Candidate Bands Research Articles

Novel discretized gravitational search algorithm for effective medical hyperspectral band selection

Medical hyperspectral imaging present a promising avenue for non-invasive diagnostic methods for diseases. Nonetheless, the sparsity of medical hyperspectral data within high-dimensional spaces introduces the “curse of dimensionality”, which diminishes the efficiency and accuracy of data processing efforts. Therefore, spectral dimensionality reduction emerges as an essential process in the analysis and utilization of MHSIs data. To retain the intrinsic properties of the spectral bands, an effective unsupervised band selection algorithm is proposed leveraging the gravitational search algorithm (GSA-UBS) to identify the optimal band subset. Taking into account the informational content and redundancy among candidate bands, a comprehensive evaluation criterion is established that incorporates a band distance matrix and an information entropy vector. Additionally, a straightforward discrete search strategy is developed that enables gravitational search algorithm to directly retrieve the original sequence numbers of the selected bands, bypassing the conventional 0–1 band weighting approach. The extensive evaluation of GSA-UBS on three publicly available invivo brain cancer MHSIs datasets and a remote sensing hyperspectral image demonstrates its superior performance compared to various state-of-the-art methods. The source code for GSA-UBS can be accessed at https://github.com/zhangchenglong1116/GSA_UBS.

FTIR determination of the degree of molar substitution for hydroxypropyl chitosan

We developed and validated a novel Fourier transform infrared (FTIR) method to determine the degree of molar substitution (MS) for hydroxypropyl chitosan (HPCS) using nuclear magnetic resonance (1H NMR) as a reference, and investigated the factors influencing the MS assay. Through extensive screening of integration methods for candidate bands in the FTIR spectrum of HPCS using 20 HPCS samples with degrees of acetylation (DA) ranging from 0.003 to 0.139, we found that when using band area at 2970 cm−1 as a probe integral, the MS values obtained via the 1H NMR method exhibited linear correlations (R2 > 0.98) with at least 16 integral ratios derived from their FTIR spectra. The optimal reference bands with high reliability are located at 3440 cm−1 and 1415 cm−1, with R2 exceeding 0.99 and a MS range of 0.17–1.92. The band at 2875 cm−1 is less affected by the trace moisture present in HPCS samples than the others. The results of the method validation demonstrated a mean recovery of 98.9 ± 2.8 % and an RSD below 10 %, suggesting a simple, robust, and highly accurate and precise method. This method could be extendable for the determination of the MS of insoluble HPCS derivatives and other hydroxypropylated polysaccharides.

An efficient antenna system with improved radiation for multi-standard/multi-mode 5G cellular communications

This paper introduces a multi-input multiple-output (MIMO) antenna array system that provides improved radiation diversity for multi-standard/multi-mode 5G communications. The introduced MIMO design contains four pairs of miniaturized self-complementary antennas (SCAs) fed by pairs of independently coupled structures which are symmetrically located at the edge corners of the smartphone mainboard with an overall size of 75 × 150 (mm2). Hence, in total, the design incorporates four pairs of horizontally and vertically polarized resonators. The elements have compact profiles and resonate at 3.6 GHz, the main candidate bands of the sub-6 GHz 5G spectrum. In addition, despite the absence of decoupling structures, adjacent elements demonstrate high isolation. To the best of the authors’ knowledge, it is the first type of smartphone antenna design using dual-polarized self-complementary antennas that could possess anti-interference and diversity properties. In addition to exhibiting desirable radiation coverage, the presented smartphone antenna also supports dual polarizations on different sides of the printed circuit board (PCB). It also exhibits good isolation, high-gain patterns, improved radiation coverage, low ECC/TARC, and sufficient channel capacity. The introduced antenna design was manufactured on a standard smartphone board and its main characteristics were experimentally measured. Simulations and measurement results are generally in good agreement with each other. Moreover, the presented antenna system delivers low SAR with adequate efficiency when it comes to the appearance of the user. Hence, the design could be adapted to 5G hand-portable devices. As an additional feature, a new ultra-compact phased array millimeter-wave antenna with super-wide bandwidth and end-fire radiation is being introduced for integration into the MIMO antenna systems. As a result, the proposed antenna system design with improved radiation and multi-standard operation is a good candidate for future multi-mode 5G cellular applications.

A Compact Planar Four-port MIMO Antenna for 28/38 GHz Millimeter-wave 5G Applications

This article presents a planar four-port microstrip line-fed Multiple-Input Multiple-Output (MIMO) antenna operating at 5G millimeter-wave candidate bands of 28 GHz and 38 GHz. A rectangular-shaped patch antenna is designed as a main radiator to obtain a resonance at 28 GHz. Etching of a single-element split-ring resonator (SRR) metamaterial unit cell from the basic patch radiator introduces an additional resonance band at 38 GHz. The suggested MIMO antenna is built on Rogers RT5880 substrate material with a dimension of 14 mm × 14 mm, a thickness of 0.8 mm, and a relative permittivity of 2.2.The measured results show that the antenna achieves bandwidths of 26.6-29 GHz and 37.3-39.3 GHz, whereas greater than 25 dB of port isolation between antenna elements over both bands is obtained without applying any complex decoupling structure. The antenna’s equivalent circuit diagram is presented with the help of lumped elements to characterize its electrical responses. The investigated diversity performance parameters, which result in an envelope correlation coefficient below 0.005, diversity gain of almost 10 dB, and channel capacity loss of less than 0.35 bits/s/Hz, are all found within their conventional limits. The findings show the viability of the design for millimeter-wave 5G applications.

Detection and Classification of Rice Infestation with Rice Leaf Folder (Cnaphalocrocis medinalis) Using Hyperspectral Imaging Techniques

The detection of rice leaf folder (RLF) infestation usually depends on manual monitoring, and early infestations cannot be detected visually. To improve detection accuracy and reduce human error, we use push-broom hyperspectral sensors to scan rice images and use machine learning and deep neural learning methods to detect RLF-infested rice leaves. Different from traditional image processing methods, hyperspectral imaging data analysis is based on pixel-based classification and target recognition. Since the spectral information itself is a feature and can be considered a vector, deep learning neural networks do not need to use convolutional neural networks to extract features. To correctly detect the spectral image of rice leaves infested by RLF, we use the constrained energy minimization (CEM) method to suppress the background noise of the spectral image. A band selection method was utilized to reduce the computational energy consumption of using the full-band process, and six bands were selected as candidate bands. The following method is the band expansion process (BEP) method, which is utilized to expand the vector length to improve the problem of compressed spectral information for band selection. We use CEM and deep neural networks to detect defects in the spectral images of infected rice leaves and compare the performance of each in the full frequency band, frequency band selection, and frequency BEP. A total of 339 hyperspectral images were collected in this study; the results showed that six bands were sufficient for detecting early infestations of RLF, with a detection accuracy of 98% and a Dice similarity coefficient of 0.8, which provides advantages of commercialization of this field.

A Planar Dual-Polarized Phased Array With Broad Bandwidth and Quasi-Endfire Radiation for 5G Mobile Handsets

A planar dual-polarized phased array is proposed for 5G cellular communications. The array has the properties of dual-polarization, wideband, and quasi-endfire radiation, which is printed on one side of a single-layer substrate. The design contains two eight-element subarrays including horizontally polarized endfire dipole antennas and vertically polarized endfire periodic slot antennas, employed on the PCB ground plane of the 5G mobile platform. Both subarrays provide wide bandwidth to cover 28 and 38 GHz (promising 5G candidate bands). The −10 dB impedance bandwidth of the proposed CPW-fed dipole and slot antennas are 26.5–39.5 GHz and 27.1–45.5 GHz, respectively. Moreover, for −6-dB impedance bandwidth, these values could be more than 20 GHz (24.4–46.4 GHz for the dipole antenna) and 70 GHz (22.3–95 GHz for the slot antenna). The fundamental characteristics of the proposed dual-polarized 5G antenna array in terms of the impedance bandwidth, realized gain, polarization, radiation pattern, and beam steering are investigated and good results are obtained. The clearance of the proposed dual-polarized 5G antenna array is less than 4.5 mm which is sufficient for cellular applications.

Millimeter-Wave Propagation Measurement and Modeling in Indoor Corridor and Stairwell at 26 and 38 GHz

Accurate propagation characteristics are essential for future indoor millimeter-wave (mmWave) small cell network planning. This paper presents propagation measurements at 26 GHz and 38 GHz which are important candidate bands for fifth generation mmWave communication. Measurements are conducted in an indoor corridor, as well as a stairwell whose mmWave channel is seldom investigated before. In these measurements, an omnidirectional biconical antenna is used as transmitter and a steerable directional horn antenna is used as receiver. The directional and omnidirectional path loss exponents, shadow factors, cross-polarization discrimination ratios and root-mean-square delay spreads are analyzed for both line-of-sight and non-line-of-sight scenarios in both co-polarization and cross-polarization, and these characteristics are compared for different frequencies and environments. It is found obvious depolarization phenomenon in non-line-of-sight scenario for higher frequency. Compared to the corridor, the stairwell has larger path loss exponents and root-mean-square delay spreads, and the depolarization is also more evident in stairwell. The results in this paper are beneficial to building efficient and robust indoor mmWave communication systems.

Deep Learning Predictive Band Switching in Wireless Networks

In cellular systems, the user equipment (UE) can request a change in the frequency band when its rate drops below a threshold on the current band. The UE is then instructed by the base station (BS) to measure the quality of candidate bands, which requires a measurement gap in the data transmission, thus lowering the data rate. We propose an online-learning based band switching approach that does not require any measurement gap. Our proposed classifier-based band switching policy instead exploits spatial and spectral correlation between radio frequency signals in different bands based on knowledge of the UE location. We focus on switching between a lower (e.g., 3.5 GHz) band and a millimeter wave band (e.g., 28 GHz), and design and evaluate two classification models that are trained on a ray-tracing dataset. A key insight is that measurement gaps are overkill, in that only the relative order of the bands is necessary for band selection, rather than a full channel estimate. Our proposed machine learning-based policies achieve roughly 30% improvement in mean effective rates over those of the industry standard policy, while achieving misclassification errors well below 0.5% and maintaining resilience against blockage uncertainty.

Plane-Wave UTD-PO Formulations for Multiple-Diffraction by Trees and Buildings at Millimeter-Wave Frequencies

Two uniform theories of diffraction or physical optics (UTD-PO) formulations for the analysis of the multiple-diffraction of millimeter plane waves which is caused by both trees and buildings, in vegetated residential areas, are hereby presented. The two solutions consider the buildings, modeled as knife-edges and rectangular sections (a more complex and realistic shape), respectively, and the influence of the tree canopies—assumed to be higher than the average rooftop height—is taken into account by considering the proper attenuation factors and phasors into the building diffraction phenomenon. The formulations have been validated through comparison with solutions previously published by other authors, and the main advantage of the proposed models is that, thanks to their recursion, only single diffractions are involved in the calculations. This way, the need of higher order diffraction terms in the diffraction coefficients is avoided, thereby lowering the computational effort. The results, focused on the 5G millimeter-wave (mmWave) candidate bands, can be applied in the planning of forthcoming mobile communication systems.

Indoor Small-Scale Spatiotemporal Propagation Characteristics at Multiple Millimeter-Wave Bands

Indoor small-scale spatiotemporal propagation characteristics across multiple 5G millimeter-wave (mmWave) candidate bands are investigated. First, using a custom-designed channel sounder, channel measurement campaigns are conducted in indoor environments to capture the delay and angles of departure and arrival of the paths. Measurement results exhibit excellent agreements with physical scatterers and radio propagation environments. Next, the layout-related multipath propagation analyses are utilized to model frequency-dependent channel parameters for different polarimetric combinations, including root-mean-square delay and angular spread. Modeling results not only complete the 3GPP channel model above 6 GHz, but also help to understand the impacts of frequency and polarization on the radio wave propagation at the mmWave bands.

Implementation of a Multi-Gbit/s and GFDM-based Optical-Wireless 5G Network

We report the implementation of an optical-wireless 5G network based on generalized frequency division multiplexing (GFDM) and multi-Gbit/s communication. Dual-drive Mach-Zehnder modulator was employed, enabling simultaneously RF signals transport using two 5G candidate bands, namely: 26 GHz band for providing a femtocell with 2 Gbit/s throughput; 700 MHz band for enabling rural access applying a supercell. A vector signal generator provides the broadband 26 GHz signal. The Brazilian GFDM-based 5G transceiver generates the lower-frequency signal, with the advantage of low out-of-band emission. An experimental digital performance analysis illustrates the suitability of the proposed solution to address 5G requirements.

A Geometry-Based Band Selection Approach for Hyperspectral Image Analysis

Band selection (BS) is a special case of the feature selection problem, and it tries to remove redundant bands and select a few informative and distinctive bands to represent the whole image cube. The maximum ellipsoid volume (MEV) method regards the band subset with the maximum volume as the optimal band combination. However, the MEV method cannot be directly applied for hyperspectral imagery due to the high dimensionality of the data sets. Therefore, we first combine MEV with the sequential forward search (SFS) and propose a new unsupervised BS method called MEV-SFS. Furthermore, a subtle relationship between the ellipsoid volume of the band set and the orthogonal projections (OPs) of the candidate bands is observed. Based on this relationship, we propose another equivalent method, namely, the OP-based BS (OPBS) method. OPBS is the fast version of MEV-SFS, and it has a better computational efficiency and the potential to determine the number of bands to be selected. We specifically explain the rationality of the MEV-based methods (MEV-SFS and OPBS) and illustrate their theoretical significance and physical meaning from different aspects. Theoretical analysis also demonstrates that OPBS can be regarded as a model or framework for BS, and thus, we further propose a third novel BS method named the OPBS-information divergence (OPBS-ID) method, which is a variant of OPBS. OPBS-ID can achieve a better classification performance than OPBS in many cases. Experimental results on different hyperspectral data sets demonstrate that the proposed methods have high computational efficiency, and the selected bands can achieve satisfactory classification performances.

Sharing Study of IMT-2020(5G) and SRS in 25.5-27GHz

Based on the WRC-19 1.13 issue research framework and the compatibility analysis requirements for the fifth generation of mobile communication candidate bands above 6GHz in China, this paper studied the coexistence between IMT-2020(5G) and Space Research(space to ground) system(SRS) in the same running bands 25.5-27GHz. The interference of IMT-2020(5G) system to the downlink of the SRS is analysed by the aggregated interference assessment method. The research shows that, IMT-2020(5G) would not interfere SRS harmfully by the certain isolation distance. The results can provide a technical basis for the actual deployment of IMT-2020(5G) and protection of SRS system in the frequency bands 25.5-27GHz in the future.

Dynamic chirality in mass regions A=105 and A=130

Chiral symmetry is dichotomic and its spontaneous breaking by the axial angular momentum vector leads to a pair of degenerate ΔI = 1 rotational bands, called chiral doublet bands. In many cases the energy degeneracy of the chiral candidate bands has almost been observed but the transition probabilities of the analogue states have been found to be different. In the angular momentum region where chirality sets in the B(E2) values of the electromagnetic transitions deexciting analogue states of the chiral twin bands should be almost equal. Correspondingly the B(M1) values should exhibit staggering. Experimental data for two nuclei from different mass regions are compared with theoretical predictions. Exited states in 134Pr were populated in the fusion-evaporation reaction 119Sn(19F, 4n)134Pr, while excited states in 102Rh were populated in the fusion-evaporation reaction 94Zr(11B, 3n)102Rh. Our lifetime measurements and level-scheme investigations show that there are similarities in both chiral candidates nuclei related to dynamic chirality.

Impact of Microwave and mmWave Channel Models on 5G Systems Performance

Channel models and measurements across a wide range of candidate bands for fifth generation wireless networks are considered. Motivated by the different propagation and spatial characteristics between different bands and channel models within a band, we investigate how key channel modeling and spatial parameter differences impact various antenna topologies in terms of sum rate, channel eigenvalue structure, effective degrees of freedom (EDOF), channel connectivity, and massive multiple-input-multiple-output (MIMO) convergence. We show that due to the sparsity of millimeter-wave (mmWave) channels, any variation in spatial parameters can dramatically affect the sum rate. In microwave scenarios, where the probability of line-of-sight (LOS) propagation is low, the structure of the eigenvalues is highly dependent on the richness of scattering. In mmWave bands, where the probability of LOS is higher, the structure of the eigenvalues is largely dependent on the LOS channel model. The uniform linear array is seen to have a superior sum rate and an eigenvalue structure due to the inherently larger interelement spacings and wider azimuth spectra. These observations are seen to affect the sum rate, EDOF, and massive MIMO convergence. Two variations of channel connectivity are then considered, and compared with EDOF, to examine the richness of scattering and channel rank.

Indoor wideband channel measurements and analysis at 11 and 14 GHz

This study reports the results of an indoor propagation measurement campaign and channel characterisation at 11 and 14 GHz, which are the candidate bands for the future communication systems. The measurement procedure allows the characterisation of both the large- and small-scale statistics of line-of-sight (LOS) and non-LOS (NLOS) channels. Based on the measurements, a log-distance path loss model is proposed, and the root-mean-square (RMS) delay spread is discussed. A Nakagami distribution is found to well describe the statistics of the small-scale fading, by using Kolmogorov–Smirnov, Chi-square, and Anderson–Darling tests. A distance dependent linear model is proposed to predict the Nakagami m-parameter. In addition, the cross-correlations of these channel parameters are analysed based on measurements, and the cross-correlations between the shadow fading, RMS delay spread and m-factor can be clearly observed for LOS condition, whereas the obstruction of NLOS reduces the cross-correlations.

Guest Editorial Deployment Issues and Performance Challenges for 5G, Part I

There are rapid developments towards the deployment of 5G and hardly a day goes by without the release of a major announcement concerning 5G. Many of these developments are happening in parallel as there is a race against time for 5G deployment. Various test beds have been established, laboratory trials and proof of concept trials of individual building blocks of 5G are already underway or have been completed, large scale system trials are also happening or are planned and standardisation efforts in the ITU, 3GPP, IEEE, etc. are also in progress. In the case of ITU/3GPP, the standards are expected to be completed by 2019. Many candidate bands for 5G in the centimetric and mm wave range were identified by the World Radio Conference (WRC) 2015 and are expected to be finalized by WRC 2019, while coexistence studies of 5G and existing systems in the new candidate bands are underway.

The Feasibility of Coexistence Between 5G and Existing Services in the IMT-2020 Candidate Bands in Malaysia

In 2015, the international telecommunication union (ITU) proposed 11 candidate millimeter-wave bands between 24 and 86 GHz for the deployment of future fifth mobile generation (5G) broadband systems. Furthermore, the ITU called for spectrum-sharing studies in these bands. Since 5G specifications are not yet defined, the utilization of radio spectrum by 5G mobile systems will assist in identifying these specifications. This paper introduces Malaysia as a case study for the deployment of 5G systems. This includes a discussion of the current status of the Malaysian telecommunication market. Then, we investigate the current services that are already deployed in the proposed bands. Our investigation shows that the fixed (F) service is the most deployed as a primary service in the candidate bands. For this reason, a preliminary spectrum-sharing study is conducted on the basis of a modified 5G spectrum-sharing model to evaluate the feasibility of coexistence between 5G and F services in the 28-GHz band. Our modified methodology can be used for spectrum-sharing studies between 5G and any other services for an initial spectrum-sharing investigation. The results show that the F service will be severely affected by the 5G system transition in the 28-GHz band, especially in the base station (BS)-to-BS sharing scenario. The best band from the perspective of current spectrum allocation for 5G systems is the 45-GHz (i.e., 45.5–47 GHz) band, since it is already reserved for mobile service for primary allocation and not utilized. This paper is carried out concurrently with current worldwide efforts investigating spectrum sharing, as requested by the ITU in agenda item 1.13 for the next world radio conference 2019.

Investigation on the performance of low‐profile insensitive antenna with improved radiation characteristics for the future 5G applications

ABSTRACTA new method to design an insensitive antenna with improved performance for fifth generation (5G) systems is proposed in this letter. In order to improve the antenna performance and also eliminate the effect of high‐loss FR‐4 substrate, the resonator of the conventional slot antenna has been converted to the air‐filled slot‐loop structure with a thickness of hsub. Since the main substrate of the resonator is the air, the antenna is insensitive for different values of permittivity, loss tangent characteristics of the substrate. So, for different kinds of substrates, the antenna has a same performance in terms of maximum gain, radiation and total efficiencies. The antenna is designed and fabricated on a low‐cost FR4 substrate and has more than 90% (−0.5 dB) radiation and total efficiencies at 22.25 GHz (center frequency). It has the reflection coefficient (S11) less than −10 dB in the frequency range of 21–23.5 GHz (more than11% fractional bandwidth) which is one of the candidate bands for future 5G communications. The antenna has a very compact size and could be used in mm‐wave phased arrays. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2148–2151, 2016

UWB CHANNEL CHARACTERIZATION IN 28 GHZ MILLIMETER WAVEBAND FOR 5G CELLULAR NETWORKS

The demands of high data rate transmission for future wireless communication technologies are increasing rapidly. The current bands for cellular network will not be able to satisfy these requirements. The millimeter wave (mm-wave) bands are the candidate bands for the future cellular networks. The 28 GHz band is the strongest candidate for 5G cellular networks. The large bandwidth at this band is one of the main parameters that make the mm-wave bands promising candidate for the future cellular networks. To know the wideband channel behavior in mm-wave bands, the wideband channel characterizations are required. In this paper, the 3D WINNER model is used to model the wideband channel at 28 GHz band. Based on this model, the time dispersion parameters at 28 GHz mm-wave band are investigated. The root mean square delay spread and the mean excess delay are the main parameters that can be used to characterize the wideband channel. Morever, the cumulative distribution function (CDF) is used to model the RMS delay spreads. The results show that the RMS delay spread varies between 4.1 ns and 443.7 ns.