error rate below 10-9.

  • adaptive 10 gbit s mobile optical wireless systems employing beam Delay Angle and power adaptation with imaging receivers
    Global Communications Conference, 2011
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a novel mobile optical wireless (OW) system that employs for the first time beam Delay adaptation, and makes use of Angle and power adaptation in a line strip multibeam spot diffusing configuration in conjunction with an imaging receiver (BDAPA-LSMS). Our ultimate goal is to improve the bandwidth, reduce the effect of inter-symbol-interference (ISI), and increase the signal to noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise and mobility. An increase in channel bandwidth from 36 MHz, typical in a conventional diffuse system (CDS), to about 9.8 GHz can be achieved when our methods of beam Delay, Angle and power adaptation coupled with an imaging receiver are employed. At a bit rate of 30 Mbit/s our proposed BDAPA-LSMS achieves about 50 dB signal-to-noise ratio gain over conventional diffuse non-imaging systems. Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gbit/s achieves about 32.3 dB signal-to-noise ratio at the worst communication path in the presence of background noise and mobility thus achieving a BER below i?10i?^(-9) .

  • GLOBECOM - Adaptive 10 Gbit/s Mobile Optical Wireless Systems Employing Beam Delay, Angle and Power Adaptation with Imaging Receivers
    2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a novel mobile optical wireless (OW) system that employs for the first time beam Delay adaptation, and makes use of Angle and power adaptation in a line strip multibeam spot diffusing configuration in conjunction with an imaging receiver (BDAPA-LSMS). Our ultimate goal is to improve the bandwidth, reduce the effect of inter-symbol-interference (ISI), and increase the signal to noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise and mobility. An increase in channel bandwidth from 36 MHz, typical in a conventional diffuse system (CDS), to about 9.8 GHz can be achieved when our methods of beam Delay, Angle and power adaptation coupled with an imaging receiver are employed. At a bit rate of 30 Mbit/s our proposed BDAPA-LSMS achieves about 50 dB signal-to-noise ratio gain over conventional diffuse non-imaging systems. Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gbit/s achieves about 32.3 dB signal-to-noise ratio at the worst communication path in the presence of background noise and mobility thus achieving a BER below i?10i?^(-9) .

J.k. Chatterjee - One of the best experts on this subject based on the ideXlab platform.

  • operational capability of inductively loaded current controlled solid state lead lag var compensator
    International Journal of Electrical Power & Energy Systems, 2003
    Co-Authors: P Shadhu K Khan, J.k. Chatterjee
    Abstract:

    Abstract Operational capability of the inductively loaded current controlled solid-state lead–lag var compensator based on theoretical and experiments results for entire range of switching Delay Angle has been presented in this paper. The model is developed by deriving the mathematical equation of the input current of one of the three phases with respect to corresponding phase voltage. The Fourier analysis of the input current then gives the compensator performances such as var handling capability, magnitude of input and dc currents, etc. The operational limits of the var compensator have also been identified. The theoretical results have been verified with the experimental ones. The effects of energy storage and other circuit elements on the var compensator capability can also be studied from this model and hence the design of the compensator becomes simple.

  • Transient performance of unregulated prime mover driven stand alone self-excited induction generator with solid-state lead-lag VAr compensator
    2000 TENCON Proceedings. Intelligent Systems and Technologies for the New Millennium (Cat. No.00CH37119), 1
    Co-Authors: P.k.s. Khan, J.k. Chatterjee, M.a. Salam, H. Ahmad
    Abstract:

    In this paper, the transient behaviour of the integrated system of stand-alone SEIG and inductively loaded current controlled solid-state (ICSL) VAr compensator has been carried out when the system is subjected to different dynamic conditions. The SEIG is considered to be driven by an unregulated micro-hydro turbine in constant water head. An analytical transient model for the system has been developed. Waveforms of the voltage build up due to self excitation of the generator at specific switching Delay Angle of the compensator, output terminal voltage, currents etc. due to perturbations in load and switching Delay Angle of the compensator and the overload condition of the generator have been analysed to bring out the special features of the integrated system under transient condition.

Ahmed F. Bendary - One of the best experts on this subject based on the ideXlab platform.

  • Elephant herding algorithm-based optimal PI controller for LVRT enhancement of wind energy conversion systems
    Ain Shams Engineering Journal, 2021
    Co-Authors: M.f. El-naggar, Mohamed I. Mosaad, Hany M. Hasanien, Tarek A. Abdulfattah, Ahmed F. Bendary
    Abstract:

    Abstract This article introduces an optimal PI controller optimized by elephant herding algorithm (EHA) to control the grid-tied four-phase 8/6 switched reluctance generator (SRG). This controller is introduced for enhancing the low voltage ride through (LVRT) capability of the grid-tied SRG during faulty conditions that affect the SRG output voltage by regulating the off-Delay Angle of the generator. These faulty conditions include faults taken place at the point of connection (POC) of the SRG to the grid and wind speed variations. The proposed optimized PI controller regulates the off-Delay Angle of the generator to keep the voltage at the POC within acceptable limits. Maintaining these acceptable voltage limits during faulty conditions that keeps the generator in connection to the grid and makes the generator complying with the grid codes. Comparison between EHA optimization technique, cuckoo search optimization and particle swarm optimization (PSO) were presented to illustrate the effectiveness of the modern optimization technique used, EHA. An experimental verification of the proposed system is introduced by rewinding the stator and reshaping the rotor of three-phase induction machine to form four-phase, 8/6 SRG. Finite element method (FEM) based on ANSYS software is utilized to get the magnetic characteristics of the reconstructed 8/6 SRG after drawing the 3-D geometrical dimension in AUTOCAD.

Mohammed Thamer Alresheedi - One of the best experts on this subject based on the ideXlab platform.

  • Hologram selection in realistic indoor optical wireless systems with Angle diversity receivers
    IEEE OSA Journal of Optical Communications and Networking, 2015
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we introduce a new adaptive optical wireless system that employs a finite vocabulary of stored holograms. We propose a fast Delay, Angle, and power adaptive holograms (FDAPA-Holograms) approach based on a divide and conquer (D&C) methodology and evaluate it with Angle diversity receivers in a mobile optical wireless system. The ultimate goal is to increase the signal-to-noise ratio (SNR), reduce the effect of intersymbol interference, and eliminate the need to calculate the hologram at each transmitter and receiver location. A significant improvement is achieved in the presence of demanding background illumination noise, receiver noise, multipath propagation, mobility, and shadowing typical in a realistic indoor environment. The combination of beam Delay, Angle, and power adaptation offers additional degrees of freedom in the link design, resulting in a system that is able to achieve higher data rates (5 Gb/s). At a higher data rate of 5 Gb/s and under eye safety regulations, the proposed FDAPA-Holograms system offers around 13 dB SNR with full mobility in a realistic environment where shadowing exists. The fast search algorithm introduced that is based on a D&C algorithm reduces the computation time required to identify the optimum hologram. Simulation results show that the proposed system, FDAPA-Holograms, can reduce the time required to identify the optimum hologram position from 64 ms taken by a classic adaptive hologram to about 14 ms.

  • 10 gb s indoor optical wireless systems employing beam Delay power and Angle adaptation methods with imaging detection
    Journal of Lightwave Technology, 2012
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a mobile optical wireless system that employs beam Delay adaptation, and makes use of our previously introduced beam Angle and power adaptation multi-beam spot diffusing configuration in conjunction with an imaging receiver. Our ultimate goal is to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility. A significant reduction in the Delay spread can be achieved compared to a conventional diffuse system (CDS) when an imaging receiver replaces a nonimaging receiver at the room's corner, where the Delay spread is reduced from 2.4 ns to about 0.35 ns. Our proposed system, beam Delay, Angle, and power adaptation in a line strip multibeam spot diffusing configuration (BDAPA- LSMS), offers a reduction in Delay spread by a factor of more than 10 compared with only the beam Angle and power adaptation LSMS. An increase in channel bandwidth from 36 MHz (CDS) to about 9.8 GHz can be achieved when our methods of beam Delay, Angle, and power adaptation coupled with an imaging receiver are employed. These improvements enhance our system and enable it to operate at a higher data rate of 10 Gb/s. At a bit rate of 30 Mb/s, our proposed BDAPA-LSMS achieves about 50 dB SNR gain over conventional diffuse systems that employ a nonimaging receiver (CDS). Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gb/s achieves about 32.3 dB SNR at the worst communication path under the presence of background noise and mobility while achieving a bit error rate below 10-9.

  • adaptive 10 gbit s mobile optical wireless systems employing beam Delay Angle and power adaptation with imaging receivers
    Global Communications Conference, 2011
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a novel mobile optical wireless (OW) system that employs for the first time beam Delay adaptation, and makes use of Angle and power adaptation in a line strip multibeam spot diffusing configuration in conjunction with an imaging receiver (BDAPA-LSMS). Our ultimate goal is to improve the bandwidth, reduce the effect of inter-symbol-interference (ISI), and increase the signal to noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise and mobility. An increase in channel bandwidth from 36 MHz, typical in a conventional diffuse system (CDS), to about 9.8 GHz can be achieved when our methods of beam Delay, Angle and power adaptation coupled with an imaging receiver are employed. At a bit rate of 30 Mbit/s our proposed BDAPA-LSMS achieves about 50 dB signal-to-noise ratio gain over conventional diffuse non-imaging systems. Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gbit/s achieves about 32.3 dB signal-to-noise ratio at the worst communication path in the presence of background noise and mobility thus achieving a BER below i?10i?^(-9) .

  • GLOBECOM - Adaptive 10 Gbit/s Mobile Optical Wireless Systems Employing Beam Delay, Angle and Power Adaptation with Imaging Receivers
    2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011
    Co-Authors: Mohammed Thamer Alresheedi, Jaafar M H Elmirghani
    Abstract:

    In this paper, we propose a novel mobile optical wireless (OW) system that employs for the first time beam Delay adaptation, and makes use of Angle and power adaptation in a line strip multibeam spot diffusing configuration in conjunction with an imaging receiver (BDAPA-LSMS). Our ultimate goal is to improve the bandwidth, reduce the effect of inter-symbol-interference (ISI), and increase the signal to noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise and mobility. An increase in channel bandwidth from 36 MHz, typical in a conventional diffuse system (CDS), to about 9.8 GHz can be achieved when our methods of beam Delay, Angle and power adaptation coupled with an imaging receiver are employed. At a bit rate of 30 Mbit/s our proposed BDAPA-LSMS achieves about 50 dB signal-to-noise ratio gain over conventional diffuse non-imaging systems. Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gbit/s achieves about 32.3 dB signal-to-noise ratio at the worst communication path in the presence of background noise and mobility thus achieving a BER below i?10i?^(-9) .

Remun Koirala - One of the best experts on this subject based on the ideXlab platform.

  • localization and throughput trade off in a multi user multi carrier mm wave system
    IEEE Access, 2019
    Co-Authors: Remun Koirala, Benoit Denis, Bernard Uguen, Davide Dardari, Henk Wymeersch
    Abstract:

    In this paper, we propose various localization error optimal beamforming strategies and subsequently study the trade-off between data and localization services while budgeting time and frequency resources in a multi-user millimeter-wave framework. Allocating more resources for the data service phase instead of localization would imply higher data rate but, concurrently, also a higher position and orientation estimation error. In order to characterize this trade-off, we firstly derive a flexible application-dependent localization error cost function combining the Cramer-Rao lower bounds of Delay, Angle of departure and/or Angle of arrival estimates at a mobile receiver over the downlink. Consequently we devise different fairness criteria based localization error optimal beamforming strategies in a multi-user context. Finally, we show the advantage of the latter beamforming strategies and assess the communication-localization trade-off with respect to various time-frequency resource division schemes.

  • Localization Optimal Multi-user Beamforming with multi-carrier mmWave MIMO
    2018
    Co-Authors: Remun Koirala, Benoit Denis, Bernard Uguen, Davide Dardari, Henk Wymeersch
    Abstract:

    In this paper, we propose optimal beamforming strategies for a millimeter wave (mmWave) system consisting of multiple users based on the localization performance bounds. We consider a single base station (BS) with prior coarse knowledge of the users' positions and formulate the optimal beamforming problem in order to minimize the localization error consisting of Cramer Rao Lower Bounds (CRLBs) of Delay, Angle of departure (AoD) and Angle of arrival (AoA) estimation at the mobile users. We first formulate the simplified CRLB of estimation parameters, taking advantage of multiple sub-carriers, and then formulate the localization error for optimization of the beamformer. Finally, we evaluate the resulting position and orientation error bounds after optimization for several fairness strategies through Monte Carlo simulations.