Antenna Array Signal Processing Research Articles

Some m-fold symmetric bi-univalent function classes and their associated Taylor-Maclaurin coefficient bounds

The Ruscheweyh derivative operator is used in this paper to introduce and investigate interesting general subclasses of the function class Σm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\Sigma_{m}$\\end{document} of m-fold symmetric bi-univalent analytic functions. Estimates of the initial Taylor-Maclaurin coefficients |am+1|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\vert a_{m+1} \\vert $\\end{document} and |a2m+1|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$\\vert a_{2 m+1} \\vert $\\end{document} are obtained for functions of the subclasses introduced in this study, and the consequences of the results are discussed. Additionally, the Fekete-Szegö inequalities for these classes are investigated. The results presented could generalize and improve some recent and earlier works. In some cases, our estimates are better than the existing coefficient bounds. Furthermore, within the engineering domain, the utilization of the Ruscheweyh derivative operator can encompass a broad spectrum of engineering applications, including the robotic manipulation control, optimizing optical systems, antenna array signal processing, image compression, and control system filter design. It emphasizes the potential for innovative solutions that can significantly enhance the reliability and effectiveness of engineering applications.

ПРИНЦИП СУБЪЕКТИВНОЙ ИЗБЫТОЧНОСТИ И МЕТОД СЖАТИЯ ДАННЫХ, ПОЛУЧАЕМЫХ ОТ ЦИФРОВЫХ АНТЕННЫХ РЕШЕТОК

The problem of limiting the capacity of the diagram-forming circuit of the digital antenna array is considered, due to the capabilities of existing communication lines with serial data transmission from the receiving channels to the computer. This problem limits the possibilities of implementing various methods of signal processing in digital antenna arrays. The subject of the study is the possibility of increasing the capacity of the diagram-forming circuit of the digital antenna array due to software compression of radar data. The purpose of the work is to create a scientific and methodological apparatus that will increase the capcity of the diagram-forming scheme by using the principle of subjective redundancy in relation to radar data processing tasks. The results of the work include: justification and formulation of the principle of subjective redundancy of radar data and the method of compression of radar data, as well as the results of numerical studies confirming the operability of the proposed scientific and methodological apparatus. The principle of subjective redundancy is based on the independence of the separation of signal processing processes in the spatial and temporal domains when receiving a single echo signal, and in the case of receiving several echo signals, on the principle of superposition of fields from various sources in the far antenna zone. The method of radar data compression is based on the principle of subjective redundancy of radar data and differs from the known iterative procedure for approximating the matrix of complex samples in the form of a superposition of products of one-dimensional cosine spectra. It is shown that the application of the radar data compression method makes it possible to increase the transmission capacity of the digital antenna array transmission lines several times.

Peculiarities of adaptive signal processing in circular antenna arrays

Formulation of the problem. Today, antenna arrays are often used as directional antennas of different radio systems. The main advantages of the such antennas over the mechanically steered directional antennas are the ability to steer the main lobe (beam) of the Radiation Pattern (RP) without the rotation of the array, and also the ability to control the shape of the RP. However, the antenna arrays also have some drawbacks. For example, a drawback of the linear and the planar antenna arrays is the varying beamwidth. This width increases as the orientation of the beam moves from the normal to the aperture to the plane of the aperture. This feature is due to the fact that when the beam is deflected, the effective aperture of the antenna array decreases, and this is the reason of the beam increase. If it is required to steer the beam in a wide range of angles while maintaining its width, then this restricts the usage of a linear and flat antenna arrays as the directional antennas. This disadvantage is practically absent in the circular antenna arrays. Therefore, such arrays are attractive for the usage, for example, in the radio communication systems, because they allow the beam to move within 360° in azimuth plane while maintaining its width practically fixed. If the antenna array is built using a digital beamforming architecture (digital array), then such an array can also be easily made as a multi-beam one, that will provide a parallel view of space. In multibeam digital antenna arrays, the same analog portion of each channel from the antenna to the digital output is used to form all the beams. And only in digital form, the separate devices for the forming of these beams are required, which multiply the channel output signal samples by the weights and add the weighted signals together to form the output signals of the antenna array. The access to the signals from the outputs also allows such an antenna array to easily become adaptive, because these signals are used to calculate the weights in all the adaptive algorithms. The adaptive signal processing allows to suppress the interferences. The suppression of the interference signals in the output signal of the antenna array is achieved due to the creation of the dips (low levels) in the RP towards the sources of these interferences. Such a change in the shape of the RP is provided by the changing weights calculated using an adaptive algorithm. Target. The paper deals with the circular adaptive antenna arrays with digital beamforming. The features of the such adaptive antenna arrays and their performance are considered. Results. The architecture of a single beam and a multibeam adaptive antenna array is considered, as well as a procedure (algorithm) for the calculation of its weights. It is also demonstrated the efficiency of a circular adaptive antenna array in terms of maintaining its beamwidth regardless of its direction and simultaneously suppressing interferences, that practically does not affect this beamwidth. Practical significance. The considered adaptive antenna array can be used as a directional antenna in radio systems where it is required to form a several beams simultaneously, to maintain their width regardless of steering directions, and also to suppress the interference signals in the output signal.

The method of adaptive signal reception with adaptive antenna arrays from moving sources

Spatial signal processing in adaptive antenna arrays should provide optimal signal reception from some desired source, this requires maximizing the signal-to-noise ratio at the output of adaptive antenna arrays. This task is well studied for the case when the signal source is fixed and point, and for mobile objects often have to use complex algorithms for controlling adaptive antenna arrays. The relevance of this study is that one of the most promising approaches to solving the problem is to increase the efficiency of signal reception is the use of adaptive antenna arrays and appropriate methods of spatial signal processing.The angular dispersion of the signal is assumed to be due to its multipath propagation in the communication channel. The configuration of adaptive antenna arrays is assumed to be arbitrary. This method allows to reduce the amount of calculations compared to the method when the weight vector with adaptive antenna arrays is optimal and is selected as the eigenvector of the signal correlation matrix and it is possible to maintain the efficiency of the signal is quite high, which determines its novelty.The article analyzes the method of adaptive reception of signals from moving sources using adaptive antenna arrays which is also called the method of quasi-optimal signal processing received by adaptive antenna arrays from a moving source with unknown angular coordinates, the possibility of its reception by mobile subscribers in angular variance. quasi-optimal signal processing with other known methods of signal processing.

Aspects of practical implementation of space-time signal processing in adaptive antenna arrays in a complex electromagnetic environment

Aspects of practical implementation of space-time signal processing in adaptive antenna arrays in a complex electromagnetic environment

Low complexity channel estimation algorithm using paired spatial signatures for UAV 3D MIMO systems

This paper proposes a low complexity channel estimation algorithm for unmanned aerial vehicle three dimension multi-user multiple-input-multiple-output (3D MIMO) systems with the uniform planar array (UPA) at base station using paired spatial signatures. With the aid of antenna array theory and array signal processing, 3D channel is firstly modeled based on the angles between the direction of arrival along x- and y-axis of the UPA. And 3D MIMO channels can be projected onto the x- and y-directions, respectively. Then, channel estimation for multi-user uplinks using small amount of training resources is divided into two phases. At the first uplink preamble phase, each user is assigned the orthogonal pilot, and the paired spatial signatures and optimal rotation angle of each user through the same pilot sequence are obtained. We also propose a user grouping strategy based on three-dimension angle-division multiple access (3D-ADMA) to ensure that the user's spatial signatures do not overlap. At the second phase during several coherence times, the same pilot sequence within a group and orthogonal pilot sequences between groups are assigned, then, the channel state information of the user's x- and y-directions are recovered by the paired space signatures and optimal rotation angle of each user obtained in the preamble phase, respectively. And dynamically updating the user's paired spatial signatures and optimal rotation angle utilizes the obtained channel parameter of x- and y-directions. Finally, the channel parameter of the x- and y-directions are reconstructed by the updated user's space signatures and the optimal rotation angle, and the 3D MIMO channel estimation is obtained through the Kronecker product. Compared with the conventional channel estimation method of the 3D MIMO system under UPA using a low-rank model, the proposed methods reduce the computational complexity without degrading the estimated performance to a large extent. Furthermore, it is carried out with limited training resources, and the pilot resource overhead of the system is greatly reduced by the 3D-ADMA packet and the two-stage pilot allocation. Simulation results verified that the proposed algorithm is effective and feasible.

Smart Antenna System for DOA Estimation using Single Snapshot

In the antenna array signal processing, a lot of interest has been given towards large number of samples which is asymptotic case. In certain cases like automotive radar applications only few or in the worst condition one sample (snapshot) of radar sensor is available for the direction finding. Hence single snapshot based direction of arrival (DOA) algorithms are required for such cases. Two such methods, namely, single snapshot root-multiple signal classification (MUSIC) and single snapshot estimation of signal parameters via rotational invariance technique (ESPRIT) algorithms using uniform linear array (ULA) are proposed. The experimental results clearly show that the proposed methods with single snapshot and the classical methods with 100 snapshots have almost similar performance. This results in ten times increase in execution. Hence the proposed methods are computationally efficient and can be used in advanced radar communications where latency is an important issue.

METHODS OF JAMMING INTERFERENCE

The article investigates the problem of providing high noise immunity radar under the influence of passive and intentional interference. The purpose of radio operation of the radar is to create conditions that would impede the operation of systems and minimize its effectiveness. The main method of radio transmission is still creating (staging) interference. Modern radar systems must solve the tasks in terms of electronic suppression using, including intentional interference and under severe time constraints. It is shown that the most effective way to improve the noise immunity of radar systems designed to operate in multipoint space, including non-stationary, interference is adaptive space-time processing of the received signals, based on the angular selection of targets, due to the formation of zeros in the directional diagram in the direction of interference sources. This problem is solved by determining the accuracy of the direction finding of interference sources and is achieved by the joint operation of the antenna array and multi-channel signal processing devices, namely the separation of interference signals on different receiving channels.

Processing of Antenna-Array Signals on the Basis of the Interference Model Including a Rank-Deficient Correlation Matrix

We propose a new method of signal processing in antenna arrays, which is called the Maximum-Likelihood Signal Classification. The proposed method is based on the model in which interference includes a component with a rank-deficient correlation matrix. Using numerical simulation, we show that the proposed method allows one to ensure variance of the estimated arrival angle of the plane wave, which is close to the Cramer–Rao lower boundary and more efficient than the best-known MUSIC method. It is also shown that the proposed technique can be efficiently used for estimating the time dependence of the useful signal.

A Unified Transmission Strategy for TDD/FDD Massive MIMO Systems With Spatial Basis Expansion Model

This paper proposes a unified transmission strategy for multiuser time division duplex (TDD)/frequency division duplex (FDD) massive multiple-input–multiple-output (MIMO) systems, including uplink (UL)/downlink (DL) channel estimation and user scheduling for data transmission. With the aid of antenna array theory and array signal processing, we build a spatial basis expansion model (SBEM) to represent the UL/DL channels with far fewer parameter dimensions. Hence, both the UL and DL channel estimations of multiusers can be carried out with a small amount of training resource, which significantly reduces the training overhead and feedback cost. Meanwhile, the pilot contamination problem in the UL training is immediately relieved by exploiting the spatial information of users. To enhance the spectral efficiency, we also design a greedy user scheduling scheme during the data transmission period. Compared with existing low-rank models, the newly proposed SBEM offers an alternative for channel acquisition without the need for channel statistics and can be applied to both TDD and FDD systems. Various numerical results are provided to corroborate the proposed studies.

Low complexity performance assessment of a sensor array via unscented transformation

Due to the advances on electronics, applications of antenna array signal processing are becoming more frequent. When employing antenna arrays for beamforming, the signal to interference and noise ratio (SINR) should be assessed. Many factors can affect the SINR such as the array element positioning error and the direction of arrival (DOA) estimation error. In these cases, the assessment is traditionally performed via the SINR average obtained using Monte Carlo (MC) simulations. However, this approach requires a great amount of realizations that demand a high computational effort and processing time due to its slow convergence. In this paper, we propose a low complexity performance assessment of the average SINR via unscented transformation. Compared to MC simulations, our proposed method requires only a few trials and has a negligible computational complexity, yet giving a comparable SINR when the DOA estimation is perturbed. When the antenna elements positioning is perturbed, a multivariate scenario arises. For multivariate scenario the proposed scheme has an exponential increase in complexity, therefore, still being advantageous for a small number of antennas.

Desired Features of Adaptive Antenna Arrays for GNSS Receivers

Adaptive antenna arrays have become the system of choice for protecting Global Navigation Satellite Systems (GNSS) receivers in strong radio frequency interference environments. GNSS receiver adaptive antenna arrays have small aperture (of the order of a wavelength) and few (e.g., less than 10) elements. In the near future, even smaller vehicles will be equipped with protected GNSS receivers. Therefore, future GNSS receiver antenna arrays will be even smaller in size. At the same time, requirements for availability, accuracy, and integrity monitoring will increase. Novel array signal processing techniques need to be developed and deployed to meet these requirements. This paper presents state-of-the-art GNSS adaptive antenna array signal processing techniques. Some drawbacks of the current GNSS antenna signal processing techniques are also discussed in this paper, and new ideas for further research and development in GNSS adaptive antennas are presented.

Direction of Arrival (DOA) Estimation in an Array of Antennas using Derivative-Free Methods

In this paper, direction of arrival estimation has been addressed using derivative free methods and their hybrid procedure in antenna array signal processing. The problem has been formulated in the root mean square error sense by considering the single snapshot. A scenario based simulation has been performed by taking different number of antenna elements with varying sources. The stability, reliability and applicability of the proposed scheme has been monitored by Monte Carlo simulation and their statistical analysis based on the fitness of the problem, global mean square error and computational budget in term of time complexity. General Terms Direction of arrival (DOA) estimation

Localization Algorithm for the PD Source in Substation Based on L-Shaped Antenna Array Signal Processing

A novel algorithm based on L-shaped antenna array signal processing is proposed in this paper for the localization of partial-discharge (PD) sources in substations. The principle of estimation of signal parameter via rotational invariance techniques has been used for finding the direction of arrival (DOA) of signals. Third-order cumulants of signals are used in this algorithm, by which Gaussian white noises and periodic narrowband interference mixed in observed signals can be efficiently suppressed. Planar location of PD sources can be obtained by solving the intersecting point of two lines in DOAs. Therefore, solving nonlinear equations can be avoided. Besides, it is convenient to replace the observed signals with their envelopes in this algorithm. The proposed algorithm is used to process mixed signals with simulated ultra-high frequency (UHF) signals by electromagnetic-wave simulation software, Gaussian white noises of different signal-to-noise ratios, and fixed-frequency noises. The planar location of PD sources is obtained approximately. UHF signals collected in substations and their envelopes have proven to be suitable to locate PD sources effectively by the proposed algorithm as well. Therefore, the accuracy and feasibility of the proposed algorithm are proved.

Research on the Conformal Phased-Array Antenna

The mathematical model of conformal antenna array is the premise and basis of the conformal array antenna signal processing. Based on the analysis of the antenna array, a design method for adjusting the direction of the conformal array antenna is proposed. Through simulation, the pattern of antenna meets the actual needs of the project and it reaches pre design requirements.

Antenna array characterisation and signal processing for an FM radio-based passive coherent location radar system

The design of passive coherent location radar, which exploits broadcasting transmitters of opportunity in the very high frequency (VHF) radio bandwidth, is presented. Here, the authors primarily focus on the system set-up and on the digital pre-processing steps. Emphasis is given to the antenna section analysis. The eight-element circular array, which is used for the signal acquisition, is analysed by means of simulations and measurements. Compensation for the mutual coupling effect between the different channels is achieved by applying a technique in the digital domain. An innovative digital beamforming algorithm is introduced to reduce the sidelobe level of the circular array pattern. Direct path interference suppression, range/Doppler data processing, greatest-of constant false alarm rate algorithm and range/Doppler-time plots extraction provide the final output of the processing chain. Experimental validation of the processing architecture is presented and the final detection results are compared with an automatic dependent surveillance broadcast data set.

A Real-Time Capable Software-Defined Receiver Using GPU for Adaptive Anti-Jam GPS Sensors

Due to their weak received signal power, Global Positioning System (GPS) signals are vulnerable to radio frequency interference. Adaptive beam and null steering of the gain pattern of a GPS antenna array can significantly increase the resistance of GPS sensors to signal interference and jamming. Since adaptive array processing requires intensive computational power, beamsteering GPS receivers were usually implemented using hardware such as field-programmable gate arrays (FPGAs). However, a software implementation using general-purpose processors is much more desirable because of its flexibility and cost effectiveness. This paper presents a GPS software-defined radio (SDR) with adaptive beamsteering capability for anti-jam applications. The GPS SDR design is based on an optimized desktop parallel processing architecture using a quad-core Central Processing Unit (CPU) coupled with a new generation Graphics Processing Unit (GPU) having massively parallel processors. This GPS SDR demonstrates sufficient computational capability to support a four-element antenna array and future GPS L5 signal processing in real time. After providing the details of our design and optimization schemes for future GPU-based GPS SDR developments, the jamming resistance of our GPS SDR under synthetic wideband jamming is presented. Since the GPS SDR uses commercial-off-the-shelf hardware and processors, it can be easily adopted in civil GPS applications requiring anti-jam capabilities.

DBF Monopulse Technique And System For Multi-Target Tracking

Abstract In this paper, a DBF (Digital Beamforming) monopulse technique & system with ability of multitazget tracking is presented based on antenna array and digital signal processing. The scheme of the DBF monopulse tracking system is given. The sum & difference beams and corresponding angle error signal of the monopulse system are formed by data processing in baseband. Algorithms for the forming of these 5 monopulse beams are proposed. Multitarget tracking is achieved by module multiplying. Finally, an example of this DBF monopulse tracking is shown.

Analysis of the efficiency of multielement antenna arrays in a random channel

Efficiency of different algorithms for signal processing in multielement antenna arrays under the conditions of loss of spatial coherence in the antenna aperture is investigated. The influence of propagation conditions on the operability of these algorithms is analyzed.

ADAPTIVE SIGNAL PROCESSING IN ANTENNA ARRAYS WITH ALLOWANCE FOR THE RANK OF THE IMPULSE-RESPONSE MATRIX OF A MULTIPATH CHANNEL

We consider adaptive spatial signal processing in antenna arrays under conditions of multipath propagation. It is shown that estimation of the elements of the matrix of multichannel impulse response (MCIR) in the receiving channels of antenna arrays is not sufficient for performing such a processing, and we should also determine the MCIR-matrix rank, which is equal to the minimum number of adaptive spatial channels for reception of a multipath signal. We propose a threshold method for estimating the rank of the MCIR matrix on the basis of the statistical properties of maximum-likelihood estimation of the elements of this matrix and a priori information on the properties of internal noise in the receiving channels of the system. The weight vectors of the beamformer processor ensuring adaptive spatial signal processing are estimated.