Wireless Sensor Networks: A Performance Study of IEEE 802.15.4 Standard

Wireless Sensor Networks (WSN) play a key role in sensing, computing and communicating the information in most of the fields bringing substantial improvements in a broad spectrum of modern technologies. Data to be routed from source to destination is very difficult in WSN due to the mobility of the network elements and lack of central administration. In this paper an attempt has been made to evaluate the performance of routing protocol Ad-hoc On-demand Distance Vector routing (AODV) for the wireless sensor nodes(IEEE 802.15.4 standard). The performance of routing protocol is analysed using various metrics like total packets received, throughput, average end-to-end delay, total bytes received and average jitter using Qualnet 5.0.2 simulator

Crystallization and preliminary crystallographic analysis of the DNA gyrase B protein from B-stearothermophilus

DNA gyrase B (GyrB) from B. stearothermophilus has been crystallized in the presence of the non-hydrolyzable ATP analogue, 5'-adenylpl-beta-gamma-imidodiphosphate (ADPNP), by the dialysis method. A complete native data set to 3.7 Angstrom has been collected from crystals which belonged to the cubic space group I23 with unit-cell dimension a = 250.6 Angstrom. Self-rotation function analysis indicates the position of a molecular twofold axis. Low-resolution data sets of a thimerosal and a selenomethionine derivative have also been analysed. The heavy-atom positions are consistent with one dimer in the asymmetric unit

Mushroom diversity in the Biligiri rangana hills of Karnataka (India)

Evergreen forests of Biligiri rangana hills (BR hills) spread over an area of 540 sq. KM over eastern most edge of Western Ghats in Karnataka. Climatic conditions are more favorable for establishment of mushrooms and complete their life cycle. In this study, fourteen mushroom species were collected from BR hills region during monsoon (June through September 2013) with the help of Solega tribe inhabited the region since many years. Of the fourteen mushrooms, two mushrooms were identified as Ganoderma lucidum and Polyporous flabelliformis based on their phenotypic characters. The other 12 mushrooms were identified by ITS (Internal Transcribed spacer)region sequence homology as Termitomyces sp. (BRM-3)., Auricularia delicate (BRM-4), Termitomyces microcarpus (BRM-5), Amanita sp. (BRM-6), Podoscypha petalodes (BRM-7), Agaricaceae sp. (BRM-8), Macrolepiota sp.(BRM-9), Calvatia holothurioides (BRM-10), Gymnopillus crociphyllus (BRM-11), Coprinus comatus (BRM-12), Gyrodontium sacchari (BRM-13) and Clitocybeafffellea (BRM-14). Among the fourteen mushrooms, three species viz., Termito-myces species, Auricularia delicate and Termitomyces microcarpus were edible. The others were non edible/poisonous species. This study reports the diverse mushroom species as addition to biodiversity at BR hills

A Performance Study of Proactive, Reactive and Hybrid Routing Protocols using Qualnet Simulator

The advancement in information technology and the need for large-scale communication infrastructures has triggered the era of Wireless Sensor Networks (WSNs). Mobile ad-hoc network (MANET) is a network of wireless mobile nodes which communicate with each other without any centralized control or established infrastructure. Routing is the process of selecting paths in a network along which data is to be sent. Routing is a critical task in MANET where the nodes are mobile. Dynamic and reliable routing protocols are required in the ad-hoc wireless networks, as they have no infrastructure (base station) and their network topology changes. There are various protocols for handling the routing problem in the ad-hoc wireless network environment. In this paper focus is given on studying the performance evaluation of various routing protocols using Qualnet simulator 5.0.2. The performance of the proactive, reactive and hybrid protocols are analyzed with different node densities for mobile and stationary nodes. The metrics used for the performance evaluation include average jitter, throughput, packet delivery ratio and average end to end delay

Scenario Based Study of On-demand reactive routing protocol for IEEE-802.11 and 802.15.4 standards

Routing data from source to destination is hard in Mobile Ad-Hoc Networks (MANET) due to the mobility of the network elements and lack of central administration. The main method for evaluating the performance of MANETs is simulation. In this paper performance of Ad-hoc On-demand Distance Vector (AODV) reactive routing protocol is studied by considering IEEE 802.11 and IEEE 802.15.4 standards. Metrics like average end-to-end delay, packet delivery ratio, total bytes received and throughput are considered for investigating simulation scenario by varying network size with 10 mps node mobility. Also simulation has been carried out by varying mobility for scenario with 50 nodes

Performance Evaluation of Connection Admission Control for IEEE 802.16 Networks

Quality of Service (QoS) provisioning to the various kinds of network traffic is one of the major design criteria of IEEE 802.16 WiMAX standard. The MAC and physical layers of 802.16 standards are designed to support different types of real time application by providing QoS. Scheduling, Connection Admission Control (CAC) and traffic policing are the major issues to ensure QoS. In standard, scheduling and admission control are kept as open issues. Admission control is the ability of a network to control admission of new traffic based on the availability of resources. As per the specification the CAC considers minimum reserved rate of a connection as an admission criterion, in which the system can admit more connections, but packets of admitted connection may encounter large delays. In this paper average data rate (avg-rate CAC) and maximum sustained rate (max-rate CAC) of the connections are considered as admission criteria in CAC, along with minimum reserved rate (min-rate CAC). The performance of the WiMAX network is evaluated and compared for min-rate, avg-rate and max-rate CAC by considering the performance metrics such as number of connections admitted, throughput and delay using QualNet simulation tool

Simulation Study on Improved AODV Routing protocol

Mobile Ad-hoc Network (MANET) is a network of wireless mobile nodes which communicate with each other without any centralized control or established infrastructure. Routing is a critical task in MANET where the nodes are mobile. In this paper an attempt has been made to evaluate the performance of prominent routing protocol of MANET: Ad-hoc On-Demand Distance Vector Routing (AODV) and Improved Ad-hoc On-Demand Distance Vector Routing (I-AODV) protocol. The performance differentials are analysed using various metrics like throughput, average end-to-end delay, total bytes received and average jitter

Comparison of DNA and RNA, and Cultivation Approaches for the Recovery of Terrestrial and Aquatic Fungi from Environmental Samples

Estimates of fungal biodiversity from environmental samples are all subject to bias. Major issues are that the commonly adopted cultivation-based approaches are suitable for taxa which grow readily under laboratory conditions, while the DNA-based approaches provide more reliable estimates, but do not indicate whether taxa are metabolically active. In this study, we have evaluated these approaches to estimate the fungal diversity in soil and freshwater samples from a subtropical forest, and compared these to RNA-based culture-independent approach intended to indicate the metabolically active fungal assemblage. In both soil and freshwater samples, the dominant taxon recovered by all three approaches was the same (Anguillospora furtiva). This taxon was cultivable from all samples and comprised 85–86 % DNA libraries and 90–91 % RNA libraries. The remaining taxa were phylogenetically diverse and spanned the Ascomycota, Basidiomycota, and Fungi incertae sedis. Their recovery was not consistent among the three approaches used and suggests that less abundant members of the assemblage may be subjected to greater bias when diversity estimates employ a single approach. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00284-012-0256-7) contains supplementary material, which is available to authorized users

Performance Analysis of ARQ Mechanism in WiMAX Networks

WiMAX (Worldwide Interoperability for MicrowaveAccess) is the IEEE 802.16 standards-based wireless technology, provides Broadband Wireless Access (BWA) for Metropolitan Area Networks (MAN). The Automatic Repeat reQuest (ARQ) mechanism in WiMAX uses a feedback channel for the confirmation of error-free packet delivery or for packet retransmission request. This method can increase network throughput when radio channel condition is worse. In this paper attempt has been made to study the effect of implementation of ARQ on the performance of WiMAX network through simulation. Simulation study has been carried out for WiMAX network with and without enabling ARQ. The performance is been compared by considering the performance metrics like throughput, delay and jitter

Geometric multiaxial representation of N-qubit mixed symmetric separable states

Study of an N qubit mixed symmetric separable states is a long standing challenging problem as there exist no unique separability criterion. In this regard, we take up the N-qubit mixed symmetric separable states for a detailed study as these states are of experimental importance and offer elegant mathematical analysis since the dimension of the Hilbert space reduces from 2N to N + 1. Since there exists a one to one correspondence between spin-j system and an N-qubit symmetric state, we employ Fano statistical tensor parameters for the parametrization of spin density matrix. Further, we use geometric multiaxial representation (MAR) of density matrix to characterize the mixed symmetric separable states. Since separability problem is NP hard, we choose to study it in the continuum limit where mixed symmetric separable states are characterized by the P-distribution function λ (ᶿ, Φ) We show that the N-qubit mixed symmetric separable state can be visualized as a uniaxial system if the distribution function is independent of ᶿ, and Φ. We further choose distribution function to be the most general positive function on a sphere and observe that the statistical tensor parameters characterizing the N-qubit symmetric system are the expansion coefficients of the distribution function. As an example for the discrete case, we investigate the MAR of a uniformly weighted two qubit mixed symmetric separable state. We also observe that there exists a correspondence between separability and classicality of states