Beam Coverage Research Articles

Integrated sensing and communication‐promoted beam tracking and coverage for complex vehicular networks

AbstractThe future vehicle‐to‐everything (V2X) scenarios greatly call for reliable and efficient communication links between roadside units (RSUs) and vehicles. Integrated sensing and communication (ISAC) represents one of the key candidate technologies for 6G, which provides new solutions for this problem. In this paper, the beam tracking design for V2X communication is investigated by exploiting the ISAC technique, where the RSU uses the echoes of the ISAC signals to estimate the motion parameters of the vehicles. Compared with traditional feedback‐based beam tracking, the proposed method can reduce the overall signaling costs and improve communication robustness. Furthermore, to achieve high accuracy and low latency for beam alignment, a Trajectory Adaptive Unscented Kalman Filter (TA‐UKF) beam tracking algorithm is proposed, which obtains the optimal state transition model following the change of the vehicle state. Considering practical application scenarios, an ISAC‐based adaptive beam coverage (ISAC‐AC) scheme is further developed for the beam tracking of extended targets, which can achieve the beam misalignment of vehicles in practical scenarios. Numerical results demonstrate that the proposed beam tracking and coverage strategies outperform baseline approaches.

High-Efficiency Wide-Angle Scanning Mechanoelectrical Hybrid Phased Array Antenna With Mechanically Reconfigurable Element Pattern

In this paper, a high-efficiency wide-angle scanning mechanoelectrical hybrid phased array antenna with mechanical-ly reconfigurable element pattern is proposed. The proposed array is composed of several linear array panels, which can be mechanically rotated. In contrast to conventional hybrid scan-ning arrays, it rotates in the elevation plane with only three fixed states enabling quick beam switching capabilities, rather than constantly rotating in the azimuth plane. The optimal element's half power beam-width (HPBW) and panel rotation angle are examined in this paper to produce the best scanning range and gain performance in the rotation plane for the array. As a proto-type, an 8×8 array formed by an equivalent magnetic dipole patch antenna, whose HPBW is properly designed to satisfy the optimal value, is configured and fabricated. Both simulated and experimental results show that the proposed array can scan its main beam from -67° to 67° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane, -75° to 75° in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane, and its 3-dB beam coverage reaches ±82°, ±90° in the two planes. Additionally, the peak efficiency of the array can reach 75%.

MmWave self-beam-tilting antenna array with low complexity and wide coverage

This paper proposes an effective planar mmWave switched beamforming antenna array with low complexity and wide beam coverage. The proposed structure is configured using multiple linearly polarized self-beam-tilting-antenna (SBTA) elements, eliminating the requirement of a phase-adjustable block for beamforming. Each SBTA element can generate different main beam directions by itself without using complicated feed networks. Moreover, unlike typical Butler matrix-based beamforming arrays, the proposed SBTA array does not require passive hybrid couplers to adjust the phases for beamforming operations. Accordingly, the proposed feed network-less antenna avoids circuit complexity, feed network insertion losses, or increases in size and fabrication costs, rendering it suitable for mmWave compact antenna applications. To verify the proposed concept and beamforming performance, a 1 × 4 SBTA array was fabricated at 28 GHz using a conventional printed circuit board (PCB) process. The size of the fabricated antenna (excluding test connectors) was 1.12 λ0 × 1.68 λ0 × 0.08 λ0 (λ0 for free-space wavelength), and the measured 10-dB impedance bandwidth was approximately 5.9 %. Furthermore, the measured main beam switching directions were found at −34°, −52°, +51°, and +38° with measured gains of 6.7, 6.1, 5.9, and 6.6 dBi, respectively, at 28 GHz.

Orthogonal frequency‐division multiplexing‐based signal design for a dual‐function radar‐communications system using circulating code array

AbstractIn this study, a dual‐function radar‐communications (DFRC) system based on the circulating code array is presented to address the contradiction between radar and communications system in beam scanning and beam coverage. Processed orthogonal frequency‐division multiplexing (OFDM) signal is transmitted by the circulating code array as the base signal to improve the data rate. Following the spatial angle of the communication receiver, the communication symbols are modulated to part of OFDM signal subcarriers occupying a specific frequency band. A significant property of the circulating code array, which provides a relationship between the baseband frequency of the base signal and the spatial angles, implements a basis for safe telecommunication transmission towards the cooperative receiver and demodulation. Moreover, the circulating code array transmits the same signal and introduces the same time interval between adjacent array elements. Therefore, the complex problems of multi‐dimensional orthogonal signal design in the traditional multiple‐input‐multiple‐output‐based DFRC system design are transformed into a simple base signal design. Finally, an omnidirectional coverage pattern is obtained. Thus, whether the communication receiver is in the mainlobe or the sidelobe of the radar beam, the communication connection can be established between the designed DFRC system and the communication users. The performance of the described DFRC system is verified through theoretical analysis and simulations.

300-GHz-Band Four-Element CMOS-InP Hybrid Phased-Array Transmitter With 36circ Steering Range

This letter presents a 300-GHz-band four-element phased-array transmitter (TX) consisting of two types of chips, CMOS and InP HBT, to achieve a high equivalent isotropically radiated power (EIRP) and wide beam coverage. The CMOS chips include mixers and control circuits for the phased-array operation and the InP HBT chips include 300-GHz-band power amplifiers (PAs) and Antipodal Vivaldi on-chip antennas. The two types of chips are connected in a flip-chip-on-chip fashion to reduce losses. A method utilizing grating lobes is devised to overcome the limited main lobe steering range. The fabricated TX achieves a maximum EIRP of 8.4 dBm with a steering range of 36 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> , which is the widest among the 300-GHz-band TXs that can handle a high modulation order. The TX also demonstrates the first-ever wireless data transmission with beam steering in the 300-GHz band and achieves a maximum data rate of 30 Gb/s over a 50-cm distance.

Enabling Spherical Beam Coverage for Millimeter-Wave Stationary and Mobile Applications: A stackable patch antenna

The limited beam-scanning angles of planar phased arrays are one of the most critical challenges for millimeter-wave (mm-wave) wireless communication systems. This article proposes a new class of antenna topology, denoted as a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">stackable patch antenna</i> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SPA</i> ), that achieves near-spherical beam-steering coverage for mm-wave applications. The proposed SPA consists of two identical rectangular patch antenna elements. By separately controlling the magnitude and phase of the excitation ports, the proposed antenna can radiate in multiple directions that are normal or parallel to the patch elements. In addition, the proposed structure has the advantage of enabling end-fire radiation when the structure is encompassed by the full metallic frame of a device. This is accomplished without any deformation or modification of the metal frame.

4D and 5D phase-space tomography using slowing-down physics regularization

We compute reconstructions of 4D and 5D fast-ion phase-space distribution functions in fusion plasmas from synthetic projections of these functions. The fast-ion phase-space distribution functions originating from neutral beam injection (NBI) at TCV and Wendelstein 7-X (W7-X) at full, half, and one-third injection energies can be distinguished and particle densities of each component inferred based on 20 synthetic spectra of projected velocities at TCV and 680 at W7-X. Further, we demonstrate that an expansion into a basis of slowing-down distribution functions is equivalent to regularization using slowing-down physics as prior information. Using this technique in a Tikhonov formulation, we infer the particle density fractions for each NBI energy for each NBI beam from synthetic measurements, resulting in six unknowns at TCV and 24 unknowns at W7-X. Additionally, we show that installing 40 LOS in each of 17 ports at W7-X, providing full beam coverage and almost full angle coverage, produces the highest quality reconstructions.

Millimeter-Wave High-Gain Dual-Polarized Flat Luneburg Lens Antenna with Reflection Cancellation

Because of its good beam coverage and beam scanning abilities, the Luneburg lens (LL) is a promising multibeam antenna for the fifth-generation (5G) wireless communications. However, the conventional LL has a spherical formfactor, exhibiting a large volume, large weight, and curvature surface, all of which limit the adoption of an LL in practice. To alleviate the problem, a flat LL is proposed, with transformation optics to convert the conventional spherical structure into a flat one. However, a high permittivity distribution is usually required in a transformed flat LL, causing of server reflections, which further degenerates the performance of the LL in terms of both gain and efficiency. In this article, a millimeter-wave dual-polarized flat Luneburg lens antenna (FLLA) is proposed following the transformation of optics, and implemented using multilayer PCBs, where a reflection cancellation method is introduced to optimize the multilayer structure to improve its gain and efficiency. The designed FLLA is exemplified in the Ka-band and fed using a dual-polarized patch antenna. The measured results show that the designed FLLA has an impedance bandwidth (|S11| ≤ −10 dB) of 27.5–32.6 GHz, a gain of 16.8–18.8 dBi over the operating band, and a beam scanning range up to ±25°/±24° with a gain loss of 1.72 dB/1.7 dB in either E- or H-plane, respectively.

Quasi-Isotropic High-Resolution Fourier Ptychographic Diffraction Tomography with Opposite Illuminations

Optical diffraction tomography (ODT) is a powerful tool for the study of unlabeled biological cells thanks to its unique capability of measuring the three-dimensional (3D) refractive index (RI) distribution of samples quantitatively and noninvasively. In conventional transmission ODT, however, certain spatial frequency components along the optical axis cannot be measured due to the limited angular coverage of the incident beam, resulting in a poor axial resolution several times worse than the lateral one. In this Letter we propose a new type of ODT method, termed opposite illumination Fourier ptychographic diffraction tomography (OI-FPDT), which produces almost isotropic resolution by combining transmissive angle-scanning and reflective wavelength-scanning. Without resorting to interferometric detection, OI-FPDT requires an intensity-only measurement, and the forward and backward scattered intensity images are synthesized in the Fourier space to recover the 3D RI distribution of samples based on an iterative ptychographic reconstruction algorithm. To the best of our knowledge, this is the first time that near-isotropic resolution (∼ 274 nm) of ODT result is obtained in a non-interferometric and sample motion-free manner. Results of simulated cell phantom, tailor-made fiberglass, and onion epidermal cell samples confirm the validity of the proposed method.

Performance analysis of dense low earth orbit satellite communication networks with stochastic geometry

The low Earth orbit (LEO) satellite communication systems have drawn much attention as a promising solution for providing global wireless connectivity. This paper studies the downlink performances of LEO satellite communication systems performing a directional beamforming with a stochastic geometry. As the beamwidth of the satellite increases, the beam coverage increases but the interference from other satellites also increases. This is vice versa for the smaller beamwidth. Accordingly, the optimal beamwidth control is necessary to balance the beam coverage and the network interference. To address such issue, we first derive the conditional distance distribution to serving line-of-sight (LoS) and non-line-of-sight (NLoS) satellites, conditioned on that there exists at least one satellite in the satellite-visible region and the user is located within the beam coverage of the satellite. Then, we derive the exact and approximated formulas for the coverage probability and the ergodic rate as a function of the beamdwidth. With some numerical examples, we investigate how various system parameters such as altitude and satellite density affect on the optimal beamwidth and demonstrate that the optimal control of the beamwidth of the satellites can maximize the performances by efficiently controlling the amount of interference and beam coverage.

3D Printed Multi-Beam OAM Antenna Based On Quasi-Optical Beamforming Network

In this paper, a multi-beam orbital angular momentum (OAM) antenna is proposed. By employing 3D printed millimeter-wave quasi-optical beamforming network (BFN), the emitted OAM wave can realize passive beam scanning capability. The antenna is composed of a pillbox BFN, a slotted waveguide antenna (SWA) array, and several full-dielectric phase elements (PEs) on the top of the SWA array. The required phase distribution of the OAM beams is turned by the phase shifts of the PEs. The pillbox BFN can generate the input waves with different phase gradients for the SWA array, and thus steer the beam direction. Moreover, the folded structure of the pillbox BFN can greatly decrease the size of the antenna. The proposed topology can be easily expanded to realize more beam number, higher directivity, and other OAM modes for its periodical structure. To verify the performance of the proposed antenna, a prototype is fabricated and measured. Two types of 3D printing technology are used, i.e., selective laser melting (SLM) for the pillbox BFN and the SWA array, and fused deposition modeling (FDM) for the PEs. The application of the 3D printed method greatly helps to decrease the fabrication difficulty. The measured results show that the antenna can achieve five +1 mode beams with ±20° 3 dB beam coverage range. Moreover, due to the full-metal structure of the BFN and the SWA array, the proposed design can achieve the minimum efficiency of 83.2%, which is much better than the other printed circuit broad (PCB) based OAM antennas. The advantages of low-cost beam scanning capability and the extensibility make the proposed antenna topology a good choice for future OAM communication and sensor systems.

Controlling the Coverage of Full Poincaré Beams through Second-Harmonic Generation

Ideal full Poincar\'e (FP) beams contain all possible polarization states on the surface of the Poincar\'e sphere and are readily created by linear optical techniques and, more recently, by nonlinear optical processes. An inherent limitation in the latter is the inability to achieve all polarization states, coined coverage, due to modal size, polarization, and modal weighting changes during the nonlinear conversion of the constituent modes. Here, we demonstrate a simple technique to control the coverage of FP beams, using second-harmonic generation as an example, from fully scalar (no coverage) to fully vectorial (full coverage). Our method for determining the coverage confirms the vectorial characteristics of the generated beams and reveals a balancing act between mode order, modal nonlinear efficiency, and initial relative modal weights, all in close agreement with that theoretically predicted. Our findings will hopefully be of value to the communities interested in nonlinear structured light, particularly for vectorial nonlinear modal creators and detectors and control of quantum hybrid entangled states.

Analysis of a Low-Earth Orbit Satellite Downlink Considering Antenna Radiation Patterns and Space Environment in Interference Situations

This paper investigates a low-Earth orbit (LEO) satellite downlink for high-speed data communication in interference situations. A choke ring horn type antenna is used as the data transmitting antenna with an isoflux pattern in the LEO satellite, which has a beam coverage of ±51.6° and a bore-sight gain of 4.4 dBi at 8 GHz. The receiving antenna on the ground station is a parabolic type antenna with a diameter of 11.3 m, and it has a half-power beam width (HPBW) of 0.2° with a maximum gain of 59 dBi at 8 GHz. The jamming-to-signal ratio (J/S) is calculated assuming that the LEO satellite transmits signals to the ground station, and an elevation angle of the interference source varies from 0° to 90° at an altitude of 10 km. Applying antenna characteristics, such as HPBWs and side lobes, to the calculated space wave path loss makes it possible to predict the J/S results according to the location of the interference source and the satellite. The results show that it is necessary to consider the space environment to accurately analyze the LEO satellite downlink, especially at the low elevation angle of the satellite.

Multibeam Blind Search of Targeted SETI Observations toward 33 Exoplanet Systems with FAST

The search for extraterrestrial intelligence (SETI) is to search for technosignatures associated with extraterrestrial life, such as engineered radio signals. In this paper, we apply the multibeam coincidence matching (MBCM) strategy, and propose a new search mode based on the MBCM which we call the MBCM blind search mode. In our recent targeted SETI research, 33 exoplanet systems are observed by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). With this blind search mode, we search for narrowband drifting signals across 1.05–1.45 GHz in two orthogonal linear polarization directions separately. There are two special signals, one of which can only be detected by the blind search mode while the other can be found by both blind and targeted search modes. This result reveals huge advantages of the new blind search mode. However, we eliminate the possibility of the special signals being ETI signals based on much evidence, such as the polarization, drift, frequency, and beam coverage characteristics. Our observations achieve an unprecedented sensitivity and our work provides a deeper understanding to the polarization analysis of extraterrestrial signals.

Analysis of Laser Cell Response Characteristics under Different Irradiation Conditions

Although the application of laser wireless energy transmission technology in many fields such as UAV power supply is increasing, the laser incidence angle and beam shift remain the key factors limiting the efficiency of long-range laser wireless energy transmission. In this study, a laser cell response test platform was built to measure and analyze the response characteristics of a laser cell under different laser incidence angles and beam shifts. The results show that the increase in the incident angle intensifies the reflection on the irradiated surface, resulting in a linear decrease in the power density received by the laser cell, which eventually leads to a significant decrease in the output power, and the output power tends to be close to 0 when the incident angle exceeds 75°. The increase in the beam offset distance increases the reverse bias of the cell, which is the main reason for the significant decrease in the output power. The local irradiation also leads to an increase in the heat generation power; when the beam coverage is below 50%, the overall output power tends to be close to 0. This study provides a reference for improving the laser wireless energy transmission efficiency and laser cell optimization.

Millimeter-wave coding radial-periodic metasurface for manipulating beam-pointing angle of conical-beam radiation

In this article, a millimeter wave coding radial-periodic metasurface conical-beam (CB) antenna for manipulating beam-pointing angle (BPA) is presented. The proposed structure is excited by a high-gain CB planar antenna. The novelty of the proposed design lies in its BPA manipulating mechanism, obtained by radial-periodic metasurfaces (MS) located on the top of the source CB antenna. Full-wave analysis and experimental validation verified the proposed design performance, achieving simulated 10.2% 10-dB impedance bandwidth (BW) covering 27.19–30.12 GHz, whereas the measured BW is 11.7%, covering 26.86–30.2 GHz; as well as 6–18° BPA coverage in the elevation plane with a measured peak gain of 7.7–9.86 dBi in the 27–28 GHz range. The proposed structure exhibits good CB radiation performance with wide BW, flexible BPA control capability, and stable gain variation. Consequently, the proposed structure can be a potential candidate for applications that need wide beam coverage.

Joint Beam-Hopping Scheduling and Coverage Control in Multibeam Satellite Systems

Beam-hopping scheduling technology is a crucial technology for improving the performance of resource-constrained multibeam satellite (MBS) systems. However, it is challenging to dynamically match the communication demands of the terrestrial cells with the beam transmission capacity. Almost all state-of-art beam-hopping scheduling approaches only consider a fixed beam coverage radius, which always results in a waste of transmission resources. In this letter, we propose a deep reinforcement learning-based algorithm to jointly optimize the beam-hopping scheduling and coverage control (called DeepBeam) which flexibly uses three degrees of freedom of time, space and beam coverage radius. In addition, to reduce the computational complexity and accelerate the training of DeepBeam, we first train a single model for one of the beams and then use this trained model for each beam in a polling manner to determine the cell to be illuminated and the beam coverage. Furthermore, the simulation results illustrate that the proposed DeepBeam can improve not only the throughput of MBS but also reduce the packet loss probability.

Delay Minimization for NOMA-mmW Scheme-Based MEC Offloading

Upon exploiting massive spectrum resources, millimeter-wave (mmW) communication can significantly improve the transmission rate of mobile-edge computing (MEC) offloading, whereas the directional mmW links are constrained by shrunk beam coverage and demand extra phase for beam alignment. To enhance the accessing efficiency, we develop the nonorthogonal multiple access (NOMA) scheme-based mmW MEC mechanism, namely, NOMA-mmW MEC, therefore motivating to minimize the average delay of the MEC offloading, by jointly optimizing the beamwidth, user equipment (UE) scheduling, and transmit power. To tackle the mixed-integer nonlinear programming (MINLP) problem of delay minimization, we develop the alternative optimization (AO) approach-based RA scheme, namely, AO-RA, to obtain the close-optimum solutions. In the AO-RA scheme, we propose the matrix control many-to-one with externality (MC-M2OE) algorithm, to find the best UE scheduling for the NOMA groupings of different types of UEs. Upon the above, we further design the joint beamwidth and transmit power (JBTP) algorithm, which determines the optimal beamwidth and transmit power for the MEC offloading transmissions. Our simulation results show the effectiveness of the proposed AO-RA scheme in minimizing the offloading delay, where our MC-M2OE and JBTP algorithms can significantly outperform the existing approaches. From the simulation results, we may conclude that it needs to carefully address the tradeoff between beam alignment overhead and transmission gain while properly balancing the loading among different NOMA groups, for the practical consideration of NOMA-mmW MEC technology.

A Shared-Aperture Cavity Slot Antenna-in-Package Concept Featuring End-Fire and Broadside Radiation for Enhanced Beam Coverage of mmWave Mobile Devices

A shared-aperture cavity slot antenna (SACSA) is proposed and demonstrated at millimeter-wave spectrum for the first time. The endfire and broadside antennas can independently operate within an identical cavity, thus sharing a common aperture. The endfire antenna is implemented as an open-ended cavity slot antenna (CSA) topology featuring <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+y$ </tex-math></inline-formula> -axis directional beam, and broadside antenna is realized as a cavity backed slot antenna featuring +z-axis directional beam. For reducing a mutual coupling between endfire and broadside antennas, two antennas are designed to feature orthogonal polarization of each other. The reflection coefficients of two antennas satisfy less than −10 dB at operating frequency band while maintaining mutual coupling coefficient under −25 dB. The realized gain of 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 SACSA is approximately 9.56 dBi for endfire antenna and 8.9 dBi for broadside antenna, and 3 dB scanning angle of both antennas is ± 45° at respective dominant directions. Accordingly, the proposed SACSA can be implemented as a compact size of antenna-in-package (AiP) by sharing the aperture of two antennas and enhancing beamforming coverage by independently steering two separate beams.

Beam Management in Ultra-Dense mmWave Network via Federated Reinforcement Learning: An Intelligent and Secure Approach

Deploying ultra-dense networks that operate on millimeter wave (mmWave) band is a promising way to address the tremendous growth on mobile data traffic. However, one key challenge of ultra-dense mmWave network (UDmmN) is beam management due to the high propagation delay, limited beam coverage as well as numerous beams and users. In this paper, a novel systematic beam control scheme is presented to tackle the beam management problem which is difficult due to the nonconvex objective function. We employ double deep Q-network (DDQN) under a federated learning (FL) framework to address the above optimization problem, and thereby fulfilling adaptive and intelligent beam management in UDmmN. In the proposed beam management scheme based on FL (BMFL), the non-rawdata aggregation can theoretically protect user privacy while reducing handoff cost. Moreover, we propose to adopt a data cleaning technique in the local model training for BMFL, with the aim to further strengthen the privacy protection of users while improving the learning convergence speed. Simulation results demonstrate the performance gain of our proposed scheme.