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SVD-updating using orthonormal μ-rotations

Journal of VLSI signal processing systems for signal, image and video technology 1996年第1期14卷 7-17页

作者： Jürgen Götze Peter Rieder Institute of Network Theory and Circuit Design Technical University of Munich Munich Germany

In this paper the implementation of the SVD-updating algorithm using orthonormal μ-rotations is presented. An orthonormal μ-rotation is a rotation by an angle of a given set of μ-rotation angles (e.g., the angles Φi = arctan2-i) which are choosen such that the rotation can be implemented by a small amount of shift-add operations. A version of the SVD-updating algorithm is used where all computations are entirely based on the evaluation and application of orthonormal rotations. Therefore, in this form the SVD-updating algorithm is amenable to an implementation using orthonormal μ-rotations, i.e., each rotation executed in the SVD-updating algorithm will be approximated by orthonormal μ-rotations. For all the approximations the same accuracy is used, i.e., onlyr≪w (w: wordlength) orthonormal μ-rotations are used to approximate the exact rotation. The rotation evaluation can also be performed by the execution of μ-rotations such that the complete SVD-updating algorithm can be expressed in terms of orthonormal μ-rotations. Simulations show the efficiency of the SVD-updating algorithm based on orthonormal μ-rotations.

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A real time downlink channel allocation scheme for an SDMA mobile radio system

A real time downlink channel allocation scheme for an SDMA m...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： C. Farsakh J.A. Nossek Institute of Network Theory and Circuit Design Technical University Munich Munich Germany

In SDMA mobile radio systems where only base stations, but no mobiles are equipped with antenna arrays, co-channel interference on the downlink has to be kept down by beamforming. The performance of the beamformer is determined by the directions of arrival (DOAs) of the users operating in the same frequency/time/code slot. Thus the full capacity of an SDMA cell can only be made use of by an effective channel allocation scheme. In this paper, a real time concept for channel allocation is presented. Furthermore, several criteria to quickly evaluate the spatial separability of subsets of users, were defined and then compared to each other by means of simulations.

关键词： Downlink Channel allocation Multiaccess communication Land mobile radio Base stations Mobile antennas Antenna arrays Interchannel interference Array signal processing Frequency

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BRASIL: the Braunschweig mixed-mode-simulator for integrated circuits

BRASIL: the Braunschweig mixed-mode-simulator for integrated...

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European design Automation Conference

作者： U. Bretthauer E.-H. Horneber Institute for Network Theory and Circuit Design Technical University of Braunschweig Brunswick Germany

BRASIL consists of a timing simulator for digital MOS circuits coupled with an algorithm for circuit simulation. The timing simulation is based upon a fast macromodelling approach and the calculation of time-variant RC networks. The circuit simulator takes advantage out of structuring the system of nodal equations. With BRASIL a fast simulation of large circuits, with special regards to systems with the need of higher accuracy, is possible.

关键词： Voltage Tin Capacitance circuits Narrowband Delay effects Inverters CMOS technology MOS devices Semiconductor device modeling

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Smooth multiwavelets based on two scaling functions

Smooth multiwavelets based on two scaling functions

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IEEE-SP International Symposium on Time-Frequency and Time-Scale Analysis

作者： P. Rieder J.A. Nossek Institute of Network Theory & Circuit Design Technical University Munich Munich Germany

In this paper new multiwavelets based on several scaling functions are designed. The resulting wavelets exhibit the following properties: compact support, symmetry and orthogonality, arbitrary approximation order as well as good frequency resolution. The new bases are quite similar to the well known splines and also have close relationships to multirate filterbanks (multiwavelets based on one scaling function). The good performance of the new wavelets with respect to the smoothness and the frequency resolution is documented. A filterbank implementation is discussed.

关键词： Discrete wavelet transforms Equations Filter bank Frequency design methodology Wavelet transforms Low pass filters Discrete transforms Artificial intelligence

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On the spatial separation potential of a uniform linear antenna array

On the spatial separation potential of a uniform linear ante...

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IEEE Conference on Vehicular Technology (VTC)

作者： C. Farsakh J.A. Nossek Institute of Network Theory and Circuit Design Technical University Munich Munich Germany

An antenna array located at the base station of a mobile radio cell allows the utilization of adaptive beamforming techniques on both uplink and downlink transmissions to significantly increase system capacity. A criterion is introduced to quantitatively evaluate the capability of an array to spatially separate users operating in the same channel. Then the dependency of this criterion on parameters like the number of antennas, the antenna spacing or the geometrical orientation of the array axis are investigated for the special case of a uniform linear antenna array (ULA).

关键词： Linear antenna arrays Base stations Multiaccess communication Antenna arrays Land mobile radio Mobile antennas Downlink Azimuth Directive antennas Transmitting antennas

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Structured least squares to improve the performance of ESPRIT-type high-resolution techniques

Structured least squares to improve the performance of ESPRI...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： M. Haardt J.A. Nossek Institute of Network Theory and Circuit Design Technical University Munich Munich Germany

ESPRIT type high-resolution (spatial) frequency estimation techniques, like standard ESPRIT, state space methods, matrix pencil methods, or Unitary ESPRIT, obtain their (spatial) frequency estimates from the solution of a highly-structured, overdetermined system of equations. Here, the structure is defined in terms of two selection matrices applied to a matrix spanning the estimated signal subspace. Structured least squares (SLS) is a new algorithm to solve this overdetermined system, the so called invariance equation, by preserving its structure. Simulations confirm that SLS outperforms the least squares (LS) and total least squares (TLS) solutions of this invariance equation, since the accuracy of the resulting (spatial) frequency estimates and the accuracy of the underlying signal subspace are improved significantly. Furthermore, SLS can be used to improve the accuracy of adaptive frequency estimating schemes that are based on fast adaptive subspace tracking techniques. Moreover, SLS has been extended to the two-dimensional (2-D) case to be used in conjunction with 2-D Unitary ESPRIT, an efficient ESPRIT-type algorithm that provides automatically paired 2-D (spatial) frequency estimates.

关键词： Least squares methods Frequency estimation Laser sintering Equations State-space methods Two dimensional displays Least squares approximation Direction of arrival estimation State estimation circuit synthesis

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CORDIC-based architectures for the efficient implementation of discrete wavelet transforms

CORDIC-based architectures for the efficient implementation ...

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IEEE International Symposium on circuits and Systems (ISCAS)

作者： S. Simon P. Rieder C. Schimpfle J.A. Nossek Institute for Network Theory and Circuit Design Technical University Munich Munich Germany

In this paper, efficient implementations of the discrete wavelet transform (DWT) are examined. A new architecture, based on single steps of the CORDIC algorithm with less operations compared to classical lattice or transversal filter structures is presented. In addition to the computational savings, a generalized implementation of a single CORDIC-based approximate rotation as a module generator is sufficient to automate the full custom layout generation of the arithmetic part of the DWT. An exemplary VLSI implementation for a typical image processing application is presented.

关键词： Discrete wavelet transforms Wavelet transforms Lattices Very large scale integration Image processing circuit synthesis Transversal filters Arithmetic Filter bank Signal analysis

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Information processing with lossless cellular neural networks

Information processing with lossless cellular neural network...

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IEEE International Workshop on Cellular Nanoscale networks and their Applications, (CNNA)

作者： J.A. Nossek Institute for Network Theory and Circuit Design Technical University Munich Munich Bavaria Germany

Summary form only given. The eigenvalues of a symmetric tridiagonal matrix can be computed via an iterative diagonalization with the aid of the QR-algorithm. Interpolating the matrices of subsequent iteration steps with continuous (time) trajectories leads to the concept of matrix flows on manifolds. This can be viewed as the transients of a nonlinear dynamical system. In the fixed point of the dynamical system, the desired eigenvalues are found. Mapping the nonlinear ODE's onto physical structures, lossless nonlinear dynamical circuits are obtained. These circuits can be interpreted as CNN's with nonlinear templates. While these lossless CNNs are interesting by themselves, the important question arises, whether a robust implementation without any power supply and, therefore, without dissipation is practically feasible indeed. Conventional realizations would necessitate (nonlinear) inductors and would not be well suited for solid state silicon implementations. Any simulation of the inductors with the aid of transistors will not alleviate the problem, because the resulting circuits will not be truly lossless any more. Future nanoscale quantum devices open up new possibilities of low loss nanoelectronic computing structures.

关键词： Information processing Cellular neural networks Symmetric matrices circuits Eigenvalues and eigenfunctions Inductors Nanoscale devices Quantum computing Nonlinear dynamical systems Robustness

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Comparison of learning algorithms for feedforward neural nets

Comparison of learning algorithms for feedforward neural net...

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IEEE International Symposium on circuits and Systems (ISCAS)

作者： J.A. Nossek P. Nachbar A.J. Schuler Institute for Network Theory and Circuit Design Technical University Munich Germany Technische Universitat Munchen Munchen Bayern DE

Several well known learning algorithms for feedforward two-layer neural nets and an improved version of Madaline I have been investigated and compared with respect to learning effort and classification capacity. These results, based on random training patterns, and their significance for generalization have been verified with real life data for ICR/OCR.

关键词： Neural networks Feedforward neural networks Backpropagation algorithms Data mining Training data Capacity planning circuit synthesis Electronic mail Optical character recognition software Supervised learning

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Lossless cellular neural networks

Lossless cellular neural networks

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IEEE International Workshop on Cellular Nanoscale networks and their Applications, (CNNA)

作者： A. Schlaffer J.A. Nossek M. Tanaka Institute for Network Theory and Circuit Design Technical University Munich Munich Germany Department of Electrical Engineering Sophia University Tokyo Japan

Since their introduction, cellular neural networks have turned out to be useful architectures for the solution of many problems, e.g. in image processing or in the simulation of partial differential equations. Therefore, there have been several attempts to introduce cell circuits suitable for large-scale integration. Up to now, all of these cells need energy and therefore power supply. Recently attempts have been made to build up circuitry able to work without an external energy supply by using the energy stored in the initial state. This principle can provide two major advantages. First, since no or at least not much energy is dissipated during computation, the circuit does not produce much heat. Therefore, there are no "hot spots" in integrated circuits, which limit integration density and operation speed. Furthermore, since there is no need for a power supply, the absence of voltage supply lines supports a high integration density. In this work an architecture for the realisation of a lossless CNN is proposed. Further, since standard learning algorithms turn out to fail for lossless systems, a way to amend these is introduced.

关键词： Cellular neural networks Differential equations Electronic mail Power supplies Coupling circuits Jacobian matrices circuit synthesis Image processing circuit simulation Large scale integration

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