R. P. Yadav

Clusterhead selection in clustering algorithms for wireless sensor networks: A survey

Most of the research in energy efficient data gathering in data centric applications of wireless sensor networks is motivated by LEACH scheme which by allowing rotation of clusterhead role among the sensor nodes tries to distribute the energy consumption over the network. Selection of sensor node for such role rotations greatly affects the energy efficiency of the network. Hence many proposals are reported in the literature suggesting different clusterhead selection strategies. However, till now, these strategies have not been talked about for their collective understanding. So, efforts have been made, in this paper, to discuss them in unison and present a global view. Comparison of their costs of clusterhead selection in different rounds and after effects like cluster formation, distribution of clusterheads and creation of clusters shows a need of more energy efficient clusterhead selection strategy.

Design and analysis of miniaturized UWB antenna with tunable notched band

We report in this paper a novel miniaturized (12 × 18 × 1.6 mm 3 ) microstrip fed UWB antenna with tunable notched band characteristics. The proposed antenna covers the tunable notched band for IEEE 802.11a wireless local area network operating in the frequency band of 5.15–5.825 GHz. The design of proposed antenna includes annular ring radiating patch with two T-shaped strips present inside it. The band notching is obtained by adjusting coupling between T-shaped strips placed inside the annular ring. In order to achieve larger bandwidth the ground plane of the microstrip antenna is modified. The simulated return loss of the proposed antenna has been verified in fabricated antenna experimentally, which has been in good agreement.

Performance analysis of Ti∶ LiNbO 3 1×2 digital photonic switch with SiO 2 buffer layer

We demonstrate a polarization and wavelength independent digital photonic switch with optimized on-chip area coverage and reduced driving voltage. A symmetrical SiO2 buffer layer was introduced between channel and electrode regions to optimize its thermal stability and to reduce absorption losses. Switching is achieved through adiabatic mode evolution in an asymmetric waveguide junction. The switch has been found satisfactory for THz operation with switching voltages in the range of ±18-to-21V and switch losses in the range of 0.50 to 0.75% only. A channel profile of titanium indiffused waveguide on an x-cut lithium niobate substrate is used for lightwave propagation.

Design of 4×4 banyan optical switch using MMI switches with low crosstalk & low coupling loss

We introduce here a Multimode Interference (MMI) based 2times2 switch that has substantially smaller device geometry than conventional Multimode Interference (MMI) structures. This multimode structure is based on special multimode region shape and refractive index. Further we used it in to design of 4times4 optical switch based on banyan architecture. This 4times4 optical switch features small size, low coupling loss, low crosstalk and a structure, which is suitable for integration with other semiconductor optical devices. The designed 4times4 optical switch is without any integrated optical amplifiers; even then it is showing better output.

Chain based Conical Clustering (CCC) framework for data gathering in WSNs

Non uniform energy consumption of the nodes is a major area of concern in cluster based data gathering architectures proposed for wireless sensor networks in the literature and is an active area of research over recent past years. The solutions suggested in the literature, for uniform distribution of energy consumption, require rotation of clusterhead role among sensor nodes but every such rotation needs reclustering of the nodes in the network. The overhead associated with such reclustering are not actual part of data gathering activities and consume energy unnecessarily only for creating and maintaining the clusters. To avoid such unnecessary wastage of energy, due to forced reclustering associated with the clusterhead role rotation, a new hybrid clustering framework, chain based conical clustering (CCC) scheme, is proposed in this paper. CCC keeps the cluster stable and rotates the clusterhead role among the cluster members using layered chains of these cluster members. It is proved, theoretically, that CCC is expected to outperform the scheme used as a benchmark, in the clustered data gathering performance comparison, in wireless sensor network literature.

Modeling of a 2x2 multimode interference switch for wider optical window operation

This paper describes the modeling of a 2×2 multimode interference (MMI) switch, with a channel profile of Titanium indiffused Lithium Niobate. Design novelty lies in its satisfactory operation for two wide optical windows (100nm each with centre wavelengths, λcentre of 1.3 μm and 1.55 μm) with low switching losses and crosstalk levels. Index tuned regions are optimized to achieve crosstalk levels of ≥ -18 dB and ≥ -14 dB for its operation in the wavelength range of 1.25 μm - 1.35 μm and 1.50 μm - 1.60 μm respectively. For either of these wavelength ranges, the switch losses (excess and insertion losses) are maintained lower than 1 dB.

Modeling of a compact and completely non-blocking 4 × 4 multimode interference switch for optical communication applications

Modelling of a compact and completely non-blocking 4×4 optical switch utilizing integrated multi-mode interference (MMI) waveguides with a channel profile of Ti-indiffused Lithium Niobate is described. Design novelty lies in its satisfactory operation for two wide optical windows (100 nm each), with center wavelengths (λcentre) of 1.3 and 1.55 µm, possessing low losses. For either of these windows, the average value of propagation losses are maintained lower than 1 dB with a vacillation of extremely low polarization dependent losses ( ≤ 0.15u2009u2009dB). Index tuned regions are optimized to achieve average crosstalk levels better than −19 and −12u2009u2009dB for its operation in the wavelength range of 1.25 to 1.35 µm and 1.50 to 1.60 µm, respectively. It is also observed that switch possess absolute loss uniformity (of the range of 0.5% to 1.6%) with a maximum of ±2.5% tolerance in the structural parameters.

Design and Analysis of Ti: LiNbO3 1x2 Digital Optical Switch with Optimized Electrode Regions

A low loss, polarization and wavelength independent 1x2 digital optical switch (DOS) with a drive voltage of±9V is presented here. A channel profile of Titanium indiffused region on x-cut Lithium Niobate substrate is used to design the switch. Effects of various design parameters have been observed and plotted. The dopant thickness and electrode regions have been optimized to reduce on chip switch area (37.5mm x 0.04mm) and overall losses, which were limited to the range of 3% to 5% only with effective width of center electrode of 5 μm and a gap of 7 μm with side electrodes, thus improving the switch performance overall.

A particle swarm approach for uniform cluster distribution in data centric wireless sensor networks

This paper presents a scheme, in which the collaborative efforts of limited number of sensor nodes provide the social guidance for localization process to be used for uniform distribution of the clusters, over the network area. Utilizing the information provided in the form of gbest value and the direction for position update as social guidance, the sensor nodes localize them iteratively adjusting their position in the swarm, relying on the measurements obtained from RSSI. Utilizing this location information, sensor nodes assign them to different clusters. Results of the simulations carried out in NS-2, show that the proposed algorithm is capable of localizing the sensor nodes and has a great potential of uniform cluster distribution, provided RSS indicators give necessary support for distance estimation.

Performance analysis for all optical switch based on MZI switching element with SOA's

In this paper, design of an all-optical switch using MZI switching elements with SOAs and its works performance is explained. The effect of variations of output power with respect to control signal wavelength, data signal power and control signal power are examined and plotted. Also the optical spectrum and time domain analysis has been done to demonstrate its operational features.