Department Publications

This paper presents the design, implementation, and the experimental verifications of a 2.4-GHz multibeam array receiver based on two-dimensional (2-D) spatially bandpass (SBP) digital plane wave (PW) filters. The digital array receiver consists of 2.4-GHz 16-element uniform linear array, and quadrature sampling is employed to process the broadband PWs at the baseband. Both 2-D finite impulse response (FIR) and infinite impulse response (IIR) digital filters having multiple trapezoidal-shaped passbands are employed as the 2-D SBP digital PW filters. Both 2-D FIR and IIR trapezoidal filters are implemented on a Xilinx Virtex 6 sx475t field programmable gate array chip that comes with the reconfigurable open architecture computing hardware version-2 (ROACH-2) platform. The 16 in-phase and quadrature-phase downconverted signals are sampled using the ROACH-2 platform and are processed using the …

A real-time directional sensing system is proposed for 2.4 GHz ISM band by exploiting the concept of spatiotemporal spectral white spaces. The proposed system consists of a 16-element patch antenna array, an FFT-based multi-beam beamformer and an energy detector. Our system operates at the baseband with quadrature sampling. Furthermore, digital architectures for two energy detectors that employ integrate-and-dump circuits are presented. With the multi-beam beamformer, the first energy detector can be employed to directional sensing and the second can be employed for both directional and spectral sensing of radio frequency sources. The multi-beam beamformer having 16 beams and the energy detectors are implemented on a ROACH-2 based FPGA system with a 160 MHz clock. With an 8-point temporal FFT, the second energy detector provides approximately 20 MHz bandwidth per temporal FFTbin …

A low-complexity wideband transmit beamformer is proposed using a digitally-fed uniform linear array of broadband Vivaldi antennas operating in the S-band. The proposed transmit beamformer employs a novel DSP feeding network based on a transmit-mode 2-D sparse finite-extent impulse response (FIR) filter having a planar passband in the 2-D frequency-wavenumber space. Electronic beam steering is achieved by changing the filter coefficients defined in closed-form and hard-thresholding (HT) is employed to obtain a sparse 2-D impulse responses of the filter. Full-wave electromagnetic simulations are used to obtain the far-field beam patterns produced by the 2-D sparse FIR filter in the frequency range 2-2.8 GHz for wideband signals with 33% fractional bandwidth. Computational complexity, beam directionality and side-lobe performance are investigated with varying HT along with quantitative comparisons …

In this paper, we introduce a novel algorithm that can dramatically reduce the number of antenna elements needed to accurately predict the direction of arrival (DOA) for multiple input multiple output (MIMO) radar. The new proposed algorithm predicts the received signal of a large antenna setup using reduced number of antenna by using coupled dictionary learning. Hence, this enables the MIMO radar to resolve more paths, which could not be resolved by the fewer antennas. Specifically, we overcome the problem of inaccurate DOA estimation due to a small virtual array setup. For example, we can use dictionary learning to predict 100 virtual array elements using only 25. To evaluate our algorithm, we used multiple signal classification (MUSIC) as a DOA estimation technique to estimate the DOA for non coherent multiple targets. The results show that using the predicted received signal, the proposed algorithm …