Search

With the rapid growth of data traffic and mobile devices, it is imperative to provide reliable and stable services during mobility. Heterogeneous Networks (HetNets) and dense networks have been identified as potential solutions to address the upcoming capacity crunch, but they also pose significant challenges related to handover optimization. This paper presents a comprehensive review of recent handover decision algorithms in HetNets, categorizing them based on their decision techniques and summarizing their input parameters, techniques, and performance evaluations. Our study highlights the technical challenges and opportunities related to handovers in HetNets and dense cellular networks and provides key findings from recent studies. The significance of this survey is to provide a comprehensive overview of handover decision algorithms in HetNets and dense cellular networks, which can aid in the development of more advanced handover optimization approaches.

Bibliometric analysis is a rigorous method to analyze significant quantities of bibliometric data to assess their impact on a particular field. This study used bibliometric analysis to investigate the academic research on diabetes detection and classification from 2000 to 2023. The PRISMA 2020 framework was followed to identify, filter, and select relevant papers. This study used the Web of Science database to determine relevant publications concerning diabetes detection and classification using the keywords "diabetes detection", "diabetes classification", and "diabetes detection and classification". A total of 863 publications were selected for analysis. The research applied two bibliometric techniques: performance analysis and science mapping. Various bibliometric parameters, including publication analysis, trend analysis, citation analysis, and networking analysis, were used to assess the performance of these articles. The analysis findings showed that India, China, and the United States are the top three countries with the highest number of publications and citations on diabetes detection and classification. The most frequently used keywords are machine learning, diabetic retinopathy, and deep learning. Additionally, the study identified "classification", "diagnosis", and "validation" as the prevailing topics for diabetes identification. This research contributes valuable insights into the academic landscape of diabetes detection and classification. [ABSTRACT FROM AUTHOR]

Sign language is undoubtedly a common way of communication among deaf and non-verbal people. But it is not common among hearing people to use sign language to express feelings or share information in everyday life. Therefore, a significant communication gap exists between deaf and hearing individuals, despite both groups experiencing similar emotions and sentiments. In this paper, we developed a convolutional neural network–squeeze excitation network to predict the sign language signs and developed a smartphone application to provide access to the ML model to use it. The SE block provides attention to the channel of the image, thus improving the performance of the model. On the other hand, the smartphone application brings the ML model close to people so that everyone can benefit from it. In addition, we used the Shapley additive explanation to interpret the black box nature of the ML model and understand the models working from within. Using our ML model, we achieved an accuracy of 99.86% on the KU-BdSL dataset. The SHAP analysis shows that the model primarily relies on hand-related visual cues to predict sign language signs, aligning with human communication patterns. [ABSTRACT FROM AUTHOR]

The traditional base station in C-RAN is divided into three parts: a pool of centralized baseband units (BBUs), a fronthaul network that links the BBUs and remote radio units (RRUs), and RRUs. This paper proposes a novel cooperative algorithm for resource optimization in a time-wavelength division multiplexed (TWDM) passive optical network (PON) incorporating a cloud radio access network (C-RAN). First, a joint collaborative strategy is deployed to optimize cooperative caching and transmission in the wireless and optical domains. Then, the quality of experience (QoE) is improved by bandwidth configuration and caching. Simulation results show that the average throughput of the proposed QoE-aware video cooperative caching and transmission mechanism (QACCTM) algorithm is approximately 30% higher than that of other algorithms. Compared with the relative average residual clutter power (RARCP) and quality-aware wireless edge caching (QAWEC) algorithms, the proposed QACCTM algorithm reduces the access delay by approximately 27.1% and 15.9%, respectively. [ABSTRACT FROM AUTHOR]

Everyone aspires to live a healthy life, but many will inevitably experience some form of disease, illness, or accident that results in disability at some point. Rehabilitation plays a crucial role in helping individuals recover from these disabilities and return to their daily activities. Traditional rehabilitation methods are often expensive, are inefficient, and lead to slow progress for patients. However, in this era of technology, various sensor-based automatic rehabilitation is also possible. A Kinect sensor is a skeletal tracking device that captures human motions and gestures. It can provide feedback to the users, allowing them to better understand their progress and adjust their movements accordingly. In this study, stroke-based rehabilitation is presented along with the Toronto Rehab Stroke Pose Dataset (TRSP). Pre-processing of the raw dataset was performed using various features, and several state-of-the-art classifiers were applied to evaluate the data provided by the Kinect sensor. Among the various classifiers, eXtreme Gradient Boosing (XGB) attained the maximum accuracy of 92% for the TRSP dataset. Furthermore, hyperparameters of the XGB have been optimized using a metaheuristic gray wolf optimizer for better performance. [ABSTRACT FROM AUTHOR]

This paper presents the deployment of a hybrid energy harvesting system that combines a wireless energy harvesting (EH) system and a 6 V, 170 mA monocrystalline solar energy derived from the Sun's rays. The hybrid energy harvesting (HEH) system comprises the rectifier, the solar cell panel, the charging circuit, and the EM4325 embedded RFID tag. This study aims to design an efficient EH system capable of increasing the read range of an active RFID tag. The proposed approach integrates a meandered line radio frequency identification (RFID) tag with an EM4325 IC chip as the receiver antenna. A halfwave doubler RF rectifier circuit is connected to the antenna using a 50 Ω SMA connector to convert the captured RF waves into usable electrical power. A solar energy charging module equipped with a Maximum Power Point Tracking (MPPT) system, a rechargeable lithium-ion battery, and a DC-DC converter is configured to manage and store the harvested energy efficiently. The UHF tag antenna operates at 919 MHz, achieving a peak gain of 3.54 dB. The proposed rectenna achieves a maximum measured harvested power conversion efficiency (PCE) of 55.14% for an input power (Pin) of 15 dBm at a distance of 5.10 cm, while the solar cell panel realizes 3.92 W of power. Experimental results demonstrate the hybrid harvester system's effectiveness, achieving a PCE of 86.49% at an output voltage (VDC) of 5.35 V. The main advantage of this approach is the creation of a compact hybrid RF and solar EH system by combining the solar cell panel with the antenna, thus enabling multi-functionality. [ABSTRACT FROM AUTHOR]

This paper develops a novel approach for reliable vehicle-to-vehicle (V2V) communication in various environments. A switched beam antenna is deployed at the transmitting and receiving points, with a beam management system that concentrates the power in each beam using a low-computation algorithm and a potential mathematical model. The algorithm is designed to be flexible for various environments faced by vehicles. Additionally, an anti-failure system is proposed in case the intelligent transportation system (ITS) system fails to retrieve real-time Packet Delivery Ratio (PDR) values related to traffic density. Performance metrics include the time to collision in seconds, the bit error rate (BER), the packet error rate (PER), the average throughput (Mbps), the beam selection probability, and computational complexity factors. The proposed system is compared with traditional systems. Extensive experiments, simulations, and comparisons show that the proposed approach is excellent and reliable for vehicular systems. The proposed study demonstrates an average throughput of 1.7 Mbps, surpassing conventional methods' typical throughput of 1.35 Mbps. Moreover, the bit error rate (BER) of the proposed study is reduced by a factor of 0.1. Additionally, the proposed framework achieves a beam power efficiency of touching to 100% at computational factor of 34. These metrics indicate that the proposed method is both efficient and sufficiently robust. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel switched beam antenna system model integrated with deep reinforcement learning (DRL) for 6G vehicle-to-vehicle (V2V) communications. The proposed system model aims to address the challenges of highly dynamic V2V environments, including rapid changes in channel conditions, interference, and Doppler effects. By leveraging the beam-switching capabilities of switched beam antennas and the intelligent decision making of DRL, the proposed approach enhances the performance of 6G V2V communications in terms of throughput, latency, reliability, and spectral efficiency. The proposed work develops a comprehensive mathematical model that accounts for 6G channel modeling, beam-switching, and beam-alignment errors. The Proposed DRL framework is designed to learn optimal beam-switching decisions in real time, adapting to the complex and varying V2V communication scenarios. The integration of the proposed antenna system and DRL model results in a robust solution that is capable of maintaining reliable communication links in a highly dynamic environment. To validate the proposed approach, extensive simulations were conducted and performance analysis using various performance metrics, such as throughput, latency, reliability, energy efficiency, resource utilization, and network scalability, was analyzed. Results demonstrate that the proposed system model significantly outperforms conventional V2V communication systems and other state-of-the-art techniques. Furthermore, the proposed approach shows that the beam-switching capabilities of the switched beam antenna system and the intelligent decision making of the DRL model are essential in addressing the challenges of 6G V2V communications. [ABSTRACT FROM AUTHOR]

This paper proposes the design of an efficient ambient solar energy harvesting (SEH) system with enhanced protection for low‐power devices. The proposed SEH system is designed and fabricated on a 1.6 mm Flame Retardant 4 (FR4) substrate using EasyEDA software. The harvester consists of a 3 W monocrystalline solar panel, a solar charger module with maximum power point tracking, a lithium‐ion rechargeable battery and a battery protection integrated circuit, and a DC–DC converter. Each of the SEH system component modules is optimized for better performance. The proposed energy harvester achieves a peak power conversion efficiency of 81.22% with a total output power of 2.35 W by using a CN3791 battery charger module. This approach is cost‐effective, highly sustainable, and virtually maintenance‐free. It can be deployed in various low‐powered devices such as wireless sensor network nodes and Internet of Things microcontrollers to extend their battery lifetimes, thereby achieving environmental‐friendly and sustainable energy harvesting. [ABSTRACT FROM AUTHOR]

Fifth generation (5G) is a recent wireless communication technology in mobile networks. The key parameters of 5G are enhanced coverage, ultra reliable low latency, high data rates, massive connectivity and better support to mobility. Enhanced coverage is one of the major issues in the 5G and beyond 5G networks, which will be affecting the overall system performance and end user experience. The increasing number of base stations may increase the coverage but it leads to interference between the cell edge users, which in turn impacts the coverage. Therefore, enhanced coverage is one of the future challenging issues in cellular networks. In this survey, coverage enhancement techniques are explored to improve the overall system performance, throughput, coverage capacity, spectral efficiency, outage probability, data rates, and latency. The main aim of this article is to highlight the recent developments and deployments made towards the enhanced network coverage and to discuss its future research challenges. [ABSTRACT FROM AUTHOR]

The RFEH design challenges can be broadly classified into overall radio frequency direct current (RF-to-DC) power conversion efficiency (PCE), form factor, operational bandwidth (BW), and compactness. A detailed overview of the essential components of an RFEH system is presented in this paper. Various design approaches have been proposed for the realization of compact RFEH circuits that contribute immensely to mm-wave rectenna design. Effective mechanisms for configuring the rectenna modules based on the recommended spectrums for the RFEH system were also outlined. This study featured a conceptual viewpoint on design tradeoffs, which were accompanied by profound EH solutions perspectives for wireless power communications. The work covers some challenges attributed to 5G EH in mm-wave rectenna: from a controlled source of communication signals to distributed ambient EH and system level design. Conversely, the primary targets of this work are to: (I) examine a wide range of ambient RF sources and their performance with various antennae and RF-rectifier layouts; (II) propose unique rectenna design techniques suitable for current trends in wireless technology; (III) explore numerous approaches for enhancing the rectenna or RF-rectifier efficiency in a low-power ambient environment; and (IV) present the findings of a comprehensive review of the exemplary research that has been investigated. These are aimed toward addressing the autonomous system's energy challenges. Therefore, with the careful management of the reported designs, the rectenna systems described in this study would influence the upcoming advancement of the low-power RFEH module. [ABSTRACT FROM AUTHOR]

This paper proposed the design of a dual-port rectifier with multifrequency operations. The RF rectifier is achieved using a combination of L-section inductive impedance matching network (IMN) at Port-1 with a multiple stubs impedance transformer at Port-2. The fabricated prototype can harvest RF signal from GSM/900, GSM/1800, UMTS/2100, Wi-Fi/2.45 and LTE/2600 frequency bands at (0.94, 1.80, 2.10, 2.46, and 2.63 GHz), respectively. The rectifier occupies a small portion of a PCB board at 0.20 μg × 0.15 λg. The proposed circuit realized a measured peak RF-to-dc (radio frequency direct current) power conversion efficiency (PCE) of (21%, 22.76%, 25.33%, 21.57%, and 22.14%) for an input power of -20 dBm. The RF harvester attains a measured peak RF-to-dc PCE of 72.70% and an output dc voltage of 154 mV for an input power of 3 dBm at 2.46 GHz. Measurement of the proposed rectifier in the ambiance gives a peak dc output voltage of 376.1 mV from the five signal tones. Similarly, a low-powered bq25504-674 evaluation module (EVM) is integrated with the rectifier. The module boost and drive the rectifier output dc voltage to 945 mV. The performance of the proposed rectifier in the ambiance environment makes it a suitablemodule for low-powered RF applications. [ABSTRACT FROM AUTHOR]

This communication presents a compact quarter-mode substrate integrated waveguide (QMSIW) cavity-backed self-diplexing tunable antenna. An open-ended slot is used to split the circular half-mode SIW (HMSIW) cavity resonator into two QMSIW cavity resonators. A varactor diode-loaded stub is added with each QMSIW resonator to achieve miniaturization and resonant frequency tuning. The miniaturization and tunability technique is demonstrated in a stand-alone QMSIW resonator and also in a QMSIW based self-diplexing antenna. The antenna is simulated, optimized, and subjected to practical testing inside a rectangular device. The device is treated as a quasi-receiver/transmitter, which consists of electronic circuitry and the proposed antenna. The resonant frequencies can be independently tuned by changing the values of the varactor diodes connected with each resonator. The simulated and measured results confirm that the proposed antenna can be tuned from 3.77 to 4.59 and from 4.96 to 6.1 GHz in the lower and higher frequency bands, respectively. The isolation between the two resonators in both bands is always better than 21 dB. The measured gains vary from 4.85 to 5.87 and 4.87 to 6.5 dBi in the lower and higher frequency bands, respectively. The proposed design shows stable and unidirectional radiation patterns in all tuning cases in both bands. The proposed self-diplexing tunable antenna is a competitive choice in compact and spectral-efficient radio frequency (RF) front ends where tuning is necessary for the efficient use of the frequency spectrum. [ABSTRACT FROM AUTHOR]

This brief proposes compact and planar substrate integrated waveguide (SIW)-based filters for single and triple band operations using two quarter-mode SIW (QMSIW) cavities. Two miniaturized QMSIW cavity resonators (QMSIWCRs) are capacitively coupled. Miniaturization in the QMSIWCR is achieved by adding an arc-shaped slot and a rectangular open-ended stub at the closed-end of the QMSIWCR. In the triple band bandpass filter (BPF), a capacitor is added to the open-ended side of the stub to enhance impedance matching at the higher modes. It has the centre frequencies of 2.1, 3.98 and 6.6 GHz with an insertion losses (ILs) of 0.93, 0.98, and 1.2 dB at the lower, middle and upper passband, respectively. Moreover, the measured fractional bandwidths (FBWs) are 16.97, 8.77, and 8.42% at the lower, middle and upper passband, respectively. Two rectangular slots are etched on the upper layer of the cavity to suppress the second mode and reduce coupling of the third mode; this realizes a single-band filter with an improved upper stopband response. It has the centre frequency of 2.1 GHz with a wide upper stop-band response, having a rejection level of 20 dB up to $3.19f_{c}$. The operation of filter is additionally discussed and verified by means of a lumped element equivalent circuit model and experimental results. The proposed filters are suitable for integration with other planar radio-frequency (RF) components due to their compact sizes, low ILs, planar structures, multiple transmission zeros (TZs) and adequate bandwidths. [ABSTRACT FROM AUTHOR]

A compact quarter-mode substrate integrated waveguide (QMSIW)-based self-quadruplexing antenna is proposed for compact radio frequency (RF) front ends. The QMSIW-based self-quadruplexing antenna has four unequal resonators resonating at the Industrial, Scientific, and Medical (ISM) band (2.45 GHz), fifth-generation (5G) band (3.5 GHz), wireless local area network (WLAN) band (4.9 GHz), and wireless fidelity band (5.4 GHz). All four resonators radiate through the open-ended wall of the QMSIW resonator and the arc-shaped slot inside the cavity. By properly optimizing the locations and dimensions of the resonators, higher isolation (> 29.9 dB) is gained. In fact, all four resonators operate on a common grounded substrate with negligible interference. A dummy rectangular device is used to keep the printed circuit board (PCB) and antenna in it to measure the S-parameters and radiation properties. The proposed antenna has a lower circuit size (0.23 λg2), reasonable gain (> 3.85 dBi), high efficiency (> 82.7 %), and high isolation (> 29.9 dB). Based on the above-mentioned attributes, it is a good candidate for compact RF front ends. [ABSTRACT FROM AUTHOR]

In this brief, a dual-mode dual-band filter based on half-mode substrate integrated waveguide (HMSIW) is presented. The proposed filter has the capability to tune the two pass-bands independently. The proposed filter consists of two HMSIW resonators coupled through a pair of ${E}$ -shaped coupling slots. Two resonating modes (TE101 and TE102) are excited in each resonator. A varactor diode is used in the proposed filter for tuning purpose. The varactor diode is placed in the structure in such a way that both bands can be tuned independently. The lower passband can be tuned from 3.26 to 3.47 GHz with insertion loss of 0.2–2.9 dB. The higher passband can be tuned from 5.47 to 6.13 GHz with low insertion loss of 0.1–2.1 dB. The presented results show the flexibility of the filter to achieve desired responses and its suitability for integration with any tunable planar structure. A good agreement between the simulated and measured results is observed. [ABSTRACT FROM AUTHOR]

Ultra-wideband is a wireless technology arisen for future high speed multimedia applications. It can provide data rate in excess of Gigabits per second by transmitting impulse signal through the free space. However, the ultra-wideband indoor channel models proposed by the IEEE P802.15.3a suffer long multipath propagation. Due to this multipath effect, several studies have been done to improve the bit-error-rate performance of the ultrawideband system in the existence of severe interference. Yet, most of the proposed algorithms were formulated based on the Gaussian distribution, which is not true in ultra-wideband. In this paper, we first analyze the statistical behavior of the CDMA-UWB signal by applying the Kullback-Leibler divergence index. Based on the analysis, a non-Gaussian equalizer is developed by deriving an enhanced bit-error-rate optimization algorithm using the Generalized Gaussian approach. The proposed equalizer has been shown to achieve a performance gain of at least 1.5dB to 2dB over the other equalizers simulated under IEEE P802.15.3a channel models. [ABSTRACT FROM AUTHOR]

A tunable multilayer diplexer using substrate integrated waveguide (SIW) technology is proposed in this letter. A multilayer design is chosen to easily control the electric and magnetic coupling through circular slots in order to achieve a wide-stopband response. The proposed diplexer works at two unique frequencies (centered at 10.5 and 13.5 GHz) with high isolation (>42dB) and a wide stopband (up to 21 GHz). A varactor diode is used in the proposed diplexer for tuning. The varactor diode is placed in the structure in such a way that both channels can be tuned independently without affecting one another. The results show the flexibility of the diplexer in achieving desired responses and its suitability for integration with any tunable component. Simulated and measured results obtained are in good agreement. [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a new high-gain wideband L-probe proximity-fed circular patch antenna using electrically thick substrate is proposed. By employing a dual-patch microstrip antenna excited by two L-probes, the bandwidths requirement for the ultrahigh frequency (UHF) and microwave radio frequency identification (RFID) application are met. The antennas integrated with slot-loading techniques are extensively studied. It is demonstrated that the proposed antenna achieves widebands of UHF and microwave for RFID application. A good agreement is obtained between the computed and measured results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1421-1424, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A single layer of equilateral triangular patch antenna is achieved, which operates at 870 MHz and 2.45 GHz suitable for UHF and microwave radio frequency identification application. By shaping the corners of triangular patch, the antenna excites the radiation modes of TM10 and TM21 and suppresses the unwanted TM20 mode to give boresight of directed radiation patterns. This also alters the excited surface distribution of the radiating patch to enhance the antenna gain. A good agreement is obtained between the simulated and experimental results. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:69-72, 2014 [ABSTRACT FROM AUTHOR]

A novel UHF printed loop antenna backed by a conducting loop reflector is proposed for near field RFID tag antenna application. The backed conducting loop reflector is adopted to achieve stronger magnetic field distribution along the loop tag antenna in order to work properly in proximity to the water and metallic object. The proposed antenna is constructed on FR4 substrate with the dimension of 30 mm × 30 mm × 3.2 mm. The simulated results exhibit constant current and uniform magnetic distribution to operate frequency at 915 MHz. The near field performance of the proposed antenna is practically verified by the read range measurement and compared with the commercially-available near field tag antenna to offer a promising solution of above-mentioned problems. [ABSTRACT FROM AUTHOR]

For low input radio frequency (RF) power from −35 to 5 dBm, a novel quad-band RF energy harvester (RFEH) with an improved impedance matching network (IMN) is proposed to overcome the poor conversion efficiency and limited RF power range of the ambient environment. In this research, an RF spectral survey was performed in the semi-urban region of Malaysia, and using these results, a multi-frequency highly sensitive RF energy harvester was designed to harvest energy from available frequency bands within the 0.8 GHz to 2.6 GHz frequency range. Firstly, a new IMN is implemented to improve the rectifying circuit's efficiency in ambient conditions. Secondly, a self-complementary log-periodic higher bandwidth antenna is proposed. Finally, the design and manufacture of the proposed RF harvester's prototype are carried out and tested to realize its output in the desired frequency bands. For an accumulative −15 dBm input RF power that is uniformly universal across the four radio frequency bands, the harvester's calculated dc rectification efficiency is about 35 percent and reaches 52 percent at −20 dBm. Measurement in an ambient RF setting shows that the proposed harvester is able to harvest dc energy at −20 dBm up to 0.678 V. [ABSTRACT FROM AUTHOR]

RF power is broadly available in both urban and semi-urban areas and thus exhibits as a promising candidate for ambient energy scavenging sources. In this research, a high-efficiency quad-band rectenna is designed for ambient RF wireless energy scavenging over the frequency range from 0.8 to 2.5 GHz. Firstly, the detailed characteristics (i.e., available frequency bands and associated power density levels) of the ambient RF power are studied and analyzed. The data (i.e., RF survey results) are then applied to aid the design of a new quad-band RF harvester. A newly designed impedance matching network (IMN) with an additional L-network in a third-branch of dual-port rectifier circuit is familiarized to increase the performance and RF-to-DC conversion efficiency of the harvester with comparatively very low input RF power density levels. A dual-polarized multi-frequency bow-tie antenna is designed, which has a wide bandwidth (BW) and is miniature in size. The dual cross planer structure internal triangular shape and co-axial feeding are used to decrease the size and enhance the antenna performance. Consequently, the suggested RF harvester is designed to cover all available frequency bands, including part of most mobile phone and wireless local area network (WLAN) bands in Malaysia, while the optimum resistance value for maximum dc rectification efficiency (up to 48%) is from 1 to 10 kΩ. The measurement result in the ambient environment (i.e., both indoor and outdoor) depicts that the new harvester is able to harvest dc voltage of 124.3 and 191.0 mV, respectively, which can be used for low power sensors and wireless applications. [ABSTRACT FROM AUTHOR]