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Electronics, Volume 8, Issue 6 (June 2019)

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Cover Story (view full-size image) Owing to increased device connectivity in the 5G environment, simultaneous multidevice [...] Read more.
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Open AccessCorrection
Correction: He, X.; et al. Wireless Power Transfer System for Rotary Parts Telemetry of Gas Turbine Engine. Electronics 2018, 7(5), 58
Electronics 2019, 8(6), 721; https://doi.org/10.3390/electronics8060721
Received: 4 June 2019 / Accepted: 5 June 2019 / Published: 25 June 2019
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Abstract
The authors wish to make the following corrections to the published paper [...] Full article
Open AccessArticle
Novel Stochastic Computing for Energy-Efficient Image Processors
Electronics 2019, 8(6), 720; https://doi.org/10.3390/electronics8060720
Received: 21 May 2019 / Revised: 17 June 2019 / Accepted: 21 June 2019 / Published: 25 June 2019
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Abstract
Stochastic computing, which is based on probability, involves a trade-off between accuracy and power and is a promising solution for energy-efficiency in error-tolerance designs. In this paper, adder and multiplier circuits based on the proposed stochastic computing architecture are studied and analyzed. First, [...] Read more.
Stochastic computing, which is based on probability, involves a trade-off between accuracy and power and is a promising solution for energy-efficiency in error-tolerance designs. In this paper, adder and multiplier circuits based on the proposed stochastic computing architecture are studied and analyzed. First, we propose an efficient yet simple stochastic computation technique for multipliers and adders by exchanging the wires used for their operation. The results demonstrate that the proposed design reduces the relative error in computation compared with the conventional designs and has smaller area compared to conventional designs. Then, a new energy-efficient and high-performance stochastic adder with acceptable error metrics is investigated. The proposed multiplier shows better error metrics than other existing stochastic multipliers, and significantly improves area utilization and power consumption compared to the exact binary multiplier. Finally, we apply the proposed stochastic architecture to an edge detection algorithm and achieve a significant reduction in area utilization (64%) and power consumption (96%). It is therefore demonstrated that the proposed stochastic architecture is suitable for energy-efficient hardware designs. Full article
(This article belongs to the Special Issue Energy Efficient Circuit Design Techniques for Low Power Systems)
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Open AccessArticle
A Dual-Perforation Electromagnetic Bandgap Structure for Parallel-Plate Noise Suppression in Thin and Low-Cost Printed Circuit Boards
Electronics 2019, 8(6), 719; https://doi.org/10.3390/electronics8060719
Received: 27 May 2019 / Revised: 20 June 2019 / Accepted: 21 June 2019 / Published: 25 June 2019
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Abstract
In this study, we propose and analyze a dual-perforation (DP) technique to improve an electromagnetic bandgap (EBG) structure in thin and low-cost printed circuit boards (PCBs). The proposed DP–EBG structure includes a power plane with a square aperture and a patch with an [...] Read more.
In this study, we propose and analyze a dual-perforation (DP) technique to improve an electromagnetic bandgap (EBG) structure in thin and low-cost printed circuit boards (PCBs). The proposed DP–EBG structure includes a power plane with a square aperture and a patch with an L-shape slot that overcomes efficiently the problems resulting from the low-inductance and the characteristic impedance of the EBG structure developed for parallel-plate noise suppression in thin PCBs. The effects of the proposed dual-perforation technique on the stopband characteristics and unit cell size are analyzed using an analytical dispersion method and full-wave simulations. The closed-form expressions for the main design parameters of the proposed DP–EBG structure are extracted as a design guide. It is verified based on full-wave simulations and measurements that the DP technique is a cost-effective method that can be used to achieve a size reduction and a stopband extension of the EBG structure in thin PCBs. For the same unit cell size and low cut-off frequency, the DP–EBG structure increases the stopband bandwidth by up to 473% compared to an inductance-enhanced EBG structure. In addition, the unit cell size is substantially reduced by up to 94.2% compared to the metallo–dielectric EBG structure. The proposed DP–EBG technique achieves the wideband suppression of parallel plate noise and miniaturization of the EBG structure in thin and low-cost PCBs. Full article
(This article belongs to the Special Issue Electromagnetic Interference and Compatibility)
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Open AccessArticle
3D Spatial Characteristics of C-V2X Communication Interference
Electronics 2019, 8(6), 718; https://doi.org/10.3390/electronics8060718
Received: 11 May 2019 / Revised: 19 June 2019 / Accepted: 21 June 2019 / Published: 25 June 2019
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Abstract
In C-V2X (cellular vehicle-to-everything) communication networks, dense spatial reuse of the available radio spectrum is required to achieve efficient spectral usage. Spectrum reuse causes severe network interference where signals from many undesired transmitters are aggregated at a receiver. This paper investigates the 3D [...] Read more.
In C-V2X (cellular vehicle-to-everything) communication networks, dense spatial reuse of the available radio spectrum is required to achieve efficient spectral usage. Spectrum reuse causes severe network interference where signals from many undesired transmitters are aggregated at a receiver. This paper investigates the 3D spatial characteristics of C-V2X communication interference in the angular domain. A 3D GIDM (Gaussian interference distribution model) is proposed, and the corresponding interference APD (angular power density) is given. Then, the closed-form expressions of some key spatial statistics of interference are derived based on the interference APD. Finally, the closed-form expressions of the probability density function and spatial correlation function of SIR (signal–to–interference ratio) are derived based on the 3D multipath APD model and spatial statistics of the Rice channel. Simulation analysis shows that 3D spatial angular directions have significant effect on these spatial statistics of interference and the spatial correlation function of SIR. The results provide useful insight on the analysis and design of the interference-limited networks. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessFeature PaperReview
A Survey on RF and Microwave Doherty Power Amplifier for Mobile Handset Applications
Electronics 2019, 8(6), 717; https://doi.org/10.3390/electronics8060717
Received: 2 May 2019 / Revised: 17 June 2019 / Accepted: 19 June 2019 / Published: 25 June 2019
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Abstract
This survey addresses the cutting-edge load modulation microwave and radio frequency power amplifiers for next-generation wireless communication standards. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. Moreover, advance design [...] Read more.
This survey addresses the cutting-edge load modulation microwave and radio frequency power amplifiers for next-generation wireless communication standards. The basic operational principle of the Doherty amplifier and its defective behavior that has been originated by transistor characteristics will be presented. Moreover, advance design architectures for enhancing the Doherty power amplifier’s performance in terms of higher efficiency and wider bandwidth characteristics, as well as the compact design techniques of Doherty amplifier that meets the requirements of legacy 5G handset applications, will be discussed. Full article
(This article belongs to the Special Issue Recent Technical Developments in Energy-Efficient 5G Mobile Cells)
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Open AccessArticle
EPSim-C: A Parallel Epoch-Based Cycle-Accurate Microarchitecture Simulator Using Cloud Computing
Electronics 2019, 8(6), 716; https://doi.org/10.3390/electronics8060716
Received: 28 May 2019 / Revised: 14 June 2019 / Accepted: 19 June 2019 / Published: 24 June 2019
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Abstract
Recently, computing platforms have been being configured on a large scale to satisfy the diverse requirements of emerging applications like big data and graph processing, neural network, speech recognition and so on. In these computing platforms, each computing node consists of a multicore, [...] Read more.
Recently, computing platforms have been being configured on a large scale to satisfy the diverse requirements of emerging applications like big data and graph processing, neural network, speech recognition and so on. In these computing platforms, each computing node consists of a multicore, an accelerator, and a complex memory hierarchy, which are connected to other nodes using a variety of high-performance networks. Up to now, researchers have been using cycle-accurate simulators to evaluate the performance of computer systems in detail. However, the execution of the simulators, which models modern computing architecture for multi-core, multi-node, datacenter, memory hierarchy, new memory, and new interconnection, is too slow and infeasible; since the architecture has become more complex today, the complexity of the simulator is rapidly increasing. Therefore, it is seriously challenging to employ them in the research and development of next-generation computer systems. To solve this problem, we previously presented EPSim (Epoch-based Simulator), which defines epochs that can be run independently by dividing the simulation run into several sections and executes them in parallel on a multicore platform, resulting in only the limited simulation speedup. In this paper, to overcome the computing resource limitations on multi-core platforms, we propose a novel EPSim-C (EPSim on Cloud) simulator that extends EPSim and achieves higher performance using a cloud computing platform. EPSim-C is designed to perform the epoch-based executions in a massively parallel fashion by using MapReduce on Hadoop-based systems. According to our experiments, we have achieved a maximum speed of 87.0× and an average speed of 46.1× using 256 cores. As far as we know, EPSim-C is the only existing way to accelerate the cycle-accurate simulator on cloud platforms; thus, our significant performance enhancement allows researchers to model and research current and future cutting-edge computing platforms using real workloads. Full article
(This article belongs to the Special Issue Cloud Computing and Applications)
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Open AccessArticle
A Bidirectional Polling MAC Mechanism for IoT
Electronics 2019, 8(6), 715; https://doi.org/10.3390/electronics8060715
Received: 3 May 2019 / Revised: 19 June 2019 / Accepted: 20 June 2019 / Published: 24 June 2019
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Abstract
The Point Coordination Function (PCF)-based access control mechanism in IEEE 802.11 allows an access point to schedule stations in order to avoid hidden nodes and collisions. However, nearly all existing performance analysis models focus on the single-directional communication scenario, and these polling mechanisms [...] Read more.
The Point Coordination Function (PCF)-based access control mechanism in IEEE 802.11 allows an access point to schedule stations in order to avoid hidden nodes and collisions. However, nearly all existing performance analysis models focus on the single-directional communication scenario, and these polling mechanisms consume a significant amount of energy resources. This study proposes a hybrid service bidirectional polling access control mechanism for transmission between an AP and N stations. To improve energy efficiency, the downlink data queue is assigned after all the uplink station queues, which allows the uplink station to sleep after it completes the data transmission, and it can remain in the sleep state until the downlink begins to broadcast. Then, a classical two-queue asymmetrical polling model is employed to analyze the performance of the PCF-based bidirectional access control system, and a Markov chain and generating function are used to derive a closed-form expression of the mean access delay for the uplink and downlink data. Simulations confirm that the proposed MAC mechanism could provide a maximum energy consumption reduction to 70% for 80 stations with respect to the limited-1 service mechanism in IEEE 802.11a PCF and the two-level polling model. Our analytical results are highly accurate for both homogeneous and heterogeneous traffic. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessReview
Planar Textile Off-Body Communication Antennas: A Survey
Electronics 2019, 8(6), 714; https://doi.org/10.3390/electronics8060714
Received: 31 May 2019 / Revised: 18 June 2019 / Accepted: 20 June 2019 / Published: 24 June 2019
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Abstract
Fully textile smart wearables will be the result of the complete integration and miniaturization of electronics and textile materials. Off-body communications are key for connecting smart wearables with external devices, even for wireless power transfer or energy harvesting. They need to fulfill specific [...] Read more.
Fully textile smart wearables will be the result of the complete integration and miniaturization of electronics and textile materials. Off-body communications are key for connecting smart wearables with external devices, even for wireless power transfer or energy harvesting. They need to fulfill specific electromagnetic (EM) (impedance bandwidth (BW), gain, efficiency, and front to back radiation (FTBR)) and mechanical (bending, crumpling, compression, washing and ironing) requirements so that the smart wearable device provides the required performance. Therefore, textile and flexible antennas require a proper trade-off between materials, antenna topologies, construction techniques, and EM and mechanical performances. This review shows the latest research works for textile and flexible planar, fully grounded antennas for off-body communications, providing a novel design guide that relates key antenna performance parameters versus topologies, feeding techniques, conductive and dielectric textile materials, as well as the behavior under diverse measurement conditions. Full article
(This article belongs to the Special Issue Intelligent Antennas)
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Open AccessArticle
Miniature Compact Folded Dipole for Metal Mountable UHF RFID Tag Antenna
Electronics 2019, 8(6), 713; https://doi.org/10.3390/electronics8060713
Received: 10 May 2019 / Revised: 14 June 2019 / Accepted: 19 June 2019 / Published: 24 June 2019
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Abstract
This article describes the design of an Ultra-High Frequency (UHF) miniature folded dipole Radio Frequency Identification (RFID) tag antenna that can be mountable on metallic objects. The compact tag antenna is formed from symmetric C-shaped resonators connected with additional arms embedded into the [...] Read more.
This article describes the design of an Ultra-High Frequency (UHF) miniature folded dipole Radio Frequency Identification (RFID) tag antenna that can be mountable on metallic objects. The compact tag antenna is formed from symmetric C-shaped resonators connected with additional arms embedded into the outer strip lines for miniaturization purposes. It is loaded with outer strip lines, resulting in a flexible tuning method that is capable of matching the integrated circuit (IC) chip’s impedance. The proposed tag is fabricated on a single layer of Polytetrafluoroethylene (PTFE) substrate. It has simple structure and does not require any metallic vias or shorting plate. The miniature tag antenna with a size of 82.75 × 19.5 × 1.5   mm 3 yields a total realized gain of 0.53   dB at the resonance frequency when attached to a 40 × 40   cm 2 metal plate. The presented design utilizes a European RFID band, and the simulated results of realized gain, read range, and input impedance are verified with measurement results. Full article
(This article belongs to the Special Issue Advanced RFID Technology and Applications)
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Open AccessArticle
Torque Coordination Control of Hybrid Electric Vehicles Based on Hybrid Dynamical System Theory
Electronics 2019, 8(6), 712; https://doi.org/10.3390/electronics8060712
Received: 16 May 2019 / Revised: 15 June 2019 / Accepted: 19 June 2019 / Published: 23 June 2019
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Abstract
In order to reduce the vibration caused by mode switching of hybrid electric vehicles (HEVs) and achieve smooth mode switching, the hybrid input and output automation (HIOA) model of power control system of a parallel HEV is established based on the theory of [...] Read more.
In order to reduce the vibration caused by mode switching of hybrid electric vehicles (HEVs) and achieve smooth mode switching, the hybrid input and output automation (HIOA) model of power control system of a parallel HEV is established based on the theory of hybrid dynamical system (HDS). Taking the switching from electric drive mode to hybrid drive mode for example, the torque coordination control is considered, and the performance is compared with the method without the torque coordination by using a rule-based control strategy. The simulation results in AVL Cruise show that, on the premise of ensuring the fuel economy and the emission, the mode switching process becomes smoother with smaller torque fluctuation and better driving comfort by considering the torque coordination. Full article
(This article belongs to the Section Electrical and Autonomous Vehicles)
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Open AccessReview
A Survey of Algorithms and Systems for Evacuating People in Confined Spaces
Electronics 2019, 8(6), 711; https://doi.org/10.3390/electronics8060711
Received: 18 May 2019 / Revised: 10 June 2019 / Accepted: 19 June 2019 / Published: 23 June 2019
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Abstract
The frequency, destruction and costs of natural and human-made disasters in modern highly-populated societies have resulted in research on emergency evacuation and wayfinding, which has drawn considerable attention. The subject is now a multidisciplinary area of research where information and communication technologies (ICT), [...] Read more.
The frequency, destruction and costs of natural and human-made disasters in modern highly-populated societies have resulted in research on emergency evacuation and wayfinding, which has drawn considerable attention. The subject is now a multidisciplinary area of research where information and communication technologies (ICT), and in particular the Internet of Things (IoT), have a significant impact on sensing and computing dynamic reactions that mitigate or prevent the worst outcomes of disasters. This paper offers state-of-the-art knowledge in this area so as to share ongoing research results, identify the research gaps and address the need for future research. We present a comprehensive review of research on emergency evacuation and wayfinding, focusing on the algorithmic and system design aspects. Starting from the history of emergency management research, we identify the emerging challenges concerning system optimisation, evacuee behaviour optimisation and data analysis, and the additional energy consumption by ICT equipment that operates the emergency management infrastructure. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Validation of a SPICE Model for High Frequency Electroporation Systems
Electronics 2019, 8(6), 710; https://doi.org/10.3390/electronics8060710
Received: 29 May 2019 / Revised: 11 June 2019 / Accepted: 20 June 2019 / Published: 23 June 2019
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Abstract
In this paper, we present an analysis and a validation of a simulation program with integrated circuit emphasis (SPICE) model for a pulse forming circuit of a high frequency electroporation system, which can deliver square-wave sub-microsecond (100–900 ns) electric field pulses. The developed [...] Read more.
In this paper, we present an analysis and a validation of a simulation program with integrated circuit emphasis (SPICE) model for a pulse forming circuit of a high frequency electroporation system, which can deliver square-wave sub-microsecond (100–900 ns) electric field pulses. The developed SPICE model is suggested for use in evaluation of transient processes that occur due to high frequency operations in prototype systems. A controlled crowbar circuit was implemented to support a variety of biological loads and to ensure a constant electric pulse rise and fall time during electroporation to be independent of the applied buffer bioimpedance. The SPICE model was validated via a comparison of the simulation and experimental results obtained from the already existing prototype system. The SPICE model results were in good agreement with the experimental results, and the model complexity was found to be sufficient for analysis of transient processes. As result, the proposed SPICE model can be useful for evaluation and compensation of transient processes in sub-microsecond pulsed power set-ups during the development of new prototypes. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
Effect of Sensors Sensitivity on Lithium-Ion Battery Modeled Parameters and State of Charge: A Comparative Study
Electronics 2019, 8(6), 709; https://doi.org/10.3390/electronics8060709
Received: 27 May 2019 / Revised: 15 June 2019 / Accepted: 19 June 2019 / Published: 22 June 2019
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Abstract
The accurate estimation of the state of charge (SOC) is usually acknowledged as one of the essential features in designing of battery management system (BMS) for the lithium-ion batteries (LIBs) in electric vehicles (EVs). A suitable battery model is a prerequisite for correct [...] Read more.
The accurate estimation of the state of charge (SOC) is usually acknowledged as one of the essential features in designing of battery management system (BMS) for the lithium-ion batteries (LIBs) in electric vehicles (EVs). A suitable battery model is a prerequisite for correct SOC measurement. In this work, the first and second order RC autoregressive exogenous (ARX) battery models are adopted to check the influence of voltage and current transducer measurement uncertainty. The Lagrange multiplier method is used to estimate the battery parameters. The sensitivity analysis is performed under the following conditions: Current sensor precision of ±5 mA, ±50 mA, ±100 mA, and ±500 mA and voltage sensor precision of ±1 mV, ±2.5 mV, ±5 mV, and ±10mV. The comparative analysis of both models under the perturbed environment has been carried out. The effects of the sensor’s sensitivity on the different battery structures and complexity are also analyzed. Results shows that the voltage and current sensor sensitivity has a significant influence on SOC estimation. This research outcome assists the researcher in selecting the optimal value of sensor accuracy to accurately estimate the SOC of the LIB. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
PBR Clutter Suppression Algorithm Based on Dilation Morphology of Non-Uniform Grid
Electronics 2019, 8(6), 708; https://doi.org/10.3390/electronics8060708
Received: 15 May 2019 / Revised: 17 June 2019 / Accepted: 20 June 2019 / Published: 22 June 2019
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Abstract
Many new challenges are faced by the PBR (passive bi-static radar) employing non-cooperative radar illuminators. After the CFAR (constant false alarm) processor, the appearance of the amount of false alarm clutter points impacts the following tracing performance. To enhance the PBR tracing performance, [...] Read more.
Many new challenges are faced by the PBR (passive bi-static radar) employing non-cooperative radar illuminators. After the CFAR (constant false alarm) processor, the appearance of the amount of false alarm clutter points impacts the following tracing performance. To enhance the PBR tracing performance, we consider to reduce these clutter points before target tracing as soon as possible. In this paper, we propose a PBR clutter suppression algorithm based on dilation morphology of non-uniform grid. Firstly, we construct the non-uniform polar grid based on the acquisition geometry of PBR. Then, with the help of the grid platform, we separate the false alarm clutter points based on the dilation morphology. To efficiently operate the algorithm, we build up its parallel iteration scheme. To verify the performance of the proposed algorithm, we utilize both simulated data and field data to do the experiment. Experimental results show that the algorithm can effectively suppress most of the clutter points. Besides, we respectively combine the proposed suppression algorithm with two typical tracking algorithms to test the performance. Experimental results reveal that the compound tracing algorithm outperforms the traditional one. It can enhance the PBR tracing performance, reduce the occurrence probability of false tracks and meanwhile save time. Full article
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Open AccessArticle
Scenario-Based Emergency Material Scheduling Using V2X Communications
Electronics 2019, 8(6), 707; https://doi.org/10.3390/electronics8060707
Received: 11 May 2019 / Revised: 19 June 2019 / Accepted: 19 June 2019 / Published: 22 June 2019
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Abstract
Vehicle-to-everything (V2X) communications can be applied in emergency material scheduling due to their performance in collecting and transmitting disaster-related data in real time. The urgency of disaster depots can be judged based on the disaster area video, and the scenario coefficient can be [...] Read more.
Vehicle-to-everything (V2X) communications can be applied in emergency material scheduling due to their performance in collecting and transmitting disaster-related data in real time. The urgency of disaster depots can be judged based on the disaster area video, and the scenario coefficient can be evaluated for building a fairness model. This paper presents a scenario-based approach for emergency material scheduling (SEMS) using V2X communications. We propose a SEMS model, with the objectives of minimum time and maximum fairness in the cases of multiple supply depots, disaster depots, commodities and transport modes for logistics management of relief commodities. We design the SEMS algorithm based on the artificial fish-swarm algorithm to obtain an optimized solution. The results demonstrate that the SEMS model can enhance the fairness of relief scheduling, especially for disaster depots with small demands compared to the Gini and enhanced Theil fairness models. Moreover, the acquired vehicle speed via V2X communications updates the SEMS model in real time, which approaches a solution closer to reality. Full article
(This article belongs to the Special Issue Smart, Connected and Efficient Transportation Systems)
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Open AccessArticle
Remote-Controlled Fully Implantable Neural Stimulator for Freely Moving Small Animal
Electronics 2019, 8(6), 706; https://doi.org/10.3390/electronics8060706
Received: 11 May 2019 / Revised: 14 June 2019 / Accepted: 18 June 2019 / Published: 22 June 2019
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Abstract
The application of a neural stimulator to small animals is highly desired for the investigation of electrophysiological studies and development of neuroprosthetic devices. For this purpose, it is essential for the device to be implemented with the capabilities of full implantation and wireless [...] Read more.
The application of a neural stimulator to small animals is highly desired for the investigation of electrophysiological studies and development of neuroprosthetic devices. For this purpose, it is essential for the device to be implemented with the capabilities of full implantation and wireless control. Here, we present a fully implantable stimulator with remote controllability, compact size, and minimal power consumption. Our stimulator consists of modular units of (1) a surface-type cortical array for inducing directional change of a rat, (2) a depth-type array for providing rewards, and (3) a package for accommodating the stimulating electronics, a battery and ZigBee telemetry, all of which are assembled after independent fabrication and implantation using customized flat cables and connectors. All three modules were packaged using liquid crystal polymer (LCP) to avoid any chemical reaction after implantation. After bench-top evaluation of device functionality, the stimulator was implanted into rats to train the animals to turn to the left (or right) following a directional cue applied to the barrel cortex. Functionality of the device was also demonstrated in a three-dimensional (3D) maze structure, by guiding the rats to better navigate in the maze. The movement of the rat could be wirelessly controlled by a combination of artificial sensation evoked by the surface electrode array and reward stimulation. We could induce rats to turn left or right in free space and help their navigation through the maze. The polymeric packaging and modular design could encapsulate the devices with strict size limitations, which made it possible to fully implant the device into rats. Power consumption was minimized by a dual-mode power-saving scheme with duty cycling. The present study demonstrated feasibility of the proposed neural stimulator to be applied to neuroprosthesis research. Full article
(This article belongs to the Special Issue Smart Electrical Circuits and Systems for Neural Interface)
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Open AccessArticle
Control Method for Phase-Shift Full-Bridge Center-Tapped Converters Using a Hybrid Fuzzy Sliding Mode Controller
Electronics 2019, 8(6), 705; https://doi.org/10.3390/electronics8060705
Received: 15 May 2019 / Revised: 18 June 2019 / Accepted: 21 June 2019 / Published: 22 June 2019
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Abstract
This paper presents a control method for phase-shift full-bridge center-tapped (PSFB-CT) converters using hybrid fuzzy sliding mode controllers (SMCs). Conventionally, the output voltage of a PSFB-CT converter is controlled by using a proportional-integral (PI) controller. However, the dynamic characteristic of the converter is [...] Read more.
This paper presents a control method for phase-shift full-bridge center-tapped (PSFB-CT) converters using hybrid fuzzy sliding mode controllers (SMCs). Conventionally, the output voltage of a PSFB-CT converter is controlled by using a proportional-integral (PI) controller. However, the dynamic characteristic of the converter is undesirable, and the converter is not robust to disturbances. In order to overcome these disadvantages, the SMC based on PI control has been applied for the PSFB-CT converter. However, there is a chattering problem when the SMC gain is increased to improve the dynamic characteristic. In this paper, a control method for the PSFB-CT converter using fuzzy logic control is proposed. By varying the gain of the SMC through the fuzzy logic control, not only can the dynamic characteristic of the PSFB-CT converter be improved, but the chattering problem can also be relieved. The effectiveness of the proposed control method for the PSFB-CT converter was verified by the simulation and experimental results. Full article
(This article belongs to the Section Power Electronics)
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Open AccessArticle
Optimal Resource Allocation for a Single-Cell Multicast Transmission Scheme with a Supplementary Multicast Channel
Electronics 2019, 8(6), 704; https://doi.org/10.3390/electronics8060704
Received: 13 May 2019 / Revised: 12 June 2019 / Accepted: 19 June 2019 / Published: 22 June 2019
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Abstract
Multicast transmission is an attractive solution when a large number of users receive the same content in a wide area, for example, as with mobile TV. Ever since the multimedia broadcast multicast service (MBMS) was introduced in the 3rd Generation Partnership Project (3GPP), [...] Read more.
Multicast transmission is an attractive solution when a large number of users receive the same content in a wide area, for example, as with mobile TV. Ever since the multimedia broadcast multicast service (MBMS) was introduced in the 3rd Generation Partnership Project (3GPP), continuing work on the multicast transmission has been done and its importance is growing in the fifth generation (5G) cellular networks. The use cases of multicast transmission have been enlarged from mobile TV and public safety to vehicular-to-everything (V2X) and unmanned aerial vehicles (UAV). Recently, for group communications in public safety networks and for geographical information sharing in automotive, airborne and social networks, multicast transmission has been targeted at fewer users in a relatively small area, which has stimulated extensive research on the single-cell multicast transmission scheme. In the proposed single-cell multicast transmission scheme, a supplementary multicast channel is additionally assigned in a single-cell multicast transmission scheme to exploit channel diversity. The resource allocation is adaptive to the channel variations of the users (responsive to users QoS needs), using channel feedback from the users, in contrast with previous approaches where resources were determined conservatively. An optimal resource allocation problem to minimize the required bandwidth while enabling every user to obtain the target multicast rate is formulated as a convex problem and an iterative algorithm is proposed in a computationally efficient way. Performance is evaluated mathematically and through intensive simulations, where other cell interference is considered using a fluid model. The proposed single-cell multicast transmission scheme provides benefits in comparison to existing multicast schemes in the simulations, under a set of various parameters including the number of multicast users and channel correlation between the multicast channels. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Enhanced Intra Prediction Based on Adaptive Coding Order and Multiple Reference Sets in HEVC
Electronics 2019, 8(6), 703; https://doi.org/10.3390/electronics8060703
Received: 5 June 2019 / Revised: 16 June 2019 / Accepted: 20 June 2019 / Published: 22 June 2019
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Abstract
High Efficiency Video Coding (HEVC) is the most recent video coding standard. It can achieve a significantly higher coding performance than previous video coding standards, such as MPEG-2, MPEG-4, and H.264/AVC (Advanced Video Coding). In particular, to obtain high coding efficiency in intra [...] Read more.
High Efficiency Video Coding (HEVC) is the most recent video coding standard. It can achieve a significantly higher coding performance than previous video coding standards, such as MPEG-2, MPEG-4, and H.264/AVC (Advanced Video Coding). In particular, to obtain high coding efficiency in intra frames, HEVC investigates various directional spatial prediction modes and then selects the best prediction mode based on rate-distortion optimization. For further improvement of coding performance, this paper proposes an enhanced intra prediction method based on adaptive coding order and multiple reference sets. The adaptive coding order determines the best coding order for each block, and the multiple reference sets enable the block to be predicted from various reference samples. Experimental results demonstrate that the proposed method achieves better intra coding performance than the conventional method. Full article
(This article belongs to the Section Computer Science & Engineering)
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Open AccessArticle
A PWM Scheme for Five-Level H-Bridge T-Type Inverter with Switching Loss Reduction
Electronics 2019, 8(6), 702; https://doi.org/10.3390/electronics8060702
Received: 21 May 2019 / Revised: 7 June 2019 / Accepted: 17 June 2019 / Published: 21 June 2019
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Abstract
In this paper, a new pulse width modulation (PWM) scheme using an offset function to reduce switching loss in the five-level H-bridge T-type inverter (5L-HBT2I) is proposed. The proposed modulation technique is implemented with a third harmonic offset voltage function. A [...] Read more.
In this paper, a new pulse width modulation (PWM) scheme using an offset function to reduce switching loss in the five-level H-bridge T-type inverter (5L-HBT2I) is proposed. The proposed modulation technique is implemented with a third harmonic offset voltage function. A new control voltage, that is adding the offset voltage into the initial control, is shifted to the top or bottom position of the carrier, simultaneously—where the absolute value of its load current is high or medium in comparison to other phase load currents. Due to reducing the intersection between a control voltage and the carriers, the number of switch commutations of the inverter is reduced. As a result of reducing the number of commutation count with a high current at the non-switching position, the switching losses of the inverter are decreased. Analysis and comparison of switching losses on the two-level and three-level inverters, which are components of 5L-HBT2I are presented. The power loss analysis on the 5L-HBT2I is performed. The proposed technique implements the switching loss reduction strategy based on setting the operation of the two-level inverter in six-step mode. PSIM software is used to clarify the proposed technique. The simulation results show that the total switching losses of the proposed technique in 5L-HBT2I reduce in comparison to the conventional sine PWM technique. A prototype is built to validate the proposed scheme. Simulation and experimental results match the analysis. Full article
(This article belongs to the Special Issue Power Converters in Power Electronics)
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Open AccessArticle
One Shot Crowd Counting with Deep Scale Adaptive Neural Network
Electronics 2019, 8(6), 701; https://doi.org/10.3390/electronics8060701
Received: 16 May 2019 / Revised: 18 June 2019 / Accepted: 19 June 2019 / Published: 21 June 2019
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Abstract
This paper aims to utilize the deep learning architecture to break through the limitations of camera perspective, image background, uneven crowd density distribution and pedestrian occlusion to estimate crowd density accurately. In this paper, we proposed a new neural network called Deep Scale-Adaptive [...] Read more.
This paper aims to utilize the deep learning architecture to break through the limitations of camera perspective, image background, uneven crowd density distribution and pedestrian occlusion to estimate crowd density accurately. In this paper, we proposed a new neural network called Deep Scale-Adaptive Convolutional Neural Network (DSA-CNN), which can convert a single crowd image to density map for crowd counting directly. For a crowd image with any size and resolution, our algorithm can output the density map of the crowd image by end-to-end method and finally estimate the number of the crowd in the image. The proposed DSA-CNN consists of two parts: the seven layers CNN network structure and DSA modules. In order to ensure the proposed method is robust to camera perspective effect, DSA-CNN has adopted different sizes of filters in the network and combines them ingeniously. In order to reduce the depth of the data to increase the speed of training, the proposed method utilized 1 × 1 filter in DSA module. To validate the effectiveness of the proposed model, we conducted comparative experiments on four popular public datasets (ShanghiTech dataset, UCF_CC_50 dataset, WorldExpo’10 dataset and UCSD dataset). We compare the proposed method with other well-known algorithms on the MAE and MSE indicators, such as MCNN, Switching-CNN, CSRNet, CP-CNN and Cascaded-MTL. Experimental results show that the proposed method has excellent performance. In addition, we found that the proposed model is easily trained, which further increases the usability of the proposed model. Full article
(This article belongs to the Section Artificial Intelligence)
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Open AccessArticle
Application for GPON Frame Analysis
Electronics 2019, 8(6), 700; https://doi.org/10.3390/electronics8060700
Received: 20 April 2019 / Revised: 13 June 2019 / Accepted: 17 June 2019 / Published: 21 June 2019
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Abstract
This article presents a design of a database model used to gather and analyze data frames transmitted over gigabit passive optical network (GPON) in the downstream direction. An issue with this kind of system is the difficulty in analyzing a transmission on the [...] Read more.
This article presents a design of a database model used to gather and analyze data frames transmitted over gigabit passive optical network (GPON) in the downstream direction. An issue with this kind of system is the difficulty in analyzing a transmission on the optical part which is caused by the difference among devices using Ethernet frames technology and passive optical network technology with usage gigabit encapsulation method. In this article, a principle of the downstream direction is described. Next, the design of the database model for the analysis of transmitted data is discussed. Based on the design and implementation of the database, a script capable of processing data gathered by a programmable network card is proposed. The script for physical layer operation, admission, and maintenance (PLOAM) messages analysis is written in the Python programming language. Full article
(This article belongs to the Special Issue Optical Communications and Networks)
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Open AccessArticle
Eco-Friendly Materials for Daily-Life Inexpensive Printed Passive Devices: Towards “Do-It-Yourself” Electronics
Electronics 2019, 8(6), 699; https://doi.org/10.3390/electronics8060699
Received: 29 May 2019 / Revised: 13 June 2019 / Accepted: 18 June 2019 / Published: 21 June 2019
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Abstract
The need for the fabrication of a new generation of devices has developed with the next generation of ‘home’ engineers, which is resulting in an ever-increasing population interested in “do-it-yourself” electronics and the Internet of Things. However, this new trend should not be [...] Read more.
The need for the fabrication of a new generation of devices has developed with the next generation of ‘home’ engineers, which is resulting in an ever-increasing population interested in “do-it-yourself” electronics and the Internet of Things. However, this new trend should not be done at the expense of the environment. Almost all previous studies, related to the low-temperature processing of devices, fail to highlight the extent of the impact that the synthesis of these technologies have on both the environment and human health. In addition, the substrates typically used, are also often associated with major drawbacks such as a lack of biodegradability. In this paper, we fabricate a simple RC filter using various domestically available printing techniques, utilising readily available materials such as: carbon soots (carbon black) as an electric conductor, and egg white (albumen) as a dielectric. These devices have been fabricated on both polyethylene terephthalate (PET) and paper, which demonstrated the same performances on both substrates and revealed that recyclable substrates can be used without compromise to the devices’ performance. The filter was found to exhibit a cut-off frequency of 170 kHz, which made it suitable for high-frequency reception applications. Full article
(This article belongs to the collection Printed and Flexible Electronics)
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Open AccessFeature PaperArticle
Light Exposure Effects on the DC Kink of AlGaN/GaN HEMTs
Electronics 2019, 8(6), 698; https://doi.org/10.3390/electronics8060698
Received: 14 May 2019 / Revised: 14 June 2019 / Accepted: 19 June 2019 / Published: 21 June 2019
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Abstract
This paper presents the effects of optical radiation on the behavior of two scaled-gate aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs). The tested devices, having a gate width of 100 and 200 µm and a gate length of 0.25 µm, [...] Read more.
This paper presents the effects of optical radiation on the behavior of two scaled-gate aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs). The tested devices, having a gate width of 100 and 200 µm and a gate length of 0.25 µm, were exposed to a laser beam with a wavelength of 404 nm (blue-ray) in order to investigate the main optical effects on the DC characteristics. Owing to the threshold shift and the charge generation, a marked increase of the gate and drain current was noticed. The occurrence of the kink effect in the absence of light exposure was identified, and a hypothesis about its origin is provided. The obtained results agree with the analysis previously carried out on gallium arsenide (GaAs)-based devices. Full article
(This article belongs to the Section Microwave and Wireless Communications)
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Open AccessArticle
Wearable Travel Aid for Environment Perception and Navigation of Visually Impaired People
Electronics 2019, 8(6), 697; https://doi.org/10.3390/electronics8060697
Received: 31 May 2019 / Revised: 18 June 2019 / Accepted: 19 June 2019 / Published: 20 June 2019
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Abstract
Assistive devices for visually impaired people (VIP) which support daily traveling and improve social inclusion are developing fast. Most of them try to solve the problem of navigation or obstacle avoidance, and other works focus on helping VIP to recognize their surrounding objects. [...] Read more.
Assistive devices for visually impaired people (VIP) which support daily traveling and improve social inclusion are developing fast. Most of them try to solve the problem of navigation or obstacle avoidance, and other works focus on helping VIP to recognize their surrounding objects. However, very few of them couple both capabilities (i.e., navigation and recognition). Aiming at the above needs, this paper presents a wearable assistive device that allows VIP to (i) navigate safely and quickly in unfamiliar environment, and (ii) to recognize the objects in both indoor and outdoor environments. The device consists of a consumer Red, Green, Blue and Depth (RGB-D) camera and an Inertial Measurement Unit (IMU), which are mounted on a pair of eyeglasses, and a smartphone. The device leverages the ground height continuity among adjacent image frames to segment the ground accurately and rapidly, and then search the moving direction according to the ground. A lightweight Convolutional Neural Network (CNN)-based object recognition system is developed and deployed on the smartphone to increase the perception ability of VIP and promote the navigation system. It can provide the semantic information of surroundings, such as the categories, locations, and orientations of objects. Human–machine interaction is performed through audio module (a beeping sound for obstacle alert, speech recognition for understanding the user commands, and speech synthesis for expressing semantic information of surroundings). We evaluated the performance of the proposed system through many experiments conducted in both indoor and outdoor scenarios, demonstrating the efficiency and safety of the proposed assistive system. Full article
(This article belongs to the Special Issue Wearable Electronic Devices)
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Open AccessArticle
Accurately Modeling of Zero Biased Schottky-Diodes at Millimeter-Wave Frequencies
Electronics 2019, 8(6), 696; https://doi.org/10.3390/electronics8060696
Received: 14 May 2019 / Revised: 13 June 2019 / Accepted: 17 June 2019 / Published: 20 June 2019
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Abstract
This paper presents and discusses the careful modeling of a Zero Biased Diode, including low-frequency noise sources, providing a global model compatible with both wire bonding and flip-chip attachment techniques. The model is intended to cover from DC up to W-band behavior, and [...] Read more.
This paper presents and discusses the careful modeling of a Zero Biased Diode, including low-frequency noise sources, providing a global model compatible with both wire bonding and flip-chip attachment techniques. The model is intended to cover from DC up to W-band behavior, and is based on DC, capacitance versus voltage, as well as scattering and power sweep harmonics measurements. Intensive use of 3D EM (ElectroMagnetic) simulation tools, such as HFSSTM, was done to support Zero Biased Diode parasitics modeling and microstrip board modeling. Measurements are compared with simulations and discussed. The models will provide useful support for detector designs in the W-band. Full article
(This article belongs to the Special Issue Terahertz Technology and Its Applications)
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Open AccessArticle
PEP Analysis of AF Relay NOMA Systems Employing Order Statistics of Cascaded Channels
Electronics 2019, 8(6), 695; https://doi.org/10.3390/electronics8060695
Received: 7 May 2019 / Revised: 6 June 2019 / Accepted: 17 June 2019 / Published: 20 June 2019
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Abstract
The precise error performance analysis is challenging for non-orthogonal multiple access (NOMA) systems due to nonlinear successive interference cancellation (SIC) processing among NOMA users. In this paper, the pairwise error probability (PEP) performance of different users is investigated for relay NOMA simultaneous wireless [...] Read more.
The precise error performance analysis is challenging for non-orthogonal multiple access (NOMA) systems due to nonlinear successive interference cancellation (SIC) processing among NOMA users. In this paper, the pairwise error probability (PEP) performance of different users is investigated for relay NOMA simultaneous wireless information and power transfer (SWIPT) systems. By employing the order statistics theory, we obtain the ordered probability density function of the cascaded channel through Source-to-Relay-to-User links. Then we derive the analytical closed-form PEP expressions for NOMA users. To obtain the approximate closed-form PEP, we explore the finite series representation of the power of the modified Bessel function to replace the integrand terms. Monte Carlo simulation results show that the approximate analytical PEP of each user is basically in agreement with the simulated PEP. Furthermore, on the basis of the closed-form PEP, the influence of relevant system parameters on the error performance is examined via numerical simulations, which manifests that the choice of power allocation coefficients should be balanced between the users’ channel conditions and the demanded quality of service. Full article
(This article belongs to the Special Issue Cooperative Communications for Future Wireless Systems)
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Open AccessArticle
Construction of Residue Number System Using Hardware Efficient Diagonal Function
Electronics 2019, 8(6), 694; https://doi.org/10.3390/electronics8060694
Received: 8 March 2019 / Revised: 12 June 2019 / Accepted: 18 June 2019 / Published: 20 June 2019
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Abstract
The residue number system (RNS) is a non-positional number system that allows one to perform addition and multiplication operations fast and in parallel. However, because the RNS is a non-positional number system, magnitude comparison of numbers in RNS form is impossible, so a [...] Read more.
The residue number system (RNS) is a non-positional number system that allows one to perform addition and multiplication operations fast and in parallel. However, because the RNS is a non-positional number system, magnitude comparison of numbers in RNS form is impossible, so a division operation and an operation of reverse conversion into a positional form containing magnitude comparison operations are impossible too. Therefore, RNS has disadvantages in that some operations in RNS, such as reverse conversion into positional form, magnitude comparison, and division of numbers are problematic. One of the approaches to solve this problem is using the diagonal function (DF). In this paper, we propose a method of RNS construction with a convenient form of DF, which leads to the calculations modulo 2 n , 2 n 1 or 2 n + 1 and allows us to design efficient hardware implementations. We constructed a hardware simulation of magnitude comparison and reverse conversion into a positional form using RNS with different moduli sets constructed by our proposed method, and used different approaches to perform magnitude comparison and reverse conversion: DF, Chinese remainder theorem (CRT) and CRT with fractional values (CRTf). Hardware modeling was performed on Xilinx Artix 7 xc7a200tfbg484-2 in Vivado 2016.3 and the strategy of synthesis was highly area optimized. The hardware simulation of magnitude comparison shows that, for three moduli, the proposed method allows us to reduce hardware resources by 5.98–49.72% in comparison with known methods. For the four moduli, the proposed method reduces delay by 4.92–21.95% and hardware costs by twice as much by comparison to known methods. A comparison of simulation results from the proposed moduli sets and balanced moduli sets shows that the use of these proposed moduli sets allows up to twice the reduction in circuit delay, although, in several cases, it requires more hardware resources than balanced moduli sets. Full article
(This article belongs to the Section Circuit and Signal Processing)
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Open AccessArticle
Multiple-Symbol Non-Coherent Detection for Differential QAM Modulation in Uplink Massive MIMO Systems
Electronics 2019, 8(6), 693; https://doi.org/10.3390/electronics8060693
Received: 21 May 2019 / Revised: 17 June 2019 / Accepted: 17 June 2019 / Published: 20 June 2019
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Abstract
In this paper, we propose a novel multiple-symbol detector based on maximum likelihood metric for differential quadrature amplitude modulation in massive multiple-input multiple-output (MIMO) systems. While current research on differential modulation in massive MIMO has focused on two consecutive symbols, our proposed detector [...] Read more.
In this paper, we propose a novel multiple-symbol detector based on maximum likelihood metric for differential quadrature amplitude modulation in massive multiple-input multiple-output (MIMO) systems. While current research on differential modulation in massive MIMO has focused on two consecutive symbols, our proposed detector is based on multiple-symbol, which is larger than or equal to two. Moreover, we derive new distance based on the proposed detector. To encode and decode data, we apply existing look-up table algorithm using the proposed distance, which is known as optimum encoding algorithm for differential modulation. Simulation results show the improvement based on the bit-error-rate performance since the proposed detector and distance vary according to the channel statistic information. Full article
(This article belongs to the Special Issue Massive MIMO Systems)
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Open AccessArticle
Urban Crowd Detection Using SOM, DBSCAN and LBSN Data Entropy: A Twitter Experiment in New York and Madrid
Electronics 2019, 8(6), 692; https://doi.org/10.3390/electronics8060692
Received: 26 April 2019 / Revised: 26 May 2019 / Accepted: 31 May 2019 / Published: 20 June 2019
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Abstract
The surfer and the physical location are two important concepts associated with each other in the social network-based localization service. This work consists of studying urban behavior based on location-based social networks (LBSN) data; we focus especially on the detection of abnormal events. [...] Read more.
The surfer and the physical location are two important concepts associated with each other in the social network-based localization service. This work consists of studying urban behavior based on location-based social networks (LBSN) data; we focus especially on the detection of abnormal events. The proposed crowd detection system uses the geolocated social network provided by the Twitter application programming interface (API) to automatically detect the abnormal events. The methodology we propose consists of using an unsupervised competitive learning algorithm (self-organizing map (SOM)) and a density-based clustering method (density-based spatial clustering of applications with noise (DBCSAN)) to identify and detect crowds. The second stage is to build the entropy model to determine whether the detected crowds fit into the daily pattern with reference to a spatio-temporal entropy model, or whether they should be considered as evidence that something unusual occurs in the city because of their number, size, location and time of day. To detect an abnormal event in the city, it is sufficient to determine the real entropy model and to compare it with the reference model. For the normal day, the reference model is constructed offline for each time interval. The obtained results confirm the effectiveness of our method used in the first stage (SOM and DBSCAN stage) to detect and identify clusters dynamically, and imitating human activity. These findings also clearly confirm the detection of special days in New York City (NYC), which proves the performance of our proposed model. Full article
(This article belongs to the Section Networks)
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