Shekhar Verma

A Power Aware Minimum Connected Dominating Set for Wireless Sensor Networks

Connected Dominating Set (CDS) problem in unit disk graph has a significant impact on an efficient design of routing protocols in wireless sensor networks. In this paper, an algorithm is proposed for finding Minimum Connected Dominating Set (MCDS) using Dominating Set. Dominating Sets are connected by using Steiner tree. The algorithm goes through three phases. In first phase Dominating Sets are found, in second phase connectors are identified, connected through Steiner tree. In third phase the CDS obtained in second phase is pruned to obtain a MCDS. MCDS so constructed needs to adapt to the continual topology changes due to deactivation of a node due to exhaustion of battery power. These topological changes due to power constraints are taken care by a local repair algorithm that reconstructs the MCDS i.e. Power Aware MCDS, using only neighbourhood information. Simulation results indicate both the heuristics are very efficient and result in near optimal MCDS.

Feature selection using Haar wavelet power spectrum

BackgroundFeature selection is an approach to overcome the curse of dimensionality in complex researches like disease classification using microarrays. Statistical methods are utilized more in this domain. Most of them do not fit for a wide range of datasets. The transform oriented signal processing domains are not probed much when other fields like image and video processing utilize them well. Wavelets, one of such techniques, have the potential to be utilized in feature selection method. The aim of this paper is to assess the capability of Haar wavelet power spectrum in the problem of clustering and gene selection based on expression data in the context of disease classification and to propose a method based on Haar wavelet power spectrum.ResultsHaar wavelet power spectra of genes were analysed and it was observed to be different in different diagnostic categories. This difference in trend and magnitude of the spectrum may be utilized in gene selection. Most of the genes selected by earlier complex methods were selected by the very simple present method. Each earlier works proved only few genes are quite enough to approach the classification problem [1]. Hence the present method may be tried in conjunction with other classification methods. The technique was applied without removing the noise in data to validate the robustness of the method against the noise or outliers in the data. No special softwares or complex implementation is needed. The qualities of the genes selected by the present method were analysed through their gene expression data. Most of them were observed to be related to solve the classification issue since they were dominant in the diagnostic category of the dataset for which they were selected as features.ConclusionIn the present paper, the problem of feature selection of microarray gene expression data was considered. We analyzed the wavelet power spectrum of genes and proposed a clustering and feature selection method useful for classification based on Haar wavelet power spectrum. Application of this technique in this area is novel, simple, and faster than other methods, fit for a wide range of data types. The results are encouraging and throw light into the possibility of using this technique for problem domains like disease classification, gene network identification and personalized drug design.

A Heuristic for Minimum Connected Dominating Set with Local Repair for Wireless Sensor Networks

Connected Dominating Set (CDS) problem in unit disk graph has a significant impact on an efficient design of routing protocols in wireless sensor networks. In this paper, an algorithm is proposed for finding Minimum Connected Dominating Set (MCDS) using Dominating Set. Dominating Sets are connected by using Steiner tree. The algorithm goes through three phases. In first phase Dominating Set is found, in second phase connectors are identified, connected through Steiner tree. In third phase the CDS obtained in second phase is pruned to obtain a MCDS. MCDS so constructed needs to adapt to the continual topology changes due to deactivation of a node due to exhaustion of battery power. These topological changes due to power constraints are taken care by a local repair algorithm that reconstructs the MCDS using only neighborhood information. Simulation results indicate both the heuristics are very efficient and result in near optimal MCDS.

An Adaptive Data Hiding Technique for Digital Image Authentication

The proposed scheme combines the advantages of cryptographic concept and imperceptibility feature of digital image watermarking in spatial domain. The watermark is first generated based on one-way hash function with the help of user key. Each bit of this new generated watermark is then embedded into respective blocks of the original image, in raster scan order. The embedding is performed by modifying the average value of pixel intensity of each block within a range specified by the contrast value for a given block. This reduces the effects of the modification as perceived by the human eye. The extraction procedure computes and compares the sum of the pixels values for the blocks of the original and watermarked image. The results demonstrates the robustness of scheme against common image processing operations like cropping, modification, low pass filter, median pass filter, scaled down and lossy JPEG compression with various quality index factor. Results also illustrate that the watermark is secure, recoverable and recognizable even after the watermarked image has been tampered, forged and modified by common image processing operations. The comparative study of proposed scheme with existing scheme has also been performed to observe the strength of the scheme.

Web Page Classification using Modified Naïve Bayesian Approach

This paper introduces the concept of a classification tool for Web pages called WebClassify, which uses modified naive Bayesian algorithm with multinomial model to classify pages into various categories. The tool starts the classification from downloading training Web text from Internet, preparing the hypertext for mining, and then storing Web data in a local database. The paper also gives an account of choosing naive Bayesian approach over other approaches for Web text mining. The experimental results along with the classification accuracy analysis with increasing vocabulary size, is also shown

A Design of Secure Watermarking Scheme for Images in Spatial Domain

Digital watermarking (DWM) technology has been proposed for the implementation of digital right management (DRM) system that can be used for establishing ownership right, ensuring authorized access and content authentication. The goal of this paper is to protect copyrights and content authentication of digital still images with the consideration of high level of robustness against changes made to invisible watermark contents in context to spatial domain. The proposed scheme combines the advantages of cryptographic concept and imperceptibility feature of digital image watermarking. The watermark is first generated based on hash function with the use of user key. Each bit of this new generated watermark is then encoded into respective blocks of 4times4 pixels of the original image, in raster scan order. The encoding is performed by modifying the average value of pixel intensity of each block with in a range specified by the contrast value for a given block. This reduces the effects of the modification as perceived by the human eyes. The experimental results show the robustness of scheme against common image processing operations. The results also demonstrate the location of modification as corresponding error in the extracted watermark

Service level agreements in IP networks

This paper provides an overview of service level agreements (SLAs) in IP networks. It looks at the typical components of an SLA and identifies three common approaches that are used to satisfy SLAs in IP networks. The implications of using the approaches in the context of a network service provider, a hosting service provider, and an enterprise are examined. While most providers currently offer a static insurance approach toward supporting SLAs, the schemes that can lead to more dynamic approaches are identified.

A New Heuristic Approach for Minimum Connected Dominating Set In Adhoc Wireless Networks

The Connected Dominating Set (CDS) of a graph acts as a virtual backbone in ad-hoc wireless network. In this paper, a simple and efficient algorithm is proposed for the determination of CDS in a graph. The algorithm starts by finding a root node in the graph; a priority queue is maintained centrally to decide whether an element would be a part of CDS. This concept is extended to distributed version of the algorithm where each dominated node maintains a priority queue and acts as dominator for its local domain only. Simulation results show that the proposed approach is very efficient in determining CDS especially in large and dense graphs.

MCDS based multicasting in mobile adhoc networks

Multicasting in resource constrained MANETs imposes a severe restriction on the message overhead for construction and maintenance of the multicast distribution tree. Algorithms based on minimum spanning trees (MST) or Steiner trees require reconstruction of the tree when members join or leave a multicast group in addition to change in network topology. In the present paper, multicasting based on MCDS with local repair is presented. The proposed MCDS algorithm tries to optimize the number of messages required for construction and maintenance of the multicast backbone. It is observed that when a node joins or leaves the multicast group, the time taken for repair with local route discovery is almost constant and is independent of multicast group size. Moreover, there is only a modest increase in the CDS size. The results are similar when a node that is not a member of the multicast group but forms a part of the MCDS moves away resulting in a change of the network topology.

Modified Directional Medium Access Protocol using Bootlace Lens

In this paper, a directional MAC protocol based on bootlace lens: a multiple beamforming network, is proposed and evaluated. The existing directional MAC (DMAC) protocols employ omnidirectional antenna to listen and switch to the directional mode for communication. The directional antennas allow spatial reuse and increased communication range. Omnidirectional antennas lead to hidden terminal problems, deafness, limitation of the communication range and decrease in overall utilization of the channel. The modified DMAC (MDMAC) proposed in the present work employs a set of directional antenna system that work in the directional mode only. The channel is sensed by a set of three directional antenna systems based on bootlace beamforming networks each covering an angular space of 120deg. Simulation results indicate that DMAC protocol based on bootlace lens gives higher throughput as compared to the basic DMAC protocol and IEEE 802.11 MAC protocol. The problem of hidden terminals does not exist and the problem of deafness is largely obviated