Low-complexity Design Research Articles

Isolation Enhancement of a Two-Monopole MIMO Antenna Array with Various Parasitic Elements for Sub-6 GHz Applications.

In this paper, a high-isolation multiple-input/multiple-output (MIMO) microstrip monopole antenna array is investigated. To reduce the mutual coupling between antenna elements, a novel composite parasitic element constituted by a T-shaped ground branch and an isolated branch was designed and analyzed. The proposed composite parasitic element is capable of generating a unique three-dimensional weak electric field, which can effectively suppress the mutual coupling between the antenna elements. To give an intuitive illustration about the design principle and decoupling strategy of the proposed antenna, the antenna design procedure was ingeniously divided into four steps, and three types of decoupling structures during the antenna evolution were meticulously analyzed at both the theoretical and the physical level. To validate the proposed decoupling concept, the antenna prototype was fabricated, measured, and evaluated. The reflection coefficient, transmission coefficient, radiation pattern, and antenna gain were studied, and remarkable consistency between the measured and simulated results was observed. The simulations showed that the antenna has a peak gain of 3.5 dBi, a low envelope correlation coefficient (ECC < 0.001), and a high radiation efficiency (radiation efficiency > 0.9). Parameters of the proposed MIMO antenna including electrical dimension, highest isolation level, and 20 dB isolation bandwidth were evaluated. Compared with the previous similar designs, the proposed antenna exhibits attractive features including compressed dimension (0.55λ0 × 0.46λ0), extremely high isolation level (approximately 43 dB), fabulous 20 dB isolation bandwidth (3.11-3.78 GHz, 19.4%), a high diversity gain (DG > 9.99 dB), an appropriate mean effective gain (-3.5 dB < MEG < -3 dB), and low design complexity.

Hybrid direct ink write 3D printing of high-performance composite structures

PurposeDirect ink writing (DIW) is a robust additive manufacturing technology for the fabrication of fiber-reinforced thermoset composites. However, this technique is currently limited to low design complexity and minimal heights. This study aims to investigate the feasibility of UV-assisted DIW of composites to enhance the green-part strength of the printed inks and resolve the complexity and the height limitations of DIW technology.Design/methodology/approachThe experimental approach involved the preparation of the thermoset inks that are composed of nanoclay, epoxy, photopolymer and glass fiber reinforcement. Composite specimens were fabricated in complex geometries from these ink feedstocks using UV-assisted, hybrid 3D-printing technology. Fabricated specimens were characterized using optical microscopy, three-point bending mechanical tests and numerical simulations.FindingsThe introduced hybrid, UV-assisted 3D-printing technology allowed the fabrication of tall and overhanging thermoset composite structures up to 30% glass fiber reinforcement without sagging during or after printing. Glass fiber reinforcement tremendously enhanced the mechanical performance of the composites. UV-curable resin addition led to a reduction in strength (approximately 15%) compared to composites fabricated without UV resin. However, this reduction can be eliminated by increasing the glass fiber content within the hybrid thermoset composite. Numerical simulations indicate that the fiber orientation significantly affects the mechanical performance of the printed composites.Originality/valueThis study showed that the fabrication of high-performing thermoset composites in complex geometries was possible via hybrid DIW technology. This new technology will tremendously expand the application envelope of the additively manufactured thermoset composites and the fabrication of large composite structures with high mechanical performance and dimensional freedom will benefit various engineering fields including the fields of aerospace, automotive and marine engineering.

Deep-Learning Approach for Fusarium Head Blight Detection in Wheat Seeds Using Low-Cost Imaging Technology

Modern techniques that enable high-precision and rapid identification/elimination of wheat seeds infected by Fusarium head blight (FHB) can help to prevent human and animal health risks while improving agricultural sustainability. Robust pattern-recognition methods, such as deep learning, can achieve higher precision in detecting infected seeds using more accessible solutions, such as ordinary RGB cameras. This study used different deep-learning approaches based on RGB images, combining hyperparameter optimization, and fine-tuning strategies with different pretrained convolutional neural networks (convnets) to discriminate wheat seeds of the TBIO Toruk cultivar infected by FHB. The models achieved an accuracy of 97% using a low-complexity design architecture with hyperparameter optimization and 99% accuracy in detecting FHB in seeds. These findings suggest the potential of low-cost imaging technology and deep-learning models for the accurate classification of wheat seeds infected by FHB. However, FHB symptoms are genotype-dependent, and therefore the accuracy of the detection method may vary depending on phenotypic variations among wheat cultivars.

Relay-Assisted Uplink Transmission Design of URLLC Packets

With the emergence and development of mission-critical applications, the design of uplink URLLC transmission has become one of the issues of concern. In this article, we consider the ultrareliable uplink transmission design between multiple robots and a central controller in a smart factory with stringent delay requirements while multiple relays are deployed for cooperative transmission. Subject to the throughput and reliability requirements, a relay-assisted two-phase transmission protocol is proposed aiming at total transmit power minimization by jointly optimizing the decoding error probability, relay selection, resource block (RB) assignment, and transmit power allocation. To support the mission-critical applications in Internet of Things (IoT) with diverse throughput targets and make full use of RBs, we investigate the optimization problem under the single-RB allocation and multi-RB allocation schemes. The problems in these two cases have an analogous structure and can be solved with a unified framework. In the solution framework, we present the optimal design solved by the nonconvex penalty (NCP)- and quadratic penalty (QP)-based successive convex approximation (SCA) algorithms and the corresponding low-complexity design with near-optimal settings of decoding error probabilities. Numerical results demonstrate the effectiveness of the proposed penalty-based iterative algorithms and confirm that the near-optimal design only causes minor power performance loss compared to the optimal design. The power performance gap under these two allocation schemes and the impact of system parameters are revealed and analyzed.

A High-Performance Low Complex Design and Implementation of QRS Detector Using Modified MaMeMi Filter Optimized with Mayfly Optimization Algorithm

Electrocardiogram (ECG) is considered as the important diagnostic tests in medical field for detecting the cardiac anomalies. But, the ECG signals are polluted with numerous noise from power line intrusion, muscle noise, baseline wander, motion artifacts, low frequency noise signals, high frequency noise signals and T-wave, which automatically affects the QRS profile. The existing method provides the result in lesser accuracy with higher rate of error detection. To overcome these issues, QRS detector using modified maximum mean minimum (MoMaMeMi) filter optimized with mayfly optimization algorithm (QRS-MoMaMeMi-MOA) is proposed in this paper for less computational cost along with resource requirements. The proposed filter design consists of two phases for detecting QRS detector, such as filtering process associated to the enhancement and detection phase. Initially, the ECG data are taken from MIT/BIH arrhythmia dataset (MIT-AD). For eradicating the baseline wander in ECG data, MaMeMi filter is used. For expanding the performance of the modified MaMeMi filter, filter parameters, such as [Formula: see text] and [Formula: see text] are optimized by MOA to accomplish the best values and measure the performance of the whole QRS detector. For high frequency noise suppression in ECG data, the range function, noise subtractors, modified triangular detector are used. Then, heart beat detection can be done with the help of adaptive thresholding technique. The proposed filter design is carried out in MATLAB and implemented on field programmable gate arrays (FPGAs). The proposed QRS-MoMaMeMi-MOA filter design had 0.93%, 0.12% and 0.19% higher accuracy and 89.32%, 50% and 62% low detection error rate, compared to the existing filters, like Kalman filtering based adaptive threshold algorithm for QRS complex detection (QRS-KF-ATA), QRS detection of ECG signal utilizing hybrid derivative with MaMeMi filter by efficiently removing the baseline wander (QRS-HD-MaMeMi), and knowledge-based QRS detection operated by cascade of moving average filters (QRS-CAF). Then, the device utilization of the proposed FPGA implementation of the QRS-MoMaMeMi-MOA filter provides 95.556% and 71.428% lower power usage compared with the existing algorithms, like Kalman filtering based adaptive threshold algorithm for QRS complex detection in FPGA (FPGA-QRS-KF-ATA), and efficient architecture for QRS detection in FPGA utilizing integer Haar wavelet transform (FPGA-QRS-IHWT).

Genome Editing Approaches with CRISPR/Cas9 for Cancer Treatment: Critical Appraisal of Preclinical and Clinical Utility, Challenges, and Future Research.

The increasing burden on human malignant diseases became a major concern for healthcare practitioners, that must deal with tumor relapse and the inability to efficiently treat metastasis, in addition to side effects. Throughout the decades, many therapeutic strategies have been employed to improve the clinical outcomes of cancer patients and great efforts have been made to develop more efficient and targeted medicines. The malignant cell is characterized by genetic and epigenetic modifications, therefore targeting those specific drivers of carcinogenesis is highly desirable. Among the genome editing technologies, CRISPR/Cas9 stood as a promising candidate for cancer treatment alternatives, due to its low complexity design. First described as a defense mechanism of bacteria against invading foreign DNA, later it was shown that CRISPR components can be engineered to target specific DNA sequences in a test tube, a discovery that was awarded later with the Nobel Prize in chemistry for its rapid expansion as a reliable genome editing tool in many fields of research, including medicine. The present paper aims of describing CRISPR/Cas9 potential targets for malignant disorders, and the approaches used for achieving this goal. Aside from preclinical studies, we also present the clinical trials that use CRISPR-based technology for therapeutic purposes of cancer. Finally, a summary of the presented studies adds a more focused view of the therapeutic value CRISPR/Cas9 holds and the associated shortcomings.

A Low Complexity and High Modularity Design for Continuously Variable Bandwidth Digital Filters

ABSTRACT Digital filters with variable bandwidth can be used for a variety of applications. Arbitrary change in the bandwidth of a digital Finite Impulse Response (FIR) filter can be acquired using sampling rate converters. In this paper, a sampling rate converter is proposed which is generated from Pascal structure, a fractional delay filter having low hardware complexity and high modularity. The proposed sampling rate converter requires lesser number of multipliers for implementation when compared with the sampling rate converters in the literature. A low pass filter having a single bandwidth sandwiched between two sampling rate converters can contribute multiple bandwidths in such a way that each bandwidth is an arbitrary variation of the original bandwidth. A two stage Frequency response masking approach (FRM) is used for the hardware efficient design of the original low pass filter. A low complexity and high modularity novel design for a continuously varying bandwidth of a digital FIR filter is proposed in this paper using the proposed sampling rate converter. The modularity of the Pascal structure can be used to control both pass band ripple as well as stop band attenuation of the continuously variable bandwidth FIR filter design. Different communication standards in a Software defined radio (SDR) channelizer is realized using the proposed design of continuously variable bandwidth filter.

A Wideband 2-Bit Transmitarray Antenna for Millimeter-Wave Vehicular Communication

A wideband transmitarray antenna based on the magnetoelectric (ME) dipole element and 2-bit phase compensation scheme is presented for vehicular communications in this paper. A wideband 90° phase shifter is proposed and combined with the rotating method to achieve four discrete phase states. Thanks to the polarization-twisting technique and the simple structure of the phase shifter, the proposed element can be easily designed. For the transmitarray design, a multi-frequency phase compensation strategy is applied to guarantee stable performance over the operating band. To validate the design, a 12 × 12 transmitarray antenna simultaneously covering vehicle-to-satellite band (20 GHz), and 5G millimeter-wave (mmWave) bands (24 GHz/28 GHz) is designed, fabricated and measured. The experimental results show that the prototype can achieve high aperture efficiencies (>40%) within a wide bandwidth (34%). The measured peak aperture efficiency is up to 53% at 23 GHz. These results demonstrate that the proposed 2-bit transmitarray antenna enjoys the advantages of wide operating bandwidth, high aperture efficiency and comparatively low design complexity. With these characteristics, the proposed transmitarray antenna can be a promising candidate for vehicular communications that require reliable satellite links and 5G millimeter-wave connections simultaneously.

A Planar Bidirectional Circularly Polarized Antenna Using Orthogonal Magnetic Dipoles Without Extra Phase Shift Line

A planar bidirectional circularly polarized (CP) antenna using orthogonal magnetic dipoles (OMDs) without an extra phase shift line is proposed in this work. It consists of a rectangular microstrip magnetic dipole antenna (MMDA) and a loop radiator with two arms directly connected to the open edge of MMDA. The working principle is revealed by the equivalent sources model to provide a clear physical insight at first. The theoretical investigations imply that by controlling the width and the feed locations of the loop antenna on the aperture, the phase and magnitude for CP radiation can be realized in both endfire and backfire directions without introducing an additional phase shift line structure. For demonstration, one antenna prototype is designed and fabricated. The experimental results indicate that an overlapping bandwidth of 5.91% from 2.30 to 2.44 GHz is attained. Compared with the counterpart using OMDs, the proposed antenna exhibits a low design complexity and improved gains of 3.56/1.83 dBic in the endfire/backfire directions.

A Dynamic-Attention-Based Heuristic Fuzzy Expert System for the Tuning of Microwave Cavity Filters

The tuning of microwave cavity filters (MCFs) is mostly conducted by experienced operators, and thus, is time and resource intensive. The automatic tuning method has received lots of research attention. However, the experience of tuning experts is not described systematically, and the existing methods are not adequate for MCFs with individual differences. Considering that fuzzy expert systems are superior in flexibility and interpretability, a dynamic-attention-based heuristic fuzzy expert system is proposed in this article to achieve automatic tuning with high applicability, accuracy, and efficiency. First, the dynamic tuning process is divided into several stages, and the evaluation function of filtering performance is designed for each stage. Second, an improved expert system with dynamic attention is constructed to facilitate the comprehensive evaluation of filtering performance and to balance tuning efficiency and accuracy. Third, a heuristic fuzzy logic system is presented to obtain appropriate tuning values, with low design complexity of fuzzy rules and high utilization of tuning process information. Finally, the effectiveness, applicability, and practicality of the proposed method are demonstrated by both simulations and experiments.

A reconfigurable high-speed and low-complexity residue number system-based multiply-accumulate channel filter for software radio receivers

PurposeFilter design plays an essential role in most communication standards. The essential element of the software-defined radio is a channelizer that comprises several channel filters. Designing filters with lower complexity, minimized area and enhanced speed is a demanding task in currently prevailing communication standards. This study aims to propose an efficient reconfigurable residue number system (RNS)-based multiply-accumulate (MAC) channel filter for software radio receivers.Design/methodology/approachRNS-based pipelined MAC module for the realization of channel finite impulse response (FIR) filter architecture is considered in this work. Further, the use of a single adder and single multiplier for realizing the filter architecture regardless of the number of taps offers effective resource sharing. This design provides significant improvement in speed of operation as well as a reduction in area complexity.FindingsIn this paper, two major tasks have been considered: first, the RNS number conversion is performed in which the integer is converted into several residues. These residues are processed in parallel and are applied to the MAC-FIR filter architecture. Second, the MAC filter architecture involves pipelining, which enhances the speed of operation to a significant extent. Also, the time-sharing-based design incorporates a single partial product-based shift and add multiplier and single adder, which provide a low complex design. The results show that the proposed 16-tap RNS-based pipelined MAC sub-filter achieves significant improvement in speed as well as 89.87% area optimization when examined with the conventional RNS-based FIR filter structure.Originality/valueThe proposed MAC-FIR filter architecture provides good performance in terms of complexity and speed of operation because of the use of the RNS scheme with pipelining and partial product-based shift and adds multiplier and single adder when examining with the conventional designs. The reported architecture can be used in software radios.

Integrated Maximum Power Point Tracking System for Photovoltaic Energy Harvesting Applications

The integrated circuits employed for power management in photovoltaic (PV) energy harvesting applications are required to perform an efficient maximum power point tracking (MPPT) process for maximizing the power production of the PV source during the continuously changing atmospheric conditions. Among the alternative MPPT methods, the perturbation and observation (P&O) technique has the advantages of operational and implementation simplicity. In this article, a novel PV MPPT control system for on-chip implementation of the P&O MPPT method is presented, which, compared to the past-proposed on-chip MPPT systems, has the advantage that it is implemented based on purely digital CMOS circuits without requiring the use of complex circuits, such as multipliers, sample and hold units, or analog-to-digital converters. Therefore, it can be easily implemented on-chip with low design complexity while simultaneously retaining the high-performance features of the P&O MPPT technique. The proposed PV MPPT system has been fabricated using the XFAB XH018 0.18- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m CMOS technology. The experimental results verify the successful operation of the on-chip PV MPPT control unit and its ability to achieve a high MPPT efficiency over a wide range of operating solar irradiation values.

Design and Implementation of a Cost-Effective Object Tracking System Based on LoRa, Firebase, and Mapbox

This paper describes the design and implementation of an object tracking system based on LoRa, Firebase, andMapbox. The proposed system allows real-time visualization of the tracking nodes in a web interface following a low-cost and low-complexity design approach. The cost of each tracking node and the gateway were USD 39.38 and USD 28.00, respectively. Regarding its performance, the energy autonomy of each tracking node was 270.6 hours with maximum coverture of 896 meters under open field conditions, which is hard reduced to 114 meters under indoor conditions.

Low-Complexity Designs of Symbol-Level Precoding for MU-MISO Systems

Symbol-level precoding (SLP), which converts the harmful multi-user interference (MUI) into beneficial signals, can significantly improve symbol-error-rate (SER) performance in multi-user communication systems. While enjoying symbolic gain, however, the complicated non-linear symbol-by-symbol precoder design suffers high computational complexity exponential with the number of users, which is unaffordable in realistic systems. In this paper, we propose a novel low-complexity grouped SLP (G-SLP) approach and develop efficient design algorithms for typical max-min fairness and power minimization problems. In particular, after dividing all users into several groups, the precoders for each group are separately designed on a symbol-by-symbol basis by only utilizing the symbol information of the users in that group, in which the intra-group MUI is exploited using the concept of constructive interference (CI) and the inter-group MUI is also effectively suppressed. In order to further reduce the computational complexity, we utilize the Lagrangian dual, Karush-Kuhn-Tucker (KKT) conditions and the majorization-minimization (MM) method to transform the resulting problems into more tractable forms, and develop efficient algorithms for obtaining closed-form solutions to them. Extensive simulation results illustrate that the proposed G-SLP strategy and design algorithms dramatically reduce the computational complexity without causing significant performance loss compared with the traditional SLP schemes.

Event-Triggered Adaptive Fault-Tolerant Control for Unknown Nonlinear Systems With Applications to Linear Motor

This article presents an event-triggered adaptive asymptotic tracking control method based on the low-complexity design architecture to reduce the communication and computational resources of uncertain nonlinear systems with unknown control directions and actuator faults. By utilizing a systematic codesign of backstepping and an event-triggered mechanism, the proposed adaptive fault-tolerant control method exploits only error transformation variables associated with prescribed performance specifications, without the use of any compensators or approximation structures to handle unknown nonlinearities and actuator and component faults. This design provides a robust method, through which the controller can effectively address external disturbances, unknown system uncertainties, and actuator and component faults, while eliminating the explosion of complexity problem in backstepping. Asymptotic stability analysis of the closed-loop system is conducted, and the Zeno behavior is avoided. The effectiveness of the proposed approach is illustrated through applications to linear motor systems.

Frequency independent, remotely reconfigurable passive coherent perfect absorber using conventional inkjet-printing technology

This work presents a systematic theoretical analysis and experimental validation of a novel coherent absorber which is printed through conventional inkjet-printing technology. The new absorber consists of a single resistively loaded sheet printed on a conventional plastic sheet, resulting a low complexity and passive design. The low-cost and easily fabricated absorber is frequency independent, polarization insensitive, wide-angle and we demonstrate its absorbance reconfigurability using a remote illumination as a control signal. Theoretical, numerical and experimental results are in good agreement. Specifically, experimental results shown that near perfect absorption (i.e., 100%) can be achieved using a printed sheet of thickness lambda /215.

Decoupling Technique Using Ferrite-Film Loading for 5G MIMO Applications

Decreasing the mutual coupling between multiple-input-multiple-output (MIMO) antenna elements requires the selection of an appropriate decoupling technique without changing the geometry or operating frequency of the antenna. In this paper, a simple and flexible approach that involves loading a small ferrite film on the radiation patch of an MIMO antenna pair has been proposed to mitigate the unwanted mutual coupling. Through a thorough investigation, the two IFA elements with an element distance of only 1.4 mm can be decoupled adequately by properly controlling the ferrite-film loading area and the thickness of the ferrite film, along with maintaining the desired operating frequencies and acceptable radiation characteristics at the LTE Band 42 (3.4–3.6 GHz). The optimum ferrite-film loading on the grounding branch of the IFA element can increase the isolation from −6.64 dB to −10.43 dB and enhance the bandwidth from 3.20–3.88 GHz to 2.83–3.65 GHz, and its efficiency can reach to 45.5%, as well as a 2 dB gain. A physical model has also been established to interpret the operating mechanism of ferrite-film loading on the IFAs. The proposed simulated procedure is validated via measurements. This technique of ferrite loading on MIMO antennas can effectively decouple the mutual coupling at a low cost and with low design complexity, indicating its potential applicability for use in MIMO antennas in mobile handsets.

Architecture Optimization for Filtered Multicarrier Waveforms in 5G

Wireless communication network is the backbone of each and every organization of today modern globe. The rapid emergence of smart devices, smart homes, internet of things and clean energy become key sources in today society. In result the data traffic, emerging of new service and application are increased every year. Hence, there is a growing demand for 5G technology in all above mentioned fields. Therefore, better waveform types for 5G technology is needed, which has ability of high spectral efficiency, lower latency and less complexity. It is predicted that the data traffic will arise 1000 × in near future. In this work filtered orthogonal frequency division multiplexing (F-OFDM) and universal filtered orthogonal frequency division multiplexing (UF-OFDM) techniques are discussed to degrade key issues such as computational complexity, peak average power ratio (PAPR), lower spectral efficiency, and higher latency. The suggested work decreases the drawbacks faced by previous work like limited capacity and complexity. We also analyze algorithms and simplification for F-OFDM and UF-OFDM waveforms from an implementation perspective towards low complexity and efficient transceiver design. Moreover, F-OFDM and UF-OFDM are studied based on multicarrier modulation and enabled to reduce to out-of-band power leakage (OOBPL) of OFDM.

IRS-Aided SWIPT: Joint Waveform, Active and Passive Beamforming Design Under Nonlinear Harvester Model

The performance of Simultaneous Wireless Information and Power Transfer (SWIPT) is mainly constrained by the received Radio-Frequency (RF) signal strength. To tackle this problem, we introduce an Intelligent Reflecting Surface (IRS) to compensate the propagation loss and boost the transmission efficiency. This paper proposes a novel IRS-aided SWIPT system where a multi-carrier multi-antenna Access Point (AP) transmits information and power simultaneously, with the assist of an IRS, to a single-antenna User Equipment (UE) employing practical receiving schemes. Considering harvester nonlinearity, we characterize the achievable Rate-Energy (R-E) region through a joint optimization of waveform, active and passive beamforming based on the Channel State Information at the Transmitter (CSIT). This problem is solved by the Block Coordinate Descent (BCD) method, where we obtain the active precoder in closed form, the passive beamforming by the Successive Convex Approximation (SCA) approach, and the waveform amplitude by the Geometric Programming (GP) technique. To facilitate practical implementation, we also propose a low-complexity design based on closed-form adaptive waveform schemes. Simulation results demonstrate the proposed algorithms bring considerable R-E gains with robustness to CSIT inaccuracy and finite IRS states, and emphasize the importance of modeling harvester nonlinearity in the IRS-aided SWIPT design.

A non-uniform strip-array decoupling structure of the MIMO antenna-arrays for the DSRC application

ABSTRACT In this paper, a non-uniform strip-array decoupling structure (SADS) of the MIMO antenna-arrays for the dedicated short-range communication (DSRC) applications in intelligent transportation systems (ITS) is presented. The SADS is composed of metal strips with non-uniform longitudinal layout, which has a simple strip-array geometry, low design and fabrication complexity, and easy to be applied to the design domain without destroying the original antenna-array. The design of the strip thickness, strip-array layout and number of strips is realised by the proposed simple and effective optimisation method. The mutual coupling between the elements can be effectively suppressed to less than −32 dB by the proposed structure in the required bandwidth (5.795 GHz~5.815 GHz). The results show that, compared with the no-strip and uniform SADS, the non-uniform SADS can improve the maximum mutual coupling reduction by 23 dB and 13 dB, respectively. Both the simulated and measured results verify the effectiveness of the proposed SADS, which makes it very suitable for the large-scale MIMO antenna-arrays.