Spatial Diversity Research Articles

Quad Port MIMO Circularly Polarized Antenna for n77/n78 5G Coverage with Spatial and Polarization Diversity

Quad Port MIMO Circularly Polarized Antenna for n77/n78 5G Coverage with Spatial and Polarization Diversity

Niche differentiation and biogeography of Bathyarchaeia in paddy soil ecosystems: a case study in eastern China

Bathyarchaeia (formerly Bathyarchaeota) is a group of highly abundant archaeal communities that play important roles in global biogeochemical cycling. Bathyarchaeia is predominantly found in sediments and hot springs. However, their presence in arable soils is relatively limited. In this study, we aimed to investigate the spatial distributions and diversity of Bathyarchaeia in paddy soils across eastern China, which is a major rice production region. The relative abundance of Bathyarchaeia among total archaea ranged from 3 to 68% in paddy soils, and Bathy-6 was the dominant subgroup among the Bathyarchaeia (70–80% of all sequences). Bathyarchaeia showed higher migration ability and wider niche width based on the neutral and null model simulations. Bathy-6 was primarily assembled by deterministic processes. Soil pH and C/N ratio were identified as key factors influencing the Bathyarchaeia composition, whereas C/N ratio and mean annual temperature influenced the relative abundance of Bathyarchaeia. Network analysis showed that specific Bathyarchaeia taxa occupied keystone positions in the archaeal community and co-occurred with some methanogenic archaea, including Methanosarcina and Methanobacteria, and ammonia-oxidizing archaea belonging to Nitrososphaeria. This study provides important insights into the biogeography and niche differentiation of Bathyarchaeia particularly in paddy soil ecosystems.

Dynamic sliding window‐cooperative spectrum sensing against massive SSDF attack in interweave cognitive internet of things

AbstractTo improve spectrum utilization, cognitive radio (CR) enables unauthorized internet of thing (IoT) devices to opportunistically access the channel underutilized by the primary user (PU) in a cognitive IoT (CIoT). To this end, cooperative spectrum sensing (CSS) plays a crucial role in CR technology, which leverages the spatial diversity of corroborative IoT devices to accurately detect the PU signal. However, this open cooperative paradigm may suffer from spectrum sensing data falsification (SSDF) attack in which malicious IoT devices intentionally mislead the fusion center (FC) by providing false sensing results to make an incorrect global decision regarding the PU status. To effectively characterize the attack behavior of malicious IoT devices, we propose a massive SSDF attack model described by the attack cycle and malicious ratio within a sensing period to characterize the malicious behaviors. Additionally, we introduce a delivery evaluation mechanism and propose a dynamic sliding window‐CSS (DSW‐CSS) to mitigate the impact of massive SSDF attack. Moreover, we introduce a sequential reporting mechanism to further reduce the number of samples required by the global decision‐making of the FC. Finally, simulation results show the flexibility and aggressiveness of the proposed attack model and demonstrate the correctness and effectiveness of DSW‐CSS.

Key Enabling-Technologies of 4G and 5G Network

This paper provides a comprehensive overview of Multiple Input Multiple Output (MIMO) technology and its pivotal role in enhancing 4G (LTE) networks. MIMO technology, characterized by the use of multiple antennas at both the transmitter and receiver, enables significant improvements in data rates, coverage, and spectral efficiency. The key functionalities of MIMO technology in 4G LTE networks are elucidated, including spatial multiplexing, improved signal quality through spatial diversity, increased coverage via transmit diversity, and enhanced spectral efficiency. MIMO technology enables increased throughput and supports bandwidth-intensive applications like file downloads and video streaming by broadcasting many data streams simultaneously over the same frequency range. Furthermore, the adaptive nature of MIMO systems is discussed, highlighting their ability to dynamically adjust antenna configurations and employ adaptive beam forming techniques. These features optimize performance in real-time, maximizing signal strength, reducing interference, and enhancing overall network reliability. In summary, this paper underscores the critical importance of MIMO technology in 4G LTE networks, showcasing its ability to deliver high-speed broadband services, improve coverage in challenging environments, and efficiently utilize the available spectrum. As the backbone of modern mobile communications, MIMO-enabled 4G networks provide users with seamless connectivity and support the growing demand for data-intensive applications

Improving rate wireless sensor network with collaborative energy among nodes with fusion center and multiple antennas sensors using game theory and energy harvesting

SummaryThis paper investigates optimizing the collaborative energy power consumption between nodes with energy harvesting (EH) capability at the fusion center (FC) and multi‐antenna sensors using game theory. Using multi‐antennas at FC on sensor networks (SNs), we can benefit from the spatial diversity in receiving the data and using multi‐antenna sensors and energy to transfer the data and optimize the SN, respectively. Also, in this paper, the data transmission in the network is formulated by considering the limitations of storage resources of each sensor, minimum data receiving, minimum EH, and maximum collaboration among sensors. In this paper, some modes are suggested to minimize the collaborative energy among sensors for transmitting the data and energy among sensors in the collaboration of sensors to optimize the power control and allocation power policy. Suggestions have been studied based on the number of antennae to transmit, using the cooperative games in sharing the data and the energy and auction game in transmitting to FC. The simulation results of the proposed problem using MATLAB software show optimization in participation function, EH, allocation in cooperation time, and transferring to FC to improve the detection of the transmitted data based on the increasing number of antennas in FC.

Geographical Types and Driving Mechanisms of Rural Hollowing-Out in the Yellow River Basin

Understanding the regional variations and mechanisms of rural hollowing-out in the Yellow River Basin (YRB) is crucial to guiding regional rural revitalization. However, further quantitative evaluation and analysis are essential to address the issue of rural hollowing-out caused by the decrease in rural population and expansion of residential land in the YRB at different spatio-temporal scales. Based on China’s census data and residential areas extracted from remote sensing images, the rural hollowing-out in the YRB is classified into five types: smart development type (SDT), human–-land recession type (HRT), population loss type (PLT), land expansion type (LET), and human–land–vacant waste type (HLW). Then, the influential features shaping the spatial diversity of rural hollowing-out types are examined, and the feature importance values at different spatio-temporal scales are assessed using the XGBoost model. The results of rural hollowing-out in the YBR indicate that (1) the geographical types of rural hollowing-out in the YRB are dominated by the HRT type and show significant heterogeneity and distribution at different spatio-temporal scales. At different time stages, the number of counties dominated by HRT in lower reaches accounts for 57% of the total counties, whereas the number of counties in the middle reaches is only 37%. Compared to the rural hollowing-out results from 2000 to 2010, the number of counties dominated by PLT and HLW from 2010 to 2020 in the middle reaches increased by 19% and 16%, respectively. (2) Precipitation had a positive effect on the variability of the rural hollowing-out distribution results based on the feature importance values, whereas agricultural productivity had a negative effect and exhibited a decreasing trend. In the entire study area, economic non-agriculturalization had a negative impact, but the topographic relief was positively correlated with the rural hollowing-out results of regional areas, and the intensity of its effect showed an increased trend from 2000 to 2020. (3) The evaluation results in the entire study area show that the main functional type and the distance from provincial capitals are the most important factors affecting rural hollowing out. Compared to other factors, the level of non-agricultural economic development has a greater impact on the spatio-temporal differentiation of rural hollowing types in different Yellow River basins. Given the significant effect of non-agricultural economic development in the evaluation of regional rural hollowing-out, it can provide methodological and indicator references for the evaluation of rural hollowing-out in different regions.

DHT-based GFDM and STC-GFDM systems for beyond 5G wireless networks

This manuscript endeavours an exploration of Generalized Frequency Division Multiplexing (GFDM) as a promising alternative to the Orthogonal Frequency Division Multiplexing (OFDM) in next-generation cellular networks. GFDM’s exceptional performance in minimizing out-of-band emissions (OOBE) and maximizing spectral efficiency (SE) makes it a compelling candidate, especially when integrated with Multi-Input Multi-Output (MIMO) technology to enhance reliability through spatial diversity. However, ensuring GFDM’s resilience against frequency-selective channels (FSCs), especially in low-latency scenarios, is crucial.This research investigates Discrete Hartley Transform (DHT) based GFDM and Space-Time Coded GFDM (STC-GFDM) systems, proposing a comprehensive framework to enhance performance metrics such as Bit Error Rate (BER) and Achievable Rate (AR). Further enhancements are achieved through a Minimum BER-Power Allocation (MBER-PA) strategy, optimizing BER and AR in QAM-based GFDM and STC-GFDM systems employing a DHT precoding scheme. Analytical expressions for BER and AR are derived and validated via Monte Carlo simulations. Additionally, a comparative analysis against traditional GFDM systems is conducted, evaluating metrics including Peak-to-Average Power Ratio (PAPR), BER, and AR.

Geographical patterns and determinants of insect biodiversity in China.

Insects play important roles in the maintenance of ecosystem functioning and the provision of livelihoods for millions of people. However, compared with terrestrial vertebrates and angiosperms, such as the giant panda, crested ibis, and the metasequoia, insect conservation has not attracted enough attention, and a basic understanding of the geographical biodiversity patterns for major components of insects in China is lacking. Herein, we investigated the geographical distribution of insect biodiversity across multiple dimensions (taxonomic, genetic, and phylogenetic diversity) based on the spatial distribution and molecular DNA sequencing data of insects. Our analysis included 18 orders, 360 families, 5,275 genera, and 14,115 species of insects. The results revealed that Southwestern and Southeastern China harbored higher insect biodiversity and numerous older lineages, representing a museum, whereas regions located in Northwestern China harbored lower insect biodiversity and younger lineages, serving as an evolutionary cradle. We also observed that mean annual temperature and precipitation had significantly positive effects, whereas altitude had significantly negative effects on insect biodiversity in most cases. Moreover, cultivated vegetation harbored the highest insect taxonomic and phylogenetic diversity, and needleleaf and broadleaf mixed forests harbored the highest insect genetic diversity. These results indicated that human activities may positively contribute to insect spatial diversity on a regional scale. Our study fills a knowledge gap in insect spatial diversity in China. These findings could help guide national-level conservation plans and the post-2020 biodiversity conservation framework.

Spatial distribution and diversity of the heterotrophic flagellates in the Cosmonaut Sea, Antarctic

As predators of bacteria and viruses and as food sources for microzooplankton, heterotrophic flagellates (HFs) play an important role in the marine micro-food web. Based on the global climate change’s impact on marine ecosystems, particularly sea ice melting, we analyzed the community composition and diversity of heterotrophic flagellates, focusing on the Antarctic Cosmonaut Sea. During the 36th China Antarctic research expedition (2019-2020), we collected seawater samples, subsequently analyzing HFs through IlluminaMiSeq2000 sequencing to assess community composition and diversity. Notable variations in HFs abundance were observed between the western and eastern sectors of the Cosmonaut Sea, with a distinct concentration at a 100-meter water depth. Different zones exhibited diverse indicators and dominants taxa influenced by local ocean currents. Both the northern Antarctic Peninsula and the western Cosmonaut Sea, where the Weddell Eddy and Antarctic Land Slope Current intersect, showcased marine stramenopiles as dominant HFs species. Our findings offer insights into dominant taxa, spatial distribution patterns among heterotrophic flagellates, correlations between taxa distribution and environmental factors, and the exploration of potential indicator taxa.

The Escarpão Plateau (South of Portugal)—a Study Case of Nested Geosites from the Aspiring Algarvensis Geopark

Located along the southern limit of the Algarvensis aspiring UNESCO Global Geopark (aUGGp), the Escarpão Plateau is a singular geomorphological structure sculpted by fluvial, karst, and tectonic processes. The plateau is deeply scarved by the Quarteira Rivulet, forming a valley that crosses the most complete Upper Jurassic sedimentary sequence of the Eastern Algarve (Southern Portugal). This sequence includes five geological formations representing different depths of carbonate ramp deposition from the Tethys Sea: Peral Formation, Jordana Formation, Cerro da Cabeça Formation, Escarpão Formation, and the upper Limestone Formation with Anchispirocyclina lusitanica (foraminifera), respectively from the oldest formation to the most recent at the top. Throughout the Quaternary Period, the karst processes shaped a landscape of sparse and poor soils, based on which successive generations adapted their subsistence agriculture and way of life. The geomorphology of the plateau and the rivulet valley, the sequence of the carbonated formations, and the diversity of sedimentary and paleontological records can be considered possible sites of diverse geological interest and with different scales that are embedded in each other, forming thus nested sites. To promote and preserve these sites, the Algarvensis aUGGp shaped an 8-km-long interpretative walking path, passing through 11 points of interest, including biosites and geosites. Their interpretative boards highlight not only the different spatial and temporal geological diversity but also its relationship with surrounding cultural and historical heritage. Finally, this work allowed the creation of new products for outreach and public awareness towards an effective geoconservation.

Estimation of polarization diversity in CPW fed compact dual band dual sense antenna with horn slot structure: 5G and WLAN applications

Estimation of polarization diversity in CPW fed compact dual band dual sense antenna with horn slot structure: 5G and WLAN applications

Dynamic parallel imaging at 9.4 T using reconfigurable receive coaxial dipoles.

Parallel imaging is one of the key MRI technologies that allow reduction of image acquisition time. However, the parallel imaging reconstruction commonly leads to a signal-to-noise ratio (SNR) drop evaluated using a so-called geometrical factor (g-factor). The g-factor is minimized by increasing the number of array elements and their spatial diversity. At the same time, increasing the element count requires a decrease in their size. This may lead to insufficient coil loading, an increase in the relative noise contribution from the RF coil itself, and hence SNR reduction. Previously, instead of increasing the channel number, we introduced the concept of electronically switchable time-varying sensitivities, which was shown to improve parallel imaging performance. In this approach, each reconfigurable receive element supports two spatially distinct sensitivity profiles. In this work, we developed and evaluated a novel eight-element human head receive-only reconfigurable coaxial dipole array for human head imaging at 9.4 T. In contrast to the previously reported reconfigurable dipole array, the new design does not include direct current (DC) control wires connected directly to the dipoles. The coaxial cable itself is used to deliver DC voltage to the PIN diodes located at the ends of the antennas. Thus, the novel reconfigurable coaxial dipole design opens a way to scale the dynamic parallel imaging up to a realistic number of channels, that is, 32 and above. The novel array was optimized and tested experimentally, including in vivo studies. It was found that dynamic sensitivity switching provided an 8% lower mean and 33% lower maximum g-factor (for Ry × Rz = 2 × 2 acceleration) compared with conventional static sensitivities.

Earth-to-HAP FSO Communication With Spatial Diversity and Channel Correlation

Earth-to-HAP FSO Communication With Spatial Diversity and Channel Correlation

Abstract B059: Epigenetically defined sub-clonal heterogeneity drives therapy resistance in triple-negative breast cancer

Abstract Background: Triple-negative breast cancer (TNBC) is a highly aggressive and heterogeneous disease with an average survival of less than 50%. Although immunotherapy is showing promising results, many patients do not respond, and chemotherapy remains the main treatment. High TNBC recurrence rates are in part due to its molecular heterogeneity. Here, we sought to characterise the sub-clonal and spatial diversity of chemotherapy resistant TNBC to identify the epigenetic hallmarks of lethal sub-populations of cells that may induce cell state transition, therapy resistance and ultimately metastatic progression. Methods: Sixteen primary untreated triple-negative breast tumours (eight chemotherapy sensitive (ChemoS) and eight chemotherapy resistant (ChemoR, who died of their disease within three years)) were subjected to cell-matched high-depth multiome single nuclei RNA- and ATAC-sequencing. Four tumours were subject to spatial RNA and ATAC profiling. Fourteen TNBC PDX models generated from patients with residual disease post NAC were subjected to single nuclei sequencing and used for validation. Meta-clustering of epithelial cells from the RNA profiles was used to identify sub-populations of cells harbouring distinct epigenetic and transcriptomic features enriched in ChemoR patients. Findings were validated in the BrighTNess TNBC NAC clinical trial and in chemotherapy treated TNBC patients from the SCAN-B study. Results: Unsupervised meta-clustering (MC) of epithelial cells in G1 phase of the cell cycle identified nine MC’s across the dataset, including a distinct immune-like MC. Two MCs were dominated by cells from ChemoR patients and were defined by hypoxia, EMT, and extra-cellular matrix signalling. Sub-populations of cells in the ChemoR dominant MCs were underpinned by both promoter and distal differential chromatin accessibility, that mapped to H3K27ac enhancer sites, suggesting a role of enhancer regulation of MC transcription. Spatial ATAC and RNA profiling of a subset of tumours identified spatially epigenetically defined regions that showed distinct chromatin profiles, suggesting that the epigenetic regulation of genes that define the MCs are spatially distinct. ChemoR clusters were independently reproduced in a cohort of fourteen residual disease TNBC PDXs. Genes pertaining to the immune-like MC were associated with a good prognosis in independent cohorts of contemporary treated TNBC (SCAN-B) and with response to NAC in the BrighTNess trial. Marker genes from ChemoR dominant MCs were associated with poor prognosis and significant levels of residual disease following NAC. Conclusions: Our multi-modal integrative analysis reveals unprecedented insight into the role of epigenetically defined spatially distinct, sub-clonal populations that pre-exist in treatment naïve TNBC and predict therapy response. This suggests pre-existing populations of cells have already acquired the epigenetic footprints and hence transcriptomic features to allow them to evade therapy. Citation Format: Fatemeh Ahmadimoghari, Yu Zhang, Ioanna Mavrommatis, Shafali Thakur, Chris Starling, Ioannis Roxanis, Syed Haider, Rachael Natrajan. Epigenetically defined sub-clonal heterogeneity drives therapy resistance in triple-negative breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr B059.

Dual-band independently tunable 8-element MIMO antenna for 5G smartphones

In this paper, a multi-input multi-output (MIMO) antenna for future mobile phone applications operating in sub-6 GHza using a novel combination of an E-shaped slot placed on the ground plane and an F-shaped probe is used to achieve a dual-band independently tunable antenna. The proposed antenna is not only self-isolated but it has also effectively achieved high isolation of greater than 17 dB in both 3.5 GHz (3.4 – 3.6 GHz) and 4.7 GHz (4.6 – 4.87 GHz) frequency bands for 8-element MIMO antenna configuration for 5G smartphones. The simple yet compact size of (0.035 λ0▪ 0.23 λ0), of the slot antenna produces a balanced slot mode which not only reduces the ground effects but also improves the isolation between two adjacent input ports. The novelty of the proposed dual-band MIMO antenna is its independent control of each band across a wide frequency band and results demonstrate higher efficiency (64% – 71%) and diversity gain performance in both frequency bands. Furthermore, the antenna is designed by the meticulous configurations of 8-antenna elements without employing any external decoupling structure to attain the desired polarization diversity. The prototype of this 8-element MIMO antenna is also fabricated and measured to validate its simulated performance. The simple structure of the proposed design and high efficiency makes it a promising candidate for 5G smartphones.

Polarization Diversity Glass Antenna for Consumer WiFi Routers

Polarization Diversity Glass Antenna for Consumer WiFi Routers

Dual band circularly polarized partially reflecting surface-loaded dielectric resonator-based MIMO antenna for mm-wave 5G applications

Abstract A two-port ceramic-based antenna loaded with partially reflecting surface (PRS) is structured and explored. Fan-shaped slot is utilized to create circularly polarized wave in both frequency ranges. Dual frequency ranges are due to hybrid mode creation inside the ceramic material, i.e. HEM11δ and HEM12δ modes. PRS is used to change the phase gradient, which in turn tilts the radiation beam (±35°) obtained from different port in opposite direction. This concept is useful to reduce the envelop correlation coefficient using far-field. Experimental verification confirms that the designed antenna works from 26.1 to 27.5 GHz and 31.7 to 33.6 GHz along with less than 3-dB axial ratio from 26.5 to 27.1 GHz and 31.9 to 33.1 GHz respectively. Orthogonal placement of ports introduces the concept of polarization diversity and decreases the coupling between ports by an amount of −25 dB. Good gain value (up to 7.0 dBi) and better value of diversity performance make the designed radiator applicable for 5 G millimeter-wave uses.

Performance analysis of FSO communications over a generalized turbulence fading channel with pointing error

SummaryQuantitatively assessing the performance of free space optical (FSO) communication systems requires an accurate description of turbulence induced fading. However, it is well known that common irradiance distributions inaccurately model intensity tail regions. Recently, a general fading model as the product of arbitrary number of Gamma with inverse Gamma was proposed and shown to accurately predict measurements, besides containing many well‐known models as special cases. This paper is concerned with analyzing the effect of discrepancies among different fading distributions on optical system performance in terms of bit error rates and capacity. Based on the general fading model a unified analysis of the channel structure effects on FSO communications in the presence of turbulence and pointing error is presented. The outage probability is investigated for both homodyne and direct detection schemes. Closed form expressions for the average probability of bit error for intensity modulation, phase shift keying and polarization shift keying, single‐input‐single‐output systems are given and verified by Monte‐Carlo simulations. Spatial diversity is also studied through single‐input‐multiple‐output systems. Also, the ergodic capacity is derived. Comparisons between the proposed distributions and other widely used distributions are carried out and show significant differences among existing fading models. This suggests possible improvements in the spectral efficiency and error performance design of optical wireless communication systems.

A Proposed Typology of Farming Systems for Assessing Sustainable Livelihood Development Pathways in the Tien Shan Mountains of Kyrgyzstan

In Kyrgyzstan, most farming systems focus on animal husbandry, which depends on mixtures of crops and pastures around settlements and higher-elevation summer pastures. These farms face the problems of insufficient fodder production and pasture degradation due to overgrazing, resulting in low productivity of livestock and reduced household incomes. The spatial diversity of farms often hampers the development of interventions aimed at improving crop and animal productivity, as well as sustainable grassland management, while the absence of a comprehensive and systematic classification system that effectively encompasses the diverse range of livelihood strategies within farming systems presents a significant obstacle to the advancement of initiatives promoting sustainable livelihoods. This study aimed to develop a consistent typology of smallholder farms in the Tien Shan using multivariate analysis. By analyzing data from 235 farm-households and evaluating key classification variables, we identified two distinct farming systems, upper mountain farms and lower mountain farms, based on socioeconomic and agro-ecological characteristics. Our typology considers elevation, grazing period, cultivated area, and off-farm income and better captures the diversity of farming activities and household income compared to current classification models. These findings will inform and tailor policies and interventions suitable for enhancing sustainable livelihoods in Kyrgyzstan’s mountain farming systems.

Security and Securitization as Topics in Sustainability and Tourism Research

There are many published bibliometric works in the literature on the broadly understood topics of tourism, sustainability, and security (STS). Most of these studies present an indexed approach, showing the impact of works, journals, spatial diversity, and the most frequently published or cited authors. The research and analysis undertaken in our work had a different goal: they were an attempt to answer questions about the degree of interest of researchers in the issue of STS, the dynamics of research devoted to the topics of STS, and internal differentiation in the broadly understood concept of security/danger in STS research. Data from the Web of Science journal database were used for the analysis. To determine the number of articles devoted to the topics of security, tourism, and sustainability, several combined keywords and simple statistical analyses were used. In the last 10, and especially 5 years (2019–2023), in each of the three topic groups, there has been an exponential increase in publications in journals indexed in the WoS database. In the sustainability category, risk and security received the most responses; in the tourism, COVID-19, and risk category; and in the tourism, sustainability, risk, and COVID-19 category. The use of keywords indicated thematic diversity in the field of security in each of the examined categories. The greatest interest among STS researchers was in studies related to the “COVID-19” threat. The results of the analysis allowed us to conclude there is an ongoing process of securitization in tourism research.