Adaptive Antenna System Research Articles

ANALYSIS OF MACHINE LEARNING METHODS FOR SOLVING ANTENNA TECHNOLOGY PROBLEMS

The scheme of modern machine learning methods classification is considered and presented. The content of each methods in the classification is briefly disclosed. A structural diagram of an adaptive antenna system with an artificial intelligence unit is presented, and the principle of this scheme operation is explained. The role and function of the artificial intelligence unit within the adaptive antenna system are elucidated. The existing classes of machine learning methods are analyzed to determine their potential applicability to adaptive antenna systems for the purpose of intelligent control of the radiation pattern. It was determined that the primary machine learning method that could potentially be utilized by adaptive antenna system with artificial intelligence unit to achieve intelligent control of its directional characteristics is reinforcement learning. It is demonstrated that the reinforcement learning method can be integrated with other machine learning techniques, such as neural network methods, to enhance the precision of directing the directivity characteristics of adaptive antenna system with artificial intelligence unit.

Application of artificial intelligence method in adaptive antenna system

The requirements for adaptive antenna systems in modern and future wireless networks of the fifth (5G) and sixth (6G) generations are analyzed. The block diagram of the adaptive antenna system is presented and the basic principle of its operation is described. It is proposed to improve the block diagram of a modern adaptive antenna system by integrating an artificial intelligence module into it. The principle of interaction of the artificial intelligence module with the adaptive antenna system in the block diagram is shown and described. One of the methods of artificial intelligence (machine learning), the intelligent agent, is described and its mathematical model is presented. The possibility of applying the considered method in the cellular environment of a wireless communication network to improve the operation of an adaptive antenna system is shown. An example of the operation of an artificial intelligence module as part of an adaptive antenna system using an intelligent agent method is given. It is shown that, using the machine learning method, an intelligent agent within a single wireless communication cell can create a certain knowledge system capable of understanding and learning, taking into account the patterns of subscribers’ movement within the cell and predicting the direction of movement of a particular subscriber terminal. The resulting knowledge system is formed in an artificial intelligence module, which is included in the block diagram of a modern adaptive antenna system proposed in this paper, and can potentially be used to more accurately control the directional pattern of an adaptive antenna system. The idea proposed in this paper potentially allows us to develop the concept of a smart antenna, as well as to improve the characteristics of adaptive antenna systems, namely, to increase the energy efficiency of these systems by more accurately realizing the directivity characteristics and intelligent control of the radiation pattern petals using artificial intelligence.

Improving the VSSNLMS adaptive beamformer for adaptive antenna systems

A new configuration for the adaptive beamforming technology has been presented in this research work. We modified the structure of the uniform linear array (ULA) in such a way that a correct beam can be formed uniformly for all azimuth angles. For ULA composed of M antennas, we place two extra elements on the top and the bottom of the configuration of the ULA (at the array axis). Then, we develop the mathematical model or the same. To investigate the efficacy of the proposed antenna configuration, we deploy the VSSLMS beamformer. The new beamformer is compared with the well-known LMS and the MLMS adaptive beamformer. Computer simulations are provided in the result section of this paper to validate that the new beamformer has enhanced convergence rate and high data transmission compared to the LMS and the NLMS methods. Also, the new method has the same performance for middle angles, near boresight and array end fires which is not possible for the LMS and the NLMS method using a ULA.

Hierarchical Networks Technology and Simulation of An Adaptive Beamforming Antenna

This paper focuses on designing and simulation of an adaptive beamforming antenna technology. This was done to ensure that the transmitted signals are beamed in a specified direction for better signal reception in the desired of specified desired stations because the problems of the weak signal emancipate if the antenna is not pointed in the right direction leading to scattering of the signals. This is to say that a beamformoing antenna radiate or receives a greater power in a specified directions allowing for increased performance and reduced interference from an unwanted sources. In order to achieve our aim, a pictorial system design of the antenna was set showing and stating the basic parameters of the systems, the transmitter, channel module, receiver module, display and control module. A practical Simulink software model without and with adaptive beamforming antenna systems were developed, tested, compared and implemented as shown in figure 1 and figure 2 respectively. Simulink model was chosen primarily for its collection of several applications specific blocks that supports different design discipline and specifically for this paper.

An Efficient HAPS Cross-Layer Design to Mitigate COVID-19 Consequences

This paper proposes a new cross-layer communication system for the provision of Internet services and applications to mitigate the negative impacts of COVID-19, due to which the massive online demands are affecting the current communication systems’ infrastructures and capabilities. The system requirements and model are investigated where it utilizes high-altitude platform (HAP) for fast and efficient connectivity provision to bridge the communication infrastructure gap in the current pandemic. The HAP is linked to the main server or gateway station located on ground and can provide communication narrow beams towards isolated areas which suffer from poor terrestrial radio coverage or lack of communication infrastructure. The vital e-learning applications using Internet services provision from the proposed HAP system are described and modelled including system adaptation parameters such as the application and physical layers to control the data rates of different e-learning applications and the overall cell data rate. On the other hand, the provision of high-speed Internet services from the proposed system is supported by using adaptive antenna arrays onboard HAP which provides high-gain beams to achieve the required high-quality transmission data rates at the student premises and provides the capability of coverage cell area adaptation for load balancing. The concentric circular antenna arrays with tapered feeding are proposed in this adaptive antenna system to control the cell mainlobe gain and reduce the out-of-coverage radiation as well. In addition, the system feasibility has been proved in two coverage scenarios including single-beam and multibeam HAP communications.

MODELING OF A LUNENBURG LENS ANTENNA WITH THE INNER METALIC SPHERE

One of the statutory principle of fifth generation mobile communications is the adaptive antenna system beam-forming technology that allow the radiation to be oriented to specific subscriber. Promising solution of the task can be using the passive antennas, which provide the direct beam-forming with no active component in the circuit, thus is low-cost. Lunenburg lens antenna is perspective solution of the task described above and allows the direct radiation to be formed in wide-angle range and keeps the required performance. Besides, it's slightly compact, so the antenna can be installed on various of city infrastructure elements, and the spherical form of device is advantage when the installation is performed on to the vehicles surface (train, car, aircraft, etc.) In the paper, the metallic sphere installation inside the spherical Lunenburg lens as a mean of attachment to constructions is described. The analysis results of the inner element impact to the antenna characteristics of the Lunenburg lens are provided. Analytical system model with the spherical conductor inside the antenna, which can also be used to calculate the presence of metallic particles impact to the average permittivity of the lens, is shown. The diffraction task is addressed by means of the Green's tensor functions application. The results of numerical modeling of the described antenna system using the Ansys Electronics Desktop (HFSS Design) are presented. Analytical and numerical calculations show that the limited-sized metallic sphere presence inside the lens does not significantly affect the focusing property of the device. The acquired formulas can be used in the future work to find the solution of the metallic element optimal radius approximation, using the neural networks as one of the mean to do it.

Prospect for Using Low-Element Adaptive Antenna Systems for Radio Monitoring Stations

This article is devoted to the analysis of prospect to apply multifunctional adaptive antenna systems for radio monitoring stations. The review of publications done demonstrates that current antennas that are developed and used in radio monitoring systems to control and measure the parameters of electromagnetic radiation should be applicable to conduct accurate measurements in wide frequency range under the condition of interferences. The analysis shows that modern adaptive antenna systems are mostly developed for radar and telecommunications applications. In this context we consider possible ways to solve the problem of adapting radio monitoring devices to a complex electromagnetic environment using antenna systems with primary processing of received signals . It was found that the developers of the antennas, which are based on adaptive interference suppression methods, focus basically on the development and implementation of adaptation processes, limiting themselves only to solving electromagnetic compatibility problems. In such approach, the functions of direction finding and measurement of radiation field parameters important exactly for radio monitoring systems are mostly ignored. Therefore, this research area opens up a wide field for identifying new possibilities for constructing multifunctional antenna systems. Focusing on this direction of research, we consider as an example the constraction of a simple two-element adaptive antenna system, which can be used to measure the parameters of the electromagnetic field in radio monitoring systems. The main relations for the error of determining the direction of arrival of the interference signal with a simple two-element antenna are investigated. The influence of the stability of the antenna array parameters and functional units of signal processing onto the errors is estimated.

USE OF ADAPTIVE ANTENNA ARRAYS FOR INCREASE THE THROUGHPUT IN LTE-A

Context. The aim of the article is to analyze the throughput of the LTE-A mobile network on the uplink using an adaptive linear equidistant antenna array. Objective. Suggestions have been made for the possibility of using adaptive antenna arrays to increase bandwidth in LTE-A mobile networks and analyze the benefits of its use compared to the standard type of base station antenna Method. To achieve this result, a computer model of noise analysis of the mobile network in the form of a flat regular hexagonal antenna array consisting of 7 three-sector cells was developed. To estimate the benefit from the use of adaptive antenna arrays, two options were analyzed: when using a standard antenna array of the LTE-A network, and an adaptive linear equidistant antenna array. During the simulation, 100 random placements of subscribers of useful and interference signals were performed and the minimum, maximum and average gain from the use of adaptive antenna arrays was calculated. The average value of the gain for the adaptive antenna array in the direction of the subscriber station, which generates a useful signal of 5.69 dB more than the standard antenna array of the LTE-A network. At the same time, there is a significant reduction in the gain of the adaptive antenna in the direction of the interference subscriber stations, namely, for those with the highest interference level, the gain is 32.84 dB and 28.33 dB, respectively. To clearly show the gain in the qualitative characteristics of the network, a bandwidth analysis was performed for different types of antennas. The bandwidth distribution (transport block size) for 50 resource blocks using an adaptive equidistant linear antenna array compared to a standard antenna array is presented. Results. It is shown that due to the use of adaptive antenna systems, the average bandwidth increases from 11 Mbit/s to 35 Mbit / s for all types of distribution considered channels. Conclusions. The article proposes the use of adaptive antenna arrays to increase the bandwidth of the LTE-A network. The simulation of bandwidth for 50 resource blocks showed that in the presence of internal system interference when using standard antennas of base stations, the average bandwidth is from 11.2 Mbps to 12.3 Mbps. At the same time, due to the use of adaptive antenna systems, the average bandwidth increases from 11 Mbit/s to 35 Mbit/s for all types of multipath channels considered.

TUNABLE POLARIZERS FOR X-BAND RADAR AND TELECOMMUNICATION SYSTEMS

Background. Nowadays processing of signal polarizations is widely applied in modern information and telecommunication radio engineering systems for different purposes. Commonly polarization processing is carried out in polarization adaptive antenna systems. The essential elements of such systems are transformation devices for polarization processing. They perform the transformation of the types of polarization and separate the different types to isolated channels. The most simple, effective, technological and actual for analysis are polarizers based on square waveguides with irises and posts. Objective. The purpose of this work is to improve the electromagnetic characteristics of an adjustable polarizer by creating a mathematical model of such device. The device must provide optimized polarization and matching characteristics. Methods. The article presents a mathematical model of a waveguide polarizer with irises and posts by the decomposition method using wave transmission and scattering matrices. The developed model takes into account the influence of the polarizer design parameters on its characteristics. Results. The article contains the results of calculations based on the developed mathematical model of the polarizer. In addition, the results of modelling of the device using the finite element method are presented for comparison. For the developed waveguide polarizer we have compared the polarization characteristics and the matching. Conclusions. The created mathematical model allows us to effectively analyse the characteristics when the design parameters change. These parameters include the size of the wall of the square waveguide, the heights of the irises and posts, the distance between them, the thickness of the irises and posts. The developed polarizer is recommended for the application in modern telecommunication and radar systems.

Features of the Use of Phase-Manipulated Pseudo-Random Signals without On-Board Processing in Satellite Communication Systems with a Nonlinear Repeater

The features of the use of phase-manipulated pseudo-random signals without on-board processing in satellite communication systems with a nonlinear repeater are analyzed. In particular, the process of passing signals through a nonlinear repeater is considered, taking into account the resulting combinational interference. In more detail, attention is paid to one of the ways of noise protection of satellite communication lines - the use of spatial signal processing and interference in antenna systems. Depending on the type and number of subscribers served by antenna systems, the implementation of the above method is possible by using spatial selection of signals and interference, based on the use of antennas with narrow directional patterns; spatial interference rejection, based on the use of adaptive antenna systems that form dips in the directional pattern in the direction of interference sources; suppression of narrow-band interference in the notch frequency filter and the joint application of all these methods of interference suppression. The placement of multipath antennas on board a repeater satellite, in addition to increasing the noise immunity of satellite communication lines, provides: an increase in the energy potential of the satellite communication line; multiple frequency reuse; multi-station access with time separation and switching of beams on board; the formation of a given service area from a system of independent partial beams with intersecting narrow radiation patterns; the protection of satellite communication lines due to the localization of electromagnetic radiation in a narrow solid angle. The use of multipath antennas with a large number of independently controlled beams on board the repeater satellite significantly complicates the repeater and worsens its weight and size characteristics. For this reason, existing satellite communication systems use multipath antennas, which, as a rule, have no more than 7...10 beams with independent control.

Time-Modulated Antenna Array for Real-Time Adaptation in Wideband Wireless Systems—Part II: Adaptation Study

In this article, an adaptive antenna system (AAS) based on a time-modulated antenna array (TMAA) and population-based metaheuristic algorithm is presented. The algorithm is driven by the signal-to-noise ratio measurements and provides real-time adaptation of the antenna pattern. This article also addresses the issue of multiband reception with a TMAA, demonstrating that the sidebands generated from frequency-diverse signals can overlap and interfere. The effectiveness of the AAS as part of a wireless communication system is presented in three different experimental scenarios that consider gradually or rapidly changing conditions as well as the interference caused by the reception of two signals with different carrier frequencies.

Load-Aware Energy Efficient Adaptive Large Scale Antenna System

This paper proposes an adaptive large scale antenna system (ALSAS) for enhancing energy efficiency in low density wireless network scenarios. The proposed ALSAS comprises of two stages, a novel adaptive discontinuous transmission (ADTx) stage and an antenna array optimization (AAO) one. The basic idea is to utilize prior knowledge of the users' quality of service (QoS) requirements as well as precoding selection in the ADTx stage to maximize the transmitter hibernation periods subject to a certain complexity constraint. In the AAO stage, further power saving is achieved by reducing the number of active antenna elements subject to a certain QoS requirement. It is shown that, relative to conventional large scale antenna system (LSAS), the proposed ALSAS system achieves significant energy efficiency improvements under various scenarios. The results show that the proposed technique can provide energy efficiency improvement between 125% and 1124% in the suburban scenario, and between 196% and 952% in the rural scenario. It is also demonstrated that for rural environments with relatively small short inter-site-distance (ISD) values, ALSAS can provide up to 500% power saving for the fixed bit rate requirement case.

On Simple-Sectored Multi-Probe Anechoic Chamber Design for mmWave Adaptive Terminal

Over-the-air (OTA) testing of millimeter-wave (mmWave) adaptive terminal is expected to be an essential step in the product design and development stage. In this paper, we investigated the simple-sectored multi-probe anechoic chamber (SS-MPAC) configuration for testing mmWave adaptive terminal under fading channel conditions. By summarizing the characteristics of the adaptive terminal antenna, four representative antenna sub-arrays were utilized to evaluate the testing performance under two spatial channel models. We also discussed two evaluation metrics to assess the accuracy of the SS-MPAC configuration. The results indicated that, the configuration parameters of SS-MPAC design were determined mainly by the position of the adaptive antenna sub-arrays and the half power beamwidth (HPBW) of adaptive antenna systems. Furthermore, to ensure accurate emulation of spatial correlation between multiple active sub-arrays on the terminal, a much more expensive setup configuration is expected, compared to single active sub-array (single adaptive array, or multiple sub-arrays with switch structure) terminal case. These findings are valuable inputs for the ongoing New Radio (NR) multiple-input multiple-output (MIMO) OTA work in the standardization.

Cournot Duopoly for Spoofing Attack in MIMO with the Adaptive Antenna System

Wireless communication capacity & performance can be enhanced by Multiple Input Multiple Output (MIMO) technology. The signal transmitted in MIMO technology is affected by path loss, attenuation due to distance and interference. An unauthorized user known as spoofer between transmitter and receiver affects the performance of MIMO technology. An adaptive antenna technology (AAT) is proposed in this work to reduce path loss and attenuation of MIMO technology. A game theoretical approach known as Cournot duopoly is also proposed where an optimum number of transmitter and receiver antenna is used to reduce spoofing in MIMO technology.

Development of an out-of-Focus Irradiator Based on a Phased Antenna Array for a Space Communications' Parabolic Reflector Antenna

Mirror antenna systems are widely used in satellite and space communication systems and radio astronomy. Development of these areas requires new efficient antenna systems' design. Possible technical solution for creating an effective mirror antenna is a “hybrid” scheme, when an adaptive phased antenna array is used as an irradiator. This paper is devoted to the development of an out-of-focus irradiator based on a phased antenna array for a space communications' parabolic reflector antenna. The aim of the work is to develop an optimal design of the irradiator with the choice of the structural element of the antenna array and experimental studies of the selected structural element.The wavefront recovery method was used as a tool for selecting the irradiator configuration. The idea of this method use is to reproduce the electromagnetic field of an incident plane wave with an irradiator in order to uniformly illuminate the aperture of the antenna mirror.In order to select the structural element of the irradiator several antennas were considered: a patch antenna, a flat spiral antenna, a conical spiral antenna. The requirements for the phased antenna array element were defined. The irradiator based on the above mentioned was simulated and the irradiator geometry was optimized according to the maximum gain criterion.The maximum gain was achieved for the irradiator based on conical spiral antennas and amounted to 30.8 dB, which for the considered mirror aperture of 2.4 m is close to traditional focal schemes. The results obtained make it possible to create an adaptive antenna system able to compensate for the deviations of the mirror's shape from the theoretical profile, as well as phase distortions in the atmosphere by changing the lattice weights coefficients.

MIMO Interference and Path Loss Reduction using Adaptive Antenna System along with Optimization of Frequency for Zero Path Loss

MIMO Interference and Path Loss Reduction using Adaptive Antenna System along with Optimization of Frequency for Zero Path Loss

Development of blind algorithm with automatic gain control

In this paper, the concept of blind algorithm with automatic gain control (AGC) is introduced in adaptive antenna system for signal optimization with an aim to estimate the desired response in adaptive fashion. Blind algorithm with AGC is a hybrid two-stage adaptive filtering algorithm; sequentially combining constant modulus algorithm (CMA) and Bessel least mean square (BLMS) algorithm. Blind Bessel beamformer with AGC does not require external reference signal to update its weight vectors and step size for convergence but updates itself from own reference signal obtained from the output of CMA. Similarly, step size is obtained from the correlation matrix which is the product of the signals induced in array elements of antenna. BLMS is the modified version of LMS algorithm; based on the non-uniform step size exploiting the asymptotic decay property of Bessel function of the first kind. The output of CMA provides input and reference signals for BLMS that makes it blind. The contributions of this paper include the development of novel blind theory concept and presentation of an AGC method in order to make the Bessel beamformer blind which can update itself electronically through the correlation matrix depending on the signal array vector with the aim to make the signal power constant.

On a silver platter

on a silver platter

A Compact Antenna for GPS Anti-Jamming in Airborne Applications

Null-steering using adaptive antenna systems is a robust method to global positioning system (GPS) receivers against hostile jamming. Conventionally, multi-antenna arrays have been utilized for such receivers, but the size and weight are often prohibitive especially for space-limited airborne applications. In this paper, we present another approach based on antenna pattern and polarization diversity to enable null-steering, and propose a design with co-located elements to achieve a small footprint. As a proof-of-concept, we present an antenna prototype with a size of only 5 × 5 × 1.9 cm 3 (0.26λ × 0.26λ × 0.1λ) at the L1 band, capable of steering two nulls. We present the simulated and measured parameters of the antenna, study its null-steering performance in various interference scenarios with a simple power minimization method, and demonstrate its capability in suppressing up to two jamming signals incident from the angular region close to horizon.

ANTENNAS OF MOBILE TERMINALS IN MODERN MOBILE COMMUNICATION NETWORKS (OVERVIEW)

In connection with the development of technology of mobile terminals (cell phones, smartphones, tablets, computers with wireless modems, etc.) in the standards of UMTS (3G) and LTE (4G) great attention of manufacturers of these devices is concentrating on the modernization and development of antenna systems of mobile stations (terminals). Currently, antenna systems of mobile stations is implementing on base of technology in form of complex configuration microstrip transmission lines, which ensure compliance with the requirements of modern wireless communication standards. Adaptive antenna arrays and MIMO antenna systems are implemented in mobile terminals for road and railway transport, which allow to achieve a sustainable reception of signals from the base stations. As you know, the difficult conditions for the propagation of radio waves in cellular mobile communication systems are associated with their absorption, multiple reflection and scattering. In these cases, the laws that are true for the line of sight conditions (LOS, Line of Sight) no longer work. The properties of antennas integrated into mobile terminals (mobile stations - MS (Mobile Station)) directly depend on the statistical characteristics of the environment and the location of the operating terminal relative to the spatial position of the user. Therefore, when designing MS antennas in UMTS and LTE mobile communication systems in the frequency ranges from 450 to 3700 MHz, it is important to consider all of the above factors.