The Experts below are selected from a list of 205263 Experts worldwide ranked by ideXlab platform

Daniel C. Kilper - One of the best experts on this subject based on the ideXlab platform.

  • edfa wavelength dependent gain spectrum measurement using weak optical probe sampling
    IEEE Photonics Technology Letters, 2018
    Co-Authors: Shengxiang Zhu, Daniel C. Kilper
    Abstract:

    Wavelength dependent gain is a critical parameter in erbium-doped fiber amplifiers and is the primary determinant of the Channel Power divergence and excursions in optical transmission systems, each of which varies with Channel loading in wavelength-division-multiplexed (WDM) systems. In an optical transmission system, measurements of the wavelength dependent gain between two locations can be used to obtain estimates of optical Power excursions that occur in optical circuit switching. Non-intrusive sampling of just 10% of the WDM Channel positions using weak probe signals achieves less than 0.15 dB error for the gain spectrum estimation of the amplifier with 5 dB tilt. In a two-span node-to-node network with a 3 dB peak-to-peak Channel Power difference, the weak probe approach further shows to provide less than 0.2 dB error in optical Channel Power excursion prediction for changes in Channel loading.

  • Channel Power excursions in gmpls end to end optical restoration with single step wavelength tuning
    Optical Fiber Communication Conference, 2012
    Co-Authors: Yan Pan, Daniel C. Kilper, Annalisa Morea, J Junio, Vincent W S Chan
    Abstract:

    Power excursions resulting from SRS tilt-induced coupling created >3dB excursion in simulations of GMPLS end-to-end restoration on a continental scale network and the impact of wavelength dependent gain is investigated for different add Channel combinations.

  • Channel Power transients in erbium doped fiber amplified reconfigurable transmission systems
    Bell Labs Technical Journal, 2010
    Co-Authors: Daniel C. Kilper, Christopher A. White, S. Chandrasekhar, Bruno Lavigne
    Abstract:

    The potential for transient optical Power excursions to disrupt transmission is well established in transparent wavelength division multiplexed systems. This paper will describe experiments that examine the evolution of such excursions in erbium doped fiber amplifier based systems with reconfigured Channel assignment at transparent nodes along the propagation path. The primary physical effects that couple excursions between different Channels will be identified and characterized in terms of the Channel loading, distance, time, and radio frequency (RF) dependence. e 2010 Alcatel-Lucent.

  • Control of Channel Power Instabilities in Constant-Gain Amplified Transparent Networks Using Scalable Mesh Scheduling
    Journal of Lightwave Technology, 2008
    Co-Authors: Daniel C. Kilper, Christopher A. White, S. Chandrasekhar
    Abstract:

    Experiments on a transparent, constant-gain-controlled amplifier ring network show that Channel-Power coupling can lead to instability in Channel Power control at add drop nodes. This instability can cause Power oscillations due to competing adjustments on multiple nodes. Sequencing Channel Power tuning on each node is shown to result in stable Power control. A distributed node scheduling algorithm that dynamically defines domains for independent node control is demonstrated through network simulations.

  • transient gain dynamics of cascaded erbium doped fiber amplifiers with re configured Channel loading
    Optical Fiber Communication Conference, 2006
    Co-Authors: Daniel C. Kilper, S. Chandrasekhar, Christopher A. White
    Abstract:

    Wavelength-division-multiplexed Channel Power transients are examined in cascaded EDFAs with variable pre-transient Channel loading through the chain. We identify different orders of transient events and characterize their uncontrolled time response and steady-state Power excursions.

Robert J. Marks - One of the best experts on this subject based on the ideXlab platform.

  • fast simultaneous optimization of Power amplifier input Power and load impedance for Power added efficiency and adjacent Channel Power ratio using the Power smith tube
    IEEE Transactions on Aerospace and Electronic Systems, 2016
    Co-Authors: Joseph Barkate, Matthew Fellows, Jennifer Barlow, Charles Baylis, Matthew Flachsbart, Zachary Hays, Lawrence Cohen, Robert J. Marks
    Abstract:

    Reconfigurable adaptive amplifiers are expected to be a critical component of future adaptive and cognitive radar transmitters. This paper details an algorithm to simultaneously optimize input Power and load reflection coefficient of a Power amplifier device to obtain the largest Power-added efficiency (PAE) possible under a predefined constraint on adjacent-Channel Power ratio (ACPR). The vector-based search relies on estimation of the PAE and ACPR gradients in the three-dimensional Power Smith tube. Accurate convergence to the optimum impedance in the Smith chart is demonstrated in simulation and measurement search experiments requiring between 20 and 60 experimental queries. This paper presents a fast search to jointly optimize the input Power level and load impedance. This method is feasible for future implementation in real-time reconfigurable Power amplifiers.

  • fast momentum aided optimization of transmitter amplifier load impedance and input Power for cognitive radio using the Power smith tube
    Radio and Wireless Symposium, 2016
    Co-Authors: Joseph Barkate, Matthew Fellows, Charles Baylis, Matthew Flachsbart, Lawrence Cohen, Alexander Tsatsoulas, Robert J. Marks
    Abstract:

    A fast search including momentum is used to quickly and simultaneously optimize Power-amplifier load impedance and input Power for the highest Power-added efficiency while maintaining adjacent-Channel Power ratio within compliance limits. This search makes use of the recently developed Power Smith Tube, and is expected to be useful in real-time reconfigurable communications and radar transmitters, as well as for fast computer and measurement aided design of Power amplifiers. Simulation and measurement results are shown to demonstrate the improved accuracy provided by adding momentum to the search.

  • the Power smith tube joint optimization of Power amplifier input Power and load impedance for Power added efficiency and adjacent Channel Power ratio
    Wireless and Microwave Technology Conference, 2015
    Co-Authors: Joseph Barkate, Matthew Fellows, Jennifer Barlow, Charles Baylis, Robert J. Marks
    Abstract:

    A new visualization tool for design is introduced: the Power Smith Tube. It provides aid in designing for optimum Power-added efficiency (PAE) while meeting adjacent-Channel Power ratio (ACPR) requirements. The Power Smith Tube is a three-dimensional cylindrical extension of the Smith Chart with input Power as the vertical axis. As such, this Smith Tube allows the visualization of design metrics, such as PAE and ACPR, as a function of both input Power and load impedance. Performance of load-pull measurements or simulations at multiple values of input Power provides data for the design. Design examples using the Power Smith Tube based on both simulation and measurement data are presented to demonstrate selection of load impedance and input Power providing the highest PAE under ACPR constraints.

  • the smith tube selection of radar chirp waveform bandwidth and Power amplifier load impedance using multiple bandwidth load pull measurements
    Wireless and Microwave Technology Conference, 2014
    Co-Authors: Matthew Fellows, Jennifer Barlow, Charles Baylis, Matthew Flachsbart, Robert J. Marks
    Abstract:

    The operation of a radar system requires a trade-off between detection capabilities, Power efficiency, and adjacent Channel Power minimization. Specifically, wide signal bandwidth is important for range detection. This paper presents how load-pull data taken for multiple linear frequency-modulated chirp waveforms with different bandwidths can be used to select the chirp waveform with the largest bandwidth possible, while meeting adjacent-Channel Power ratio and Power-added efficiency requirements. This approach utilizes plots of adjacent-Channel Power ratio and Power-added efficiency surfaces within a Smith tube, a three-dimensional, cylindrical extrapolation of the traditional Smith chart. A measurement example is given to illustrate the design approach. This approach will be useful in the design of range radars, and also is likely to find use in enabling real-time reconfiguration of future radars for varying spectral environments and efficiency requirements.

  • Direct algorithm for the Pareto load-pull optimisation of Power-added efficiency and adjacent-Channel Power ratio
    IET Radar Sonar & Navigation, 2014
    Co-Authors: Matthew Fellows, Charles Baylis, Lawrence Cohen, Joshua Martin, Robert J. Marks
    Abstract:

    Adaptive radar systems will be required to operate in different frequency bands with spectrum requirements that will likely change both in time and with geographic region. A new algorithm is presented that allows direct optimisation of an amplifier's load reflection coefficient to find a Pareto optimum between the Power-added efficiency (PAE) and adjacent-Channel Power ratio. Comparisons of simulation and measurement results are presented. The new algorithm's results compare well with traditionally acquired data and show consistency between the optimum values for PAE that are obtained from different starting points. Measurement comparison is performed with the previous optimisation algorithm reported by the authors, and results show that up to a 50% reduction in the number of measured experimental queries can be obtained. This translates into a significant time savings in reconfiguring a radar transmitter Power amplifier.

Monika Pinchas - One of the best experts on this subject based on the ideXlab platform.

  • a novel expression for the achievable mse performance obtained by blind adaptive equalizers
    Signal Image and Video Processing, 2013
    Co-Authors: Monika Pinchas
    Abstract:

    In this paper, I propose for the noisy, real, and two independent quadrature carrier case, an approximated closed-form expression for the achievable minimum mean square error (MSE) performance obtained by blind equalizers where the error that is fed into the adaptive mechanism which updates the equalizer’s taps can be expressed as a polynomial function of the equalized output of order three like in Godard’s algorithm. The proposed closed-form expression for the achievable MSE is based on the step-size parameter, on the equalizer’s tap length, on the Channel Power, on the signal to noise ratio (SNR), on the nature of the chosen equalizer, and on the input signal statistics. Since the Channel Power is measurable or can be calculated if the Channel coefficients are given, there is no need anymore to carry out any simulation with various step-size parameters, different values for the signal to noise ratio (SNR) and equalizer’s tap length for a given equalization method, and input signal statistics in order to find the MSE performance in the convergence state.

  • a closed form approximated expression for the achievable residual isi obtained by blind adaptive equalizers in a simo fir Channel
    IEEE Convention of Electrical and Electronics Engineers in Israel, 2012
    Co-Authors: Monika Pinchas
    Abstract:

    Recently, a closed-form approximated expression was derived by the same author for the achievable residual intersymbol interference (ISI) for the single-input single-output (SISO) case that depends on the step-size parameter, equalizer's tap length, input signal statistics, signal to noise ratio (SNR) and Channel Power. But, this expression is not valid for the single-input multiple-output (SIMO) case. In this paper, a closed-form approximated expression is derived for the achievable residual ISI for the SIMO case that depends on the step-size parameter, equalizer's tap length, input signal statistics, Channel Power, SNR and number of receive antennas. Since the Channel Power is measurable or can be calculated if the Channel coefficients are given, there is no need anymore to carry out any simulation with various step-size parameters in order to reach the required residual ISI.

  • a new closed approximated formed expression for the achievable residual isi obtained by adaptive blind equalizers for the noisy case
    Wireless Communications Networking and Information Security, 2010
    Co-Authors: Monika Pinchas
    Abstract:

    Recently, a closed approximated formed expression was derived by the same author for the achievable residual intersymbol interference (ISI) for the noiseless case that depends on the step-size parameter, equalizer's tap length, input signal statistics and Channel Power. This approximated expression is applicable for type of blind equalizers where the error that is fed into the adaptive mechanism which updates the equalizer's taps can be expressed as a polynomial function of the equalized output. It should be pointed out that Godard's algorithm for example, belongs to the mentioned type of blind equalizers. As mentioned before, this expression was derived for the noiseless case, thus can not be helpful for the wireless case where the expected signal to noise ratio (SNR) may have values down to 10 dB. In this paper, a closed approximated formed expression is derived for the achievable residual ISI that depends on the step-size parameter, equalizer's tap length, input signal statistics, Channel Power and on the SNR. Since the Channel Power is measurable or can be calculated if the Channel coefficients are given, there is no need anymore to carry out any simulation with various step-size parameters and different values for the SNR in order to reach the required residual ISI.

  • a closed approximated formed expression for the achievable residual intersymbol interference obtained by blind equalizers
    Signal Processing, 2010
    Co-Authors: Monika Pinchas
    Abstract:

    In this paper I propose for the noiseless, real and independent quadrature carrier case a closed approximated formed expression for the achievable residual intersymbol interference (ISI) that depends on the step-size parameter, equalizer's tap length, input signal statistics and Channel Power. In addition, a new closed formed approximated expression is proposed for the above mentioned case, that indicates if the chosen blind equalization method leads to perfect equalization performance from the residual ISI point of view. This new approximated expression can be a useful tool for equalization performance comparison between blind equalizers. Since the Channel Power is measurable or can be calculated if the Channel coefficients are given, there is no need anymore to carry out any simulation with various step-size parameters in order to reach the required residual ISI. The new approximated expression for the residual ISI is applicable for type of blind equalizers where the error that is fed into the adaptive mechanism which updates the equalizer's taps can be expressed as a polynomial function of the equalized output. It should be pointed out that Godard's algorithm for example, belongs to the mentioned type of blind equalizers.

David W Boertjes - One of the best experts on this subject based on the ideXlab platform.

  • Channel Power optimization of wdm systems following gaussian noise nonlinearity model in presence of stimulated raman scattering
    Journal of Lightwave Technology, 2017
    Co-Authors: Ian Roberts, Joseph M Kahn, James Harley, David W Boertjes
    Abstract:

    The impact of interChannel stimulated Raman scattering (SRS) on optimization of Channel Powers to maximize the minimum Channel margin is examined using a discrete Gaussian noise model for the Kerr nonlinearity. The simultaneous consideration of these two nonlinear effects is found to be incompatible with the goal of a convex SNR expression that can be optimized globally. A sequence of convex optimizations is employed to obtain a locally optimal solution, along with a bound on the degree of suboptimality. Optimization results obtained are most accurate for Gaussian-distributed signals, such as probabilistically shaped high-order-modulated signals. In a dispersion-uncompensated 4000-km fiber system utilizing the full C -band with perfect per-span SRS gain compensation, Power optimization yields benefits of 0.25 to 2 dB over optimal spectrally flat Power allocations. In systems including both C- and L -band, an optimization method that accounts for both SRS and Kerr nonlinearity effects provides a 0.23 to 0.60 dB margin benefit over a method compensating for SRS gain alone. In a system spanning only the C -band, per-span SRS gain compensation is not critical, as the maximum benefit is a 0.14 dB gain in minimum margin for optimized Power allocations. By contrast, in a system spanning both C- and L -band, per-span SRS gain compensation provides a gain of up to 1.23 dB with optimized Power allocations and larger gains with suboptimal Power allocations.

  • convex Channel Power optimization in nonlinear wdm systems using gaussian noise model
    Journal of Lightwave Technology, 2016
    Co-Authors: Ian Roberts, Joseph M Kahn, David W Boertjes
    Abstract:

    Optimization of Channel Powers to maximize minimum margin or total capacity in WDM systems is studied. Using a Gaussian noise nonlinearity model, the signal-to-noise ratio (SNR) in each Channel is expressed as a convex function of the Channel Powers. Using the SNR expression, convex optimization problems with objectives of maximizing the minimum Channel margin or maximizing the fiber capacity minus a coding cap are formulated. Performance gains from software-based Power optimization are observed in mesh networks and in point-to-point links having heterogeneous SNR requirements. By contrast, in systems with uniform amplifier noise and modulation formats, the optimized Power allocation provides very little improvement over a traditional flat Power allocation. In the 14-node NSFNET network, a margin gain of 1.5 dB on average is achieved through Power optimization, as compared to a flat Power allocation. Margin gains averaging 1.4 dB are found for subsets of this network with three to 13 nodes.

S. Chandrasekhar - One of the best experts on this subject based on the ideXlab platform.