Digital Beamforming Approach Research Articles

SINR Management in Roundabout Vehicular Ad Hoc Networks: A Control and Reinforcement Learning With Digital Beamforming Approach

SINR Management in Roundabout Vehicular Ad Hoc Networks: A Control and Reinforcement Learning With Digital Beamforming Approach

Low Power Analog Processing for Ultra-High-Speed Receivers With RF Correlation

Ultra-high-speed data communication receivers (Rxs) conventionally require analog digital converters (ADC)s with high sampling rates which have design challenges in terms of adequate resolution and power. This leads to ultra-high-speed Rxs utilising expensive and bulky high-speed oscilloscopes which are extremely inefficient for demodulation, in terms of power and size. Designing energy-efficient mixed-signal and baseband units for ultra-high-speed Rxs requires a paradigm approach detailed in this paper that circumvents the use of power-hungry ADCs by employing low-power analog processing. The low-power analog Rx employs direct-demodulation with RF correlation using low-power comparators. The Rx is able to support multiple modulations with highest modulation of 16-QAM reported so far for direct-demodulation with RF correlation. Simulations using Matlab, Simulink R2020a® indicate sufficient symbol-error rate (SER) performance at a symbol rate of 8 GS/s for the 71 GHz Urban Micro Cell and 140 GHz indoor channels. Power analysis undertaken with current analog, hybrid and digital beamforming approaches requiring ADCs indicates considerable power savings. This novel approach can be adopted for ultra-high-speed Rxs envisaged for beyond fifth generation (B5G)/sixth generation (6G)/ terahertz (THz) communication without the power-hungry ADCs, leading to low-power integrated design solutions.

An Effective Kalman Based Hybrid Beamforming for Millimeter Wave Massive MIMO System by Using 2D Overlapped Partially Connected Sub-Array Structure

In 5G mobile communication networks, millimeter-wave (mmWave) technology plays a key role. To deal with the problem of path loss that happens in the mmWave band, competent beamforming employing a large antenna array is required. Fully digital beamforming approaches currently require separate radio frequency chains (RF chains) for each antenna, which adds to the computational complexity and hardware expense. In a multi-user environment, fully digital beamforming suffers from a larger antenna array layout, whereas analog beamforming solutions are prone to numerous performance concerns. Hybrid beamforming, on the other hand, offers a promising solution for multi-user mmWave communication. This work proposes a two-dimensional overlapping partially connected (2D-OPC) sub-array structure to reduce the antenna structure's hardware complexity and cost. The suggested technique comprises several sub-arrays that are overlapped in 2D space in the form of a Uniform Planar Array (UPA). The suggested scheme's performance is assessed using Kalman-based hybrid beamforming, which exhibits a considerable increase in spectral efficiency when compared to existing hybrid beamforming techniques. The suggested technique, which uses Kalman based hybrid beamforming and 2D-OPC provides 3.14% and 4.96% improvement over the MMSE hybrid beamforming and ZF pre-coding technique respectively.

Guest Editorial Low-Cost Wide-Angle Beam-Scanning Antennas

One of the key antenna requirements in many modern wireless systems for communications and sensing is wide-angle beam-scanning <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . The traditional method to achieve wide-angle beam-scanning is to employ mechanically controlled reflectors or lenses, which are bulky, heavy, and suffer from slow beam scanning speed. Other important limitations of mechanical scanning antennas include the lack of multi-beam scanning capability and the ability to conform with non-planar structures (conformal geometries), which are essential in a number of emerging systems requiring very low-profile antennas. An alternative technique is to employ electronically beam-scanning antennas using passive or active phased arrays <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . Main disadvantages of phased arrays are high complexity, high power consumption, and high cost due to a large number of radio frequency (RF) or microwave phase shifters and T/R modules required. The problems worsen for phased arrays at millimeter-wave, sub-THz, and THz frequencies, due to significant losses in phase shifters and feed networks at higher frequencies combined with lower efficiency of power amplifiers <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> . The digital beamforming approach is even more costly and energy hungry due to the employment of large number of RF modules and digital devices <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> , <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> , <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> .

A New Beamforming Approach Using 60 GHz Antenna Arrays for Multi-Beams 5G Applications

Recent studies and research have centred on new solutions in different elements and stages to the increasing energy and data rate demands for the fifth generation and beyond (B5G). Based on a new-efficient digital beamforming approach for 5G wireless communication networks, this work offers a compact-size circular patch antenna operating at 60 GHz and covering a 4 GHz spectrum bandwidth. Massive Multiple Input Multiple Output (M–MIMO) and beamforming technology build and simulate an active multiple beams antenna system. Thirty-two linear and sixty-four planar antenna array configurations are modelled and constructed to work as base stations for 5G mobile communication networks. Furthermore, a new beamforming approach called Projection Noise Correlation Matrix (PNCM) is presented to compute and optimise the fed weights of the array elements. The key idea of the PNCM method is to sample a portion of the measured noise correlation matrix uniformly in order to provide the best representation of the entire measured matrix. The sampled data will then be utilised to build a projected matrix using the pseudoinverse approach in order to determine the best fit solution for a system and prevent any potential singularities caused by the matrix inversion process. The PNCM is a low-complexity method since it avoids eigenvalue decomposition and computing the entire matrix inversion procedure and does not require including signal and interference correlation matrices in the weight optimisation process. The suggested approach is compared to three standard beamforming methods based on an intensive Monte Carlo simulation to demonstrate its advantage. The experiment results reveal that the proposed method delivers the best Signal to Interference Ratio (SIR) augmentation among the compared beamformers.

Design and Performance Estimation of a Photonic Integrated Beamforming Receiver for Scan-on-Receive Synthetic Aperture Radar

Synthetic aperture radar is a remote sensing technology finding applications in a wide range of fields, especially related to Earth observation. It enables a fine imaging that is crucial in critical activities, like environmental monitoring for natural resource management or disasters prevention. In this picture, the scan-on-receive paradigm allows for enhanced imaging capabilities thanks to wide swath observations at finer azimuthal resolution achieved by beamforming of multiple simultaneous antenna beams. Recently, solutions based on microwave photonics techniques demonstrated the possibility of an efficient implementation of beamforming, overcoming some limitations posed by purely electronic solutions, offering unprecedented flexibility and precision to RF systems. Moreover, photonics-assisted RF beamformers can nowadays be realized as integrated circuits, with reduced size and power consumption with respect to digital beamforming approaches. This paper presents the design analysis and the challenges of the development of a hybrid photonic-integrated circuit as the core element of an X-band scan-on-receive spaceborne synthetic aperture radar. The proposed photonic-integrated circuit synthetizes three simultaneous scanning beams on the received signal, and performs the frequency down-conversion, guaranteeing a compact 15 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -form factor, less than 6 W power consumption, and 55 dB of dynamic range. The whole photonics-assisted system is designed for space compliance and meets the target application requirements, representing a step forward toward a deeper penetration of photonics in microwave applications for challenging scenarios, like the observation of the Earth from space.

Multi-target tracking and activity classification with millimeter-wave radar

The millimeterwave radar has made possible high resolution tracking, activity classification, and vital signs detection, at higher precisions than is possible with most other wireless approaches. However, detecting multiple moving targets is a challenge, as dynamic scene with a lot of motion leads to clutter and noise, which interfere with the responses of targets of interest. We present a digital beamforming approach using the MIMO radar, with a range resolution of 6.4 cm and a Doppler resolution of 0.18 m/s, which reduces interference between closely neighboring targets. Thus, measurements of individual target micro-Doppler signatures are possible, even in the presence of multiple other moving targets, and the signatures are, thereby, used to train a Deep Neural Network (DNN) for activity classification. The DNN has been applied to recognize six exercise-based classes, correctly predicting with over 95% classification accuracy for all classes, but that is extendable to fall detection and other activities.

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.

Improved digital beam‐forming approach with scaling function for range multi‐channel synthetic aperture radar system

For the next generation of space-borne synthetic aperture radar (SAR) remote sensing satellites, high resolution and wide coverage are important goals. Digital beam forming (DBF) with multiple channels in elevation (e.g.SCan-On-REceive) is a promising candidate to cover ultra-wide swaths. This scheme could increase the receiver gain and signal-to-noise ratio so as to enhance the performance of an SAR system. As the swath width expanding, ultra-wide beam in range for illuminated scene is needed. However, in this case, the signals received by different channels cannot always be co-registered during the receiving window before combining them due to the imaging geometry of the DBF–SAR system. The relative migration would cause gain loss while performing DBF. In this study, according to the geometric relationship among the receiving channels, the migration of signal received by each elevation channel is analysed and the explicit expressions are derived in detail. Then, an improved DBF approach based on scaling function is proposed for registering the received signals of different channels and combining them. This proposed process can be implemented with better performance than other approach. Finally, the simulation results validate this improved method.

BLASTDAR—A Large Radar Sensor Array System for Blast Furnace Burden Surface Imaging

In this paper, we present a radar sensor system for real-time blast furnace burden surface imaging inside a fully operative blast furnace, called BLASTDAR, the blast furnace radar. The designed frequency-modulated continuous-wave (FMCW) radar sensor array operates in the frequency band around 77 GHz and consists of several nonuniformly spaced receive and transmit antennas, making it a multiple-input multiple-output radar system with large aperture. Mechanical steering is replaced by digital array processing techniques. Off-the-shelf automotive-qualified multichannel monolithic microwave integrated circuits are used. By means of this configuration, a virtual antenna array with 256 elements was developed that guarantees the desired angular resolution of better than 3°, and a range resolution of about 15 cm. Based on the single-channel FMCW signal model, this paper will derive a multichannel signal model in combination with a digital beamforming approach and further advanced signal processing algorithms. The implementation of a simulation tool covering the whole design process is shown. Based on these simulation results, a system configuration is chosen and the obtained setup is defined and presented. A description of the manufactured cost-efficient radio frequency and baseband boards together with the housing design shows the practical implementation of the sensor. For the system calibration, two different methods are listed and compared regarding their performance. Verification measurements confirm the predicted performance of the developed sensor. Several measurements inside a fully operational blast furnace demonstrate the proper long-term functionality of the system, to the best of our knowledge, for the first time worldwide. It is in continuous operation since about two years in blast furnace #5 of voestalpine Stahl GmbH, Linz.

Digital Beamforming on Receive in Elevation for Multidimensional Waveform Encoding SAR Sensing

This letter investigates the performance of a waveform-separation approach employing a posteriori digital beamforming (DBF) in elevation for multidimensional waveform encoding SAR sensing. The signal-to-noise ratio scaling factor in elevation and full-Doppler-band range ambiguity-to-signal ratio are defined to give global assessment of the DBF approach. Constraints for the selection of elevation subaperture number and their relevant influence on image quality are investigated. By theoretical analysis and simulation, the subaperture number can be appropriately selected by a tradeoff between the data volume and imaging performance. Further strategies for data reduction and performance optimization are briefly discussed.

Coding-based ultra-wideband digital beamformer with significant hardware reduction

We propose a novel transceiver architecture for cognitive sensing. The architecture supports agile beam forming, jamming mitigation, as well as MIMO communications. An essential aspect of the new architecture is its departure from the traditional digital beamforming approaches. Specifically, a single ADC is assigned to a group of array elements instead of having one ADC per element. To facilitate this approach, code division multiplexing is applied to each received antenna signal prior to combining them for digitization using a single ADC. Thus full signal recovery is possible at digital baseband via decoding. The proposed architecture significantly reduces the number of ADCs and I/O channels and hence drastically improves size, weight, area, power and cost of the system with minimal impact on receiver signal-to-noise ratios.

A new digital beamforming approach for SDMA using spreading sequence array weights

A novel space division multiple access (SDMA) digital beamformer (DBF) is proposed which can replace traditional approaches to DBF. This new approach does not perform digital phase shifting nor does it rely on adaptive methods; however, multiple beams are produced in directions of interest. An array correlation matrix is not needed, array weights are not adapted, and an a priori knowledge of the signal environment is not required. Rather, a spreading technique is utilized that uniquely defines all received directions of interest. This receiver can create virtual contiguous beams or it can selectively look in any specific directions of interest. This approach blends the virtues of switched beam and adaptive array technologies. The new receiver has the same spatial resolution as traditional arrays while simultaneously looking in all desired directions of interest.

Digital phased array beamforming using single-bit delta-sigma conversion with non-uniform oversampling.

Digital beamforming based on oversampled delta-sigma (delta sigma) analog-to-digital (A/D) conversion can reduce the overall cost, size, and power consumption of phased array front-end processing. The signal resampling involved in dynamic delta sigma beamforming, however, disrupts synchronization between the modulators and demodulator, causing significant degradation in the signal-to-noise ratio. As a solution to this, we have explored a new digital beamforming approach based on non-uniform oversampling delta sigma A/D conversion. Using this approach, the echo signals received by the transducer array are sampled at time instants determined by the beamforming timing and then digitized by single-bit delta sigma A/D conversion prior to the coherent beam summation. The timing information involves a non-uniform sampling scheme employing different clocks at each array channel. The delta sigma coded beamsums obtained by adding the delayed 1-bit coded RF echo signals are then processed through a decimation filter to produce final beamforming outputs. The performance and validity of the proposed beamforming approach are assessed by means of emulations using experimental raw RF data.