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Arbitrary Near-Field spatial signal processing

IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 2021年第4期69卷 2072-2082页

作者： Liu, Ruizhi Wu, Ke Polytech Montreal Polygrames Res Ctr Montreal PQ H3T 1J4 Canada

Electromagnetic waves have been widely exploited as signal, carrier, and power for wireless and wireline systems over the electromagnetic spectrum. As the classical approach, parametric interactions among localized or discrete signal processing devices are usually accomplished by electromagnetic fields or waves guided in conductor and/or dielectric bounded structures. These structures feature specific circuit functions in an electronic or photonic manner. Such electromagnetic circuits now face a number of application issues, such as geometrical complexity, power handling capability, and flexible reconfigurability, when they are used in certain large-scale electromagnetic systems, like in a massive multiple-input and multiple-output (MIMO). In this work, we propose and present an unconventional approach to realize a desired interaction or operation among devices. Such an interaction relies on wave or field interferences induced by a set of coherent antenna array over their near-field region where signal processing can be accomplished spatially. Fundamental functions and operation mechanisms of the proposed spatial signal processing approach are discussed and demonstrated in this work. It is worth mentioning that the proposed approach is universally applicable to all physical wave devices and systems, such as acoustic and electromagnetic waves.

关键词： Array signal processing Interference Linear antenna arrays Delays Mathematical model Antenna array coherent antenna array near field near-field antenna near-field multifocus (NFMF) spatial signal processing

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BAYESIAN MODEL SELECTION APPLIED TO spatial signal-processing

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IEE PROCEEDINGS-VISION IMAGE AND signal processing 1994年第1期141卷 76-80页

作者： NALLANATHAN, A FITZGERALD, WJ Dept. of Eng. Cambridge Univ. UK

In the paper, inference is applied to the problem of direction of arrival estimation and the determination of the number of sources present in the case of signals impinging on a linear array of sensors. The method is discussed, and the algorithm is found to outperform methods such as AIC and MDL even in the case of very low signal-to-noise ratios and closely spaced sources. The two levels of inference involved in any data analysis problem are introduced and this inference methodology, using the concept of evidence, is then applied to this problem. Simulation results illustrate the power of the method and it is shown that one of the advantages of the present approach is that it is able to handle special cases such as coherent and correlated signals of any functional form, and it does not assume the receivers to be equally spaced.

关键词： BAYESIAN MODEL spatial signal processing DATA MODELING

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On the use of spatial time frequency distributions for signal extraction

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MULTIDIMENSIONAL SYSTEMS AND signal processing 1998年第4期9卷 349-354页

作者： Belouchrani, A Amin, MG Villanova Univ Dept Elect & Comp Engn Villanova PA 19085 USA

This paper deals with the extraction of signals from their instantaneous linear mixtures using time-frequency distributions. Fundamentally this problem is a signal synthesis from the time-frequency (t-f) plane. However with the incorporation of the spatial information provided by a multisensor array, the problem can be posed as special case of blind source separation. So far, the blind source separation has been solved using only statistical information available on the source signals. Herein, we propose to solve the aforementioned problem using time-frequency signal representations and the spatial array aperture. The proposed approach relies on the difference in the t-f signatures of the sources to be separated. It is based on the diagonalization of a combined set of spatial time-frequency distribution matrices. A numerical example is provided to illustrate the effectiveness of our method.

关键词： time-frequency distribution spatial signal processing blind signal estimation

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spatial pre-coding with phase flipping for wireless communications

Spatial pre-coding with phase flipping for wireless communic...

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IEEE Wireless Communications and Networking Conference

作者： Kaiser, Stefan DoCoMo Commun Labs Europe GmbH D-80687 Munich Germany

ISBN: (纸本)9781424406586

The performance of spatial pre-coding schemes depends on the amount of channel state information available at the transmitter. A novel approach is spatial pre-coding with phase flipping investigated in this paper. The scheme is referred to as spatial phase coding (SPC). Two flipping criteria, the angle criterion (AC) and the absolute value criterion (AVC), are proposed which change the phase relation of the signals between multiple transmit antennas such that the probability of constructive superposition of the signals at the receiver antenna is increased. Compared to known pre-coding schemes, SPC AVC does not need knowledge about the channel from each transmit antenna for pre-coding. Instead, it requires only information about the absolute value of the superimposed channel. This paper shows that SPC can achieve an array gain additional to the diversity gain. This is not possible with schemes like transmitter antenna selection diversity (SD). The lower bounds for SPC are defined by equal gain transmission (EGT) and maximum ration transmission (MRT).

关键词： spatial signal processing pre-coding transmit diversity phase flipping spatial phase coding SPC

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Array Acoustic signal processing in Shallow-Water Channels under Conditions of a Priori Uncertainty: Estimates of the Efficiency Loss

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ACOUSTICAL PHYSICS 2022年第4期68卷 382-394页

作者： Malekhanov, A., I Smirnov, I. P. Russian Acad Sci Fed Res Ctr Inst Appl Phys Nizhnii Novgorod 603155 Russia Lobachevskii Natl Res Nizhni Novgorod State Univ Nizhnii Novgorod 603950 Russia

The objective of this study is a comparative analysis of the efficiency of the matched-field and optimal spatial signal processing methods in a shallow-water sound channel under conditions of inaccurate knowledge of its parameters. It is assumed that a signal of a remote localized source is received by a vertical antenna array against the background of an intense interference, which is also created by a localized source, while the vertical profile of the sound velocity, the channel depth, the sound velocity in underlying bottom, and its density are known with arbitrary deviations from actual values within specified intervals. The processing efficiency is characterized by the array gain in terms of the signal/(noise + interference) ratio normalized to the number of the array elements. The stochastic modeling technique is used to show that with an increase in the a priori uncertainty in the estimation of these parameters, the efficiency losses for these two processing methods not only have significantly different values, but can reveal the nonmonotonic character. The permissible error levels in the estimation of the channel parameters are determined, at which the gain loss does not exceed the specified level (3 dB) for each of the methods. The results are important to specify the requirements for facilities of operational oceanography that provide the effective operation of receiving antenna systems in real shallow-water conditions.

关键词： shallow-water acoustic channel vertical antenna array multimode signal spatial signal processing gain of the antenna array mismatch of the channel model

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Adaptive transmission in heterogeneous networks

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IET COMMUNICATIONS 2017年第4期11卷 604-613页

作者： Li, Zhao Zhen, Lu Dai, Xiaoqin Shen, Biao Bai, Yujiao Ren, Xiaohui Shin, Kang G. Xidian Univ State Key Lab Integrated Serv Networks 2 South Taibai Rd Xian Peoples R China Univ Michigan Dept Elect Engn & Comp Sci 2260 Hayward St Ann Arbor MI 48109 USA

An Adaptive tranSmission mechanism exploiting both interference loCality and the relationship between dEsired signal and inTerference (ASCENT) is proposed for uplink transmission in heterogeneous networks. The authors adopt both X channel and Z channel models according to which spatial signal processing is designed. In the X channel, the picocell base station (PBS) exploits information the macrocell base station (MBS) shares to cancel local interference, and cooperatively decodes the data carried by strong interference from a macro-user (MU), which is then fed to the MBS. As a result, a pico-user (PU) can transmit simultaneously with an MU on the same channel. In addition, adaptive reception is employed to achieve good tradeoff between interference suppression and the desired level of signal distortion. For the Z channel, the PU and the PBS adopt signal processing suitable for their own channel state. At a PBS, interference cancellation is adopted to eliminate disturbance from an MU via inter-base station collaboration. ASCENT is also extended to the case of multiple picocells. The authors' simulation results show that in X channel mode, the achievable uplink rate of an MU can be significantly enhanced. In the case of Z channel, the PU's rate is improved while guaranteeing the MU's data rate.

关键词： picocellular radio interference suppression signal processing wireless channels heterogeneous networks adaptive transmission mechanism interference locality ASCENT desired signal and interference Z channel models X channel models spatial signal processing picocell base station PBS macrocell base station MBS pico user PU adaptive reception interference suppression signal distortion signal processing

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Comparative Analysis of Horizontal Array signal processing in a Shallow-Water Channel with a Rough Windy Surface

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ACOUSTICAL PHYSICS 2019年第5期65卷 507-516页

作者： Zavolskii, N. A. Malekhanov, A., I Raevskii, M. A. Russian Acad Sci Inst Appl Phys Nizhnii Novgorod 603950 Russia

The recent study [1] addressed how the characteristics of low-frequency acoustic signal propagation in a shallow-water channel under wind wave conditions affect the output performance of a horizontal phased array (PA) is further developed with the aim of comparative analysis of the efficiency of various array signal processing methods. The main focus is quantitative estimates of the additional array gain from optimal processing in comparison to the standard PA method compensated in the direction to the signal source, in dependence on the key parameters: direction and distance to the source, wind speed, and wave dimensions of the array. Numerical simulation is performed for a typical winter hydrological conditions of the Barents Sea, a signal frequency of 250 Hz, and a wide range of distances up to 500 km It is shown that the additional gain from optimizing the array processor can vary widely (from fractions of to a few dB), while the PA efficiency also varies widely and may have a nonmonotonic dependence on distance.

关键词： underwater sound channel shallow water wind waves spatial signal processing coherence function array gain phased array optimal spatial processing

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Air-coupled ultrasound inspection of glued laminated timber

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HOLZFORSCHUNG 2011年第3期65卷 377-387页

作者： Sanabria, Sergio J. Furrer, Roman Neuenschwander, Juerg Niemz, Peter Sennhauser, Urs Empa Swiss Fed Labs Mat Sci & Technol Elect Metrol Reliabil Lab CH-8600 Dubendorf Switzerland Swiss Fed Inst Technol Inst Bldg Mat Lab Wood Phys & Nondestruct Testing Methods Zurich Switzerland

A novel air-coupled ultrasound (ACU) 120 kHz normal transmission system enabled successful imaging of bonding and saw cut defects in multilayered glulam beams up to 280 mm in height with a signal-to-noise ratio (SNR) of 40 dB. The main wave propagation paths were modeled;quasi-longitudinal and quasi-transverse modes were coupled in each lamella and the sound field was found to be shifted from the insonification axis as a function of the ring angle, leading to interference of wave paths in the receiver and to 15 dB amplitude variability in defect-free glulam. The assessment was improved with spatial processing algorithms that profited from the arbitrary scanning resolution and high reproducibility of ACU. Overlapped averaging reduced in-band noise by 15 dB, amplitude tracking captured only the first incoming oscillation, thus minimizing diffraction around defect regions, and image normalization compensated 6 dB of systematic amplitude variability across the fiber direction. The application of ACU to in situ defect monitoring was demonstrated by using multiparameter difference imaging of measurements of the same sample with and without saw cut defects. The segmentation of the defect geometry was improved significantly and the amplitude variability was reduced by 10 dB. Further work is planned to model additional insonification setups and grain and density heterogeneities.

关键词： air-coupled ultrasound amplitude tracking bonding quality delamination energy flux shift glued laminated timber in situ flaw monitoring multiparameter difference imaging non-contact ultrasonics non-destructive evaluation saw cut defect spatial signal processing ultrasound wave propagation wood heterogeneity

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The Influence of the A Priori Uncertainty of the Shallow Sea Sound Channel Model on the Vertical Array Gain

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ACOUSTICAL PHYSICS 2023年第5期69卷 640-654页

作者： Malekhanov, A. I. Smirnov, A. V. Russian Acad Sci AV Gaponov Grekhov Inst Appl Phys Nizhnii Novgorod 603950 Russia Nizhnii Novgorod State Univ Lobachevsky State Univ Nizhny Novgorod Nizhnii Novgorod 603950 Russia

The purpose of this paper is to numerically demonstrate and comparatively analyze the critically strong and ambiguous impact of the a priori uncertainty of a shallow sea waveguide model in its main physical parameters on the output performance of model-based methods for spatial processing of multimode signals received by a vertical antenna array. The scenario is specified when a relatively weak signal of a remote underwater source is received against the background of intensive interference excited by a subsurface source (like a ship, for example) and ambient sea noise excited by wind waves. The considered array processing methods include matched-signal processing, optimal processing of the signal on the background of interference and noise, and suboptimal processing based on matched-mode array filtering of one of the signal-carrying modes with adaptive selection of its number. Quantitative estimates are obtained from above for the environment uncertainties, or model errors, with respect to the sound velocity in the water column and geoacoustic parameters of the underlying bottom, at which the array gain loss does not exceed a given level. It is shown that such estimates are very different both for different environmental parameters and for processing methods, with the determining role played by the conditions of useful signal reception, namely, the modal composition and intensity levels of the interference and sea noise at the array input. The problem statement and results are considered to be useful to detail the requirements for operational oceanography tools designed to support the effective operation of sonar antenna systems in real sea environments.

关键词： shallow sea waveguide vertical antenna array spatial signal processing array gain matched-signal processing optimal processing matched-mode filtering operational oceanography

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THE USE OF SYNCHRONOUS DETECTION OF ULTRASONIC signalS TO INCREASE THE ACCURACY OF MEASUREMENTS OF THE THICKNESS OF ARTICLES MADE OF MATERIALS WITH COMPLEX STRUCTURES

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MEASUREMENT TECHNIQUES 2009年第11期52卷 1211-1215页

作者： Rodin, A. B. Tech Univ Moscow Power Engn Inst Moscow Russia

It is shown that, in the ultrasonic measurement of the thickness of articles made of materials of complex structure, a measurement error arises due to the structural inhomogeneity of the material (structural noise), which can be minimized by using a multichannel method of measurement with subsequent summation (accumulation) of the results of the measurements. The effect of synchronous detection on the error in determining the delay of the total echo signal and the thickness of the article is considered.

关键词： ultrasonic thickness measurement materials of complex structure spatial signal processing synchronous detection

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