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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

JOINT INTERFERENCE SUPPRESSION AND QRD-M DETECTION FOR SPATIAL MULTIPLEXING MIMO SYSTEMS IN A RAYLEIGH FADING CHANNEL

Tsai, Chiou-Wei, Cagley, Richard E., Iltis, Ronald A. 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / Spatial multiplexing (SM) systems have received significant attention because the architecture offers high spectral efficiency. However, relatively little research exists on optimization of SM systems in the presence of jamming. In a spatially uncoded SM system, such as V-BLAST, the channel state information is assumed to be unavailable a priori at both transmitter and receiver. Here, Kalman filtering is used to estimate the Rayleigh fading channel at the receiver. The spatial correlation of the jammer plus noise is also estimated, and spatial whitening to reject the jammers is employed in both the Kalman channel estimator and detector. To avoid the exponential complexity of maximum-likelihood (ML) detection, the QRD-M algorithm is employed. In contrast to sphere decoding, QRD-M has fixed decoding complexity of order O(M), and is thus attractive for hardware implementation. The performance of the joint Kalman filter channel estimator, spatial whitener and QRD-M detector is verfied by simulations.
2

Compensation For Gain/Phase Imbalance And DC Offset At Quadrature Modulator And Demodulator With Adaptive Inverse QRD-RLS Algorithm

Huang, Chun-Ying 08 July 2002 (has links)
There has been much effort in new design for transceiver used in mobile communications. The general approach is to combine RF functions with DSP to allow linear modulation techniques and permit flexibility of modulation format and receiver processing. In practice, with the quadrature modulation technique there is always some imbalance between the I- and Q channels of modulator and demodulator. This is mainly due to finite tolerances of capacitor and resistor values used to implement the analog components. The unavoidable imbalance between the I- and Q channels is known to degrade the performance of quadrature communication system. The main concern of this thesis is to propose a new blind scheme and with fast convergence algorithm, such as the inverse QRD-RLS algorithm, to deal with the problem described above for compensation in the transmitter and receiver. First, for the transmitter, the so-called adaptive estimation and compensation with power measurement implemented by the inverse QRD-RLS algorithm is employed. While in the receiver, a new blind adaptive filtering approach of the nonlinear parameters estimation and compensation, along with the power measurement in the receiver, is devised to adaptively compensate for the gain/phase imbalance and DC offsets in a quadrature demodulator. Where the conventional inverse QRD-RLS algorithm is employed for estimating the parameters of compensator, without using any reference signal transmitted from the transmitter. To document the merits of the proposed scheme, computer simulation for the coherent 16-PSK-communication system is carried out. With our proposed method a great improvement for eliminating the effects of the imbalance and offset over the existing techniques has verified. It has rapidly convergence rate and the smaller mean square error in steady state.
3

Accelerator for Flexible QR Decomposition and Back Substitution

January 2020 (has links)
abstract: QR decomposition (QRD) of a matrix is one of the most common linear algebra operationsused for the decomposition of a square/non-square matrix. It has a wide range of applications especially in Multiple Input-Multiple Output (MIMO) communication systems. Unfortunately it has high computation complexity { for matrix size of nxn, QRD has O(n3) complexity and back substitution, which is used to solve a system of linear equations, has O(n2) complexity. Thus, as the matrix size increases, the hardware resource requirement for QRD and back substitution increases signicantly. This thesis presents the design and implementation of a exible QRD and back substitution accelerator using a folded architecture. It can support matrix sizes of 4x4, 8x8, 12x12, 16x16, and 20x20 with low hardware resource requirement. The proposed architecture is based on the systolic array implementation of the Givens algorithm for QRD. It is built with three dierent types of computation blocks which are connected in a 2-D array structure. These blocks are controlled by a scheduler which facilitates reusability of the blocks to perform computation for any input matrix size which is a multiple of 4. These blocks are designed using two basic programming elements which support both the forward and backward paths to compute matrix R in QRD and column-matrix X in back substitution computation. The proposed architecture has been mapped to Xilinx Zynq Ultrascale+ FPGA (Field Programmable Gate Array), ZCU102. All inputs are complex with precision of 40 bits (38 fractional bits and 1 signed bit). The architecture can be clocked at 50 MHz. The synthesis results of the folded architecture for dierent matrix sizes are presented. The results show that the folded architecture can support QRD and back substitution for inputs of large sizes which otherwise cannot t on an FPGA when implemented using a at architecture. The memory sizes required for dierent matrix sizes are also presented. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2020
4

Linear Algebra for Array Signal Processing on a Massively Parallel Dataflow Architecture

Savaş, Süleyman January 2009 (has links)
This thesis provides the deliberations about the implementation of Gentleman-Kung systolic array for QR decomposition using Givens Rotations within the context of radar signal processing. The systolic array of Givens Rotations is implemented and analysed using a massively parallel processor array (MPPA), Ambric Am2045. The tools that are dedicated to the MPPA are tested in terms of engineering efficiency. aDesigner, which is built on eclipse environment, is used for programming, simulating and performance analysing. aDesigner has been produced for Ambric chip family. 2 parallel matrix multiplications have been implemented to get familiar with the architecture and tools. Moreover different sized systolic arrays are implemented and compared with each other. For programming, ajava and astruct languages are provided. However floating point numbers are not supported by the provided languages. Thus fixed point arithmetic is used in systolic array implementation of Givens Rotations. Stable and precise numerical results are obtained as outputs of the algorithms. However the analysis results are not reliable because of the performance analysis tools.
5

Linear Algebra for Array Signal Processing on a Massively Parallel Dataflow Architecture

Savaş, Süleyman January 2008 (has links)
<p>This thesis provides the deliberations about the implementation of Gentleman-Kung systolic array for QR decomposition using Givens Rotations within the context of radar signal </p><p>processing. The systolic array of Givens Rotations is implemented and analysed using a massively parallel processor array (MPPA), Ambric Am2045. The tools that are dedicated to the MPPA are tested in terms of engineering efficiency. aDesigner, which is built on eclipse environment, is used for programming, simulating and performance analysing. aDesigner has been produced for Ambric chip family. 2 parallel matrix multiplications have been implemented </p><p>to get familiar with the architecture and tools. Moreover different sized systolic arrays are implemented and compared with each other. For programming, ajava and astruct languages are provided. However floating point numbers are not supported by the provided languages. </p><p>Thus fixed point arithmetic is used in systolic array implementation of Givens Rotations. Stable and precise numerical results are obtained as outputs of the algorithms. However the analysis </p><p>results are not reliable because of the performance analysis tools.</p>
6

Linear Algebra for Array Signal Processing on a Massively Parallel Dataflow Architecture

Savaş, Süleyman January 2009 (has links)
<p>This thesis provides the deliberations about the implementation of Gentleman-Kung systolic array for QR decomposition using Givens Rotations within the context of radar signal processing. The systolic array of Givens Rotations is implemented and analysed using a massively parallel processor array (MPPA), Ambric Am2045. The tools that are dedicated to the MPPA are tested in terms of engineering efficiency. aDesigner, which is built on eclipse environment, is used for programming, simulating and performance analysing. aDesigner has been produced for Ambric chip family. 2 parallel matrix multiplications have been implemented to get familiar with the architecture and tools. Moreover different sized systolic arrays are implemented and compared with each other. For programming, ajava and astruct languages are provided. However floating point numbers are not supported by the provided languages. Thus fixed point arithmetic is used in systolic array implementation of Givens Rotations. Stable </p><p>and precise numerical results are obtained as outputs of the algorithms. However the analysis results are not reliable because of the performance analysis tools.</p>
7

Linearly Constrained Constant Modulus Inverse QRD-RLS Algorithm for Modified Gaussian Wavelet-Based MC-CDMA Receiver

Yu, Hung-ming 13 February 2007 (has links)
In this thesis, the problem of multiple access interference (MAI) suppression for the multi-carrier (MC) code division multiple access (CDMA) system, based on the multi-carrier modulation with modified Gaussian wavelet, associated with the combining process is investigated for Rayleigh fading channel. The main concern of this thesis is to derive a new scheme, based on the linearly constrained constant modulus (LCCM) criterion with the robust inverse QR decomposition (IQRD) recursive least squares (RLS) algorithm to improve the performance of the wavelet-based MC-CDMA system with combining process. To verify the merits of the new algorithm, the effect due to imperfect channel parameters estimation and near-far effect are investigated. We show that the proposed robust LCCM IQRD-RLS algorithm outperforms the conventional LCCM-gradient algorithm, in terms of output SINR, for MAI suppression under channel mismatch environment. Also, the performance of the modified Gaussian wavelet-based MC-CDMA system is superior to the one with wavelet-based MC-CDMA system. It is more robust to the channel mismatch and near-far effect. Moreover, the modified Gaussian wavelet-based MC-CDMA system with robust LCCM IQRD-RLS algorithm does have better performance over other conventional approaches, such as the LCCM-gradient algorithm, maximum ratio combining (MRC), and blind adaptation algorithm, in terms of the capability of MAI suppression and bit error rate (BER).
8

Návrh a měření parametrů akustických difúzních prvků / Design and Measurement of Parameters of Acoustic Diffusors

Burda, Jan January 2018 (has links)
This work focuses on the issue of acoustic diffusers. The introductory chapter describes the necessary theory of the sound distribution through enclosed space. Acoustic fields are also described. A description of the different diffusion element types and theirs design methods follows. It focuses mainly on design, which uses pseudo-random mathematical sequences. The aim of the work is to produce several types of acoustic diffusors and to verify their diffusion properties by means of measurements. The work uses the AFMG Reflex to simulate the diffusion properties of the proposed elements. Further, the thesis contains a description of the diffusion properties measurement process by the boundary plane method and the process of evaluating the measured data using the Matlab program.

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