Transmit Diversity Research Articles

Cluster-Based Transmission Diversity Optimization in Ultra Reliable Low Latency Communication

Intra-vehicular communication is an emerging technology explored spontaneously due to higher wireless sensor-based application demands. To meet the upcoming market demands, the current intra-vehicular communication transmission reliability and latency should be improved significantly to fit with the existing 5G and upcoming 6G communication domains. Ultra-Reliable Low-Latency Communication (URLLC) can be widely used to enhance the quality of communication and services of 5G and beyond. The 5G URLLC service is highly dependable for transmission reliability and minimizing data transmission latency. In this paper, a multiple-access scheme named Cluster-based Orthogonal Frequency Subcarrier-based Multiple Access (C-OFSMA) is proposed with 5G URLLC’s high requirement adaptation for intra-vehicular data transmission. The URLLC demanded high reliability of approximately 99.999% of the data transmission within the extremely short latency of less than 1 ms. C-OFSMA enhanced the transmission diversity, which secured more successful data transmission to fulfill these high requirements and adapt to such a network environment. In C-OFSMA, the available sensors transmit data over specific frequency channels where frequency selection is random and special sensors (audio and video) transmit data over dedicated frequency channels. The minimum number of subcarrier channels was evaluated for different arrival rates and different packet duplication conditions in order to achieve 99.999% reliability within an air-interface latency of 0.2 ms. For the fixed frequency channel condition, C-OFSMA and OFSMA were compared in terms of reliability response and other packet duplication. Moreover, the optimal number of clusters was also evaluated in the aspects of the reliability response for the C-OFSMA system.

Integration of rhythmic metabolome and transcriptome provides insights into the transmission of rhythmic fluctuations and temporal diversity of metabolism in rice.

Various aspects of the organisms adapt to cyclically changing environmental conditions via transcriptional regulation. However, the role of rhythmicity in altering the global aspects of metabolism is poorly characterized. Here, we subjected four rice (Oryza sativa) varieties to a range of metabolic profiles and RNA-seq to investigate the temporal relationships of rhythm between transcription and metabolism. More than 40% of the rhythmic genes and a quarter of metabolites conservatively oscillated across four rice accessions. Compared with the metabolome, the transcriptome was more strongly regulated by rhythm; however, the rhythm of metabolites had an obvious opposite trend between day and night. Through association analysis, the time delay of rhythmic transmission from the transcript to the metabolite level was ∼4 h under long-day conditions, although the transmission was nearly synchronous for carbohydrate and nucleotide metabolism. The rhythmic accumulation of metabolites maintained highly coordinated temporal relationships in the metabolic network, whereas the correlation of some rhythmic metabolites, such as branched-chain amino acids (BCAAs), was significantly different intervariety. We further demonstrated that the cumulative diversity of BCAAs was due to the differential expression of branched-chain aminotransferase 2 at dawn. Our research reveals the flexible pattern of rice metabolic rhythm existing with conservation and diversity.

ILP models and improved methods for the problem of routing and spectrum allocation

Elastic Optical Networks (EONs) using a flexible wavelength allocation technique with smaller granularity of spectrum can improve the efficiency and flexibility for diverse traffic transmission. However, due to the small granularity in EONs, the resource allocation problems become more complicated than that of the existing network architecture. By classifying the integer linear programming (ILP) models for solving the resource allocation problem on EONs into four categories, i.e., path/slot, path/channel, node/slot and node/channel, the characteristics of each are reviewed and tighter lower bounds estimation schemes for these ILP models are designed. Also, for channel models (i.e., path/channel and node/channel models), we propose two improved channel generation methods in pre-processing to reduce the number of variables. In the comparative experiments, we show the superiority of our methods, and by using them, analyze the characteristics of the four models.

An Aggregated Data Integration Approach to the Web and Cloud Platforms through a Modular REST-Based OPC UA Middleware.

The Internet of Things (IoT) empowers the development of heterogeneous systems for various application domains using embedded devices and diverse data transmission protocols. Collaborative integration of these systems in the industrial domain leads to incompatibility and interoperability at different automation levels, requiring unified coordination to exchange information efficiently. The hardware specifications of these devices are resource-constrained, limiting their performance in resource allocation, data management, and remote process supervision. Hence, unlocking network capabilities with other domains such as cloud and web services is required. This study proposed a platform-independent middleware module incorporating the Open Platform Communication Unified Architecture (OPC UA) and Representational State Transfer (REST) paradigms. The object-oriented structure of this middleware allows information contextualization to address interoperability issues and offers aggregated data integration with other domains. RESTful web and cloud platforms were implemented to collect this middleware data, provide remote application support, and enable aggregated resource allocation in a database server. Several performance assessments were conducted on the developed system deployed in Raspberry Pi and Intel NUC PC, which showed acceptable platform resource utilization regarding CPU, bandwidth, and power consumption, with low service, update, and response time requirements. This integrated approach demonstrates an excellent cost-effective prospect for interoperable Machine-to-Machine (M2M) communication, enables remote process supervision, and offers aggregated bulk data management with wider domains.

Field Evaluation of Transmit Diversity Code Filter Sets in ATSC 3.0 Single Frequency Networks

Advanced Television Systems Committee (ATSC) 3.0, a recently developed terrestrial broadcasting standard, supports a Single Frequency Network (SFN), which extends service coverage and enhances received field strength without additional frequency resources. In SFN, multiple transmitters emit identical ATSC 3.0 broadcasting signals, which may cause constructive or destructive interference on a receiver side. The worst situation occurs when two signals from different transmitters are received with the opposite phase and similar power within a sample time, causing the cancellation of the received signal. In order to prevent such signal cancellation, ATSC 3.0 adopted transmitter diversity code filter sets (TDCFS), which is a frequency domain pre-distortion scheme to minimize cross-correlation among multiple transmitter signals in SFN. This paper sets up an ATSC 3.0 SFN consisting of two transmitter sites, transmitting high definition (HD) for mobile service and 4K ultra high definition (UHD) for fixed service. Layered division multiplexing (LDM) and time division multiplexing (TDM) are used to simulcast the two services with different robustness in the same radio frequency (RF) channel. Then, performance is evaluated using a threshold of visibility (ToV) and a successful reception rate. The time and frequency channel responses are changed at the same reception area when TDCFS is applied so the results show that reception performance is improved in the worst situation in SFN.

Transmit diversity scheme design for rectangular pulse shaping based OTFS

This paper investigates the transmission scheme of the orthogonal time frequency space (OTFS) system with multiple antennas. Previous works have studied the multi-antenna transmitter diversity scheme with the ideal pulse shaping in OTFS systems assuming the wireless channels of two consecutive frames duration are invariant. However, the ideal pulse shaping can not be realized in practice and the channel varies rapidly in two consecutive frames in the high-speed mobility scenarios. To this end, we redesign the multi-antenna transmitter diversity scheme to ensure its practicability in the rectangular-pulse-based OTFS systems. At first, the information symbols of each antenna are divided into two half frames along the Doppler domain. Then, the guard symbols are carefully arranged to eliminate the interference between two half frames, and to ensure the equivalent channels of two half frames being identical. By considering the positions of the guard symbols, the transmission codeword is designed and a low complexity linear detection is proposed. Finally, simulation results validate that the bit error rate performance of the proposed scheme has the superiority over the existing works.

Transmission potential of human schistosomes can be driven by resource competition among snail intermediate hosts

Predicting and disrupting transmission of human parasites from wildlife hosts or vectors remains challenging because ecological interactions can influence their epidemiological traits. Human schistosomes, parasitic flatworms that cycle between freshwater snails and humans, typify this challenge. Human exposure risk, given water contact, is driven by the production of free-living cercariae by snail populations. Conventional epidemiological models and management focus on the density of infected snails under the assumption that all snails are equally infectious. However, individual-level experiments contradict this assumption, showing increased production of schistosome cercariae with greater access to food resources. We built bioenergetics theory to predict how resource competition among snails drives the temporal dynamics of transmission potential to humans and tested these predictions with experimental epidemics and demonstrated consistency with field observations. This resource-explicit approach predicted an intense pulse of transmission potential when snail populations grow from low densities, i.e., when per capita access to resources is greatest, due to the resource-dependence of cercarial production. The experiment confirmed this prediction, identifying a strong effect of infected host size and the biomass of competitors on per capita cercarial production. A field survey of 109 waterbodies also found that per capita cercarial production decreased as competitor biomass increased. Further quantification of snail densities, sizes, cercarial production, and resources in diverse transmission sites is needed to assess the epidemiological importance of resource competition and support snail-based disruption of schistosome transmission. More broadly, this work illustrates how resource competition can sever the correspondence between infectious host density and transmission potential.

Parity-Check Coding Transmit Diversity for Wireless Communications With High Mobility

Highmobility is an important scenario for the 5G wireless communications. However, the high mobility results in serious time-varying fading, bringing challenges to the reliabilities of wireless transmission. Diversity technique is an essential method to overcome the effect of fading. It is noted that an LDPC (low-density parity-check) code is a concatenation of single parity-check codes (SPC) and repetition codes (REP) by a random interleaver, and a REP can be viewed as a typical example for achieving time/frequency diversity. Thus, it is appealing to jointly consider LDPC codes and diversity techniques. This paper presents parity-check coding transmit diversity (PCTD) schemes based on half-rate invertible LDPC codes, which are capable of achieving both diversity and coding gains from the time-varying fading channels. Besides, we investigate two types of PCTD schemes, and take into consideration two transmission modes, which are single-carrier (SC) and orthogonal frequency division multiplexing (OFDM) transmission modes. A chase combining based message passing algorithm (CC-MPA) is proposed for the proposed schemes, which can take full advantages of signal processing and coding gains. Furthermore, the Shannon limits of time-varying fading channels with BPSK signaling are deduced. Simulation results show that the proposed PCTD with CC-MPA algorithm can provide better BER performances than the classical time-domain diversity scheme in time-varying fading channels, which is appealing for the high mobility communications.

Performance Evaluation of Channel Equalizer Techniques in LTE-Advanced under Vehicular Environments

The 3GPP LTE standard has developed into the most innovative wireless technology for future generations, capable of data transmission data at rates exceeding 1 Gbps. Improving total user communication performance highly depends on selecting the detection technique correctly, however, by choosing the proper mode of transmission. We analyzed channel equalization techniques Minimum Mean Square Error (MMSE) and Soft-Sphere Decoder (SSD), at the downlink of physical-layer of LTE‑A system under MIMO technology, besides studying the characteristics of utilizing various transmission schemes such-as Transmit Diversity (TxD) and Spatial Multiplexing (SM) (Open-Loop SM (OLSM) and Closed-Loop SM (CLSM)). For MIMO technology, the 4x2 configuration of transmitter-receiver antennas is preferred. To simulate and evaluate the system’s performance in throughput and Bit Error Rate (BER) used the LTE-A link level simulation program developed by “The Vienna University of Technology” which used in MATLAB, across various channel type including Vehicular-A (VehA) at a speed of 30km/s and Vehicular-B (VehB) at a speed of 120km/s.

A Multi-Cluster-Based Distributed CDD Scheme for Asynchronous Joint Transmissions in Local and Private Wireless Networks

In this paper, a multiple cluster-based transmission diversity scheme is proposed for asynchronous joint transmissions (JT) in private networks. The use of multiple clusters or small cells is adopted to reduce the transmission distance to users thereby increasing data-rates and reducing latency. To further increase the spectral efficiency and achieve flexible spatial degrees of freedom, we consider that a distributed remote radio unit system (dRRUS) is installed in each of the clusters. A key characteristic of deploying the dRRUS in private networks is the associated multipath-rich and asynchronous delay propagation environment. Therefore, we consider asynchronous multiple signal reception at the remote radio units and propose an intersymbol interference free distributed cyclic delay diversity (dCDD) scheme for JT to achieve the full transmit diversity gain without requiring full channel state information of the private network. The spectral efficiency of the proposed dCDD-based JT is analyzed by deriving a new closed-form expression, and then compared with link-level simulations for non-identically distributed frequency selective fading over the entire network. Due to its distributed structure, the dRRUS relies on backhaul communications between the private network server and cluster master (CM), which is the main backhaul connection, and between the CM to remote radio units, which are the secondary backhaul connections. Thus, it is important for us to investigate the impact of reliability of main and secondary backhaul connections on the system. Our results show that the resulting composite backhaul connections can be accurately modeled by our proposed product of independent Bernoulli processes.

Performance Analysis of Cooperative Multiple Access With Minimum Interference Range for Large Scale Wireless Networks

Cooperative communication techniques are widely used in large-scale wireless networks for improving network throughput. This is achieved through the creation of transmission diversity by forming multiple cooperative transmission links which involve several relaying nodes as helpers for an end-to-end data transmission. Consequently, link interference range will inevitably be enlarged, which will adversely hamper the diversity created and offset the network throughput improvement as a result. This problem has not been properly addressed by most cooperative communication protocols reported so far. In this paper, a novel protocol that performs cooperative medium access control as well as minimizes the interference range, namely MIR-CMAC, is proposed to directly address the enlarged link interference range problem introduced by cooperative communication. Specifically, functions like channel reservation, cooperative priority differentiation and contention for relay selection are collectively enabled in MIR-CMAC to reduce channel access collision and select the suitable helper node that can maximize the integrated link data rate and minimize the link interference concerned. In addition, a full interference model is established to evaluate the effect of interference across the whole process from channel access to packet transmission and derive a new network throughput analysis method for MIR-CMAC. Both numerical and simulation results demonstrate the effectiveness of MIR-CMAC and its performance improvements over other protocols.

HIGH QUALITY LOW BITRATE VOICE CODEC FOR TRANSMISSION OVER ADVANCED LTE

In mobile communication systems bit-rate reductions while maintaining an acceptable voice quality are necessary to achieve efficiency in channel bandwidth utilization and users satisfaction. As Long-Term Evolution(LTE) converging towards all-IP solutions and supporting VOIP service, the voice signals are converted into coded digital bit-stream and sent over the network. This paper proposes the implementation of codebook excited linear prediction (CELP) voice codec algorithm based on two source-rates of low 9.6Kbps and medium 16Kbps for achieving a perceptible level of voice quality, while efficiently using available bandwidth during the transmission over advanced LTE. The architecture of proposed CELP codec model is implemented to decompose the voice signal into a set of parameters that characterize each particular frame at the encoder part, these parameters are quantized and encoded for transmission to the decoder. The investigation showed that the configuration of the link and the applied CELP codec mode mainly influence on the obtained voice capacity and quality. The quantifying also shows that the voice quality can be traded for the enhanced capacity, since the low rate codec will produce lower voice quality than higher rate codec. Also, this paper is achieved, during theconfiguration of the system with higher channel quality indicator (CQI) index, increasing in the capacity gain to a saturated value of about 500 and 1000 users per cell over 5MHz bandwidth for transmit diversity (TD) and Open-Loop Spatial Multiplexing (OLSM) respectively and up to 1000 and 2000 users per cell over 10MHz channel bandwidth for TD and OLSM respectively.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from two provinces in South Africa: a retrospective study.

Background:Herpes simplex virus (HSV) is a widely distributed human pathogen that is known for its ulcerative lesions at the infection site. HSV can cause persistent infection in the host that is often followed by a period of latency within the neurons. Considering the high rate of HIV infection in South Africa, it is important to assess the seroprevalence of HSV with a focus to determine the epidemiological association between HSV-DNA and HIV-1 in the population. Methods:A total of 44 sera samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results:Of the 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The PCR results, with the use of type specific primers, showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using the chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions:There is a significant positive association between HSV-2 and HIV-1 in the study population. Our study shows that some of the HSV-2 isolates are not related to the clinical isolate SD90e from South Africa, suggesting diversity in HSV-2 viral transmission.

Eastern Equine Encephalitis Virus Taxonomy, Genomics, and Evolution.

Eastern equine encephalitis virus (EEEV; Togaviridae, Alphavirus) is an arthropod-borne virus (arbovirus) primarily maintained in an enzootic cycle between Culiseta melanura (Coquillett) and passerine birds. EEEV, which has the highest reported case- fatality rate among arbovirus in the Americas, is responsible for sporadic outbreaks in the Eastern and Midwest United States. Infection is associated with severe neurologic disease and mortality in horses, humans, and other vertebrate hosts. Here, we review what is known about EEEV taxonomy, functional genomics, and evolution, and identify gaps in knowledge regarding the role of EEEV genetic diversity in transmission and disease.

Low Complexity Anti-Interference Equalization for Broadband Single-Carrier Systems With Transmit Diversity

In this paper, we consider single carrier system with transmit diversity and a new multi-antenna transmission waveform is carefully designed to enable low-complexity anti-interference adaptive equalization. We propose a new space-frequency adaptive equalization method which makes use of the mutual interferences among different antennas from the desired user rather than attempts to completely remove them. We further propose two different ways to significantly reduce the computational complexity based on the idea of subband-wise processing with little sacrifice of equalization performance. Simulation results show that the proposed method exhibits a significant gain over conventional anti-interference schemes.

Teaching Culturally Diverse Choral Music With Intention and Care: A Review of Literature

In this literature review, I examined choral education research that extends beyond Eurocentric norms and in which researchers focused on the transmission of culturally diverse music and/or culturally diverse transmission practices that may connect to culturally diverse choral singers. I focused on practical implications for teaching culturally diverse music with intention and care. Research findings and implications illuminate possibilities for authentic, respectful, and culturally responsive teaching preparation, such as ways to decide on the song(s) one will teach, locate informants and resources, and learn about particular music. Additionally, one can draw meaningful insights for transmission and implementation, such as considerations for teaching context, foreign languages, vocal tone, expression, and movement.Ultimately, I summarized reported practices around building community, collaborative learning, and “horizontal leadership,” which may be apt for building firsthand appreciation and awareness of (culturally diverse) choir peers.

Optical Wireless Communications Using Signal Space Diversity with Spatial Modulation

A signal space diversity (SSD) scheme was proposed to be incorporated with spatial modulation (SM) in an intensity-modulation/direct-detection-based multiple-input-single-output (MISO) indoor optical wireless communication (OWC) system to improve bit-error-rate (BER) performance and system throughput. SSD was realized via signal constellation rotation and diversity interleaving using different channel gains to improve the BER. With SM incorporated, the MISO-OWC system throughput increased. Theoretical BER expressions of the SSD scheme were established for the first time by investigating the distance of neighboring constellation symbols upon maximum-likelihood detection. Such BER expressions were further verified by numerical results. The results showed that, except for the slightly-lower-accuracy performance brought by comparable distances of neighboring constellation symbols in cases of low signal-to-noise ratios, these BER expressions were accurate in most scenarios. Moreover, theoretical investigations of channel gain distributions were performed at different signal constellation rotation angles to show the capability of the SSD scheme to improve the BER. The results showed that a significantly improved BER by two orders of magnitude could be achieved using a reasonably high channel-gain ratio and a larger constellation rotation angle. The SSD-SM scheme provides a promising option to achieve transmitter diversity with an enhanced throughput in high-speed indoor OWC systems.

Inter-Module Physical Interactions: A Force-Transmissive Modular Structure for Whole-Body Robot Motion

Robots are required to be significantly compliant and versatile to work in unstructured environments. In a number of studies, robots have positively exploited the environments during interactions and completed tasks from a morphological viewpoint. Modular robots can help realize real-world adaptive robots. Researchers have been investigating the actuation, coupling, and communication mechanisms among these robots to realize versatility. However, the diverse force transmission among modules needs to be further studied to achieve the adaptive whole-body dynamics of a robot. In this study, we fabricated a modular robot and proposed the realization of force transmission on this robot, by constructing fluid transferable network systems on the actuation modules. By exploiting the physical property variations of the modular robot, our experimental results prove that the robot’s motion can be changed by switching the connection pattern of the system.

Seroprevalence and characterisation of herpes simplex virus from human immunodeficiency virus in samples collected from two provinces in South Africa: a retrospective study

Background: Herpes simplex virus (HSV) is a widely distributed human pathogen that is known for its ulcerative lesions at the infection site. HSV can cause persistent infection in the host that is often followed by a period of latency within the neurons. Considering the high rate of HIV infection in South Africa, it is important to assess the seroprevalence of HSV with a focus to determine the epidemiological association between HSV-DNA and HIV-1 in the population. Methods: A total of 44 sera samples were screened for HSV and HIV-1 using the highly sensitive enzyme-linked immunosorbent assay (ELISA). The ELISA positive samples were characterized using polymerase chain reaction (PCR) to confirm the positivity of both viruses and to further differentiate HSV into HSV-1 and -2. Thereafter, the samples were analysed for relatedness using phylogenetic analysis. Results: Of the 44 samples, 36 (81.8%) were positive for HIV-1, while 35 (79.5%) were positive for HSV when screened with ELISA kits. The PCR results, with the use of type specific primers, showed that 4/35 (11.4%) samples were specific for HSV-1 while 30/35 (85.7%) were specific for HSV-2. Statistical analysis performed using the chi-squared goodness-of-fit test showed that there is a significant relationship between HSV-2 and HIV-1 transmission. Conclusions:There is a significant relationship between HSV-2 and HIV-1 in the study population. Our study shows that some of the HSV-2 isolates are not related to the clinical isolate SD90e from South Africa, suggesting diversity in HSV-2 viral transmission.

SARS-CoV-2 whole-genome sequencing using reverse complement PCR: For easy, fast and accurate outbreak and variant analysis.

During the course of the SARS-CoV-2 pandemic reports of mutations with effects on spreading and vaccine effectiveness emerged. Large scale mutation analysis using rapid SARS-CoV-2 Whole Genome Sequencing (WGS) is often unavailable but could support public health organizations and hospitals in monitoring transmission and rising levels of mutant strains. Here we report a novel WGS technique for SARS-CoV-2, the EasySeq™ RC-PCR SARS-CoV-2 WGS kit. By applying a reverse complement polymerase chain reaction (RC-PCR), an Illumina library preparation is obtained in a single PCR, thereby saving time, resources and facilitating high-throughput screening. Using this WGS technique, we evaluated SARS-CoV-2 diversity and possible transmission within a group of 173 patients and healthcare workers (HCW) of the Radboud university medical center during 2020. Due to the emergence of variants of concern, we screened SARS-CoV-2 positive samples in 2021 for identification of mutations and lineages. With use of EasySeq™ RC-PCR SARS-CoV-2 WGS kit we were able to obtain reliable results to confirm outbreak clusters and additionally identify new previously unassociated links in a considerably easier workaround compared to current methods. Furthermore, various SARS-CoV-2 variants of interest were detected among samples and validated against an Oxford Nanopore sequencing amplicon strategy which illustrates this technique is suitable for surveillance and monitoring current circulating variants.