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Millimeter wave (mmWave) radar technology has potential applications in vital signs detection and medicine. In order to minimize the influence of human micro-movements and respiratory harmonics on heart rate estimation, the vital signs detection method based on mmWave radar is studied in this paper. First, we use median filtering to eliminate baseline drift caused by human micromotion. Next, a differential recursive least squares multiple classification (DR-MUSIC) algorithm is proposed based on the combination of recursive least squares-based adaptive filter (RLS) and multiple signal classification (MUSIC) algorithm. This algorithm effectively suppresses respiratory harmonics and separates respiratory and heartbeat signals. Finally, heart rate value can be precisely estimated using spectral peak search. We invite a number of people to participate in the experiment, which demonstrate that the method successfully suppresse the impact of respiratory harmonics at low SNR. The error rate between the estimated heart rate and the reference heart rate is only 1.69% to 2.61%, which is significantly better than the existing algorithms. [ABSTRACT FROM AUTHOR]

A cutting-edge antenna system has been developed for new radio (NR) millimeter wave operating from 36.0 to 40.0 GHz frequency range 2 (FR 2) n260 band applications. This innovative system incorporates metasurface-inspired printed dual-port MIMO technology, which includes LP to CP conversion features. The positional orientation of the elements of the MIMO antenna with stacked metasurface provoked the spatial diversity. To convert linearly polarised (LP) waves to circularly polarised (CP) waves, the metasurface layer is suspended above the MIMO antenna. LP to CP polarisation conversion occurs when the conducting strip and rectangular space between strips on the substrate generate π/2 phase-shifted electric field components (Ex and Ey). The proposed stepped impedance-fed antenna elements and metasurface are fabricated on commercially available high-frequency laminates using a double-layer printed circuit board (PCB) fabrication facility. The test findings exhibit a satisfactory level of concurrence with the calculated/measured findings regarding scattering parameters, diversity performance parameters, and realized gain. The result is a highly efficient and versatile antenna system that is ideal for advanced engineering applications. [ABSTRACT FROM AUTHOR]

Millimeter waves (mmWave) are the only viable solution that is practical to fulfil the enormous bandwidth requirement of the modern era communication systems. Accurate estimation of the wireless channels is necessary for mmWave based multiple input multiple output (MIMO) systems that use directional beamforming. Nevertheless, due to the short wavelengths, mmWave channels exhibit significant variability, which poses a major obstacle to their successful recovery within limited training durations traditionally, there are two conventional channel estimation methods have been used for the operation. One is by using the low rank property of channel matrix and the other is to exploit the sparsity of the channel matrix in angle domain. However, the conventional estimation approaches may have necessitated a high-dimensional channel matrix, so substantially augmenting the intricacy of the traditional channel estimation process. This study addresses the channel estimation problem of wideband mmWave MIMO system by utilizing both low rank and sparsity simultaneously. The fundamental concept of the proposed technique is to frame the channel estimation issue as a combined optimization problem that creates an objective function comprising of l 1 - n o r m and nuclear norm minimization problems. The joint optimization problem is tackled using the expanded version of alternating direction method of multipliers (ADMM) algorithm which takes the advantage of the low rank and sparseness of the channel matrix by using the relaxation technique of the variables. The simulation findings clearly illustrate the superiority of proposed approach in comparison to other benchmarks. [ABSTRACT FROM AUTHOR]

This research article presents wideband multiport (two, four, and six) high isolation multiple-input multiple-output (MIMO) antennas for 5G millimeter wave communication systems. The MIMO single unit uses a partially grounded slotted patch structure to achieve wideband response in a minimal footprint. The MIMO structure attains high port isolation through spatial and polarization diversity schemes. In addition, coupling the four-port MIMO antenna to an artificial magnetic conductor (AMC) plane results in a large (threefold) improvement in gain. The proposed antenna prototypes are fabricated and tested. The prototype results are also compared with the reported state-of-the-art results. The AMC-coupled MIMO antenna offers large bandwidth (43%), high gain (8.54 dBi), high isolation (> 25 dB), and excellent diversity metrics (envelope correlation coefficient (ECC), diversity gain (DG), mean effective gain (MEG), and channel capacity loss (CCL)). The listed credentials are ideal for 5G communication networks and devices. [ABSTRACT FROM AUTHOR]

This paper presents an ultra-wideband polarization converting metasurface (PCM) for millimeter wave which can manipulate the linear polarized (LP) incident wave to its orthogonal counterpart in the frequency range of 49.7 to 142.2 GHz with an ultra-wide bandwidth of 92.5 GHz and a fractional bandwidth (FBW) of 96%. The proposed PCM shows outstanding results in achieving higher fractional bandwidth with overall polarization conversion ratio (PCR) > 90% in the desired band. The proposed PCM has low profile dimensions with thickness and periodicity of 0.5 mm (0.083 λo) and 1.43 mm (0.24 λo), where λo is the maximum wavelength at the lower operating frequency. Surface current distribution is studied to show the physics of polarization conversion. The design is versatile and adoptable in low-profile applications where minimum thickness is required and can be utilized in remote sensing, microwave relays, and astronomy. [ABSTRACT FROM AUTHOR]

A millimeter wave interferometer based on a Ka-band CW signal generator and a high-speed oscilloscope has been implemented, which makes it possible to carry out measurements without frequency conversion. The experimental measurements of the amplitude of transverse deformations of a metal rod caused by impact loading have been carried out. A good agreement between the calculated and measured data was revealed, demonstrating the possibility to measure microsecond-duration surface deviations with an accuracy of about 1 μm and a relative error of about 8%. [ABSTRACT FROM AUTHOR]

In the fifth generation (5G) new radio (NR) wireless communication system, using a multiple-input multiple-output (MIMO) system for signal transmission and reception of the millimeter wave frequency band can effectively improve data rate performance and received signal quality. Besides, precoding is an important method of beamforming in MIMO transmission. With the properly selected precoding matrices, the transmitter and receiver can adjust the transmitting and receiving behaviors in accordance with the changes of the current channel state to reduce the interferences between users and increase the received signal strength. In this paper, a low complexity precoding selection method is proposed based on the steering angle characteristics of the precoding matrices of 5G NR. In addition, for this paper, we used the software defined radio to implement the precoding selection following the requirement of the specifications of 5G. With this implementation, both the transmitter and receiver can determine the suitable precoding matrices according to different precoding selection methods. Results showed that with a little error vector magnitude performance degradation, the proposed precoding selection method can reduce at least 50% of the required computational complexity of the full search method. [ABSTRACT FROM AUTHOR]

We consider a millimeter wave (mmWave) multiple input multiple output (MIMO) multiple-relay aided system in beyond 5G (B5G) and 6G with a multiple antennas source, multiple amplify-and-forward (AF) X-duplex (XD) relays with single transmit and single receive antenna, and one multiple antennas destination. XD relays can switch adaptively between half-duplex (HD) relaying and full-duplex (FD) relaying modes to improve the system performance. We derive an expression for the outage probability of the system by assuming a relay selection scheme based on the maximum end-to-end (E2E) signal to interference plus noise ratio (SINR). Moreover, both Rician small scale fading and large scale fading includes blockage effect and path-loss are considered in source to relay and relay to destination mmWave channels, in addition, a realistic model for residual self-interference is studied. Simulation results present the accuracy of the theoretical expression of the outage probability of XD relaying in the mmWave MIMO system and show that it has superior outage performance compared with both HD and FD relaying. [ABSTRACT FROM AUTHOR]

Network densification is a key technology to meet the rapid growth of 5G traffic. Millimeter wave has rich spectrum resource, short propagation distance and obvious directivity. Therefore, the dense millimeter wave network can reduce co-frequency interference and improve network capacity. To make full use of spectrum resource, this paper proposes a user association algorithm in multi-band millimeter wave network, which maximizes the weighted total rate of network while meeting the requirement of users and backhaul bandwidth constraint of base stations (BS). To enrich resource management method of network, the resource proportion of BS allocated to each user is also jointly optimized. For the mixed integer optimization problem which is difficult to solve after modeling, we adopt penalty function and Marks–Wright algorithm to obtain solution. Simulation results show that compared with three similar algorithms, the proposed scheme can rationally utilize network resource, avoid load imbalance, and has the highest total rate of network. [ABSTRACT FROM AUTHOR]

The combination of non-orthogonal multiple access (NOMA) and intelligent reflective surface (IRS) is an efficient solution to significantly increase the energy efficiency of the wireless communication system. This paper considers a downlink IRS-based Millimeter wave (mmWave) massive Multiple-Input Multiple-Output (MIMO)-NOMA system. In this work, a two-layer hierarchical AGglomerative NESting- DIvisie ANAlysis Clustering Algorithm (AGNES-DIANA) user grouping (2L-HAD-UG) is proposed to group users. In the proposed 2L-HAD-UG, the first layer will use the AGNES algorithm to efficiently group the users into different clusters. After the first level of clustering, some user groups are larger than others, and perhaps some users with weakly correlated channels are assigned to the same groups. To address these concerns, the large user groups are divided into several smaller groups, and each user whose channels are weakly correlated is isolated as a separate group. In the second layer, the DIANA Hierarchical Clustering is used to divide the larger clusters based on the channel correlation value. After user grouping, a new joint active and passive beam-forming design problem is formulated to maximize the achievable rate of each user in each cluster under the Quality of Service (QoS) requirements of other users, the conditions of Successive Interference Cancellation (SIC) decoding rate, the constraints of IRS reflection components and the transmission power restrictions. The formulated optimization problem is solved by proposing a new Successive Chaotic Group Search Approximation (SCGSA) algorithm. With the proposed massive mmWave MIMO-NOMA system, the spectral efficiency, energy efficiency, and sum rate are achieved to 18.56 bits per second (bps)/Hertz (Hz), 57.56 bps/Hz/Watt (W) and 21.58 bps/Hz, respectively. [ABSTRACT FROM AUTHOR]

Fifth generation new radio (5G NR) is bringing revolutions in almost every field such as healthcare, industrial automation, smart farming, and defense. These fields utilize three major use case scenarios of 5G NR viz. eMBB, URLLC, and mMTC. 5G NR deployment relies on two major frequency bands such as sub-6 GHz and high-frequency bands (millimeter waves). Among all sub-6 GHz bands, the n78 band (3300–3800 MHz) is gaining popularity due to its unique characteristics viz. higher capacity and coverage, wide bandwidth, and higher data rate. Despite these unique characteristics, in the 5G standalone architecture, users expect high-speed video/voice transmission without delay and good quality of services (QoS) requirements. QoS is one of the important paradigms that indicates the quality of services experienced by end users instead of services claimed by service providers. In this work, we have designed a QoS scenario that utilizes the n78 band with an "urban macro mixed office scenario with low loss" path loss model. As per types of services are concerned, the scenario utilizes six different traffic templates (i.e., FTP, Voice, Video, COAP, CBR, and Email). The path loss model operates on non-line-of-sight scenarios with Rayleigh fading and eigen beamforming using 64 × 32 antenna elements. The performance of the proposed scenario is examined through different metrics i.e., throughput, packet drop ratio, and delay. Here, priorities to different traffic templates are assigned based on GBR and non-GBR resource types. In addition, the proportional fair scheduling algorithm is employed to schedule the resources. It was observed that video services achieved a higher throughput of 25.93 Mbps due to their prioritization in the QoS model. Conversely, FTP services experienced higher delay, measured at 64 ms, and a packet delivery ratio of 5.94%. [ABSTRACT FROM AUTHOR]

Nonlinear mechanism of photodetector in the communication band of 1550 nm was researched in this article. Then nonlinear frequency doubling mechanism was used to generate millimeter wave signals that can be used in millimeter wave communication systems. In the article, the layer structure of the photodetector was optimized to further improve the power of millimeter wave signals. Different from the fundamental frequency output power, the frequency doubling output signal exhibits completely different characteristics at low input optical power and high input optical power. Therefore, the structure design of the photodetector was optimized for different input optical power application scenarios. Finally, the influence of the incident optical field distribution on the nonlinear output of the photodetector was studied. The results showed that when the photodetector did not reach saturation, the Gaussian distribution situation could produce a larger nonlinear signal power than uniform distributed optical field. [ABSTRACT FROM AUTHOR]

In recent years, the significance of millimeter wave sensors has achieved a paramount role, especially in the non-invasive and ubiquitous analysis of various materials and objects. This paper introduces a novel IoT-based fake currency detection using millimeter wave (mmWave) that leverages machine and deep learning algorithms for the detection of fake and genuine currency based on their distinct sensor reflections. To gather these reflections or signatures from different currency notes, we utilize multiple receiving (RX) antennae of the radar sensor module. Our proposed framework encompasses three different approaches for genuine and fake currency detection, Convolutional Neural Network (CNN), k-nearest Neighbor (k-NN), and Transfer Learning Technique (TLT). After extensive experiments, the proposed framework exhibits impressive accuracy and obtained classification accuracy of 96%, 94%, and 98% for CNN, k-NN, and TLT in distinguishing 10 different currency notes using radar signals. [ABSTRACT FROM AUTHOR]

A novel chamfered V-shaped microstrip meander line (MML) slow-wave structure (SWS) based on the V-shaped MML SWS for W-band traveling-wave tube (TWT) is proposed to decrease the transmission loss and thus to improve the output power and beam-wave interaction efficiency. The high-frequency characteristics, transmission characteristics, and the beam-wave interaction processes of the novel structure are investigated by simulations. The simulation results show that the S21 parameters of the chamfered V-shaped MML SWS are improved by 4.3 dB for 100 periods compared with that of the traditional V-shaped MML SWS at 95 GHz. Besides, the particle-in-cell simulations indicate that the output power of the TWT with the novel structure is 30% higher than the V-shaped MML SWS in W-band. Finally, two types of SWSs with 100 periods are fabricated, assembled, and experimentally tested. According to the experimental test results, while the S11 parameters are below − 20 dB, the "cold" S21 parameters are − 17.04 dB vs − 20.74 dB at 95 GHz, which shows potential advantages of the proposed novel SWS in millimeter wave and even terahertz spectrum. [ABSTRACT FROM AUTHOR]

Beamforming using highly directional antennas is inevitable to compensate the propagation losses and enable communication in the millimeter wave (mmWave) band. However, this directivity makes mmWave links fragile and sensitive to environment dynamics and blockage. Consequently, initial access and management of the mmWave links in dynamic environments turns to be a big challenging issue, especially in dense network scenarios. In particular, a massive amount of beamforming training (BT) overhead with high delay is needed to establish the mmWave link between a user device (UD) and the deployed small cells (SCs). The consequences are become more severe in case of mobility, since frequent handovers (HOs) between different beams/SCs is needed to preserve the connection with moving UDs. Inspired by the fact that directionality makes the mmWave communications to be geometry and location driven, this paper proposes a geometry-based schemes for the initial access and management of mmWave links. In the proposed schemes, geometric information of the target area including the UDs locations, SCs coordinates and the target area maps are exploited to alleviate the complexity of the exhaustive-based BT. The high impact of the proposed mmWave link initial access and management schemes over the conventional ones in different terms such as BT complexity and total energy consumption rates is proved via simulation analysis. [ABSTRACT FROM AUTHOR]

In this paper, a novel negative refractive index metamaterial (NIM) is developed and characterized. The proposed metamaterial exhibits negative effective permittivity (εeffe) and negative effective permeability (µeffe) at millimeter wave frequency of 28 GHz. This attractive feature is utilized to enhance the gain of a microstrip patch antenna (MPA). Two thin layers of 5 × 5 subwavelength unit cell array of NIM are placed above a single MPA to enhance the gain of the antenna. Each unit cell has an area of 3.4 × 3.4 mm2. A gain increase of 7.9 dBi has been observed when using the proposed NIM as a superstrate. Furthermore, the NIM array is placed over a 2 × 2 array of MPAs with four ports to demonstrate versatility of the metamaterial. The total size of the 2 × 2 antenna array system with N-MTM is about 61.1 × 34 × 16mm3 (5.71λ × 3.18λ × 1.5λ, where λ is the free-space wavelength at 28 GHz). The measurement result indicate that the maximum gain of the antenna array is 13.5dBi. A gain enhancement of 7.55 dB in E-Plane and 7.25 dB in H-Plane at the resonant frequency of 28 GHz is obtained. The proposed antenna structure is suitable for 5G millimeter wave communications, in particular, for possible implementation in future millimeter wave access points and cellular base stations. [ABSTRACT FROM AUTHOR]

A compact low-profile multi-band millimeter-wave (mm-wave) reflectarray metasurface design is presented for coverage enhancement in 5G and beyond cellular communication. The proposed single-layer metasurface exhibits a stable reflection response under oblique incidence angles of up to 60 ∘ at 24 and 38 GHz, and transmission response at 30 GHz, effectively covering the desired 5G mm-wave frequency bands. The proposed reflectarray metasurface is polarization insensitive and performs equally well under TE and TM polarized incident waves due to the symmetric pattern. In addition, the low profile of the proposed metasurface makes it appropriate for conformal applications. In comparison to the state-of-the-art, the proposed reflectarray metasurface unit cell design is not only compact (3.3 × 3.3 mm 2 ) but also offers two reflections and one transmission band based on a single-layer structure. It is easy to reconfigure the proposed metasurface unit cell for any other frequency band by adjusting a few design parameters. To validate the concept of coverage enhancement, a 32 × x32 unit-cell prototype of the proposed reflectarray metasurface is fabricated and measured under different scenarios. The experimental results demonstrate that a promising signal enhancement of 20–25 dB is obtained over the entire 5G mm-wave n258, n259, and n260 frequency bands. The proposed reflectarray metasurface has a high potential for application in mm-wave 5G networks to improve coverage in dead zones or to overcome obstacles that prevent direct communication linkages. [ABSTRACT FROM AUTHOR]

We established a design method for a Magic-T with a single-layer dielectric/metal structure suitable for both wideband and multi-element applications for millimeter and submillimeter wave imaging observations. The design method was applied to a Magic-T with a coupled-line, stubs, and single-stage impedance transformers in a frequency-scaled model (6–14 GHz) that is relatively easy to demonstrate through manufacturing and evaluation. The major problem is that using the conventional perfect matching condition for a coupled-line alone produces an impractically large width coplanar coupled-line (CPCL) to satisfy the desired bandwidth ratio. In our study, by removing this constraint and optimizing impedances utilizing a circuit simulator with high computation speed, we found a solution with a ∼ 180 μm wide CPCL, which is approximately an order of magnitude smaller than the conventional analytical solution. Furthermore, considering the effect of transition discontinuities in the transmission lines, we optimized the line length and obtained a design solution with return loss < − 20 dB, amplitude imbalance < 0.1 dB, and phase imbalance < 0.5 ∘ from 6.1 to 14.1 GHz. [ABSTRACT FROM AUTHOR]

In this paper, four-element Multiple-Input Multiple-Output (MIMO) antenna system has been proposed for Intelligent Internet of Everything (IIoE) and high-speed data applications. The presented antenna design operates at 4.9 GHz (5G millimeter wave applications) with high isolation in a small size. Defected Microstrip Structure (DMS), slot modification and orthogonal polarization are used to generate the desired frequency band, improve the impedance bandwidth, and enhance the isolation between antenna elements at 4.9 GHz, respectively. Furthermore, the usefulness of the proposed MIMO antenna has been verified by comparing the simulated and the measured results using a fabricated version of the considered 4 × 4 MIMO antenna. In addition, the results indicate a high diversity performance in terms of: Envelope Correlation Coefficient (ECC), Diversity Gain (DG), Efficiency, Gain, Total Active Reflection Coefficient (TARC) and Total Channel Capacity Loss (CCLTotal). [ABSTRACT FROM AUTHOR]

The 3D object recognition has become one of hot topics in computer vision with the increasing of application scenarios of 3D data, such as robotic systems, autonomous driving, and security check systems using active millimeter wave. Although 3D convolutional neural network (CNN) has achieved some good results in 3D object recognition, its key performances such as computational efficiency and realtimeness still need to be improved due to its huge amount of parameters of 3D convolutions. In this paper, we present a powerful tool LVNet which is a lightweight volumetric CNN designed for real-time and high-performance recognition of 3D objects. Meanwhile, all of standard 3D convolutions are replaced with depthwise separable convolutions in the LVNet so as to reduce the model size and computation complexity. Furthermore, the attention mechanism is combined with the depthwise separable convolutions to compensate for the performance loss caused by the reduction of parameter number. In order to further improve the performance of LVNet, some auxiliary methods are employed also, such as data augmentation with multiple rotations of objects and information fusion of different orientations. A series of experimental results on public datasets show that the proposed LVNet achieves competitive recognition performance with less burden of computation and memory. [ABSTRACT FROM AUTHOR]

As a form of body language, the gesture plays an important role in smart homes, game interactions, and sign language communication, etc. The gesture recognition methods have been carried out extensively. The existing methods have inherent limitations regarding user experience, visual environment, and recognition granularity. Millimeter wave radar provides an effective method for the problems lie ahead gesture recognition because of the advantage of considerable bandwidth and high precision perception. Interfering factors and the complexity of the model raise an enormous challenge to the practical application of gesture recognition methods as the millimeter wave radar is applied to complex scenes. Based on multi-feature fusion, a gesture recognition method for complex scenes is proposed in this work. We collected data in variety places to improve sample reliability, filtered clutters to improve the signal's signal-to-noise ratio (SNR), and then obtained multi features involves range-time map (RTM), Doppler-time map (DTM) and angle-time map (ATM) and fused them to enhance the richness and expression ability of the features. A lightweight neural network model multi-CNN-LSTM is designed to gestures recognition. This model consists of three convolutional neural network (CNN) for three obtained features and one long short-term memory (LSTM) for temporal features. We analyzed the performance and complexity of the model and verified the effectiveness of feature extraction. Numerous experiments have shown that this method has generalization ability, adaptability, and high robustness in complex scenarios. The recognition accuracy of 14 experimental gestures reached 97.28%. [ABSTRACT FROM AUTHOR]

To satisfy the capacity requirements of future mobile systems, under-utilized millimeter wave frequencies can be efficiently exploited by employing massive multiple input-multiple output (MIMO) technology with highly directive beamforming. Hybrid analog-digital beamforming has been recognised as a promising approach for large-scale MIMO implementations with a reduced number of costly and power-hungry radio frequency (RF) chains. In comparison to fully connected architecture, hybrid beamforming (HBF) with partially connected RF architecture is particularly appealing for the practical implementation due to less complex RF power division and combining networks. In this paper, we first formulate single- and multi-user rate maximization problems as weighted minimum mean square error (WMMSE) and derive solutions for hybrid beamformers using alternating optimization. The algorithms are designed for the full-array- and sub-array-based processing strategies of partially connected HBF architecture. In addition, we propose lower complexity sub-array-based zero-forcing algorithms. The performance of the proposed algorithms is evaluated in two different channel models, a simple geometric model and a realistic statistical model. The performance results of the WMMSE HBF algorithms are meant to reveal the potential of partially connected HBF and serve as upper bounds for lower complexity methods. Numerical results imply that properly designed partially connected HBF has the potential to provide an good compromise between hardware complexity and system performance in comparison to fully digital beamforming. [ABSTRACT FROM AUTHOR]

The non-orthogonal multiple access (NOMA)has emerged as a promising 5G technology as it supports ultra-low latency and massive connectivity of devices with diverse Quality of service (QoS) and transmit rates which are the key requirements for the enabling Vehicle-to-anything (V2X) communication. In this paper we investigate the performance analysis of a decentralized Full duplex non-orthogonal multiple access (FD-NOMA) model at millimeter (mm) wave frequency. The analysis has been done on both crowded urban as well as non-crowded semi-urban scenarios, the capacity expression for both this scenario has been calculated and compared. The simulation results interprets that the system provides better channel capacity with increasing NOMA power at mm-wave frequency range, number of vehicular devices and Rician factor along with a superior performance in terms of latency compared to other systems. The proposed model achieved the ultra-low latency of 16 nano seconds with the capacity of 950 Gbps for the Urban dense scenario and 990 Gbps for the semi-urban sparse scenario. The simulation results illustrate that FD-NOMA can offer noteworthy performance gains over half-duplex NOMA and orthogonal multiple access. [ABSTRACT FROM AUTHOR]

Millimeter wave technology attracts a lot of attention towards 60 GHz applications. Due to advantage of continuous scaling of CMOS technology and speed of transistors, 90 nm CMOS technology is selected for designing the circuits. In this paper, broadband low power low noise amplifier (LNA) is designed using 90 nm CMOS process at the operating range of 55 GHz to 67 GHz. Inductively degenerated cascode two stage LNA is designed to achieve low power, high gain and good return loss. Optimization techniques take an advantage to optimize the parameters in analog circuits within a short period of time. Such optimization algorithms such as genetic, random, hybrid, Quasi Newton, random and simulated annealing are used to optimize the designed LNA parameters. The designed LNA provides 27.9 dB gain, -18.7 dB return loss, 1.92 dB noise figure, 5.56 mW power consumption and FoM of 5.45. Optimization algorithms provide better FOM while comparing the designed LNA without optimization. Hybrid algorithm produces high FOM of 48 when compared with other algorithms. [ABSTRACT FROM AUTHOR]

Given the disparity in signal transmission properties for both current bandwidths and millimeter wave radio frequencies, the present propagation models used for low frequency range up to few gigahertz are not suitable to be utilized for the path loss modelling techniques as well as modulation schemes for the high frequency ranges such as millimeter wave (mmWave) spectra. As a result, rigorous research on link analysis as well as path loss modeling are needed to create a broad and suitable transmission scheme with modeling variables that can handle a broad spectrum of mmWave frequency spectra. This paper proposes an improved path loss model for estimating the path loss in an indoor space wireless communication at 28 GHz and 38 GHz frequencies. The test results for the interior non-line-of-sight (NLOS) situations were collected every two meters over spacing of 24 m separating the transmitting and receiving antenna locations to make a comparison the well-known and improved large-scale generic path loss models. The results of the experimental studies obviously demonstrate that the improved propagation model works significantly better than the CI model, owing to its simple setup, precision, and accurate function. The results show that the presented improved model gives better performance. It is observed that the standard deviation of shadow fading can be significantly reduced in the NLOS scenario, implying greater accuracy in predicting the path loss in an indoor environment. [ABSTRACT FROM AUTHOR]

The proliferation of integrated sensing techniques in Sixth Generation (6G) networks is an increasingly significant aspect in facilitating efficient end-to-end communication for all users. The suggested methodology employs a digital signal processed with terahertz bandwidth to assess the impact of 6G networks. The primary focus lies in the design of 6G networks, emphasizing key parameters such interference, loss, signal strength, signal-to-noise ratio, and dual band channels. The aforementioned factors are combined with two machine learning algorithms in order to determine the extent of spectrum sharing among all available resources. Thus suggested approach for detecting signals in the terahertz communication spectrum is evaluated using 10 devices across four situations, which involve interference, signal loss, strength, and time margins for integrated sensing. Also the assumptions are based on signal processing devices operating within millimeter waves ranging from 5 to 10 terahertz. Interference and losses in the specified spectrum are seen to be less than 1%, but the time margin for integrated sensing with 99% maximized signal intensity remains at 85%. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) is envisioned to be a promising solution to enhance coverage and capacity of future wireless networks. With the deployment of multiple RISs, the optimal placement and topology are crucial issues that need to be addressed, which are significantly different from that of active BSs/relays. This paper considers a mmWave MIMO system aided by multiple RISs in a circular layout to observe the effect of RIS placement and power scaling law. The active and passive beamforming are configured to combine the signals coherently to improve the spectral efficiency (SE). To this end, we investigate the effect of quantization error on the SE and derive an upper bound. It indicates that the SE loss is only affected by the number of quantization bits and numerical results show that 5-bit quantizer is sufficient to ensure an acceptable SE degradation. Furthermore, we evaluate the performance of the system by formulating the tight upper bounds on the average ergodic spectral efficiency and propose three effective schemes for RIS selection. Our simulation results verify the derivations and validate that the performance of deploying the RISs close to BS is significantly better than that of deploying the RISs randomly in the cell. [ABSTRACT FROM AUTHOR]

Rainfall can reduce the radar signal through a radome. The effects of different water layers on the radome transmission are studied using quasi-optical measurement from 26 to 330 GHz including water permittivity characterization. The water is deposited as drops of different sizes or as a uniform layer while keeping a constant volume, highlighting the importance of the control of the total wet surface for radar applications. A compact model is proposed to predict the signal loss due to water on the radome depending on the rain flow. [ABSTRACT FROM AUTHOR]

A novel method to generate and two frequency 16-tupling millimeter wave (MMW) and distribute the generated MMW over fiber system (MMOF) with two base stations (BS) by the remodulation with Mach–Zehnder modulators (MZM) is proposed. At the central station(CS), the ± 4th order optical sidebands generated by a dual parallel MZM (DPMZM) are split into two branches, one of which is injected into a photodetector (PD) to generate the 8th harmonic of the RF drive signal of the MZM, which acts as the RF driving signal for the remodulation, and the other acts as the carrier for the remodulation. The remodulation is realized by injecting the outputs of the two branches into an MZM. After remodulation, the signal which contains mainly the ± 20th, ± 12th and ± 4th order optical sidebands is divided into two branches, in which the positive and negative sidebands are filtered out by two optical band-pass filters (OBPF) first and the 4th and − 4th order sidebands are filtered by two fiber Bragg gratings (FBG) later, with which the data of the downlink are modulated on it. At the two BSs, the 12th and − 12th order sidebands in the downlink optical signal are first filtered out by two FBGs, with which the data of the uplink are modulated onto it and transmitted to the CS via optical fibers for carrier reuse; the output signals of the FBGs are injected into two PDs to produce two 16-tupling frequency MMWs with the data of downlinks. The feasibility of our scheme is verified by theoretical analysis and simulation experiments. The main innovations of our designed scheme are that the modulation index of MZM is greatly reduced by using the remodulation method, the power utilization rate is greatly improved by using all the main sidebands and the cost of the system is reduced by using the two BSs structures with carrier reuse. [ABSTRACT FROM AUTHOR]

This paper presents a super wideband and high-gain log periodic dipole array (LPDA) antenna. The overall structure of the antenna was constructed using microwave studio computer simulation technology. The optimal sizes of the planned antenna are 39 × 10× 0.254 mm3. The engineered antenna arrangement is implemented on an RT5880 substrate as a dielectric medium. The LPDA is arranged in four arms that are equally spaced on both lines. The main 50Ω feeder line is partially grounded at the back of the substrate. A combination of circular director units is being studied and tuned in a regular pattern at a predefined distance from the antenna. An improvement in gain of 3 dBi is the response of the director units. The Conformist LPDA is adjusted to achieve a wide range of millimeter wave bands ranging from 40 to over 70 GHz. The antenna resonates at 60 GHz, where the maximum realized gain of 14.97 dBi is attained. The antenna was tested for utilization in the V-band involving wireless personal area network (WPAN) applications recommended by IEEE 802.11ad and IEEE 802.15.3c. The outcomes of the constructed antenna elements' tests and simulations agree fairly well. The proposed layout works better than previous efforts in this field. [ABSTRACT FROM AUTHOR]

Background: The rapid expansion of modern smart applications, demanding faster data transfer and extensive bandwidth, has prompted the development of new-generation networks like 5G and 6G. These networks encompass additional frequency bands such as sub-6 GHz, millimeter waves, and terahertz bands to meet the growing bandwidth requirements. However, despite the substantial bandwidth available in these bands, several challenges must be addressed to overcome unfavorable propagation characteristics. Moreover, numerous applications necessitate wireless devices with antennas that exhibit high flexibility and exceptional radiation responses, particularly when subjected to bending effects. This requirement highlights the importance of polymers-based antennas that can adapt to changing conditions while maintaining optimal performance. The present comprehensive study delves into the performance evaluation of rectangular and circular microstrip antennas utilizing PMMA (polymethyl methacrylate) polymer substrate with varying thicknesses. Results: Notably, CNTs (Carbon Nanotubes) are employed as an alternative to traditional copper for the conductive part and ground plane. Both PMMA-based antennas, integrated with CNTs, exhibit a compact footprint of 27.8 × 47.8 × 1.5 mm3 for the circular antenna and 22.8 × 39.5 × 1.5 mm3 for the rectangular antenna. Impressively, the realized gain of both antennas surpasses 5 dBi, demonstrating robust performance in both flat and bending scenarios across different substrate thicknesses. Conclusions: The rectangular antenna achieves a bandwidth of approximately 200 MHz, while the circular microstrip antenna showcase annotable bandwidth of 500 MHz. These exceptional outcomes position the two microstrip antennas as highly suitable for a diverse range of emerging applications within the sub-6 GHz band (the frequency range below 6 GHz in the radio spectrum). Thus, the combination of PMMA substrate, CNTs and the compact form factor of the antennas presents a compelling solution for meeting the demands of modern applications requiring efficient wireless communication with enhanced performance and bandwidth. [ABSTRACT FROM AUTHOR]

Millimeter wave massive multiple-input and multiple-output (MIMO) systems support several antennas at the receiver and transmitter sides to serve several users in a communication system. Due to its several antennas, the system cost is very high and faces challenges such as blockage, path loss, and interference. To solve the above interference problem, beamforming technology and LMS Kalman filter-based Hybrid Precoding are used in millimeter wave massive MIMO system by directing the signal in the desired direction and to get a reduced bit error rate. Therefore, proposed hybrid precoding aims to leverage the advantages of both digital and analog beamforming while significantly reducing the number of RF chains compared to the number of antennas, all while maintaining the benefits of spatial multiplexing. This paper compares the performance of various precoding techniques, including Analog-only Beamsteering, Zero Forcing (ZF), Minimum Mean Square Error (MMSE), Kalman, Minimum Square Error Fully digital (MSE Fully digital), and Proposed Least Mean Squares (LMS) Kalman Hybrid Precoding, using performance metric parameters such as spectral efficiency, energy efficiency, bit error rate, and Information rate. The LMS Kalman Hybrid Precoding improved the spectral efficiency by almost 6.228 bps/Hz at 10 dB with ten channel paths concerning the Analog-only Beamsteering and almost 3.748, 2.974, 2.758, and 0.399 bps/Hz for the Zero Forcing (ZF) Hybrid Precoding, MMSE, Kalman, and MSE Fully Digital Hybrid Precoding techniques, respectively, which shows the superiority of the Proposed Least Mean Squares (LMS) Kalman Hybrid Precoding. [ABSTRACT FROM AUTHOR]

We proposed a newly devised method for measuring the complex permittivity of high-loss materials at the millimeter wave frequency range. In this paper, we employed a geometrical gap between samples, which allows us to evaluate the complex permittivity of high-loss materials. By introducing this gap, we obtain a characteristic shape of the transmittance, which enables us to fit the data and obtain a more precise complex permittivity value. The proposed method has been supported by experimental results with a very low error bar compared to the existing fundamental transmission line method. We measured diverse samples including alumina, Teflon, Vero family, and AlN-SiC, and confirmed that the proposed gap method achieves much higher precision than the existing method by 3 to over 10 times. Particularly for high-loss materials like the AlN-SiC sample, the average error of the relative permittivity evaluated by the existing transmission line method is 2.05% whereas the error by the proposed method is 0.05%. Moreover, the average error of the loss tangent measured by the existing method and the suggested method is 1.85% and 0.3%, respectively, which confirms the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

The millimeter wave spectrum fulfills the demand for higher data rates with low latency. Moreover, futuristic wearable gadgets demand flexible antennas operating at these frequencies, such that they can easily be accommodated. Therefore, the article focuses on designing a compact and highly flexible antenna with the aid of characteristic mode analysis (CMA). A thin polyimide substrate of 0.1 mm thickness is used to maintain flexibility. The overall antenna profile is 0.61 λ 0 × 0.61 λ 0 . The design evolves through four stages, where, in each stage, the solution to the surface current through eigenvalue leads to significant modes. The final stage design generated Mode 2 fundamental mode at 30.5 GHz along with contributing Modes 3 and 5 with a bandwidth range of 28-31.5 GHz. Further, the design is simulated using electromagnetic simulation software, and the prototype is fabricated. The simulated and measured reflection coefficient |S11| > 10 dB in 28.72-32 GHz and 28.9-31.75 GHz. The CMA analyzed, simulated, and measured gain is 4.82 and 5.6 dBi, respectively. The proposed antenna has a stable response for conformal orientations along the x and y-axis. The antenna has resulted in bidirectional radiation in the XZ plane with simulated and measured half-power-beam-width (HPBW) of 58° and 54°. In the YZ plane, it resulted in omnidirectional radiation. The simulated and measured results are in good agreement. The article also performs the link budget analysis. It suggested that the antenna can communicate 100 Mbps of data to a distance of 100 m and 1 Gbps of data up to 70 m. Thus, the proposed antenna structure is suitable for wearable, IoT, and other 5G wireless applications. [ABSTRACT FROM AUTHOR]

Many vehicle applications requiring large capacity, minimal latency, and excellent dependability are anticipated to be made possible by 5G. To help with this, 5G suggests using highly focused mmWave networking implementation, denser, more minor cell innovation, and various new sophisticated communications techniques to increase networking bandwidth, lower latency, and offer high dependability. Robust mobility managing strategies are needed in these networks to enable automotive connection wherein the points are very dynamic to reduce transmission costs and disruptions during periodic transfers. Engineers working on technology for communication have to tackle this significant obstacle to fulfil the potential of 5G networks enabling V2X and comparable purposes. Therefore, a new implementation strategy is essential to support 5G functionalities. A possible approach for the 5G system installation optimization challenge is predicted to involve using meta-heuristics. To reduce the number of basis stations (BSs) as well as optimize the assignments in millimetre wave (mmWave) frequency ranges (such as 28 GHz as well as 38 GHz) within the framework of such 5G system while fulfilling customer data rates requirements, a deployment regarding a meta-heuristic method depending upon swarming intelligence is presented in this paper. After that, a sequential procedure is used to eliminate unnecessary BSs. [ABSTRACT FROM AUTHOR]

To achieve a green and sustainable wireless communication network, the reconfigurable intelligent surface (RIS) technology has emerged as an emerging technology. The RIS-assisted mmWave massive MIMO vehicle-to-everything (V2X) communications can support enhanced V2X applications for connected and automated vehicles. The design of RIS-assisted mmWave V2X communications is though not exempt of challenges as a result of fast time-varying propagation and highly dynamic vehicular networks and topologies. To address some of these challenges, we propose an attention-deep reinforcement learning jointly beamforming based on tensor decomposition for RIS-assisted mmWave massive MIMO system to improving the safety and traffic efficiency of cooperative automated driving. The received signal of the vehicle is decomposed into four-dimensional tensors and study the channel, frequency and time attention (CFTA) algorithm using the low order tensor characteristics of mmWave channels. This algorithm can extract the frequency and time characteristics of the channel, and obtain the millimeter wave characteristic channel between the corresponding base station (BS) and the vehicles. The problem of jointly optimization of beamforming matrix at the BS and the phase shift matrix on the RIS is constructed and solved using deep reinforcement learning (DRL). Unlike traditional alternating optimization methods, the integration of DRL techniques into the optimal design of the system enables the observation of immediate rewards, learning from the environment and improving it to obtain optimal solutions to high-dimensional jointly beamforming optimization problems ultimately. The simulation results show that the proposed algorithm has meaningful performance compared with other methods. [ABSTRACT FROM AUTHOR]

The attachment of 5G with millimeter wave (mmWave) frequencies offers massive capacity and low latency to reveal the full 5G experiences. High directive gain and beamforming are considered essential for mmWave 5G systems. The main requirements of the beamforming network for 5G mmWave applications are the scanning coverage of ± 60° and SLL > 10 dB in a wide operational bandwidth over the standard 5G frequency bands. In this paper, a novel PCB-based wide-angle Rotman lens beamformer is designed, simulated, and successfully measured to meet the mentioned requirements for 5G mmWave applications. A comprehensive improved design methodology is provided for all components of the Rotman lens to reach a wide scanning angle, enhanced sidelobe level, and low scan loss. The end-fire Vivaldi antenna is selected as an array element for easy integration to the beamforming network as well as its capability to use in dual-polarization configuration. The proposed Rotman lens is operational in the 24–30 GHz frequency band covering 5G n257, n258, and n261 frequency bands. The results show a nearly constant 8 beams across the whole bandwidth steering from − 53° to 53° in 15° increments to provide ± 60° coverage with the SLL > 10 dB and scan loss < 1.9 dB. The retrieved novelties from this work contain an effective design methodology for an optimized Rotman lens with wide-scan angle and low phase and amplitude error, non-uniform distribution based array ports, and integration with end-fire antenna for possible dual polarization and 2-D beamforming capabilities. The comparison of the proposed beamformer with the most recent works shows several advantages in terms of integrated structure and performances including bandwidth, wide scanning angle, SLL, and scan loss. With such performances, this beamformer can be used for various mmWave and 5G applications such as advanced antenna systems, massive MIMO systems, and hybrid beamforming systems. [ABSTRACT FROM AUTHOR]

Radio Frequency (RF) Nano Electro Mechanical Switches (NEMS) using Carbon Nanotube (CNTs) are preferred for electronic switching due to its high stiffness, switching speeds and ultra-low mass over several GHz range. CNT switch for microwave and millimeter wave applications utilizing a maximum of three CNTs with fixed starting positions of CNTs from zero level offset to obtain better isolation (S21) of the switch in DOWN State has already been studied. The motive of this paper is to obtain better RF performance in terms of return loss (S11) and isolation loss by modelling the switch in DOWN-state by varying the random positioning of CNTs, interelement spacing between CNTs, number of CNTs and frequency is predicted and reported using XG—Boost approach. Time-consuming optimization methods to predict the S-parameters in customized Electromagnetic (EM) simulators such as HFSS (High Frequency Structure Simulator) have been resolved using the proposed XG-Boost regression approach. In this paper, the proposed XG-Boost approach minimizes the switch design time with random placement of CNTs by 99.81% compared to the conventional EM simulator which requires about 120 h for 400 simulations in an Intel-Core processor (2.50 GHz) with 8 GB RAM. To validate the results, they are compared to the HFSS model, and a high degree of agreement is found. Mean Square Error (MSE) of the switch in the DOWN- state after comparing the EM simulation values and XG-Boost regression values is 6.832e−03. [ABSTRACT FROM AUTHOR]

Hybrid precoding is an emerging solution for millimeter wave massive MIMO system to achieve reduced complexity and enhanced spectral efficiency. Hybrid precoding fully exploits spatial information to achieve high channel gain which reduces excessive path loss. The research presented in this paper is aiming at the design of optimal precoder which is based on Logarithmic hyperbolic cosine cost function with ZA and RZA criterion and has the advantage of reduced RF Chains. The channel state information (CSI) is generated by using random values of angle of arrival (AoA) and angle of departure (AoD) information. This CSI information is crucial to generate the precoding matrices and the row wise elements of the digital precoding matrix are recursively updated by using hyperbolic cosine filtering algorithm. Proposed precoder achieves spectral efficiency of 13 bps/Hz with 20 dB SNR which is comparatively higher than the precoders designed using other state of art methods. The performance is tested by varying base station antennas, mobile station antennas and number of users. The achievable spectral efficiency with variation of antenna elements and users establish the superior performance of the precoder. Thus the design can be suitable for fifth and next generation wireless communication systems when higher data rate is the requirement in millimeter wave band. [ABSTRACT FROM AUTHOR]

Massive multiple-input multiple-output (MIMO) systems at millimeter wave have been touted as a possible technology for 5 G wireless communications. The massive MIMO systems, gathering channel information using a beam tracking approach is crucial for tracking user movement. Conventional beam tracking algorithms for narrowband systems using the classic hybrid precoding framework suffers from the beam split effect and hence cannot be effectively adapted to wideband massive MIMO systems. To address this problem, we describe a long-short term memory (LSTM) network for detecting user movement and calibrating beam direction based on received signals from earlier beam training to improve noise resilience. Simulation findings demonstrate that the proposed approach may reach near-optimal achievable sum-rate performance with little beam training overhead. [ABSTRACT FROM AUTHOR]

Fixed Point-to-Point microwave wireless systems with high spectral efficiency are needed to meet the pervasive and increasing demand for capacity in back-haul networks of mobile radio systems. In this context, spatially multiplexed LoS-MIMO (Line-of-Sight Multiple Input Multiple Output) systems have been studied for about twenty years, particularly in the millimeter wave frequency bands (above 15 GHz). However, their deployment in real networks has been really limited, to the authors' knowledge. This has been due to several factors, i.e. the practical possibility of using extremely high-level modulation formats (nowadays up to 8192-QAM), the joint use of co-channel dual polarization, and the availability of wider channel bands in the new high frequency ranges (e.g. E-Band). In addition, a crucial reason has been the difficulty of installing multiple antennas spaced apart in order to maximize the MIMO spatial multiplexing so providing the maximum capacity gain. This optimal antenna separation, even for the classical MIMO M × N with M = 2 antennas at the receiver and N = 2 antennas at the transmitter, can be several meters, e.g. 5.71 m at 23 GHz on a 5 km link. In this article, we analyze the performance of LoS-MIMO systems where antenna separation is highly sub-optimal, for limiting the array size, and a satisfactory performance is made possible by the exploitation of specific bit loading and power allocation strategies and the setting of the working region of the RF transmitter power amplifiers to operate at a given Signal-to-Inter Modulation Distortion Ratio (SIMDR). The result is an overview of the advantages and drawbacks of compact LoS-MIMO from a wider perspective than in the existing literature, including fundamental aspects for the practical implementation of these systems. Performance is discussed in many cases of interest and compared with the state of the art SISO (Single Input Single Output) system. [ABSTRACT FROM AUTHOR]

In this paper, a broadband, polarization-independent metamaterial absorber for millimeter waves is proposed. Operating across the frequency range of 22.7 GHz to 37.2 GHz, our broadband, polarization-independent absorber demonstrates exceptional efficacy by capturing over 90% of incident wave power. Distinguished by an array of conductive square patches on a dielectric substrate, the proposed structure boasts a remarkably low thickness, measuring less than a quarter of the free space wavelength of the central point within its operational spectrum (excluding the ground layer thickness). Leveraging a combination of circuit modeling and transmission line theory, this paper presents the design of this absorber and also elucidates its underlying operating principles. The combination of broadband operation, low thickness, and systematic design is rarely seen in previous works. To validate the proposed approach, a physical prototype is realized using 3D printing technology, employing conductive polylactic acid (C-PLA) patches on a light polyvinyl chloride (L-PVC) substrate. The proposed absorber has various potential applications in communication, electromagnetic shielding, and satellite technologies. Finally, a comparison with recent works is performed to demonstrate the feasibility of the proposed structure for millimeter-wave applications. [ABSTRACT FROM AUTHOR]

Small-scale motion detection using non-invasive remote sensing techniques has recently garnered significant interest in the field of speech recognition. Our dataset paper aims to facilitate the enhancement and restoration of speech information from diverse data sources for speakers. In this paper, we introduce a novel multimodal dataset based on Radio Frequency, visual, text, audio, laser and lip landmark information, also called RVTALL. Specifically, the dataset consists of 7.5 GHz Channel Impulse Response (CIR) data from ultra-wideband (UWB) radars, 77 GHz frequency modulated continuous wave (FMCW) data from millimeter wave (mmWave) radar, visual and audio information, lip landmarks and laser data, offering a unique multimodal approach to speech recognition research. Meanwhile, a depth camera is adopted to record the landmarks of the subject's lip and voice. Approximately 400 minutes of annotated speech profiles are provided, which are collected from 20 participants speaking 5 vowels, 15 words, and 16 sentences. The dataset has been validated and has potential for the investigation of lip reading and multimodal speech recognition. [ABSTRACT FROM AUTHOR]

The quality of the signal received at any location in communication channel depends on the degree of losses and attenuation experience along its path. The existing models are not suitable for 5G network propagation due to heavy channel interference and signal loss applicable at millimeter wave (mmWave) spectrum. The issues of Path Loss (PL) and signal interference in 5G New Radio (NR) network needs special attention. It is expected that 5G NR and 4G LTE-A networks will coexist for a very long time using the existing infrastructure. Hence, it is important to develop a good model to mitigate signal attenuation and co-channel interference that comes with the deployment of the 5G NR network. The existing models and measured data were compared to find out the closest model to the measured value. This paper proposed a modify Okumura-Hata (Ok-Hata) model for signal propagation in new 5G network. Also, an improved Autoregressive Particle Swarm Intelligent (APSI) algorithm was presented to enhance the proposed model for better performance. The modified Ok-Hata model outperformed all the existing models. The modified model has the potential to mitigate the effect of interference in 5G NR at 3.5 GHz frequency. The proposed new model has the capacity to solve some network issues such as; path loss, co-channel interference in 5G network. The result shows that there was no signal interference between the existing, and modified models. The result also shows that enhanced APSI is suitable for 5G NR network planning in Abuja, Nigeria. [ABSTRACT FROM AUTHOR]

The evolution to 5G millimeter wave (mmWave) is opening doors to many novel applications and services by leveraging the higher carrier frequency of 24 GHz and beyond. 5G mmWave promises to deliver extreme bandwidth, ultra-low latency, faster data speeds and responsiveness – thereby facilitating broadband connectivity to densely populated areas. Nevertheless, millimeter waves suffer from significant path loss, imposing severe range constraints. Beamforming is a promising technique to alleviate this impediment. Integrated photonics is sophisticated technology to realize cost-effective, compact, and power-efficient beamformers. In this paper, we propose photonically controlled continuously tunable single side coupled racetrack resonator based 1 × 8 broadband beamformer on CMOS-compatible silicon-on-insulator platform. A beam steering angle of 31.001˚ is achieved for 28 GHz mmWave wave signal. The proposed beamformer can provide maximum continuously tunable true time delay of 125 ps for delay bandwidth of 32.46 GHz. Therefore, the beam scanning range of 0–90° can be attained by properly tuning the coupling coefficient and resonance frequency of the racetrack resonator based delay element. [ABSTRACT FROM AUTHOR]

Multiple input multiple output (MIMO) system with Millimeter Wave spectrum is currently used in most wireless applications and all cellular system to provides high data rates. with using large antenna array which is possible by decrease the wavelength to achieve high beamforming gain and improve the spectral efficiency. in this paper, used low complexity with hybrid precoding at the transmitting side and combining at the receiver side with limited feedback system, by using the concept of orthogonal matching pursuit (OMP) in single and multi-user cases, and compared the results with analog only beasmstring. The results of simulation showed that when used Minimum Mean Square Error (MMSE) precoders performed better than other hybrid precoding approaches, in addition the MMSE hybrid precoding /combining technique offers higher spectral efficiency compared with analog only beamstring. [ABSTRACT FROM AUTHOR]

The bandwidth limitation is an arduous challenge to deploy the large-scale Internet of Things (IoTs) beyond fifth-generation (B5G) communication networks. Although the millimeter wave (mmWave) technology can provide greater bandwidth at the cost of complex processors in harsh environments, it can be a solution to establish large-scale IoTs. Still, its cost and power requirements become obstacles to widespread adoption. In this context, Reconfigurable Intelligent Surfaces (RISs) can be a crucial technology to meet this challenge. In this paper, we study the B5G RIS-assisted MIMO simultaneous wireless-information and power-transfer (SWIPT) mmWave large-scale IoTs, where active BS transmitted beamformer and passive RIS reflection vector are jointly optimized to maximize the minimum signal-to-interference-plus-noise-ratio (SINR) of all the information decoders (ID) and the minimum harvested power of all the energy receivers (ER) is maintained. The simulation result demonstrates the effectiveness of the proposed system. [ABSTRACT FROM AUTHOR]

Millimeter wave bands (30–300 GHz) are attracting a lot of research attention because they can possibly lead to data rates of nearly 10 Gbits/s, a lot of accessible bandwidth, narrow beam, good transmission quality, and excellent detection abilities compared to microwave frequencies which are restricted to 1 Gbits/s. This paper presents a comprehensive survey of the recent research developments on antenna designing specifically at 30, 60 and 120 GHz mmWave wireless communication bands along with their characteristics, applications, limitations, material selection, challenges, and proposed solutions. Several mmWave antennas published in the literature are covered in this study, including their type, characteristics, design challenges, and future research prospects. A comparison of various mmWave antennas published recently are analysed in terms of gain, bandwidth, efficiency, number of elements and type of antenna technology. At last, the design techniques such as Antenna-in-Package (AiP), Antenna-on-Chip (AoP) and various fabrication technologies are described including their merits as well as demerits. [ABSTRACT FROM AUTHOR]

Non-contact gesture recognition is a novel form of human–computer interaction. It has broad prospects in many applications, such as Augmented Reality/Virtual Reality, smart homes and intelligent medical systems. Therefore, it has become a research hotspot in recent years. This paper investigates a lightweight micro-motion gesture recognition method based on Multiple Input and Multiple Output millimeter wave radar. We employ TI's MMWCAS radar, comprising four cascaded AWR1243 radar boards, to collect gesture data. During the data pre-processing stage, we extract the Range-time Map, Doppler-time Map, Azimuth-time Map and Elevation-time Map of the dynamic gestures to characterize the dynamic motion features. These maps are then simplified into a one-dimensional vector to reduce data volume. We propose an 8HBi-GRU model, which combines the Bidirectional Gate Recurrent Unit (Bi-GRU) with a multi-head self-attention mechanism, to identify twelve types of micro-motion gestures using feature vectors. The model achieves an accuracy of 98.24 % , with precision and recall rates exceeding 0.97 and 0.98, respectively, for ten of the gesture types. Experimental results demonstrate that the proposed 8HBi-GRU model achieves lightweight gesture recognition rapidly and requires minimal storage space compared to image-based deep learning methods. [ABSTRACT FROM AUTHOR]

This study presents a parametric analysis of the steady-state temperature elevation in rat skin models due to millimeter wave exposure at frequencies from 6–100 GHz. The statistical data of the thickness of skin layers, namely epidermis, dermis, dermal white adipose tissue, and panniculus carnosus, were measured for the first time using the excised tissues of real male Sprague–Dawley rats. Based on the precise structure obtained from the histological analysis of rat skin, we solve the bioheat transfer equation to investigate the effects of changes in parameters, such as body parts and thermal constants, on the absorbed power density and temperature elevation of biological tissues. Owing to the notably thin dermal white adipose tissue layer, the surface temperature elevation in the rat head and dorsal skin at 6–100 GHz is 52.6–32.3% and 83.3–58.8% of the average values of different human skin models, respectively. Our results also reveal that the surface temperature elevation of rat skin may correlate with the tissue thickness and deep blood perfusion rates. [ABSTRACT FROM AUTHOR]