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Digital Systolic Architectures for UWB Beamforming using 2-D IIR Spatio-temporal Frequency-planar Beam Filters

Kondapalli, Soumya
http://rave.ohiolink.edu/etdc/view?acc_num=akron1376925582

Abstract Details

2013, Master of Science, University of Akron, Electrical Engineering.
A Design method and an FPGA-based prototype implementation of massively parallel systolic-array VLSI architectures for 2nd-order and 3rd-order frequency-planar plane-wave beam filters are proposed. The proposed filters work based on the principle of beamforming which selectively enhances plane-waves based on direction of arrival of the signals. Frequency-planar beamforming enables filtering highly-directional UWB RF beams at low computational complexity compared to digital phased-array feed techniques. Plane-wave filters have applications in high-speed beamforming in wireless communications at RF. The 2nd-order and 3rd-order frequency-planar beam plane-wave filters are designed to achieve higher attenuation and sharper transition between passband and stop-band of the filter. The proposed architectures operate using 2's complement finite precision digital arithmetic. The fixed-point performance of the filters is studied by calculating L2 errors for each design with respect to ideal infinite precision outputs. The realtime throughput is maximized using look-ahead optimization applied locally to each processor in the proposed massively-parallel realization of the filter. From sensitivity theory, it is shown that 15 and 19-bit precision for filter coefficients results in better than 3% error for 2nd and 3rd-order beam filters. Folding together with K-times multiplexing is applied to the proposed beam architectures such that throughput can be traded for K-fold lower complexity for realizing the 2-D fan filter banks. Prototype FPGA circuit implementations of these filters are proposed using a Virtex 6xc6vsx475t-2ff1759 device. The FPGA-prototyped architectures are evaluated using area (A), critical path delay (T), and metrics AT and AT2. The L2 errors are used as a metric for evaluating fixed-point noise levels and the accuracy of the finite precision digital arithmetic circuits. In this work, a systolic array VLSI architecture for the real-time implementation of the 2-D IIR plane-wave beam filter has also been designed by replacing unit delays along both space and time dimensions with first order discrete integrators, thereby leading to lower sensitivity to filter coefficient quantization which in turn results in improved RF beam accuracy. The proposed designs have reduced error in the magnitude transfer function compared to the usual direct-form structures. Beam filters of order 1, 2 and 3 are designed using integral-form realization. The designs show small gain magnitude error of 0.3% for 1st-order beam filter with respect to digital feedback coefficients of the filter which have been chosen at 13-bits of precision. The design examples also show a small gain magnitude error of 1.5% in a 2nd-order beam filter with filter feedback coefficients having 15-bits of precision. This is an improvement over comparable direct form architectures. Prototype circuits for the proposed integral form beam filters have been designed and simulated using Xilinx Virtex 6 xc6vsx475t-1ff1759 FPGA devices.
Arjuna Madanayake, Dr. (Advisor)
S.I. Hariharan, Dr. (Committee Member)
Kye Shin Lee, Dr. (Committee Member)
97 p.
Computer Engineering; Electrical Engineering

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Citations

  • Kondapalli, S. (2013). Digital Systolic Architectures for UWB Beamforming using 2-D IIR Spatio-temporal Frequency-planar Beam Filters [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376925582

    APA Style (7th edition)

  • Kondapalli, Soumya. Digital Systolic Architectures for UWB Beamforming using 2-D IIR Spatio-temporal Frequency-planar Beam Filters. 2013. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1376925582.

    MLA Style (8th edition)

  • Kondapalli, Soumya. "Digital Systolic Architectures for UWB Beamforming using 2-D IIR Spatio-temporal Frequency-planar Beam Filters." Master's thesis, University of Akron, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376925582

    Chicago Manual of Style (17th edition)

akron1376925582
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© 2013, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.