Efficient user clustering, receive antenna selection, and power allocation algorithms for massive MIMO-NOMA systems

Massive multiple-input multiple-output (MIMO) and nonorthogonal multiple access (NOMA)-based technologies are considered as essential parts in the 5G systems to fulfill the escalating demands of higher connectivity and data rates for emerging wireless applications. In this paper, a new approach of massive MIMO-NOMA with receive antenna selection (RAS) is considered for the uplink channel to significantly increase the number of connected devices and overall sum rate capacity with improved user-fairness and less complexity. The proposed scheme is designed from two multiuser MIMO (MU-MIMO) clusters, based on the available number of radio frequency chains (RFCs) at the base station and channel conditions, followed by power-domain NOMA for the simultaneous signal transmission. We derive the sum rate and capacity region expressions for MIMO-NOMA with RAS over Rayleigh fading channels. Then, an optimal and three highly efficient sub-optimal dynamic user clustering, RAS, and power allocation algorithms are proposed for sum rate maximization under received power constraints and minimum rate requirements of the allowed users. The effectiveness of designed algorithms is verified through extensive analysis and numerical simulations compared to the reference MU-MIMO and MIMO-NOMA systems. The achieved results show a substantial increase in connectivity, up to two-fold for the accessible number of RFCs, and overall sum rate capacity while satisfying the minimum users’ rates. Besides, important tradeoffs can be realized between system performances, hardware and computational complexities, and desired user-fairness in terms of serving more users with equal/unequal rates

Extending the user capacity of MU-MIMO systems with low detection complexity and receive diversity

Multiple-input multiple-output (MIMO) based technologies are considered as an integral part of the upcoming 5G communications to fulfil the ever-increasing demands of wireless applications with high spectral efficiency requirements. However, in uplink multiuser MIMO (MU-MIMO) channels, the number of allowed users is limited by the number of receive antennas associated with radio frequency (RF) chains at the base-station and the complexity burden of multiuser detection (MUD). In this paper, a novel group layer MU-MIMO scheme with low complexity MUD is proposed to increase the number of served users well beyond the available RF chains. By taking the advantage of power control and inherent path loss in cellular systems, the allowed users are divided into groups based on their received power. Efficient group power allocation and group layer MUD (GL-MUD) are utilized to provide a valuable tradeoff between complexity and achieved performance. Furthermore, when more receive antennas than RF chains is implemented, a generalized norm based antenna selection algorithm is proposed to enhance the error performance. Symbol error probability expressions are derived and the effectiveness of proposed scheme is demonstrated through numerical simulations compared with the conventional MU-MIMO and non-orthogonal multiple-access (NOMA) systems over Rayleigh fading channels. The results show a substantial increase in user capacity up to two-fold for the available number of RF chains. In addition, significant signal-to-noise ratio gain is achieved using GL-MUD compared with different MUD techniques

PHYTOCHEMICAL STUDY OF BIOACTIVE CONSTITUENTS FROM SATUREJA MONTANA L. GROWING IN EGYPT AND THEIR ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES

 Objective: This work aimed to investigate the lipid constituents and flavonoidal compounds of Satureja montana, in addition to evaluation of different extracts and/or isolated compounds as antimicrobials and antioxidants.Methods: The volatile and lipid constituents were extracted with n-hexane by partition from hydroalcoholic extract of S. montana L. aerial parts, after then were fractionated to unsaponifiable matters and fatty acid methyl esters which were identified by gas–liquid chromatography and/or gas chromatography–mass spectrometry. The phenolic constituents were isolated from the ethyl acetate fraction of the aqueous methanolic extract of the aerial parts of the plant. The antimicrobial activity of different extracts and the isolated compounds was evaluated against Gram-positive, Gram-negative bacteria, yeast, and fungus using a modified Kirby-Bauer disc diffusion method.Results: The identified compounds are luteolin-7-rhamnoside-4'-O-β-glucopyranoside (1), quercetin-3-O-α-L-rhamnopyranoside (2), quercetin- 7-O-glucopyranoside (3), luteolin-7-O-glucopyranoside (4), 5-hydroxy-6,7,8,4'-tetramethoxy flavone (5), gallic acid (6), 2,3-hexahydroxydiphenoyl 1-galloyl glucopyranoside (7), and quercetin (8). The structure of all isolated compounds was established using different chromatographic and spectroscopic measurements (PC, thin-layer chromatography, ultraviolet [UV], 1D, 2D-nuclear magnetic resonance, and MS). Compound-2 showed the highest antibacterial activity against all the tested microorganisms. Hydroalcoholic extract exhibited high antioxidant activity (87.7%). On the other hand, hexane fraction showed a low antioxidant activity (46.4%), in addition to the compound-8 showed the highest antioxidant activity (96.27%) in 2,2-diphenyl-1-picrylhydrazyl assay.Conclusion: It can be concluded that the hydroalcoholic extract of S. montana showed significant antimicrobial and antioxidant activity

Detection of equid herpesviruses among different Arabian horse populations in Egypt

Equid herpesviruses (EHVs) threaten equine health and can cause significant economic losses to the equine industry worldwide. Different equid herpesviruses, EHV‐1, EHV‐2, EHV‐4 and EHV5 are regularly detected among horse populations. In Egypt, monitoring is sporadic but EHV‐1 or EHV‐4 have been reported to circulate in the horse population. However, there is a lack of reports related to infection and health status of horses, likely due to the absence of regular diagnostic procedures. In the current study, the circulation of four infectious equid herpesviruses (EHV‐1, EHV‐2, EHV‐4 and EHV‐5) among different Arabian horse populations and donkeys residing the same farm was monitored. Different samples were collected and DNA was extracted and subjected to quantitative (q)‐PCR to detect the four equid herpesviruses using specific primers and probes. Antibody titres against EHV‐1 and EHV‐4 were tested using virus neutralization test and type‐specific ELISA. The results showed that EHV‐1, EHV‐2, EHV‐4 and EHV‐5 are endemic and can be a continuous threat for horses in the absence of vaccination programs and frequent virus reactivation. There is an urgent need for introduction of active regular surveillance measures to investigate the presence of different equid herpesviruses, and other equine viral pathogens, in various horse populations around Egypt and to establish a standardized cataloguing of equine health status

Resistance to Soybean Cyst Nematode: Rhg1

The genes underlying rhg1 lie at a sometimes dominant sometimes co-dominant locus, necessary for resistance to all Hg types of the soybean (Glycine max (L.) Merr.) cyst nematode (Heterodera glycines). Genomic research identified; nucleotide changes within a candidate gene encoding a receptor like kinase (RLK) that were capable of altering root development and thereby part of the resistance to Hg types 0 (race 3); changes in a laccase that are capable of altering cyst development; and genes underlying changes in membrane biology. This set of three genes are subject to co-selection with a modifier locus on another linkage block. Root development is slowed in the resistant seedling and results in end of season yield loss when SCN is not present. However, in the presence of SCN resistant seedling roots grow just as vigorously as the now slower growing parasitized susceptible roots and therefore show little loss to SCN parasitism. In some genotypes but not others the RLK can act alone to confer resistance. Functional paralogs of the three gene cluster have been found on other linkage groups including A1, B1, G, and O and these can be functional in different sources of resistance like G. soja, PI 437654 and PI438489B. At rhg1 the allele differences change the structure, interacting partners and activity of the LRR protein and the laccase. The changes between the alleles result in about 30 other proteins (judged by 2 D gels), 112 metabolites (by FTICRMS) and 8 metabolites (by GCMS) to increase in abundance in roots during SCN infection in the resistant NILs. Understanding the basis of root stunting by resistance alleles will be used to improve methods for developing new nematode resistant soybean cultivars that do not suffer from the yield suppression and low seed germination rates of existing cultivars

Multi-environmental evaluation of wheat tetraploid genotypes for agronomic traits under rainfed conditions in Syria

This study was conducted at Homs, Al-Swaida and Tartous, General Commission for Scientific Agricultural Research, Syria during 2016/2017 season. Seven wheat genotypes were planted under rainfed conditions in randomized complete block design with three replications. Studied traits were days to maturity, plant height, number of grain per spike, grain weight per spike, 1000 kernal weight and grain yield per plant to evaluate variance between genotypes and locations. Results showed existence of high variance between studied genotypes in all traits especially plant height. It resulted that genotype W45193 was significantly superior in grain yield per plant with an increasing rate of 69.62% comparing to control Sham 5. Also, it was significantly superior in spike numbers with an increasing rate of 53.53%, 57.24% compared to both controls Sham 3 and Sham 5, respectively. Genotype W45064 was significantly superior in grain weight per spike and 1000 kernal weight compare to both controls Sham 3 and Sham 5. W 45194 was significantly superior in 1000 kernal weight comparing to control Sham 5 (36.34, 31.16 g), respectively. Furthermore, all studied traits (except spike number per plant) were more significant in Tartous compare to both Homs and Al-Swaida

Generation of correlated Rayleigh fading channels for accurate simulationof promising wireless communication systems

In this paper, a generalized method is proposed for the accurate simulation of equal/ unequal power correlated Rayleigh fading channels to overcome the shortcomings of existing methods. Spatial and spectral correlations are also considered in this technique for different transmission conditions. It employs successive coloring for the inphase and quadrature components of successive signals using real correlation vector of successive signal envelopes rather than complex covariance matrix of the Gaussian signals which is utilized in conventional methods. Any number of fading signals with any desired correlations of successive envelope pairs in the interval [0, 1] can be generated with high accuracy. Moreover, factorization of the desired covariance matrix is avoided to overcome the shortcomings and high computational complexity of conventional methods. Extensive simulations of different representative scenarios demonstrate the effectiveness of the proposedtechnique. The simplicity and accuracy of this method will help the researchers to study and simulate the impact of fading correlation on the performance evaluation of various multi-antenna and multicarrier communication systems. Moreover, it enables the engineers for efficient design and deployment of new schemes for feasible wireless application

The receptor like kinase at Rhg1-a/Rfs2 caused pleiotropic resistance to sudden death syndrome and soybean cyst nematode as a transgene by altering signaling responses

Background: Soybean (Glycine max (L. Merr.)) resistance to any population of Heterodera glycines (I.), or Fusarium virguliforme (Akoi, O’Donnell, Homma & Lattanzi) required a functional allele at Rhg1/Rfs2. H. glycines, the soybean cyst nematode (SCN) was an ancient, endemic, pest of soybean whereas F. virguliforme causal agent of sudden death syndrome (SDS), was a recent, regional, pest. This study examined the role of a receptor like kinase (RLK) GmRLK18-1 (gene model Glyma_18_02680 at 1,071 kbp on chromosome 18 of the genome sequence) within the Rhg1/Rfs2 locus in causing resistance to SCN and SDS. Results: A BAC (B73p06) encompassing the Rhg1/Rfs2 locus was sequenced from a resistant cultivar and compared to the sequences of two susceptible cultivars from which 800 SNPs were found. Sequence alignments inferred that the resistance allele was an introgressed region of about 59 kbp at the center of which the GmRLK18-1 was the most polymorphic gene and encoded protein. Analyses were made of plants that were either heterozygous at, or transgenic (and so hemizygous at a new location) with, the resistance allele of GmRLK18-1. Those plants infested with either H. glycines or F. virguliforme showed that the allele for resistance was dominant. In the absence of Rhg4 the GmRLK18-1 was sufficient to confer nearly complete resistance to both root and leaf symptoms of SDS caused by F. virguliforme and provided partial resistance to three different populations of nematodes (mature female cysts were reduced by 30–50%). In the presence of Rhg4 the plants with the transgene were nearly classed as fully resistant to SCN (females reduced to 11% of the susceptible control) as well as SDS. A reduction in the rate of early seedling root development was also shown to be caused by the resistance allele of the GmRLK18-1. Field trials of transgenic plants showed an increase in foliar susceptibility to insect herbivory. Conclusions: The inference that soybean has adapted part of an existing pathogen recognition and defense cascade (H.glycines; SCN and insect herbivory) to a new pathogen (F. virguliforme; SDS) has broad implications for crop improvement. Stable resistance to many pathogens might be achieved by manipulation the genes encoding a small number of pathogen recognition proteins

Statistical inference for the Nadarajah-Haghighi distribution based on ranked set sampling with applications

In this article, the maximum likelihood and Bayes inference methods are discussed for determining the two unknown parameters and specific lifetime parameters of the Nadarajah-Haghighi distribution, such as the survival and hazard rate functions, with the inclusion of ranked set sampling and simple random sampling. The estimated confidence intervals for the two parameters and any function of them are developed based on the Fisher-information matrix. Metropolis-Hastings algorithm and Lindley-approximation are used for generating the Bayes estimates and related highest posterior density credible ranges for the unknown parameters and reliability parameters under the presumption of conjugate gamma priors. A Monte-Carlo simulation study and a real-life data set have been used to assess the efficacy of the proposed methods