Single Antenna Systems Research Articles

Enhancing PAPR reduction efficiency in MIMO-OFDM systems via selective mapping and metaheuristic algorithms

The relentless evolution of communication systems, driven by the demands of 5G and the impending 6G networks, necessitates heightened data rates and spectral efficiency. orthogonal frequency division multiplexing (OFDM), a form of multicarrier modulation employed in multi-input multi-output (MIMO) systems, stands as a pivotal technology. Yet, OFDM grapples with challenges, notably the peak-to-average power ratio (PAPR) issue. Selective mapping (SLM) has been a favored technique for mitigating PAPR in OFDM, albeit challenged by computational complexities in its pursuit of discovering optimal phase factors. This paper pioneers a transformative approach by integrating metaheuristic algorithms genetic algorithm (GA), particle swarm optimization (PSO), and the innovative fireworks algorithm (FWA) into SLM for PAPR reduction while minimizing computational complexity. Simulation results not only affirm the efficacy of SLM-based techniques but also spotlight the potential of metaheuristic algorithms in addressing PAPR challenges in modern communication systems. The study transcends single-antenna systems, extending to MIMO-OFDM systems based on WiMAX standards, validating the efficacy of these techniques in multi-antenna configurations. Crucially, the FWA, proposed for the first time in this paper, emerges as a robust candidate, striking an enviable balance between computational efficiency and performance, achieving a notable PAPR reduction with a favorable search number.

GNSS visibility and performance implications for the GENESIS mission

The GENESIS mission prepared for launch in 2027 integrates the four space-geodetic techniques on a single spaceborne platform in medium Earth orbit. With its unique observations and alternative tie concepts, the mission aims to contribute to an improved accuracy and homogeneity of future terrestrial reference system realizations. To assess the expected contribution of Global Navigation Satellite System (GNSS) tracking, a comprehensive GNSS coverage analysis is performed based on detailed link-budget simulations, taking into account the best available gain patterns and signal-specific transmit power estimates derived for this work from measurements of a high-gain dish antenna. The benefit of different receiver antenna concepts for the GENESIS spacecraft is assessed, and it is demonstrated that a single-antenna system with either a nadir-looking or side-looking boresight is a viable alternative to the dual-antenna configuration considered in initial mission studies. Compared to terrestrial users and missions in low Earth orbit, GENESIS will collect GNSS signals transmitted at up to two times larger off-boresight angles. Only limited information on the actual transmit antenna phase patterns is presently available in this region, which hampers a quantitative assessment of the expected measurement and orbit determination accuracy. As such, a comprehensive release of manufacturer calibrations is encouraged for all blocks of GPS and Galileo satellites. In parallel, a need for in-flight characterization and calibration of the GNSS transmit antennas for off-boresight angles of up to 30^circ using observations of the GENESIS mission itself is expected. The impact of such calibrations on the overall quality of terrestrial reference frame parameters will need to be assessed in comprehensive simulations of global GNSS network solutions with joint processing of terrestrial and GENESIS GNSS observations.

Analysis of Grating Lobe Effects on GEO DSC Distributed Antennas

Traditional single-antenna systems have inherent limitations in terms of antenna gain, anti-interference capability, and flexibility. To overcome these challenges, satellite-mounted distributed antenna systems disperse multiple antennas at different positions on the satellite to improve the reception quality and signal-to-noise ratio of satellite signals, enhancing the performance of the satellite communication system without additional bandwidth or transmission power. However, the dispersed locations and long distances between antennas on the satellite result in less compact spacing compared to terrestrial distributed antennas, leading to the generation of a significant number of grating lobes. The distributed satellite cluster (DSC) approach revolutionizes the traditional mode of satellite utilization, enabling close collaboration among distributed loads. In this study, we analyzed the impact of grating lobes produced by DSC distributed antennas in geostationary Earth orbit (GEO) and simulated the grating lobe patterns of two 1 m circular aperture satellite antenna arrays in GEO. The simulation results revealed that the relative position change of the satellites affected the width and number of interference fringes in a certain ground area, while change in the carrier phase led to the translation of the interference fringes. To mitigate the grating lobes, we employed a sparse array technique. The simulation results demonstrated that the sparse array effectively suppressed the grating lobes but at the expense of a decrease in the sidelobe level and beamwidth.

A Two-element Interferometer for Millimeter-wave Solar Flare Observations

In this paper, we present the design and implementation of a two-element interferometer operating in the millimeter-wave band (39.5–40 GHz) for observing solar radio emissions through nulling interference. The system is composed of two 50 cm aperture Cassegrain antennas installed on a common equatorial mount, with a separation of 230 wavelengths. The cross-correlation of the received signals effectively cancels out the quiet solar component of the high flux density (∼3000 sfu) that reduces the detection limit due to atmospheric fluctuations. The system performance is as follows: the noise factor of the analog front end in the observation band is less than 2.1 dB, system sensitivity is approximately 12.4 K (∼34 sfu) with an integration time constant of 0.1 ms (default), the frequency resolution is 153 kHz, and the dynamic range is ≥30 dB. Through actual testing, the nulling interferometer observes a quiet Sun with a low level of output fluctuations (up to 50 sfu) and has a significantly lower radiation flux variability (up to 190 sfu) than an equivalent single-antenna system, even under thick cloud cover. As a result, this new design can effectively improve observation sensitivity by reducing the impact of atmospheric and system fluctuations during observation.

Wireless Surface Strain Mapping by Passive Electromagnetic Resonators

A wireless multipoint strain sensing system is demonstrated via compact and passive electromagnetic-coupling based array of resonators. The system incorporates nested split-ring resonators (NSRR) as the sensing element, since this geometry is known to enable higher sensitivity and miniaturization. The strain sensing system can be configured in two ways: 1) A single-antenna system where the near-field coupling of the antenna creates high field localization on the array, 2) A two-channel system (TX and RX), where the transmitter can be placed at a distant location to allow remote illumination of the array. Both configurations are validated by measurements, which demonstrate that the system exhibits at least 10-μm-level displacement resolution, corresponding to 1000 microstrains, and a sensitivity of 100 Hz/microstrain. Results of experiments with various antenna types, different number of elements and array alignments are presented, along with simulations to understand the system characteristics. The results prove that frequency shifts of the sensors can be tracked without complex processing as long as the initial resonance frequency and allocated bandwidth of each sensor are selected so as to avoid overlaps. The system is particularly advantageous for Structural Health Monitoring (SHM) applications, where measurement of two-dimensional strain is critical in assessment of the deformation in concrete, metal or composite materials.

Generation of Mixed-OAM-Carrying Waves Using Huygens’ Metasurface for Mm-Wave Applications

Antennas that generate orbital angular momentum (OAM) have the potential to significantly enhance the channel capacity of upcoming wireless systems. This is because different OAM modes that are excited from a shared aperture are orthogonal, which means that each mode can carry a distinct stream of data. As a result, it is possible to transmit multiple data streams at the same time and frequency using a single OAM antenna system. To achieve this, there is a need to develop antennas that can create several OAM modes. This study employs an ultrathin dual-polarized Huygens' metasurface to design a transmit array (TA) that can generate mixed-OAM modes. Two concentrically-embedded TAs are used to excite the desired modes by achieving the required phase difference according to the coordinate position of each unit cell. The prototype of the TA, which operates at 28 GHz and has a size of 11 × 11 cm 2, generates mixed OAM modes of -1 and -2 using dual-band Huygens' metasurfaces. To the best of the authors' knowledge, this is the first time that such a low-profile and dual-polarized OAM carrying mixed vortex beams has been designed using TAs. The maximum gain of the structure is 16 dBi.

On Outage Analysis in Overlay CCRN with RF Energy Harvesting and Co-channel Interference

This paper studies the effect of co-channel interference (CCI) on energy harvesting (EH) from radio frequency (RF) signal and the performance of reliable communication. An overlay mode of cooperative cognitive radio network (CCRN) model is considered that may support one-way communication between primary users (PUs) and two-way communications between secondary users (SUs). Closed form PU and SU outage expressions are derived in presence of CCI at two SU nodes and multiple antennas at PU transmitter. The absolute impact of CCI on the performance of the proposed system is analysed with respect to various parameters like, transmission power, interference-to-noise-ratio (INR), power splitting factor, number of CCI sources and number of antennas. About 20% and 15% improvements are achieved for PU and SU outage using two antennas compared to single antenna system model.

Wireless power transmission technologies

The article consists of three parts. The analysis of existing technologies of wireless power transfer (WPT) is carried out in the first part. It is noted that one of the factors that determines the choice of one or another WPT technology is the distance over which the power is transmitted and the type of electromagnetic (EM) energy used. The essence of WPT technologies in the near zone, Fresnel zone and Fraunhofer zone is explained. A generalized block diagram of the WPT system is presented. Areas of application and trends in the further development of the WPT technologies over short distances using induction and resonance methods, the WPT technologies over long distances, the technology of EM energy harvesting from the surrounding space and its conversion into direct current for powering low-power devices are considered.
 The achievements of the team of the antenna laboratory of the Kharkiv National University of Radio Electronics (KhNURE) in the area of WPT are presented in the second part of the article. Namely, the electrodynamics’ approach is considered which is based on a single idea about the functioning of WPT systems and which include antennas and their circuits and ways of excitation with nonlinear elements. The stages of building a nonlinear mathematical model (MM) of the electrodynamics’ level of the WPT system are presented, according to which the entire WPT system, which generally includes the transmitting subsystem and the receiving subsystem, is considered as a single multi-input antenna system with nonlinear characteristics. The proposed MM provides a complete representation of the WPT systems operation of a wide class and purpose, in which fundamentally different WPT technologies are used.
 The third part of the article presents new results related to continued research. The analysis of the adequacy of the developed MM of WPT system is carried out. The results of simulation of WPT systems with the induction method of energy transfer (near zone) and their comparison with theoretical and experimental data of other authors showed the reliability and universality of the proposed approach and the MM of WPT system developed on its basis.

A COMPACT 4 PORT MIMO DIVERSIFIED ANTENNA FOR X-BAND APPLICATIONS

Antennas Currently there is large scope in wireless applications due to increased scalability and mobility. Users need these technologies to improve data accessing information from anywhere along with high data speed giving rise to 5G technology. Today’s recent growth increased by huge capacity, data rate and high throughput with single antenna system fulfilling the given requirement more likely to do multipath fading and had low data rate. The drawbacks can be overcome by the MIMO antenna in the wireless communication system.In this paper we designed a rectangular patch antenna with semicircle defective ground substrate which improves the efficiency and reduce interference. These might have wide range of applications in WLAN and WiMAX. This has an advantage of less interference using MIMO antenna. The proposed antenna will be working at frequency of 4-6GHZ (c-band) and frequency (x-band) applications mainly satellite and WiMAX applications.

MIMO Radio Frequency Identification: A Brief Survey.

In this paper, we briefly look at the latest state-ot-the-art in the domain of multi-input multi-output (MIMO) radio frequency identification (RFID) systems while detailing the work done in the domain of anti-collision, range enhancements, bit error rate (BER) improvements and security. Various passive ultra-high frequency (UHF) RFID implementations are considered that employ multiple antennas at the reader and single or multiple antennas at each tag. We look at several recent works those explored MIMO for RFID receivers. When using MIMO at the backscatter channel, significant improvements can be achieved in the BER as well as range extension. With the extra reliability and increased throughput, such systems can be deployed in many important applications like large tag reading scenarios and accurate tracking. Increased throughput is directly dependent on estimation of tag quantity in a bulk reading environment and usually estimators designed for single antenna systems under-perform in such settings causing low signal to noise ratio (SNR) when employed in MIMO systems where tag signal overlapping can happen more often. One of the key challenges is to keep the design of the RFID tag simple, cutting cost and power requirement when employing anti-collision schemes. We provide a brief survey in some of the recent developments related to MIMO RFID systems, the protocols and algorithms used, and improvements achieved.

Model-Free Radio Map Estimation in Massive MIMO Systems via Semi-Parametric Gaussian Regression

Accurate radio maps will be very much needed to provide environmental awareness and effectively manage future wireless networks. Most of the research so far has focused on developing power mapping algorithms for single and omnidirectional antenna systems. In this letter, we investigate the construction of crowdsourcing-based radio maps for 5G cellular systems with massive directional antenna arrays (spatial multiplexing), proposing an original technique based on semi-parametric Gaussian regression. The proposed method is <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">model-free</i> and provides highly accurate estimates of the radio maps, outperforming fully parametric and non-parametric solutions.

INFLUENCE OF LOCATION OF ONE AND MULTIPLE ANTENNAS ON CAPACITY OF C2C COMMUNICATION SYSTEMS

Due to the variety of existing and future wireless services, the number of antennas installed on a vehicle is constantly increasing. However, due to design limitations or the addition of more components of electrical equipment, the number of user-friendly antenna positions is reduced. To ensure stable data connections or even higher data rates with the remaining installation space, a possible solution is to use multiple antenna systems. This document discusses and evaluates 16 possible positions of antennas for communication between cars (C2C). The radiation pattern of all antennas is determined by the antenna synthesis maximization method, which takes into account real-world limitations such as space availability, transmission power, number and location of antennas. Channel bandwidth is used to compare different settings. This bandwidth is calculated using virtual disks based on typical application scenarios. The results of this study show which antenna positions and which combinations of antenna positions are most suitable for communication between C2C. Additional time and cost constraints, as well as an increase in the range of products for the automotive industry and a large number of degrees of freedom for the multi-purpose antenna necessitate the use of advanced modeling models and design strategies. Thus, this is the starting point for this work. Here is presented and used a technique that allows you to optimize single and multiple antenna systems. The main purpose of the proposed synthesis is to optimize the radiation profiles of antennas based on constraints specific to vehicles. For antenna design, this document identifies different scenarios based on typical C2C security scenarios. The simulation is carried out in a typical worst case in urban and rural areas or on highways.

A Cross-Correlation-Based Approach to Pattern Distortion and Mutual Coupling for Shared-Aperture Antennas

This paper proposes a pattern distortion coefficient as a new figure of merit to quantitatively evaluate both mutual coupling and pattern distortions in multi-antenna systems. The proposed coefficient is defined as a cross correlation between unaffected and affected far-field patterns of antennas under test, and the input patterns are weighted using a Gaussian function to consider the target operation angle. The feasibility of the proposed approach is validated using a two-antenna system composed of an inverted-F antenna and a microstrip patch antenna, and the amount of mutual coupling is adjusted by changing the distance between the two antennas. The evaluation is further extended to a single-antenna system with a conducting wall that produces strong platform effects with serious pattern distortions. The results demonstrate that the proposed figure of merit provides quantitative insight into the amplitude and phase distortions of far-field patterns that can be caused by both mutual coupling and platform effects.

Wide-angle scanning phased-array system using arc-shorted half elliptic elements

Vehicles to everything (V2X) communication includes a variety of types, so wide-angle scanning is integral. For wide-angle scanning, the half power beam width (HPBW) of a single antenna must be wide. Moreover, the gain, low cross-polarization level, and impedance bandwidth are essential factors in high communication performance. In this paper, a wide-angle scanning phased-array system using an arc-shorted half-elliptic patch antenna at 5.8 GHz is presented. The design of both a single antenna and the entire phased-array system are covered, and to verify the design method, the proposed single antenna and phased array system were fabricated. The proposed antenna had 162 HPBW in the E-plane and 8.63 dBi of peak gain. Its fractional bandwidth was 5%, and the level of cross-polarization was −16.8 dBi. Furthermore, the measured 3 dB scanning angle of the phased-array system was from to 90. The proposed system has wide-angle scanning.

Statistical CSI Driven Transmit Antenna Selection and Power Adaptation in Underlay Spectrum Sharing Systems

In underlay spectrum sharing, transmit antenna selection (TAS) improves the performance of a secondary system and helps it control the interference it causes to a primary system. TAS does so with a hardware complexity and cost comparable to a single antenna system. We present a novel and optimal joint TAS and continuous power adaptation rule for a practically relevant, less explored model in which the secondary transmitter knows only the statistics of channel gains from itself to one or more primary receivers. The rule minimizes the average symbol error probability (SEP) of the secondary system for an entire class of stochastic interference constraints. This general class subsumes the average interference constraint and its novel generalization, and the interference-outage constraint. We derive closed-form expressions for the transmit power and selected antenna. We then develop a general analysis of the optimal average SEP that applies to several widely-used fading models. We also present computationally-efficient approaches to determine the parameters that specify the optimal rule. Our comprehensive numerical results characterize the very different impacts of the interference constraint on both secondary and primary systems. They show that the optimal rule reduces the average SEP by two orders of magnitude compared to conventional approaches.

A compact Ultra Wideband dielectric resonator antenna with dual‐band circular polarization characteristics

A new design of a compact dielectric resonator (DR) wideband antenna, catering the ultra-wideband (UWB) spectrum and beyond, along with dual-band circular polarization characteristics is presented in this literature. The antenna is realized by placing a pair of orthogonally placed DRs over a planar “I”-shaped monopole. Fundamental modes of TE10δ ( TE 10 δ x and TE 10 δ y ) and TE11δ ( TE 11 δ x and TE 11 δ y ) are excited at 3.8 and 6 GHz by incorporating a pair of orthogonally placed DRs that generate the lower and upper band of circular polarization, from 3.7 to 4.4 GHz (17.28%) covering downlink and from 5.8 to 6.2 GHz (11.56%) for uplink C-band communication satellites. The antenna provides an overall impedance bandwidth of 2.1 to 13 GHz (146.33%), thus covering UWB and lower end of the Ku-band. Novelty of this work lies in achieving UWB and dual-band circular polarization characteristics in a single antenna system.

Throughput Performance Evaluation of LTE-Advanced with Inter-band Carrier Aggregation

The increasing number of mobile smartphone users requires additional spectrum to maintain cellular quality of service. The 800 MHz band is a good candidate to achieve this goal. It can be used as standalone spectrum or aggregated with other licensed bands to increase the available bandwidth. This paper compares through physical layer simulation the downlink throughput versus distance performance of LTE-Advanced in two different bands. We consider a high frequency band at 2.6 GHz and the 800 MHz to model bands 7 and 20 of inter-band carrier aggregation CA_7-20 respectively. The link level simulation is performed for single antenna system at three different urban locations. The channel is modelled using an enhanced 3D ITU-R channel model combined with measured 3D radiation patterns for the base station and user equipment antennas. The BER versus SNR results show that the 800 MHz band enjoys a gain of up to 1 dB as a result of higher Ricean K-factors. Moreover, for the assumed simulation parameters, at distances beyond 400 m the throughput of the 800 MHz band is significantly higher than the 2.6 GHz band. At a distance of 750 m, the throughput for the 800 MHz band is 4.5 times greater than the 2.6 GHz band. These benefits are shown to relate to the lower path loss values observed in the 800 MHz band.

Integrated Antenna for Receiving Satellite Navigation Signals with a Built-In Inertial Measuring Unit

The present article proposes an approach to ensuring the stable position of an active satellite navigation antenna relative to the inertial measuring unit when installing an inertial navigation system on a vehicle. The task of determining the coordinates of the navigation antenna relative to the inertial unit is accomplished by integrating the two elements into a single structure – an integrated antenna. When manufacturing an integrated antenna, the described approach allows the required coordinates to be determined under factory conditions. As well as explaining the operating principles of individual integrated antenna units, the article considers practical aspects of the integrated antenna’s use in inertial GNSS navigation systems. A specific consideration of the two-way digital information exchange between the antenna and computing device is presented. It is shown that the use of single-type cable modems provides the opportunity for a half-duplex exchange of information between the integrated antenna and the navigation receiver. Various uses of this information exchange to perform common navigation tasks are proposed. The independent measurement basis of the integrated antenna is noted. Approaches to acccounting for the orientation of this basis in the practical application of integrated antennas in single-antenna and multi-antenna inertial GNSS navigation systems are discussed.

Secure Outage Analysis for Cooperative NOMA Systems With Antenna Selection

The secrecy outage probability (SOP) performance is investigated for a cooperative non-orthogonal multiple access system under eavesdropping attack, where a base station transmits signals to a far user via a full-duplex relay, and to a near user directly at the same time, in the presence of an eavesdropper. All nodes are configured with multiple antennas and antenna selection is adopted by the base station and relay to enhance the security performance. The exact and asymptotic closed-form SOP expressions are derived, which incorporate the impact of imperfect channel state information and apply to general cases considering the quality of service of the far and near users, whether or not the wiretap channel is known, and the location of the eavesdropper. Monte Carlo simulations corroborate the analysis and the superiority of the proposed system over the single-antenna system and the one without antenna selection. It is also revealed that the asymptotic SOP performance of the near user is nearly independent of the power allocation.

Performance Analysis of Quantized Uplink Massive MIMO-OFDM With Oversampling Under Adjacent Channel Interference

Massive multiple-input multiple-output (MIMO) systems have attracted much attention lately due to the many advantages they provide over single-antenna systems. Owing to the many antennas, low-cost implementation and low power consumption per antenna are desired. To that end, massive MIMO structures with low-resolution analog-to-digital converters (ADC) have been investigated in many studies. However, the effect of a strong interferer in the adjacent band on quantized massive MIMO systems have not been examined yet. In this study, we analyze the performance of uplink massive MIMO with low-resolution ADCs under frequency selective fading with orthogonal frequency division multiplexing in the perfect and imperfect receiver channel state information cases. We derive analytical expressions for the bit error rate and ergodic capacity. We show that the interfering band can be suppressed by increasing the number of antennas or the oversampling rate when a zero-forcing receiver is employed.