Optimal variable step size for the LMS/Newton algorithm withapplication to subband adaptive filtering

An efficient approach for the computation of the optimum convergence factor for the LMS (least mean square)/Newton algorithm applied to a transversal FIR structure is proposed. The approach leads to a variable step size algorithm that results in a dramatic reduction in convergence time. The algorithm is evaluated in system identification applications where two alternative implementations of the adaptive filter are considered: the conventional transversal FIR realization and adaptive filtering in subbands     

A statistical analysis of the affine projection algorithm for unity step size and autoregressive inputs

This paper presents a new statistical analysis of the affine projection (AP) algorithm. An analytical model is derived for autoregressive (AR) inputs for unity step size (fastest convergence). Deterministic recursive equations are derived for the mean AP weight and mean-square error for large values of N (the number of adaptive taps). The value of N is also assumed large compared to the algorithm order (number of input vectors used to determine the weight update direction). The model predictions display better agreement with Monte Carlo simulations in both transient and steady-state than models previously presented in the literature. The model's accuracy is sufficient for most practical design purposes.     

A least-squares parameter estimation algorithm for switched hammerstein systems with applications to the VOR

A "Multimode" or "switched" system is one that switches between various modes of operation. When a switch occurs from one mode to another, a discontinuity may result followed by a smooth evolution under the new regime. Characterizing the switching behavior of these systems is not well understood and, therefore, identification of multimode systems typically requires a preprocessing step to classify the observed data according to a mode of operation. A further consequence of the switched nature of these systems is that data available for parameter estimation of any subsystem may be inadequate. As such, identification and parameter estimation of multimode systems remains an unresolved problem. In this paper, we 1) show that the NARMAX model structure can be used to describe the impulsive-smooth behavior of switched systems, 2) propose a modified extended least squares (MELS) algorithm to estimate the coefficients of such models, and 3) demonstrate its applicability to simulated and real data from the Vestibulo-Ocular Reflex (VOR). The approach will also allow the identification of other nonlinear bio-systems, suspected of containing "hard" nonlinearities.     

Physical and Medium Access Control criteria for the optimal Medium Access Control protocol data unit size in Automatic Repeat Request‐enabled connections in IEEE 802.16e/ WiMAX systems

In this paper, we address an aspect of the mutual influence between the physical (PHY) layer budding blocks (forward error correction (FEC) blocks) and the medium access control (MAC) level allocations in the uplink and downlink of IEEE 802.16e/WiMAX systems. In these systems, it is possible to transmit MAC level frames, denoted MAC protocol data units (PDUs), such that a PDU contains an integral number of fixed size data blocks. We compute the optimal size of a PDU according to two criteria, one related to the PHY layer and one related to the MAC layer. In relation to the PHY layer, the criterion maximizes the average number of data bits that are transmitted in a PHY slot. In relation to the MAC layer, the criterion maximizes the goodput of the PDU. The goodput depends on the success probability of the PDU, which in turn depends on the FEC blocks over which the PDU is allocated. We then compare the maximal PDU goodputs in different sizes of the FEC blocks and the data blocks. The main outcome is that the PDU goodput is sensitive in those cases in which data blocks are very large. We also give guidelines on how to choose the best modulation/coding scheme to use in a scenario where the signal‐to‐noise ratio can change significantly during transmissions, to maximize the PDU goodput. Finally, we compare between the two criteria. Copyright © 2013 John Wiley & Sons, Ltd.     

An algorithm for determination of the amplitudes of external and internal waves in the case of counterpropagating waves incident on a multilayer structure with a step inhomogeneity

A simple algorithm is proposed for deriving analytic expressions for the amplitudes of reflected, transmitted, and internal waves in individual layers of a multilayer stepwise inhomogeneous structure with an arbitrary number of layers. Functioning of the algorithm is exemplified by the solution of problems of wave propagation in a stepwise inhomogeneous structure with the wave number variation along the structure’s length.     

Maximum likelihood predictive densities for the inverse Gaussian distribution with applications to reliability and lifetime predictions

Maximum likelihood predictive densities (MLPD) for the inverse Gaussian distribution are derived for the cases of one or both parameters unknown. They are then applied to obtain estimators of the reliability function and prediction or shortest prediction intervals for a future observation. Comparisons with the existing likelihood or frequentist methods show that the MLPD estimators of reliability gives smaller bias and smaller MSE for a wide range of population values, and that the MLPD prediction intervals are shorter while preserving the correct coverage probability. The shortest MLPD prediction intervals further sharpen the above equitailed MLPD intervals in terms of interval lengths.     

Compressors for combined source and channel coding with applications to the generalized Gaussian family (Corresp.)

The twin tools of asymptotic quantization theory and rate-distortion theory are used to find an expression for the approximate total mean-squared distortion of the series connection of a nonuniform quantizer and a noisy channel. The nonuniform quantizer is modeled as a compressor followed by a uniform quantizer. The approximate total mean-squared error distortion is minimized over a class of parameterized compressor characteristics for input processes whose univariate probability density functions are members of the generalized Gaussian family.     

An algorithm for calculating the lower confidence bounds of CPU and CPL with application to low-drop-out linear regulators

In assessing the performance of normal stable manufacturing processes with one-sided specification limits, process capability indices C_PU and C_PL have been widely used to measure the process capability. The purpose of this paper is to develop an algorithm to compute the lower confidence bounds on C_PU and C_PL using the UMVUEs of C_PU and C_PL. The lower confidence bound presents a measure on the minimum capability of the process based on the sample data. We also provide tables for the engineers/practitioners to use in measuring their processes. A real-world example taken from a microelectronics device manufacturing process is investigated to illustrate the applicability of the algorithm. Implementation of the existing statistical theory for capability assessment fills the gap between the theoretical development and the in-plant applications.     

Examination of the data rate obtainable with low‐gain non‐tracking antenna applied to user terminal used for mobile communications and broadcasting services provided by quasi‐zenithal satellites

Link budgets between the mobile user terminal and a feeder link station (2‐m‐diameter antenna) through the quasi‐zenithal satellite system (QZSS) (7‐m‐diameter antenna for Tx, 5‐m‐diameter antenna for Rx) under the power flux density (PFD) limit were calculated for the Ka‐ and Ku‐band. The PFD limit for non‐geostationary satellites is applied for frequency sharing between QZSS and geostationary satellites. The maximum data rate in the Ka‐band was 1.7 times higher than in the Ku‐band in the forward link, while the maximum data rate at Ku‐band is nine times higher than that in the Ka‐band in the return link when the transmit power derived from the regulations of the PFD is applied. And it is more than three times higher than that in the Ka‐band when transmit power is fixed to 2W. In the forward link, maximum data rates are 149 kbps in the Ka‐band and 86 kbps in the Ku‐band when the user terminal antenna is non‐tracking (gain at the satellite direction is 7.1 dBi) and the frequency bandwidth per beam is 30 MHz. Required bandwidth per channel for a certain data rate is large, e.g. in Ka‐band, 20.9 MHz for 64 kbps, 125 MHz for 384 kbps, and 326 MHz for 1 Mbps. In the return link, the maximum data rates are 44 kbps in the Ku‐band and 13.6 kbps in the Ka‐band when the user terminal antenna gain in the satellite direction is 7.1 dBi and transmit power is 2 W. Copyright © 2005 John Wiley & Sons, Ltd.