Beamforming Capabilities Research Articles

Evaluation of Three Auditory-Sculptural Qualities Created by an Icosahedral Loudspeaker

The icosahedral loudspeaker (IKO) was previously established as an electroacoustic instrument enabling the musical creation and orchestration of sculptural sound phenomena in the room. This is technically achieved by manipulating the strengths of the available acoustic reflection paths by using the IKO’s acoustic beamforming capabilities. In its use, listeners perceive auditory sculptures whose characterization needs investigation. We present a proposed set of sculptural quality attributes directionality, contour, and plasticity and a series of listening experiments investigating them. The experiments employ documented beam layouts using a selected set of sounds as conditions, and they evaluate the recognizability, perceivable grading, and discernibility of the proposed sculptural qualities.

Constant-${\epsilon}_{r}$ Lens Beamformer for Low-Complexity Millimeter-Wave Hybrid MIMO

It is well established that the utilization of unused millimeter-wave (mmWave) spectrum is inevitable due to unavailability of required bandwidth in the conventional RF band to support the high data demands of 5G. Large antenna arrays with beamforming capabilities are required to compensate for the high path loss at mmWave frequencies. We are at the verge of a massive mmWave radio front-end deployment, and low-complexity low-cost hardware beamforming solutions are required now at this stage than ever before. In this paper, one such solution is demonstrated and analyzed. A high-performance and low-complexity lens-based beamformer consisting of constant dielectric material ( $\epsilon _{r}$ ) with antenna feeds is presented for multibeam operation. A prototype is developed based on the classical synthesis approach, and in line with the requirements of mmWave hybrid multiuser multiple-input multiple-output (MU-MIMO) systems. A characterization at 28 GHz is performed wherein an uplink signal-to-noise ratio of user terminals is evaluated with the zero-forcing (ZF) baseband signal processing. Radiation performance of a single-source beamformer is measured in an anechoic environment, and end-to-end ergodic sum spectral efficiency performance is estimated based on the measured data. It is shown that the constant- $\epsilon _{r}$ -based beamformer solution is simple, yet significantly outperforms conventional antenna array beamformers with analog phase shifter networks, making it a promising candidate for future hybrid massive MIMO systems.

Design of Series-Fed Bandwidth-Enhanced Microstrip Antenna Array for Millimetre-Wave Beamforming Applications

A novel series-fed microstrip patch array antenna for 37/39 GHz beamforming is proposed. To improve the antenna bandwidth, two of the patches are modified with truncated corners in the diagonal direction. This truncation generates two degenerate resonances which result in a flattened frequency response of the input impedance. Then, the recessed microstrip feeds for the other two patches are designed to yield a proper current distribution for radiation while maintaining minimal return loss, wide bandwidth, and low sidelobes. Though the individual patch antenna is elliptically polarized due to the truncated corners, a phased array with linear polarization can still be obtained by alternately deploying left-handed and right-handed elliptically polarized patches. For validation of the proposed design, an array is fabricated with 16 elements on a substrate with 10 mil thickness and εr =2.2. The beamforming capability of the proposed array is also demonstrated. The experiment results agree well with the simulation and show that the antenna gain and the return loss bandwidth can be more than 21 dBi and 8%, respectively.

Angle-range-polarization-dependent beamforming for polarization sensitive frequency diverse array

In this paper, we present a polarization sensitive frequency diverse array (PSFDA), which benefits both from frequency diverse array (FDA) and polarization sensitive array (PSA), producing angle-range-polarization-dependent beamforming capability. To simultaneously improve the angle, range and polarization resolution, the ℓ1-norm minimization-based sparse constraint and ℓ∞-norm constraint for sidelobe region are further applied. Besides, the performance of the optimal output signal-to-interference-plus-noise ratio (SINR) is analyzed for such a high-dimensional arrays. Numerical results demonstrate that the proposed PSFDA provides both range and polarization resolution as well as target angle estimation. Moreover, the PSFDA virtually increases the array size by exploiting multiple electromagnetic fields at each physical point. In addition, the proposed beamforming method can effectively null interferences, without degrading the array gain for the signals of interest.

Multi-carrier, multi-band, and multi-layer cellular layouts using 3D beamforming for 5G ultradense networks

Three-dimensional (3D) beamforming and higher order sectorization (HOS) represent two fundamental features to boost the capacity of ultradense heterogeneous networks and fulfill the huge data rate requirements for next-generation mobile networks (5G). The capacity gain depends on the antenna pattern, the inter-cell interference (ICI), and the cellular layout whose design is considered as the main step in the life cycle of a cellular network. Indeed, it decides the operational expenditure (OPEX), the capital expenditure (CAPEX), and the long-term quality of service (QOS). In this paper, we propose new multi-carrier, multi-layer, and multi-band cellular layouts. By exploiting the capability of the 3D beamforming as well as the 3D channel model conceived by the third-generation partnership project (3GPP), the layouts comprise macro and virtual small cell (VSC) layers, which are planned based on geolocation data and a user-grouping algorithm. We have demonstrated that the simulation of the new proposed cellular layouts results in a significant coverage enhancement and interference mitigation, as compared to the reference cellular layout which is 3GPP case 1.

Emerging Technology: Enhanced B-mode Tissue Characterization

Ultrasound imaging continues to break through scientific and engineering ceilings that have formerly restricted the type and quality of information available. Limited by the temporal, data acquisition, and processing constraints inherent in traditional beamforming technology, ultrasound systems did not have the capacity to acquire and process large amounts of raw acoustic data fast enough to move beyond standard imaging modalities. While traditional beamforming capabilities can provide high-quality and high-resolution images, sensitive Doppler modes, and other advanced imaging applications, there have been limitations to creating new applications that use the information contained within the received acoustic data set. This has all changed with the introduction of ultrasound imaging systems that acquire and process significantly more acoustic data quickly. Upgraded, state-of-the-art digital signal processing (DSP) capabilities have made new imaging possibilities, including enhanced B-mode tissue characterization. This modality helps to differentiate areas within a region of interest based on the unique acoustic characteristics of the tissues insonated.

Single-Carrier Spatial Modulation for the Internet of Things: Design and Performance Evaluation by Using Real Compact and Reconfigurable Antennas

In this paper, for the first time, we propose two new solutions to boost the data rate between small connected objects such as glasses and cams and the 5th generation (5G) mobile network, based on spatial modulation, single carrier waveform, compact reconfigurable antennas at the object side and massive multiple input multiple output (M-MIMO) at the network side. In the first new wireless communication system, a "transmitting object" uses transmit spatial modulation with a compact reconfigurable antenna and a constant envelop amplifier to transmit in high data rate with a low complexity and low power consumption. The space-time digital processing capability of the M-MIMO 5G base station is used to detect such signal. In the second new wireless communication system, a "receiving object" uses receive spatial modulation, a compact multiport antenna and a low complexity detection algorithm to receive in high data rate with a low complexity signal processing. The space-time beamforming capability of the M-MIMO 5G base stations is exploited to deliver a signal that is pre-equalized enough to be detected by the object. For the first time, we present experiments showing that M-MIMO allows for the re-introduction of single carrier modulation waveform. For the first time, we present performance results obtained with real existing compact antennas and compact reconfigurable antennas, showing that the two new communication systems outperform conventional modulation in terms of energy efficiency and complexity.

Robust Constrained Inverse Beamforming Algorithm Based on Space Time Adaptive Processing

The power of Beidou satellite signals is very low, so it is vulnerable to interfering sources and in the presence of jamming. Therefore, a robust constrained inverse beamforming algorithm based on space-time adaptive processing is proposed, which can not only reduce the sidelobe level to suppress interference better, but also achieve the lower complexity, and then introducing the steering vector uncertainty set model into the algorithm to improve its stability. In the simulation, the proposed algorithm can be verified to have good beamforming capability and higher signal-to-interference noise ratio (SINR) improvement even in the case of low signal to noise ratio (SNR) and high interference to noise ratio (INR).

Optimisation of antenna arrays installed on non‐conductive unmanned aerial vehicle

This study presents the study of beamforming capabilities of arrays installed on a non-conductive unmanned aerial vehicle (UAV). The main purposes of this study are the application of a beamforming algorithm by including the airframe in the optimisations and the study of simplifications of the aircraft model, so as to allow performing full-wave simulations, even though the UAV is much larger than the operating wavelength. To validate the simplified electromagnetic model, antenna arrays have been designed and installed onto the UAV. Radiation pattern measurements demonstrate that the proposed simplifications yielded very good radiation pattern predictions and can be used as guidelines for simulation of other kinds of non-conductive aircrafts.

Beam‐forming capabilities of a plasma circular reflector antenna

A gaseous plasma antenna array (PAA) is an aggregate of plasma discharges and possibly conventional metallic radiating elements, and it constitutes a promising alternative to metallic antennas for applications in which fast reconfiguration of radiation pattern, and gain is desired; such properties can be achieved by exploiting the electronic switch on/off condition of plasma discharges, and tuning of the plasma parameters. Here, the authors present a reconfigurable PAA that features a central metallic half-wavelength dipole working around 1.45 GHz, surrounded by a planar circular lattice of cylindrical plasma discharges. Customised plasma discharges have been realised, and filled with argon gas at 2 mbar so as to have a complete control on the plasma discharge properties (e.g. plasma frequency, collisional frequency). The magnitude of the reflection coefficient, and the gain pattern on the H -plane have been investigated numerically and experimentally; numerical and experimental results exhibit a good agreement and show that the central intrinsically omnidirectional antenna can provide simple beamforming capabilities upon turning on a subset of plasma discharges; as these plasma discharges are turned on, the authors have observed a maximum gain of ~5 dBi, a half-power beam width of 80°, and an angular steering resolution of ~15°.

The ALMA Phasing System: A Beamforming Capability for Ultra-high-resolution Science at (Sub)Millimeter Wavelengths

The Atacama Millimeter/submillimeter Array (ALMA) Phasing Project (APP) has developed and deployed the hardware and software necessary to coherently sum the signals of individual ALMA antennas and record the aggregate sum in Very Long Baseline Interferometry (VLBI) Data Exchange Format. These beamforming capabilities allow the ALMA array to collectively function as the equivalent of a single large aperture and participate in global VLBI arrays. The inclusion of phased ALMA in current VLBI networks operating at (sub)millimeter wavelengths provides an order of magnitude improvement in sensitivity, as well as enhancements in u–v coverage and north–south angular resolution. The availability of a phased ALMA enables a wide range of new ultra-high angular resolution science applications, including the resolution of supermassive black holes on event horizon scales and studies of the launch and collimation of astrophysical jets. It also provides a high-sensitivity aperture that may be used for investigations such as pulsar searches at high frequencies. This paper provides an overview of the ALMA Phasing System design, implementation, and performance characteristics.

Investigations on Dual Slant Polarized Cavity-Backed Massive MIMO Antenna Panel With Beamforming

A cavity-backed dual slant polarized and low mutual coupling antenna array panel with frequency band from 4.9 to 6 GHz is analyzed and realized for the MIMO antenna 5G applications. The beamforming capability of this array is also explored. The printed cross dipoles fed with balun and enclosed in a cavity are used as radiating elements. The two cross dipoles are placed at an angle of 45° and 135° giving slant polarizations. A $4 \times 4$ subarray of dimension $2.8\lambda \times 2.8\lambda \times 0.26\lambda $ where $\lambda $ is free space wavelength at 6 GHz is designed, fabricated, and experimentally verified. It shows good impedance matching, port isolation, envelope correlation coefficient, and radiation characteristics which are desired for MIMO applications. Beamforming capability in the digital domain is verified using the Keysight SystemVue simulation tool for both $4 \times 4$ and $16\times 16$ panel arrays which employ measured 3-D embedded element radiation pattern data of the fabricated $4 \times 4$ subarray. Four simultaneous beams using digital beamforming approach are also presented for the $16 \times 16$ array for multiuser environment base station antenna applications.

Indoor Multipath Assisted Angle of Arrival Localization.

Indoor radio frequency positioning systems enable a broad range of location aware applications. However, the localization accuracy is often impaired by Non-Line-Of-Sight (NLOS) connections and indoor multipath effects. An interesting evolution in widely deployed communication systems is the transition to multi-antenna devices with beamforming capabilities. These properties form an opportunity for localization methods based on Angle of Arrival (AoA) estimation. This work investigates how multipath propagation can be exploited to enhance the accuracy of AoA localization systems. The presented multipath assisted method resembles a fingerprinting approach, matching an AoA measurement vector to a set of reference vectors. However, reference data is not generated by labor intensive site surveying. Instead, a ray tracer is used, relying on a-priori known floor plan information. The resulting algorithm requires only one fixed receiving antenna array to determine the position of a mobile transmitter in a room. The approach is experimentally evaluated in LOS and NLOS conditions, providing insights in the accuracy and robustness. The measurements are performed in various indoor environments with different hardware configurations. This leads to the conclusion that the proposed system yields a considerable accuracy improvement over common narrowband AoA positioning methods, as well as a reduction of setup efforts in comparison to conventional fingerprinting systems.

New perspective on single-radiator multiple-port antennas for adaptive beamforming applications.

One of the most challenging problems in recent antenna engineering fields is to achieve highly reliable beamforming capabilities in an extremely restricted space of small handheld devices. In this paper, we introduce a new perspective on single-radiator multiple-port (SRMP) antenna to alter the traditional approach of multiple-antenna arrays for improving beamforming performances with reduced aperture sizes. The major contribution of this paper is to demonstrate the beamforming capability of the SRMP antenna for use as an extremely miniaturized front-end component in more sophisticated beamforming applications. To examine the beamforming capability, the radiation properties and the array factor of the SRMP antenna are theoretically formulated for electromagnetic characterization and are used as complex weights to form adaptive array patterns. Then, its fundamental performance limits are rigorously explored through enumerative studies by varying the dielectric constant of the substrate, and field tests are conducted using a beamforming hardware to confirm the feasibility. The results demonstrate that the new perspective of the SRMP antenna allows for improved beamforming performances with the ability of maintaining consistently smaller aperture sizes compared to the traditional multiple-antenna arrays.

Design and evaluation of symmetric space–time adaptive processing of an array antenna for precise global navigation satellite system receivers

The most effective method for overcoming the interference vulnerability of global navigation satellite system (GNSS) receivers is to use an adaptive array antenna which has the capability of nulling or beamforming to a certain direction. The space–time adaptive processing (STAP) algorithm, which is very effective in signal processing of the array antenna for anti-interference, is studied. The phenomenon of pseudorange error in STAP is analysed with a new superposition method of linear line correlation functions. From this analysis, a new symmetric STAP algorithm, which uses an appropriate constraint condition for GNSS signals, is proposed to completely prevent this pseudorange error. The new STAP algorithm performance is verified and confirmed by simulations and experiments with a four-element array antenna. According to the simulation results, the new STAP algorithm has no pseudorange error, whereas the already existing STAP algorithm has an error of 1.6 m. Also experiments with four RF channels analogue-to-digital converter data and a real-time receiver confirm the effectiveness of their precise STAP algorithm which is easy to implement.

A Broadband High-Efficiency Reconfigurable Reflectarray Antenna Using Mechanically Rotational Elements

Design of a circularly polarized reconfigurable reflectarray antenna (RRA) at X band is presented. The RRA element employs concentric dual split rings, and can be mechanically rotated to obtain continuous 360° phase coverage with negligible element loss. A prototype with $15\times15$ manually rotated elements is first computed, simulated, and measured. Full-wave simulations show that the gain of the beam focused in ( $\theta =20^{\circ }$ , $\varphi = 0^{\circ }$ ) direction is 25.8 dB and the 1-dB gain bandwidth is over 28.6%. The measured results show that the beam at ( $\theta = 20^{\circ }$ , $\varphi = 0^{\circ }$ ) direction achieves the maximum gain of 25.6 dB, corresponding to an aperture efficiency of 51.8%. The beam-steering capability of the RRA is measured within ±60° angular range, and well-defined scanned beams are obtained with maximum scan loss of 3.7 dB. The versatile beam-forming capability of the RRA is also verified by synthesizing a square shaped beam and a cosecant shaped beam. Another micromotor-controlled prototype with 756 elements on an octagonal aperture is fabricated and its measured radiation performance validates the feasibility of the proposed design as well.

Achieving 3D-MIMO With Massive Antennas From Theory to Practice With Evaluation and Field Trial Results

Exploiting multiple-input–multiple-output (MIMO) techniques by using massive antennas can significantly improve the capacity and reliability of wireless systems and has been considered as one key technique in future fifth-generation mobile communications system. Considering the limitation of antenna panel size, placing the massive antennas in 2-D grid is an effective way for its commercialization, which is termed as “3D-MIMO.” In this paper, we study the performance of 3D-MIMO with massive antennas by system-level simulation using practical assumption and 3-D channel model and test the 3D-MIMO in field trial with commercial terminal and networks. In addition, we compare the system-level simulation results and the field trial test measurements. Our system-level simulation results show that the 3D-MIMO with 64 antennas can significantly improve the performance with 56% and 147% gain on cell-average and cell-edge throughputs compared with 2D-MIMO. We perform field trial to test the 3D-MIMO, and the results verify its performance gain obtained by simulation. Furthermore, the measurement in typical high-rise scenario shows that the 3D-MIMO can significantly enhance the data rate of users located at higher floors due to the capability of flexible elevation beamforming.

Equalized Time Reversal Beamforming for Frequency-Selective Indoor MISO Channels

Time-reversal (TR) is a beamforming technique for wireless frequency-selective channels, which has received increasing attention due to its high energy efficiency and low computational complexity. In this paper, we present two contributions on TR beamforming for single-user indoor wideband MISO systems. First, we provide novel analyses of a baseband TR system using two commonly used indoor propagation channel models. We derive closed-form approximations for the inter-symbol interference (ISI) with these channel models in order to characterize the influence of propagation conditions (such as the power-delay profile, delay spread, and bandwidth) on TR performance metrics. In particular, we analyze spatial focusing and time compression performance of TR beamforming, and their impact on the bit error rate (BER). As a second contribution, we introduce an equalized TR (ETR) technique that mitigates the ISI of conventional TR. The proposed ETR utilizes a zero-forcing pre-equalizer at the transmitter in a cascade configuration with the TR pre-filter. Unlike previous approaches to ISI mitigation in TR systems, we derive theoretical performance bounds for ETR and show that it greatly enhances the BER performance of conventional TR with minimal impact to its beamforming capabilities. By means of numerical simulations, we verify our closed-form approximations and show that the proposed ETR technique outperforms conventional TR with respect to the BER under any SNR.

Multi-Antenna Enabled Cluster-Based Cooperation in Wireless Powered Communication Networks

In this paper, we consider a wireless powered communication network (WPCN) consisting of a multi-antenna hybrid access point (HAP) that transfers wireless energy to and receives sensing data from a cluster of low-power wireless devices (WDs). To enhance the throughput performance of some far-away WDs, we allow one of the WDs to act as the cluster head (CH) that helps forward the messages of the other cluster members (CMs). However, the performance of the proposed cluster-based cooperation is fundamentally limited by the high energy consumption of the CH, who needs to transmit all the WDs' messages including its own. To tackle this issue, we exploit the capability of multi-antenna energy beamforming (EB) at the HAP, which can focus more transferred power to the CH to balance its energy consumption in assisting the other WDs. Specifically, we first derive the throughput performance of each individual WD under the proposed scheme. Then, we jointly optimize the EB design, the transmit time allocation among the HAP and the WDs, and the transmit power allocation of the CH to maximize the minimum data rate achievable among all the WDs (the max-min throughput) for improved throughput fairness among the WDs. An efficient optimal algorithm is proposed to solve the joint optimization problem. Moreover, we simulate under practical network setups and show that the proposed multi-antenna enabled cluster-based cooperation can effectively improve the throughput fairness of WPCN.

On the Implementation of Blind Interference Alignment With Single-Radio Parasitic Antennas

This paper studies the electronically steerable parasitic array radiator (ESPAR) antenna as a solution for beam pattern switching to implement blind interference alignment (BIA). The ESPAR antenna uses a single radio-frequency (RF) chain, and its beamforming is achieved by simply tuning the reactance loads of parasitic elements. Furthermore, ESPAR's beam pattern can be designed to enhance the received signal-to-noise ratio (SNR), thereby improving the performance of BIA. The focus of this work is the design of the ESPAR beam pattern to realize and improve BIA. In the first approach, each receiver ESPAR antenna dynamically selects the proper beam patterns from among the sector beam patterns, which are pre-designed to access different angular sectors with constant optimal antenna efficiency. We also propose a singular value decomposition (SVD) beamforming method, by means of the available channel state information at the receiver and a dynamic matching network for a high antenna efficiency. The simulation results illustrate the improvement of BIA with proposed methods, especially in the low and moderate SNR region, due to ESPAR's beamforming capability.