Multibeam System Research Articles

A Wideband If Receiver Chip for Flexibly Scalable mmWave Subarray Combining and Interference Rejection

Large-scale multibeam phased array systems suffer from interbeam interference (IBI) that should be canceled either in the analog or digital domain. In wideband systems such as fifth generation (5G), interference rejection over a wide bandwidth is challenging to achieve, not only due to nonidealities of the receiver chain but also due to the properties of the radio channel. This article presents a scalable IBI cancellation (IBIC) scheme at intermediate frequency (IF) using an IF receiver (IF-RX) chip. The IF-RX provides the flexibility of not just interference rejection between the subarrays but also wideband signal combining over multiple subarrays. It also provides wideband filtering before the analog-to-digital converter (ADC) to support 5G channel bandwidths of up to 800 MHz, high linearity, and low noise figure. A calibration method is proposed to find the cancellation coefficients for the IF-RX in measurements. Furthermore, a simplified over-the-air (OTA) IBIC model for analyzing rejection bandwidth limitations is presented. Interference rejection performance is demonstrated through the OTA measurements using 5G new radio (5G NR) signals. In the OTA measurements, 34–37-dB rejection was achieved for 50–100-MHz signals, while error vector magnitude (EVM) requirements of the 5G standards were met with good margins. Finally, the interference rejection over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\ttimes 100$</tex-math> </inline-formula> MHz carrier aggregated 5G NR waveform was demonstrated.

Model-Driven Multibeam Line Measurement System Design

Multibeam bathymetric system is a complex combination of multi-sensor system. The multibeam bathymetric system is mainly used in the measurement of water depth of waterways, and the scientific layout of the survey line can improve the measurement efficiency, and at the same time, truly and perfectly reflect the topography of the waterway. This paper establishes a mathematical model of coverage width and overlap rate between adjacent strips for multibeam bathymetry, and calculates the parameters such as water depth, coverage width and overlap rate between adjacent strips at the center point of different survey lines. Firstly, a single slope multibeam line model was established to calculate the coverage width and the overlap rate between adjacent strips of the multibeam bathymetric system, taking into account the influence of the slope of a single slope. Then, considering the influence of the angle between the direction of the survey line and the projection of the normal direction of the seafloor slope on the horizontal plane, a mathematical model of multibeam bathymetry with variable survey line direction is established by downscaling the geometrical relationship in the three-dimensional space to the two-dimensional plane. Again, based on the principle of line design, all the lines with overlap rate between 10% and 20% are comprehensively screened, and the enumeration method is adopted to find out the optimal lines under each group of conditions. Finally, a three-dimensional seabed model is constructed based on the actual sea depth data, and the optimal measurement direction and spacing of the survey lines are determined based on the real seabed topographic features, which achieves the goal of minimizing the length of the survey lines, and at the same time, ensures that the survey lines can cover the entire sea area to be surveyed, and the iterative method is used to search for the final direction of the survey lines and find the optimal solution.

Research on Multibeam Bathymetric System Based on Geometrical Relation Mo Model

In this paper, the basic principles of multibeam bathymetry system are discussed in depth, the development of which originates from the single-beam bathymetry technology. Through profound mathematical modelling and geometric relationship derivation, a systematic and detailed analysis is carried out for the coverage width of multibeam bathymetry and the overlap rate between two adjacent bands in the case that the survey line is parallel to the horizontal plane. Adopting the idea of combining numbers and shapes, combined with the triangle side angle relationship, we established a geometrical-mathematical model with an α-slope slant line, which lays a solid theoretical foundation for solving the problem. In this study, we successfully solved the expression of seawater depth D of the multibeam bathymetric system in the case that the direction of the survey line is parallel to the horizontal plane by the method of listing relations. At the same time, we make full use of the sine-cosine theorem of triangles to derive the coverage width of the bathymetric strip in depth. Combining these two organically, a complete and detailed expression for the coverage width is formed, which provides a powerful mathematical tool for the further study of deep-sea bathymetry technology. In addition, by applying the mathematical model to the vacant data in Table 1, we successfully fill in this missing information, demonstrating the feasibility and accuracy of the model in practical applications. This study not only makes remarkable progress in theory, but also provides strong support for practical applications in the field of ocean bathymetry.

Research on Measurement of Multi-beam Transducer Based on Analytic Geometry Method

The ocean is inseparable from the survival and development of human beings. It not only provides rich resources for human beings, but also provides a large number of samples for human scientific research. For the efficient development of the ocean, detailed and accurate seabed topography and geomorphology information is needed as a prerequisite. In this paper, aiming at the problem of multi-beam detection system detecting full coverage water depth strip in waterway, the measurement model of multi-beam transducer under different survey lines is established. Based on the combination of numbers and shapes, firstly, this paper considering the special situation that the survey line is perpendicular to the horizontal component of the normal of the seabed slope, it is concluded that the depth of seawater is positively correlated with the width of the survey line. Secondly, when the angle of the survey line is arbitrary, and the spatial rectangular coordinate system model is established, this paper considering the law of the width of the survey line at different angles and distances. Finally, through analytic geometry method, the measuring line equations at different positions and angles are expressed in this paper, and the measuring line width is quantified according to the distance formula between two points. The results show that the coverage width is unchanged at the center of the sea area or when the direction of the survey line is perpendicular to the horizontal component of the normal of the submarine slope. The coverage width is symmetrically distributed at the survey line angle. The results show that the multi-beam transducer measurement model is effective.

Optimization Model of Survey Line Layout for Multibeam Bathymetric Systems

Multibeam bathymetric system is an underwater terrain measurement technology with high efficiency, high accuracy and high resolution. Based on the multibeam bathymetric system, this paper establishes an ideal geometric model and an isobath iterative model. Through the physical method of ideal model, the actual physical problem of multibeam sounding is abstracted into a geometric model about a conic curve, and under the constraint of overlap rate, the coordinates of the next survey line are iterated according to the current depth to solve the optimal set of survey lines. First, the seawater depths, strip coverage widths, and overlap rates with the previous line are calculated for lines at different distances from the center point. Then, the angle between the direction of the survey line and the projection of the normal direction of the seafloor slope on the horizontal plane is introduced to solve for the current coverage width of the survey line. Again, the optimal set of survey lines is solved under the constraint of the overlap rate. Finally, Sobel edge detection is used to divide the surface of the seafloor terrain into multiple planes with defined slope angles to solve the optimal line set for the entire seafloor surface. The structure of the proposed mathematical model is clear and simple, which is in line with the actual situation.

ВИЗНАЧЕННЯ ТА ВРАХУВАННЯ СИСТЕМАТИЧНИХ ПОХИБОК ПРИ ВИМІРЮВАННІ НАВІГАЦІЙНИХ ГЛИБИН

The scientific study considers the issue of studying the features and determining the inherent values of systematic errors that occur when measuring navigation depths with multibeam echosounders, the elimination of these errors from the measurement results, which requires a special organization and methodology for performing multibeam echosounders tests. Systematic errors of navigation data can affect as on the magnitude of the depth itself, as well as on its planned position, and their influence should be evaluated after studying the angular measurements by echo sounder beams and calibration. The calibration of multi-beam systems, as well as the horizontal and vertical movements of the vessel, is much more significant and complicated compared to the calibration of single-beam systems. It is necessary to perform system accuracy control tests to confirm the reliability of multibeam echosounder data. These tests should preferably be carried out on board before taking depth measurements. For this, it is necessary to capture data, process and edit them in real time. Periodic performance of accurate calibration and testing is necessary to confirm that the multibeam survey meets the accuracy requirements. Multibeam echosounders calibration tests are performed with the aim of minimizing errors, taking into account the delay time of data acquisition, sea waves and changes in the ship's course. Keywords: multibeam echosounder, systematic errors, sensor calibration, hydrographic surveys, relief of the seabed, marine navigation chart, measured tacks, survey software.

Research on Adaptive Transmit Diversity Strategy for Reducing Interference in Underwater Optical Multi-Beam Non-Orthogonal Multiple Access Systems

With the rapid development of the underwater Internet of Things (IoT), the number of underwater communication nodes is rapidly increasing. The access capacity of a traditional multi-antenna communication system is limited by the number of transmitting antennas, and multi-beam communication systems using non-orthogonal multiple access (NOMA) technology can enhance the access capacity of the system. However, this can lead to serious inter-beam and intra-beam interference. To address the severe issues of inter-beam and intra-beam interference in underwater multi-beam NOMA systems, we propose an adaptive transmit diversity strategy. We design an algorithm for adaptive selection and merging beams based on the degree of interference between beams in space, which merges LED beams with high interference. Diversity technology is used to reduce interference between beams, and spatial multiplexing is still performed between LED groups with low interference. Within the same beam, we use an OFDM-NOMA scheme to match and group the users. Signals from different user groups are sent through different subcarriers to improve resource utilization. This enhances access capacity while reducing NOMA inter-user interference. Simulation results show that the bit error rate (BER) of users with the adaptive transmit diversity strategy satisfies the forward error correction (FEC) limits in the presence of high inter-beam interference and has a better reachable rate and BER performance compared to the multi-beam access system without interference management. We also analyze the system BER performance of the proposed strategy in the multi-user case, and the BER of all 32 access nodes are lower than the FEC threshold at a communication distance of 5 m. This demonstrates that the strategy can effectively reduce the interference of the multi-beam NOMA system.

A Robust Symbol-Level Precoding Method for Multibeam Satellite Systems

Compared to interference mitigating precoding, interference exploiting symbol-level precoding (SLP) requires less transmit power to guarantee the quality of service in a multibeam satellite system. However, due to the large roundtrip time (RTT), it is impractical to obtain real-time channel state information on the satellite side. The random channel state information (CSI) phase error of outdated CSI could cause serious performance deterioration of SLP. To compensate the CSI phase error, we propose an outdated CSI-based robust SLP (RSLP) method, which optimizes the transmit power under outage probability constraints. The central limit theorem (CLT) and second-order Taylor expansion are used to relax the outage probability constraints into convex ones. In addition, because only outdated CSI-based robust block-level precoding exists, we present two comparative RSLP methods accordingly. Without violating outrage probability constraints, the proposed RSLP method requires much lower transmit power than comparative RSLP and existing robust block-level precoding methods. The complexity of the proposed RSLP method is also lower than that of two comparative RSLP methods.

Formation of Beams of Charged Particles in Multibeam Systems of an Electric Dipole Configuration at a Multipetawatt Power Level

Formation of Beams of Charged Particles in Multibeam Systems of an Electric Dipole Configuration at a Multipetawatt Power Level

A Novel Cone Model Filtering Method for Outlier Rejection of Multibeam Bathymetric Point Cloud: Principles and Applications.

The utilization of multibeam sonar systems has significantly facilitated the acquisition of underwater bathymetric data. However, efficiently processing vast amounts of multibeam point cloud data remains a challenge, particularly in terms of rejecting massive outliers. This paper proposes a novel solution by implementing a cone model filtering method for multibeam bathymetric point cloud data filtering. Initially, statistical analysis is employed to remove large-scale outliers from the raw point cloud data in order to enhance its resistance to variance for subsequent processing. Subsequently, virtual grids and voxel down-sampling are introduced to determine the angles and vertices of the model within each grid. Finally, the point cloud data was inverted, and the custom parameters were redefined to facilitate bi-directional data filtering. Experimental results demonstrate that compared to the commonly used filtering method the proposed method in this paper effectively removes outliers while minimizing excessive filtering, with minimal differences in standard deviations from human-computer interactive filtering. Furthermore, it yields a 3.57% improvement in accuracy compared to the Combined Uncertainty and Bathymetry Estimator method. These findings suggest that the newly proposed method is comparatively more effective and stable, exhibiting great potential for mitigating excessive filtering in areas with complex terrain.

Quantification and Analysis of Carrier-to-Interference Ratio in High-Throughput Satellite Systems

Recently, the demand for high data traffic transmission is experiencing unstoppable growth, and multi-beam high-throughput satellite (HTS) systems have proven to be effective solutions. However, how to manage and eliminate the co-channel interference caused by frequency reuse in multi-beam HTS systems is still a challenging issue. Motivated by this background, this paper begins with discussing the interference mechanism in the uplink and downlink of HTS systems and then uses the quantification method of carrier-to-interference ratio (CIR), whereby the influencing factors of the CIR are accordingly analyzed. In addition, the common CIR selection strategies are summarized and compared with each other in terms of their advantages and disadvantages. Based on the proposed CIR quantification and statistical selection methods, two frequency plan cases are simulated for the scenario of 19 beams with 4-color reuse. The results show that the proposed quantification and selection methods are rather practical and offer a feasible approach for frequency plan adjustment based on CIR optimization. Finally, a simulation analysis of the CIR under different power spectral density (PSD) values is conducted, and the results show that the PSD has a substantial impact on the CIR.

E-Plane-Focused Partial Maxwell Fish-Eye Lens Antenna for Multibeam Wide-Angle Scanning

This letter presents a multi-beam wide-angle scanning antenna based on the E-plane-focused partial Maxwell fish-eye (PMFE) lens operating in Ka-band. The gradient equivalent refractive index distribution of the lens is realized by the parallel plate waveguide (PPW) partially filled with dielectric material, which can support the E-plane focus. The lens is fed by a series of rectangular waveguides arranged along the straight cut line to realize the multiple beams. To improve the impedance matching, the dielectric wedges are loaded in the interface between the feeders and the lens. The E-plane broadening of waveguide feeding ports effectively alleviates the gain drop of wide-angle scanning. The measured results of the prototype show a beam scanning range more than ±90° with the aperture efficiencies between 57% and 85.7%. The good impedance matching is also obtained in the operating band. The proposed PMFE lens antenna has the application potential in the low-cost millimeter wave (MMW) multi-beam systems.

Steerable Simultaneous Multibeam Antenna Based on Reconfigurable Reflectarray

Multi-beam system is a core part for wireless concurrent communication and massive MIMO applications. Traditional concurrent communication techniques, like phased-array or digital beam-forming (DBF) system, suffer from massive RF frontends or power-hungry high speed ADCs, which makes them complex and expensive in fabrication. Inheriting the advantages of reflectarray and passive multi-beam system, we reported in this letter a novel and cost-effective concept of steerable simultaneous multi-beam antenna (SMBA). New features and the practicality of it are fully verified with theoretical analysis and experimental implementation of a prototype working at 7GHz with 300MHz bandwidth. With multiple beams steered simultaneously, the SMBA can eliminate the crossover regions between adjacent beams of passive multi-beam antenna. Experimental results indicate its potential in the design of diverse concurrent communication systems such as base stations and point-to-point links.

A High-Gain Dual-Band Multibeam Antenna System for MIMO Wi-Fi Application

A compact dual-band multibeam antenna system with high gain is presented for multiple-input-multiple-output (MIMO) Wi-Fi application. The antenna system is composed of four rotationally symmetric antenna panels occupying a compact size of 60 × 200 × 7.2 mm3. Two series-fed microstrip patch antenna (MPA) arrays are proposed to operate at the 5-GHz band. They are fed with ±90° phase difference signals for two directional radiation patterns with about 45° horizontal 3-dB beamwidth and distinct radiation directions. Two dual-function metasurface based on periodically loaded parallel lines is designed and compactly placed between the two MPA arrays. The metasurface works as a 2.4-GHz antenna with about 90° 3-dB beamwidth in the azimuth. Besides, the application of metasurface improves the gains at the 5-GHz band. Then, four antenna panels are placed in a rotating arrangement with an electric size of 0.59λL × 0.59λL × 1.57λL (λL is the free-space wavelength at the lowest operating frequency). The antenna system was manufactured and demonstrated the characteristics of 360° pattern coverage in azimuth and high gain. The measured average gains are respectively higher than 8 dB and 12 dB at the 2.4-and 5-GHz bands.

Sub-millisecond 4D X-ray tomography achieved with a multibeam X-ray imaging system

A proof-of-concept experiment for sub-millisecond temporal and 10 μm order spatial resolution 4D X-ray tomography imaging using a multibeam X-ray imaging system is reported. The 3D structure of a tungsten wire during mechanical deformation was reconstructed using a super-compressed sensing-based algorithm from 28 projection images acquired simultaneously with a temporal resolution of 0.5 ms. The multibeam imaging system does not require rotation of the sample, X-ray source or detector. The experiment demonstrates the potential for improving the time resolution in observing non-repeatable dynamic phenomena, such as those occurring in fluids, living beings, or material fractures.

Multi-beam X-ray optical system for high-speed tomography using a σ-polarization diffraction geometry

A multi-beam X-ray optical system using a σ-polarization diffraction geometry is proposed and its potential for high-speed tomography using synchrotron radiation is experimentally evaluated. Projection images of a sample are obtained simultaneously from different directions with X-ray beams generated by diffraction of a white synchrotron radiation beam at silicon single crystals. This makes it possible to record a tomographic dataset without rotation of the sample or X-ray source. Data sets of two samples obtained in a proof-of-principle experiment with an exposure time of 1 ms were successfully reconstructed using an advanced compressed-sensing algorithm.

Load balancing for multi-beam additive manufacturing systems

Load balancing for multi-beam additive manufacturing systems

Multi-beam piezoelectric systems by means of dynamically equivalent stiffness concept

Energy harvesting devices allow to obtain forms of energy present in nature and to convert them into electrical energy. One way of generating energy from mechanical vibrations is by using beams of piezoelectric materials. This paper proposes an alternative methodology for characterizing the dynamic behavior of a vibrating composite system composed of a cantilever steel base beam (primary system) and a piezoelectric beam attached to it. The approach involves representing the piezoelectric beam using an equivalent dynamic stiffness at its base. This simplifies the mathematical representation of the compound system and enables the system dynamics to be described solely in terms of the generalized coordinates of the primary system, which is advantageous in optimization environments where a reduced number of equations can facilitate analysis. To determine the equivalent dynamic stiffness, different mathematical models of one and multiple degrees of freedom are presented, including the description of the polyamide base of the piezoelectric sheet. An inverse problem is used to identify system parameters, and the energy generation over a wide range of frequencies is analyzed. Experimental frequency response functions of the voltage–acceleration type are obtained to validate numerical findings, demonstrating that the proposed methodology is a cost-effective alternative for parameter identification or optimal design in energy generation.

Research on theoretical and experimental of Interference processing based on three-channel mutual injection phase-locked laser

With the advantage of obtaining multiple phase-locked laser outputs at the same time without complicated modulation devices, the multi-channel mutual injection technique provides a new idea to solve the problem of excessive use of beam splitting devices in traditional multi-beam interference processing systems. In this paper, we analyzed the phase-locking mechanism of the mutual injection technique, studied in detail the locking process of the phase difference of three lasers with time when their energy is injected into each other, and discussed the coherence characteristics of the three Gaussian beams after convergence. Accordingly, we built a three-beam interferometric processing system based on the three-channel mutual injection solid-state laser to process the surface of silicon material. The surface of the material was observed by SEM to exhibit a clear structure of regular shaped microporous arrays with a period of 3.0 µm distributed according to the regular pattern of positive hexagon, which was consistent with the interference pattern obtained from the simulation. The comprehensive theoretical and experimental results show that the laser obtained based on the three-channel mutual injection technique has good coherence characteristics and can be effectively applied in interference processing. This opens up a new idea for the development of interference processing equipment and has positive significance for the development of multi-beam interference processing.

Effect of Wavefront Distortion in Non-Kolmogorov Turbulence on the Performance of Multi-Beam Transmission Coherent Detection

This study aims to address the multi-beam transmission problem of optical wireless coherent communication systems under the influence of non-Kolmogorov turbulence. This paper establishes the mathematical model for mixing efficiency and BER of non-Kolmogorov turbulence wavefront distortion and multi-beam transmission coherent detection systems. The influence of factors such as spectral power-law index, zenith angle, and transmission distance on the communication performance of the system is analyzed, and an experimental system is built using adaptive optics equipment to test the proposed theory. Numerical analyses show that in a non-Kolmogorov turbulence environment, as the spectral power-law index, zenith angle, transmission distance, Fresnel zone, and pointing error attenuation increase, the mixing efficiency of the coherent detection system decreases and the BER increases; under the same conditions, the mixing efficiency and BER of the system are improved after increasing the number of transmission beams at the transmitting end. Experimental research shows that, for the coherent detection system after wavefront correction using adaptive optics, the wavefront PV and RMS variances are 1.68 μm2 and 0.05 μm2 when a single beam of light is transmitted at the transmitting end, and the wavefront PV and RMS variances are 0.23 μm2 and 0.01 μm2 when two beams are transmitted. It is verified that using multi-beam transmission wavefront superposition to suppress wavefront distortion and wavefront jitter can effectively improve the mixing efficiency and BER of the coherent detection system at the receiving end.