The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform

Torbjorn Wigren - One of the best experts on this subject based on the ideXlab platform.

  • Soft Uplink Load Estimation in WCDMA
    IEEE Transactions on Vehicular Technology, 2009
    Co-Authors: Torbjorn Wigren
    Abstract:

    Wideband code-division multiple-access (WCDMA) enhanced uplink (EUL) channel transmissions are typically scheduled to time intervals where the interference and load conditions of a cell are favorable-hence, load estimation is central for EUL performance. This paper first proves that the uplink load, which is expressed as the rise over Thermal (RoT), is unobservable with any linear estimation technique using measurements in a single radio base station (RBS) of (1) received total wideband Power (RTWP) and (2) cell channel Powers. A soft nonlinear Bayesian load estimator is proposed to circumvent these problems. The three-stage algorithm first estimates the RTWP, as well as residual Power consisting of the sum of the Thermal Noise floor Power and the neighbor cell interference. A time-variable Kalman estimator is used for this first step. The Thermal Noise Power is then approximated by the Bayesian conditional probability density function (pdf) of the minimum of the estimated residual Power. The 1-D conditional pdf of the RoT then follows from the quotient of two pdf's-the estimated pdf of the RTWP and the estimated conditional pdf of the Thermal Noise Power. After discretization, the optimal RoT is calculated as a conditional mean.

  • VTC Fall - Estimation of Uplink WCDMA Load in a Single RBS
    2007 IEEE 66th Vehicular Technology Conference, 2007
    Co-Authors: Torbjorn Wigren, Per Hellqvist
    Abstract:

    The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the Thermal Noise Power floor is unobservable when using Power measurements in a single base station. The problem is due to the neighbor cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered Power samples, this minimum approximating the Thermal Noise Power floor of the digital receiver. The load can then be estimated from the total wideband Power of the cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.

  • Estimation of Uplink WCDMA Load in a Single RBS
    2007 IEEE 66th Vehicular Technology Conference, 2007
    Co-Authors: Torbjorn Wigren, Per Hellqvist
    Abstract:

    The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the Thermal Noise Power floor is unobservable when using Power measurements in a single base station. The problem is due to the neighbor cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered Power samples, this minimum approximating the Thermal Noise Power floor of the digital receiver. The load can then be estimated from the total wideband Power of the cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.

Per Hellqvist - One of the best experts on this subject based on the ideXlab platform.

  • VTC Fall - Estimation of Uplink WCDMA Load in a Single RBS
    2007 IEEE 66th Vehicular Technology Conference, 2007
    Co-Authors: Torbjorn Wigren, Per Hellqvist
    Abstract:

    The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the Thermal Noise Power floor is unobservable when using Power measurements in a single base station. The problem is due to the neighbor cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered Power samples, this minimum approximating the Thermal Noise Power floor of the digital receiver. The load can then be estimated from the total wideband Power of the cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.

  • Estimation of Uplink WCDMA Load in a Single RBS
    2007 IEEE 66th Vehicular Technology Conference, 2007
    Co-Authors: Torbjorn Wigren, Per Hellqvist
    Abstract:

    The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the Thermal Noise Power floor is unobservable when using Power measurements in a single base station. The problem is due to the neighbor cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered Power samples, this minimum approximating the Thermal Noise Power floor of the digital receiver. The load can then be estimated from the total wideband Power of the cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.

Colin Lyden - One of the best experts on this subject based on the ideXlab platform.

  • Sampling Circuits That Break the kT/C Thermal Noise Limit
    IEEE Journal of Solid-State Circuits, 2014
    Co-Authors: Ron Kapusta, Colin Lyden
    Abstract:

    Several circuit-level techniques are described which are used to reduce or cancel Thermal Noise and break the so-called kT/C limit. kT/C Noise describes the total Thermal Noise Power added to a signal when a sample is taken on a capacitor. In the first proposed technique, the sampled Thermal Noise is reduced by altering the relationship between the sampling bandwidth and the dominant Noise source, providing a Powerful, new degree of freedom in circuit design. In the second proposed technique, Thermal Noise sampled on an input capacitor is actively canceled using an amplifier, so that the Noise at the amplifier output can be controlled independently of input capacitor size. Measurements from two test chips are presented which demonstrate sampled Thermal Noise Power reduction of 48% and 67%, respectively, when compared with conventional kT/C-limited sampling.

  • CICC - Sampling circuits that break the kT/C Thermal Noise limit
    Proceedings of the IEEE 2013 Custom Integrated Circuits Conference, 2013
    Co-Authors: Ron Kapusta, Colin Lyden
    Abstract:

    Several circuit-level techniques are described which are used to reduce Thermal Noise and break the so-called kT/C limit. kT/C Noise describes the total Thermal Noise Power added to a signal when a sample is taken on a capacitor. In the first proposed technique, the sampled Thermal Noise is reduced by altering the relationship between the sampling bandwidth and the dominant Noise source, providing a Powerful, new degree of freedom in circuit design. In the second proposed technique, Thermal Noise sampled on an input capacitor is actively cancelled using an amplifier, so that the Noise at the amplifier output can be controlled independently of input capacitor size. Measurements from two test chips are presented which demonstrate sampled Thermal Noise Power reduction of up to 70% when compared to conventional kT/C-limited sampling.

  • Sampling circuits that break the kT/C Thermal Noise limit
    Proceedings of the IEEE 2013 Custom Integrated Circuits Conference, 2013
    Co-Authors: Ron Kapusta, Colin Lyden
    Abstract:

    Several circuit-level techniques are described which are used to reduce Thermal Noise and break the so-called kT/C limit. kT/C Noise describes the total Thermal Noise Power added to a signal when a sample is taken on a capacitor. In the first proposed technique, the sampled Thermal Noise is reduced by altering the relationship between the sampling bandwidth and the dominant Noise source, providing a Powerful, new degree of freedom in circuit design. In the second proposed technique, Thermal Noise sampled on an input capacitor is actively cancelled using an amplifier, so that the Noise at the amplifier output can be controlled independently of input capacitor size. Measurements from two test chips are presented which demonstrate sampled Thermal Noise Power reduction of up to 70% when compared to conventional kT/C-limited sampling.

Antonia Papandreou-suppappola - One of the best experts on this subject based on the ideXlab platform.

  • Computationally Efficient Estimation of Compound K-Distribution Sea Clutter in Thermal Noise and Its Application to Sea Echo Reflectivity Observations
    IEEE Transactions on Aerospace and Electronic Systems, 2020
    Co-Authors: Judith Northrop, Antonia Papandreou-suppappola
    Abstract:

    We consider the parameter estimation of the K-plus-Noise distribution model of sea clutter intensity single-pulse observations with unknown Thermal Noise Power. We propose two methods that yield comparable estimation accuracy to existing methods while improving computational cost for real-time processing. These methods iteratively integrate one-dimensional nonlinear curve fitting with integer and fractional intensity moment computations. We provide numerically computed Cramér–Rao lower bounds for the shape estimate as a bench mark for asymptotically unbiased estimators. Performance is demonstrated using simulations and two high-resolution sea echo reflectivity datasets.

  • ACSSC - Estimation of Compound K-distribution Modeling Parameters of Sea Clutter with Unknown Thermal Noise Power
    2018 52nd Asilomar Conference on Signals Systems and Computers, 2018
    Co-Authors: Judith Northrop, Antonia Papandreou-suppappola
    Abstract:

    This paper explores a new and efficient method for estimating the parameters of the compound K-distribution model of sea clutter when the Thermal Noise Power is also unknown. Current methods for the model parameter estimation include the intensity moments approach that assumes knowledge of the Thermal Noise Power and a three-dimensional (3-D) curve fitting approach that is very computationally intensive. The proposed method integrates the intensity moments with a nonlinear one-dimensional (1-D) curve-fitting procedure to also allow for an efficient estimate of the Thermal Noise Power. It is also extended to incorporate fractional moments used under the condition of known clutter-to-Noise ratios. The performance of the new approach is demonstrated using both simulated and real sea clutter observations.

  • Estimation of Compound K-distribution Modeling Parameters of Sea Clutter with Unknown Thermal Noise Power
    2018 52nd Asilomar Conference on Signals Systems and Computers, 2018
    Co-Authors: Judith Northrop, Antonia Papandreou-suppappola
    Abstract:

    This paper explores a new and efficient method for estimating the parameters of the compound K-distribution model of sea clutter when the Thermal Noise Power is also unknown. Current methods for the model parameter estimation include the intensity moments approach that assumes knowledge of the Thermal Noise Power and a three-dimensional (3-D) curve fitting approach that is very computationally intensive. The proposed method integrates the intensity moments with a nonlinear one-dimensional (1-D) curve-fitting procedure to also allow for an efficient estimate of the Thermal Noise Power. It is also extended to incorporate fractional moments used under the condition of known clutter-to-Noise ratios. The performance of the new approach is demonstrated using both simulated and real sea clutter observations.

Snezana Krusevac - One of the best experts on this subject based on the ideXlab platform.

  • Mutual Coupling Effect on Thermal Noise in Multi-Element Antenna Systems
    Progress in Electromagnetics Research-pier, 2020
    Co-Authors: Snezana Krusevac, Predrag Rapajic, Rodney A. Kennedy
    Abstract:

    In this paper, we investigate the Thermal Noise behavior of the multi-antenna communication systems, when antenna elements are closely spaced. We analyze the mutual coupling effect on Thermal Noise. We apply the Nyquist’s Thermal Noise theorem to determine Thermal Noise Power in the multi-antenna system and to confirm the partial correlation of Thermal Noise for antenna spacing lower then one wavelength. Simulation results confirm the decrease of Thermal Noise Power level when antenna spacings drop below a half of wavelength.

  • Channel Capacity of MIMO Systems with Closely Spaced Terminated Antennas
    2007 IEEE International Symposium on Information Theory, 2007
    Co-Authors: Snezana Krusevac, Predrag Rapajic
    Abstract:

    We investigate the antenna impedance mismatching effect on Thermal Noise Power, in addition to the mutual coupling effect on signal and Noise. We provide an analysis of the channel capacity of multiple antennas terminated by three most common matching decoupling networks. We confirm that the achievable information rate of the multiple antennas terminated by self- and characteristic impedance matching network is below the information throughput that could be achieved by the multiple antennas terminated by the multi-port conjugate match. Yet the actual information rate degradation due to the imperfect matching network is lower than the case when the Noise coupling is omitted from the analysis. The result indicates on the potential of the transit output Power savings. Therefore, we suggest that the design of the matching decoupling networks should be based on the maximum signal-to-Noise ratio criteria rather than maximum achievable signal Power as both signal and Noise Powers are affected by the mutual coupling effect and consequently by antenna mismatching impedance.

  • ISSPA - SNR estimation for multi-antenna communication systems with closely spaced antenna elements
    Proceedings of the Eighth International Symposium on Signal Processing and Its Applications 2005., 2005
    Co-Authors: Snezana Krusevac, Predrag Rapajic, Rodney A. Kennedy
    Abstract:

    In this paper, we investigate the performance of the multiantenna communication systems, when antenna elements are closely spaced. We analyze the combined mutual coupling effect on both, signal and Thermal Noise. We apply the Nyquist’s Thermal Noise theorem to determine the Thermal Noise in the multi-antenna system and to confirm the partial correlation of Thermal Noise for antenna spacing lower then one wavelength. Then, we evaluate the Thermal Noise Power behavior for the coupled multi-element antenna system. Simulation results show that the signalto-Noise ratio level is underestimated if the effect of mutual coupling for Thermal Noise is not accounted for.

  • Mutual coupling effect on Thermal Noise in multi-antenna wireless communication systems
    2005 Australian Communications Theory Workshop, 2005
    Co-Authors: Snezana Krusevac, Predrag Rapajic, Rodney A. Kennedy, P. Sadeghi
    Abstract:

    This paper presents a framework for the Thermal Noise analysis of mutually-coupled antennae in the multi-antenna system. The electromagnetic coupling for Thermal Noise is included in the analysis of the multi-antenna system with small antenna element spacings. The method for Thermal Noise Power calculation for the multi-antenna system with coupled antennae is presented. The Thermal Noise behavior in the multi-antenna system is determined by applying the Nyquist's Thermal Noise theorem. The partial correlation of Thermal Noise for antenna spacing lower then a wavelength is confirmed. The signal-to-Noise ratio (SNR) for the closely spaced antennae in the multi-antenna system is then estimated, using presented method for Thermal Noise analysis. Simulation results confirm that as the antenna spacing decreases to zero, the multi-antenna system starts to act like a single antenna system