skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Toward Electronically Reconfigurable Rims for Reflectors in Radio Astronomy
This paper presents full-wave simulation results of a reflector-reflectarray hybrid antenna used as a spatial beamformer for mitigating interference in radio astronomy applications. Such antennas employ fixed reflectors with electronically tunable reflectarray along their rim to dynamically form nulls in the direction(s) of interferer(s). Results from realistic models of such antenas demonstrate their potential in producing nulls and potentially effectiveness in mitigating interference from satellites with the field of view of the instrument.  more » « less
Award ID(s):
2128506
PAR ID:
10535303
Author(s) / Creator(s):
; ;
Publisher / Repository:
IEEE
Date Published:
ISBN:
978-9-4639-6809-6
Page Range / eLocation ID:
1 to 3
Format(s):
Medium: X
Location:
Sapporo, Japan
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, IEEE Transactions on Microwave Theory and Techniques)
    Active control of interference is necessary with increased cell density, more complicated environmental reflections, and coexistence of multiple networks for next-generation wireless communications. The existing radio receiver architectures for spatial interference cancellation (SpICa) are limited by the spatial nulls created by a phased-antenna array (PAA) and cannot cover wide modulated bandwidths (BWs). We propose a discrete-time-delay-compensating technique for canceling spatial interferences with wide modulated BWs to reduce the dynamic range requirement for the data converter. Integral to the proposed circuit is a switched-capacitor-based multiply-and-accumulate processor that incorporates a reconfigurable phase interpolator and time interleaver for precise digitally tunable delays and multiplication of the input signal to an orthogonal matrix. The digital time interleaver enables 5-ps resolution with a reconfigurable range up to 15 ns. The measured results demonstrate greater than 35-dB SpICa over 80-MHz modulated BWs in the 65-nm CMOS with 52 mW of power consumption. 
    more » « less
  2. ; (, Sensors)
    To address practical challenges in establishing and maintaining robust wireless connectivity such as multi-path effects, low latency, size reduction, and high data rate, we have deployed the digital beamformer, as a spatial filter, by using the hybrid antenna array at an operating frequency of 10 GHz. The proposed digital beamformer utilizes a combination of the two well-established beamforming techniques of minimum variance distortionless response (MVDR) and linearly constrained minimum variance (LCMV). In this case, the MVDR beamforming method updates weight vectors on the FPGA board, while the LCMV beamforming technique performs nullsteering in directions of interference signals in the real environment. The most well-established machine learning technique of support vector machine (SVM) for the Direction of Arrival (DoA) estimation is limited to problems with linearly-separable datasets. To overcome the aforementioned constraint, the quadratic surface support vector machine (QS-SVM) classifier with a small regularizer has been used in the proposed beamformer for the DoA estimation in addition to the two beamforming techniques of LCMV and MVDR. In this work, we have assumed that five hybrid array antennas and three sources are available, at which one of the sources transmits the signal of interest. The QS-SVM-based beamformer has been deployed on the FPGA board for spatially filtering two signals from undesired directions and passing only one of the signals from the desired direction. The simulation results have verified the strong performance of the QS-SVM-based beamformer in suppressing interference signals, which are accompanied by placing deep nulls with powers less than −10 dB in directions of interference signals, and transferring the desired signal. Furthermore, we have verified that the performance of the QS-SVM-based beamformer yields other advantages including average latency time in the order of milliseconds, performance efficiency of more than 90%, and throughput of nearly 100%. 
    more » « less
  3. ; (, 2017 5th IEEE Global Conference on Signal and Information Processing)
    A time-varying filter is proposed which improves by 5 dB upon traditional FRESH and Wiener filters when rejecting a pulsed radar signal. The filter is a Time-Varying FRESH (TVFRESH) filter, which applies different sets of filter weights in a periodic manner, with the same periodicities of the received signal. Matching the periodicities of the filter to that of the signal improves the rejection of interference, producing a better estimate of the desired signal. The simulated results show mitigating the interference from a radar signal to an Orthogonal Frequency Division Multiplexing (OFDM) signal. 
    more » « less
  4. ; ; ; ; ; ; (, Nature Communications)
    Abstract mmWave devices can broadcast multiple spatially-separated data streams simultaneously in order to increase data transfer rates. Data transfer can, however, be compromised by interference. Photonic blind interference cancellation systems offer a power-efficient means of mitigating interference, but previous demonstrations of such systems have been limited by high latencies and the need for regular calibration. Here, we demonstrate real-time photonic blind interference cancellation using an FPGA-photonic system executing a zero-calibration control algorithm. Our system offers a greater than 200-fold reduction in latency compared to previous work, enabling sub-second cancellation weight identification. We further investigate key trade-offs between system latency, power consumption, and success rate, and we validate sub-Nyquist sampling for blind interference cancellation. We estimate that photonic interference cancellation can reduce the power required for digitization and signal recovery by greater than 74 times compared to the digital electronic alternative. 
    more » « less
  5. ; (, ICASSP 2023 - 2023 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP))
    This paper explores reconfigurable intelligent surfaces (RIS) for mitigating cross-system interference in spectrum sharing applications. Unlike conventional reflect-only RIS that can only adjust the phase of the incoming signal, a hybrid RIS is considered that can configure the phase and modulus of the impinging signal by absorbing part of the signal energy. We investigate two spectrum sharing scenarios: (1) Spectral coexistence of radar and communication systems, where a convex optimization problem is formulated to minimize the Frobenius norm of the channel matrix from the communication base station to the radar receiver, and (2) Spectrum sharing in device-to-device (D2D) communications, where a max-min scheme that optimizes the worst-case signal-to-interference-plus-noise ratio (SINR) among the D2D links is formulated, and then solved through fractional programming. Numerical results show that with a sufficient number of elements, the hybrid RIS can in many cases completely eliminate the interference, unlike a conventional non-absorptive RIS. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email