Usage Of Bands Research Articles

Design of novel microstrip patch antenna for millimeter-wave B5G communications

Introduction: The simplicity of integration and co-type features of microstrip antennas make them intriguing for a broad variety of applications, particularly with the growing usage of mmWave bands in wireless communications and the constant rise in data transfer in communication situations.Method: This paper proposes a novel design of micrstrip patch antenna for mmWave B5G communication. The main idea is to realize four-mode antenna the operates in four different frequencies. The geometry is rectangular patch whose resonance frequency is adjusted by varying the walls and pins of the structure.Results: Simulation results show that the proposed antenna design has improved fractional bandwidth and performance as compared with existing antennas.Discussion: The observed curve indicates that, in agreement with the modeling findings, there are four resonance spots in the operational frequency region of 2.5–3.4 GHz: 2.68 GHz, 2.9 GHz, 3.05 GHz, and 3.3 GHz, which correspond to TM1/2,0, TM3/2,0, and TMRS, respectively, and TM1/2,2 four resonant modes, within the frequency range, the observed antenna gain peak is around 9 dBi, which is consistent with the measured results.

A method based on improved ant colony algorithm feature selection combined with GWO-SVR model for predicting chlorophyll-a concentration in Wuliangsu Lake.

Chlorophyll-a (Chl-a) is an important parameter in water bodies. Due to the complexity of optics in water bodies, it is difficult to accurately predict Chl-a concentrations in water bodies by current traditional methods. In this paper, using Sentinel-2 remote sensing images as the data source combined with measured data, taking Wuliangsu Lake as the study area, a new intelligent algorithm is proposed for prediction of Chl-a concentration, which uses the adaptive ant colony exhaustive optimization algorithm (A-ACEO) for feature selection and the gray wolf optimization algorithm (GWO) to optimize support vector regression (SVR) to achieve Chl-a concentration prediction. The ant colony optimization algorithm is improved to select remote sensing feature bands for Chl-a concentration by introducing relevant optimization strategies. The GWO-SVR model is built by optimizing SVR using GWO with the selected feature bands as input and comparing it with the traditional SVR model. The results show that the usage of feature bands selected by the presented A-ACEO algorithm as inputs can effectively reduce complexity and improve the prediction performance of the model, under the condition of the same model, which can provide valuable references for monitoring the Chl-a concentration in Wuliangsu Lake.

Global and direct solar irradiance estimation using deep learning and selected spectral satellite images

To fully exploit the spectral information of modern geostationary satellites, this work proposes a deep learning framework using convolutional neural networks (CNNs) and attention mechanism for 5-min ground-level global horizontal irradiance (GHI) and direct normal irradiance (DNI) estimations. The inputs are spectral satellite images with the target ground station in the center, and the labels are irradiance measurements normalized by their clear-sky estimations. The use of CNNs and attention mechanism aims to better extract the spatial information for estimating ground-level solar irradiance. To improve the modeling efficiency, only a subset of spectral bands is selected based on correlation analysis, which has comparable performance with the usage of all satellite bands. The results show that the proposed method produces GHI estimation with a normalized root mean squared error (nRMSE) of 20.57% and a normalized mean bias error (nMBE) of −2.04%, and the DNI estimation has an nRMSE of 23.63% and the nMBE is 0.36%. Compared with the national solar radiation database (NSRDB), GHI and DNI estimations of the proposed method has the nRMSE reduction of 5.15% and 13.77%, respectively. Meanwhile, the proposed models generally yield better GHI and DNI estimations under different intervals of clear-sky index than NSRDB. The combination of deep learning and remote sensing shows potential in better extracting the cloud information via multispectral satellite images, which can better support solar resource assessment, especially for cloudy conditions.

African Religio-Cultural Heritage of ‘Charms and Amulets’

Abstract This article investigates the increase in the usage of ‘symbolic ritual wrist bands’ as symbols of power, protection, and healing in neo-Pentecostals seen as resonating with the religio-cultural practice of ritual bands in African primal religions. The study demonstrates that such practices indirectly satisfy the deep yearning of traditional communities who maintain a strong feeling of the versatility of symbolic ritual bands. The fact that most Africans remain deeply ingrained in their religio-cultural environment where it is believed that ritual bands attended to their spiritual and physical needs, the usage of symbolic wrist bands in most neo-Pentecostal churches is seen as bridging the gap created by missionary Christianity. This study employs the missio-cultural theory to explore the extent to which neo-Pentecostals are reconceptualising the idea of ritual wrist bands in the practice of African Christianity. It concludes that the neo-Pentecostal proliferation of wrist bands is relevant in the spiritual, psychological, social, cultural and theological missionising effort in Africa.

Estimating Plant Nitrogen by Developing an Accurate Correlation between VNIR-Only Vegetation Indexes and the Normalized Difference Nitrogen Index

Nitrogen is crucial for plant physiology due to the fact that plants consume a significant amount of nitrogen during the development period. Nitrogen supports the root, leaf, stem, branch, shoot and fruit development of plants. At the same time, it also increases flowering. To monitor the vegetation nitrogen concentration, one of the best indicators developed in the literature is the Normalized Difference Nitrogen Index (NDNI), which is based on the usage of the spectral bands of 1510 and 1680 nm from the Short-Wave Infrared (SWIR) region of the electromagnetic spectrum. However, the majority of remote sensing sensors, like cameras and/or satellites, do not have an SWIR sensor due to high costs. Many vegetation indexes, like NDVI, EVI and MNLI, have also been developed in the VNIR region to monitor the greenness and health of the crops. However, these indexes are not very well correlated to the nitrogen content. Therefore, in this study, a novel method is developed which transforms the estimated VNIR band indexes to NDNI by using a regression method between a group of VNIR indexes and NDNI. Training is employed by using VNIR band indexes as the input and NDNI as the output, both of which are calculated from the same location. After training, an overall correlation of 0.93 was achieved. Therefore, by using only VNIR band sensors, it is possible to estimate the nitrogen content of the plant with high accuracy.

Multishape radio: new approach to utilizing the physical properties of electromagnetic waves

Usage of higher frequency bands enable a new possibility for the exploitation of the physical properties of electromagnetic waves such as bended propagation, nondiffractive propagation, and orbital angular momentum. We characterize new concept that takes full advantage of such physical properties a “multishape radio.” As a representative case, we explore the Airy wave that has the unique feature of bended propagation with asymmetric sidelobe distribution. We experiment using sub-THz frequency bands to demonstrate that Airy waves can be used for parallel transmission of multiple streams without causing harmful interference.

Broadband millimeter-wave absorbers: a review

AbstractThis paper reports an exhaustive review of recent research progress in the development of millimeter-wave absorbers. With the advancement in technologies, microwave absorbers have shown their evolution in several applications such as defense, security identification, stealth technology, and several more. The importance of these absorbers is increasing due to electromagnetic interference (EMI) effects. Primarily, an abundant amount of absorbers has been developed in lower frequency bands and with the increasing demand for 5G technology, the usage of millimeter-wave bands has gained attention. This in turn requires the development of millimeter-wave absorbers to provide EMI shielding in several applications. Out of several materials, polymers have grabbed attention in the mitigation of EMI. An absorber that combines carbonaceous elements with polymers offers large design flexibility and tunability per the filler concentration. This paper focuses on the classification of these absorbers based on geometry as well as that by using polymers with their design challenges, merits, and demerits with their industrial applications. Comparative studies of geometrically based absorbers and polymeric-based absorbers are also shown.

An Efficient MAC with Spectrum Handoff and Frame Fragmentation Strategies for Cognitive Radio Networks

The rapid development of advanced wireless technologies has raised a large demand for spectrum bands. Cognitive radio network (CRN) has been proposed to solve the problem of spectrum scarcity. It enables a set of secondary users (SUs) to use the available spectrum allocated to the primary users (PUs) in an opportunistic way. In fact, there is a lack of in-depth topics in both centralized and distributed cognitive radio models, particularly on the subject of Media Access Control (MAC) protocol. In CRN, the MAC layer is required to perform new functions for efficient usage of spectrum bands. This paper proposes a new CRN MAC protocol to improve the spectrum utilization efficiency that enhances the SUs quality of service (QoS) without interfering the PUs. The main drawbacks of the existing protocols include their weakness in determining the portions of the spectrum that are available, managing the resource access with other users and vacating the occupied resource when a PUs are arrived. To better overcome the shortcomings of the existing protocols and handle the spectrum utilization and SUs QoS, it employs two efficient techniques: the channel handoff and the frame fragmentation. The channel handoff is used for switching the SU between free channels. The fragmentation technique is used to efficiently allow SUs to utilize the smaller spectrum holes. The performance of the proposed protocol is evaluated and compared to the existing basic CRN MAC protocol in terms of total system utilization, SU total loss probability, and SU average waiting time. The results show that the proposed protocol has an advantage over the basic protocol in all scenarios. In addition, it provides a better balance between the SUs QoS improvement and the QoS protection for PUs, while increasing the system utilization beyond 90%.

Optimized Analog Multi-Band Carrierless Amplitude and Phase Modulation for Visible Light Communication-Based Internet of Things Systems.

This paper presents a multi-user Visible Light Communication (VLC)-based Internet of Things (IoT) system using multi band-Carrierless Amplitude and Phase (m-CAP) modulation for IoT applications. The proposed system uses a digital m-CAP modulator embedded in a ceiling LED light fixture and analog receivers, aiming at low-cost, low-power, and small-sized IoT devices. The performance was evaluated in terms of the filtering stage design and the usage of guard bands. Different pairs of emitter and receiver filters were considered. While Bessel and Butterworth analog filters were tested in the analog receiver, the digital m-CAP modulator pulse shaping filter considered raised cosine filters, as well as digital matched filters for the analog Bessel and Butterworth filters. Regarding the guard bands, two approaches were considered: either by using the raised cosine roll-off factor (bandwidth compression) or by suppressing the even bands. The Bit Error Rate (BER) performance was obtained by simulation. The usage of the Bessel filter in the receiver, along with a digital matched filter, proved to be the best solution, achieving a BER lower than for an Eb/No of 6 dB, using a third-order filter. Furthermore, guard bands should be used in order to mitigate inter-band interference in order to have improved performance when multiple users intend to simultaneously communicate.

Comparative analysis of tribological properties of friction bands used in lifting and transport machinery

The comparative tests of asbestos-containing EM-1 and asbestos-free BAC friction bands were conducted. The results indicate that BAC friction bands provide more stable friction coefficients. The usage of BAC friction bands may reduce maintenance costs for the brakes of powered industrial machines.

The diversity of the genus Aricidea (Polychaeta: Paraonidae) from the Sea of Marmara, with descriptions of two new species and two new records for the Mediterranean fauna.

This paper reports 13 Aricidea species from the Sea of Marmara. The Aricidea specimens were collected at 98 stations in the region in 2012 and 2013 from soft and hard substrata at depths ranging from 0 to 1200 m. Among the material, two new species, namely Aricidea (Acmira) katzmanni n. sp. and Aricidea (Acmira) pseudoassimilis n. sp., and 11 known species were discovered. Aricidea mirunekoa and A. bulbosa are new records for the Mediterranean fauna; A. (Acmira) annae and A. (Aricidea) wassi are new records for the Sea of Marmara. Aricidea (Acmira) katzmanni n. sp. is characterized by having a long, digitiform antenna; no notopodial papillae on the posterior part of the branchial region; and hook shaped modified neurochaetae with a strong hood and fragile arista. Aricidea (Acmira) pseudoassimilis n. sp. is characterized by having a short, digitiform antenna; interramal lobes between notopodia and neuropodia; hook-shaped modified neurochaeta that gets subterminally thinner with a rounded tip. As A. (Strelzovia) bulbosa has been only previously reported from the Gulf of Suez (Red Sea), it could be a new alien species for the Sea of Marmara and Mediterranean Sea. Based on the characters that have been overlooked so far, the subspecies A. suecica meridionalis and A. capensis bansei were raised to species level, A. meridionalis n. stat. and A. bansei n. stat. The present paper reports the usage of ciliary bands and slits on the prostomium and body, swellings/ridges in the branchial region, and the shape and distribution of sense organs in the taxonomy of Aricidea. All species were described and figured.

Learning to Pay Attention on Spectral Domain: A Spectral Attention Module-Based Convolutional Network for Hyperspectral Image Classification

Over the past few years, hyperspectral image classification using convolutional neural networks (CNNs) has progressed significantly. In spite of their effectiveness, given that hyperspectral images are of high dimensionality, CNNs can be hindered by their modeling of all spectral bands with the same weight, as probably not all bands are equally informative and predictive. Moreover, the usage of useless spectral bands in CNNs may even introduce noises and weaken the performance of networks. For the sake of boosting the representational capacity of CNNs for spectral-spatial hyperspectral data classification, in this work, we improve networks by discriminating the significance of different spectral bands. We design a network unit, which is termed as the spectral attention module, that makes use of a gating mechanism to adaptively recalibrate spectral bands by selectively emphasizing informative bands and suppressing less useful ones. We theoretically analyze and discuss why such a spectral attention module helps in a CNN for hyperspectral image classification. We demonstrate using extensive experiments that in comparison with state-of-the-art approaches, the spectral attention module-based convolutional networks are able to offer competitive results. Furthermore, this work sheds light on how a CNN interacts with spectral bands for the purpose of classification.

Optimizing and Updating LoRa Communication Parameters: A Machine Learning Approach

LoRa is an extremely flexible low-power wide-area technology that enables each IoT node to individually adjust its transmission parameters. Consequently, the average per-node throughput of LoRa-based networks has been mathematically formulated and the optimal network-level configuration derived. For end nodes to update their transmission parameters, this centrally computed global configuration must then be disseminated by LoRa gateways. Unfortunately, the regional limitations imposed on the usage of ISM bands—especially those related to the maximum utilization of the band—pose a potential handicap to this parameter dissemination. To solve this problem, a set of tools from the machine learning field have been used. Precisely, the updating process has been formulated as a reinforcement learning (RL) problem whose solution prescribes optimal disseminating policies. The use of these policies together with the optimal network configuration has been extensively analyzed and compared to other well-established alternatives. Results show an increase of up to 147% in the accumulated per-node throughput when our RL-based approach is employed.

Towards software defined antenna for cognitive radio networks through appropriate selection of RF-switch using reconfigurable antenna array

There is a continuous demand for wireless devices that can adapt to different channel characteristics, while operating on high transmission data-rates utilizing several communication bands. Cognitive Radio (CR), and Software-Defined Radio (SDR) emerge as a favorable settlement to improve spectrum utilization and maximize the usage of frequency bands between users. CR relies on dynamic resource sharing between primary and secondary users through frequency hopping facilitated by the attached SDR tunable antenna. This paper proposes efficient, flexible antenna array design with reconfigurable frequency bands through radio frequency switches (RF-switches) towards enabling a Software Defined Antenna (SDA). RF-switches are used to enable reconfigurable antennas to manipulate frequency, bandwidth, and directivity. The proposed antenna design is verified using Electromagnetic High Frequency Simulation Software (HFSS) tool. Moreover, we address extensive ON/OFF switching cases to determine the proper selection of RF-switch(s) configurations and types to best serve CR networks. The proposed antenna design can be integrated with programmable kits as front end radio element to dynamically enable band manipulation through software programs. Thence, we exploit a queueing model for better spectrum sharing between CR networks users. Results show the efficiency of using Field Effect Transistor (FET) as RF-switches for the proposed antenna design in CR networks.

The Progress of Glucose Monitoring-A Review of Invasive to Minimally and Non-Invasive Techniques, Devices and Sensors.

Current glucose monitoring methods for the ever-increasing number of diabetic people around the world are invasive, painful, time-consuming, and a constant burden for the household budget. The non-invasive glucose monitoring technology overcomes these limitations, for which this topic is significantly being researched and represents an exciting and highly sought after market for many companies. This review aims to offer an up-to-date report on the leading technologies for non-invasive (NI) and minimally-invasive (MI) glucose monitoring sensors, devices currently available in the market, regulatory framework for accuracy assessment, new approaches currently under study by representative groups and developers, and algorithm types for signal enhancement and value prediction. The review also discusses the future trend of glucose detection by analyzing the usage of the different bands in the electromagnetic spectrum. The review concludes that the adoption and use of new technologies for glucose detection is unavoidable and closer to become a reality.

Design of Reconfigurable Digital IF Filter With Low Complexity

Due to limited frequency resources, new services are being applied to the existing frequencies, and service providers are allocating some of the existing frequencies for newly enhanced mobile communications. Because of this frequency environment, repeater and base station systems for mobile communications are becoming more complicated, and frequency interference caused by multiple bands and services is getting worse. Therefore, a heterodyne receiver using intermediate frequency (IF) filters with high selectivity has been used to minimize the interference between frequencies. However, repeater and base station systems in mobile communications employing fixed IF filters cannot actively cope with the usage of multiple frequency bands, the application of various services, and frequency recycling. Therefore, this brief proposes a reconfigurable digital IF filter with variable center frequency and bandwidth while achieving high selectivity as existing IF filters. The center frequency of a filter can vary from 10 MHz to 62.5 MHz, and the filter bandwidth can be selective to one of 10 MHz, 15 MHz, and 20 MHz. The proposed digital filter also reduces the complexity of adders and multipliers by 38.81% and 41.57%, respectively, compared to an existing digital filter by using a filter bank and a multi stage structure. This digital IF filter is fabricated on a 130-nm CMOS process and occupies 5.90 mm2.

Cognitive Radio Spectrum Sensing Mechanisms in TV White Spaces: A Survey

Frequency spectrum is a limited resource and the increasing demand caused by emerging services, augmented number of wireless users along with the demand for high-quality multimedia applications have resulted in the overcrowding of the allocated spectrum bands. The overcrowding of spectrum bands has exacerbated by the current spectrum licensing policy which has emerged as a bottleneck to efficient spectrum utilization, due to its inflexibility, resulting in most of the licensed spectrum being severely under-utilized. However, the problem of scarcity of spectrum bands and the inefficient utilization of the already allocated radio spectrum can be smartly addressed through spectrum sharing by enabling opportunistic usage of the underutilized frequency bands. One of the most exciting ways of spectrum sharing is cognitive radio technology which allows a wireless node to sense the environment, detect the network changes, and then make intelligent decisions by dynamically changing its reception or transmission parameters to communicate while ensuring that no interference is affected to the licensed users. It thus improves the spectrum utilization by reusing the unused or underutilized spectrum owned by the incumbent systems (primary systems). In this paper, a comprehensive survey and review of recent research about the advances in cognitive radio technology will be carried out. We will also evaluate the various spectrum sensing techniques in a cognitive radio network in the UHF/VHF bands allocated for TV broadcasting.

Design of Compact Dual Band Circular Polarized Micro-strip Antenna for High Efficiency WLAN 802.11ax-2019

Design of antennas for the latest upcoming standards of WLANs is considered as a key challenge in the science of Mobile Communication Engineering. Micro strip antennas are supposed to have some quality features in mobile and wireless network systems. Their weight and size are reduced and they are capable of having low power capacity. All these interesting features enabled these type of antennas suitable for the communication of IEEE 802.11ax-2019 high speed WLANs. Shape of these antennas can be designed in an efficient manner to achieve required gain and bandwidth. In this paper the concept of circular polarization has been introduced along with compact design of antennas in order to achieve return loss and axial ratio of less than -10 dB and 3dB respectively. Antenna has been designed and simulated on CST MW studio software and usage of dual bands 2.4 and 5.2GHz having circular polarization is properly elucidated for 802.11ax-2019.

Optimal Policy Derivation for Transmission Duty-Cycle Constrained LPWAN

Low-power wide-area network (LPWAN) technologies enable Internet of Things (IoT) devices to efficiently and robustly communicate over long distances, thus making them especially suited for industrial environments. However, the stringent regulations on the usage of certain industrial, scientific, and medical bands in many countries in which LPWAN operate limit the amount of time IoT motes can occupy the shared bands. This is particularly challenging in industrial scenarios, where not being able to report some detected events might result in the failure of critical assets. To alleviate this, and by mathematically modeling LPWAN-based IoT motes, we have derived optimal transmission policies that maximize the number of reported events (prioritized by their importance) while still complying with current regulations. The proposed solution has been customized for two widely known LPWAN technologies: 1) LoRa and 2) Sigfox. Analytical results reveal that our solution is feasible and performs remarkably close to the theoretical limit for a wide range of network activity patterns.

Integration of LoRaWAN and 4G/5G for the Industrial Internet of Things

Current forecasts predict that the Industrial Internet of Things will account for about 10 billion devices by 2020. Simultaneously, unlicensed low-power wide area networks are gaining momentum due to their low cost, low power, and long range characteristics, which are suitable for many IIoT applications, in addition to the usage of unlicensed bands. In this article, a solution is proposed to seamlessly integrate LoRaWAN, an open and standardized LPWAN technology, with 4G/5G mobile networks, thus allowing mobile network operators to reutilize their current infrastructures. This proposal is transparent to LoRaWAN end devices and to the EPC, since only the LoRaWAN gateway needs to be modified. The gateway acts as an evolved Node B from the core network perspective, implementing part of the eNB protocol stack. All data packets transported over the core network are both encrypted and integrity protected, hence achieving end-toend security. As a proof of concept, this solution has been implemented and validated with an open source EPC.