Recent Trends in Networks and Communications

The rapidly increasing importance of wireless communications together with the rapid growth of high speed networks, pose new challenges to transmission control protocol (TCP). To overcome them, a wide variety of TCP enhancements has been presented in the literature with different purposes and capabilities. Cross-layering represents a perspective design principle for adapting natively wired protocols to the wireless scenario and for improving their performance. In this paper, a novel cross-layer approach (Link Layer CLAMP –TCP [L

2

CLAMP-TCP]) designed for performance enhancement of TCP over a large variety of wireless networks is proposed. L

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CLAMP-TCP avoids TCP Acknowledgement (ACK) packet transmission over the wireless channel, thereby saving time, which can be utilized by the nodes for data packet delivery. The TCP Acknowledgement is generated at the base station itself. The congestion measure is also calculated at the base station based on which the receiver advertised window is calculated. The protocol performance is compared with existing TCP New Reno and TCP New Reno with CLAMP.

Several approaches have been introduced in literature for active noise control (ANC) systems. Since FxLMS algorithm appears to be the best choice as a controller filter, researchers tend to improve performance of ANC systems by enhancing and modifying this algorithm. In this paper, the existing FxLMS algorithm is modified which provides a new structure for improving the tracking performance and convergence rate. The secondary signal y (n) is thresholded by Wavelet transform to improve tracking. The convergence rate is improved dynamically by varying the step size of the error signal.

The main objective of this paper is to explore the effectiveness of perceptual features combined with pitch for text independent speaker recognition. In this algorithm, these features are captured and Gaussian mixture models are developed representing L feature vectors of speech for every speaker. Speakers are identified based on first finding posteriori probability density function between mixtures of speaker models and test speech vectors. Speakers are classified based on maximum probability density function which corresponds to a speaker model. This algorithm gives the good overall accuracy of 98% for mel frequency perceptual linear predictive cepstrum combined with pitch for identifying speaker among 8 speakers chosen randomly from 8 different dialect regions in “TIMIT” database by considering GMM speaker models of 12 mixtures. It also gives the better average accuracy of 95.75% for the same feature with respect to 8 speakers chosen randomly from the same dialect region for12 mixtures GMM speaker models. Mel frequency linear predictive cepstrum gives the better accuracy of 96.75% and 96.125% for GMM speaker models of 16 mixtures by considering speakers from different dialect regions and from same dialect region respectively. This algorithm is also evaluated for 4, 8 and 32 mixtures GMM speaker models. 12 mixtures GMM speaker models are tested for population of 20 speakers and the accuracy is found to be slightly less as compared to that for the the speaker population of 8 speakers. The noteworthy feature of speaker identification algorithm is to evaluate the testing procedure on identical messages for all the speakers. This work is extended to speaker verification whose performance is measured in terms of % False rejection rate, % False acceptance rate and % Equal error rate. % False acceptance rate and % Equal error rate are found to be less for mel frequency perceptual linear predictive cepstrum with pitch and % false rejection rate is less for mel frequency linear predictive cepstrum. In this work, F-ratio is computed as a theoretical measure on the features of the training speeches to validate the experimental results for perceptual features with pitch.

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distribution tool is used to perform the statistical justification of good experimental results for all the features with respect to both speaker identification and verification.

Due to the high complexity of modern circuit designs, verification has become the major bottleneck of entire design process. Common industry estimates are that functional verification constitutes near 70% of the total effort on any ASIC project. In this paper, we have tried to describe various ways to optimize verification time, comparing their effect on verification time and complete design cycle, with the conclusion of selecting modeling as better mechanism. The present paper has proved modeling as the best approach for optimizing ASIC design cycle with the experimentation taking a case-study.

Radio Frequency Identification (RFID) comprises of uniquely identifiable, less expensive tags and readers that monitor these tags through Radio Frequency signals. The information in the tags will be collected with the help of the readers. The load for any reader is the number of tags that the reader has to monitor. For the effectiveness of the RFID system several algorithms like Load Balancing algorithm and Redundant Reader Elimination algorithm were proposed. In these existing schemes the former concentrates on the load of the reader while the latter concentrates on reducing the power consumption by the RFID system. Here in Optimal Solution for RFID load balancing, a solution for optimizing the effectiveness of the RFID system by focusing on two parameters is provided. Load of the reader and Power consumption by the RFID readers are the parameters considered. Here the maximum number of readers that can be switched off without leaving any of the readers overloaded is found out. And also the relocation of the tags from the reader which got overloaded to the least loaded reader in the RFID system increases the overall performance of the RFID system for the same power consumption. A mobile agent, RFID Mobile Agent (RMA) is implemented to collect workload information, from RFID middleware embedded in each RFID reader and execute load balancing strategy for RFID middleware.

Network faults are mutative in nature; it could not be ignored due to its vital importance irrespective of grid type and setup. Hence managing those faults is not an easy task to be carried out, it requires complete knowledge regarding the entire grid workflow. An agent based sensor network sensing the workflow for grid network fault management is proposed in this paper. The agents are trained to regularize the flow of activities within the network. As the grid is highly distributed and large, a cluster based approach is carried out. Working nodes are allowed to concentrate more on the job assigned to them rather in management activity which is carried out by the proxies created. As the proxies are configured based on the individual links, they provide quick consensus time in detection. At the same time, the failure detection is also made at a linear time and minimum bandwidth utilization. The relationship between inter and intra cluster timings are found out through the timer agents. This analysis ensures more reliability into the detection. An agent repository is created which can be used as a sensor system for any kind of grid supporting scalability and distributiveness.

Ecommerce is an area where an Autonomic Computing system could be very effectively deployed. Ecommerce has created demand for high quality information technology services and businesses are seeking quality of service guarantees from their service providers. These guarantees are expressed as part of service level agreements. Properly adjusting tuning parameters for enforcement of the service level agreement is time-consuming and skills-intensive. Moreover, in case of changes to the workload, the setting of the parameters may no longer be optimum. In an ecommerce system, where the workload changes frequently, there is a need to update the parameters at regular intervals. This paper describes an approach to automate the tuning of MaxClients parameter of Apache web server using a proportional controller based on the required response time and the current workload. This is an illustration of the self-optimizing characteristic of an autonomic computing system.

Cloud computing is generally believed to the most gifted technological revolution in computing and it will soon become an industry standard. It is believed that cloud will replace the traditional office setup. However a big question mark exists over the network performance when the cloud traffic explodes. We call it “explosion” as in future we know that various cloud services replacing desktop computing will be accessed via cloud and the traffic increases exponentially. This paper aims at addressing some of these doubts better called “dangers” about the network performance, when cloud becomes a standard globally. Our study concentrates on, that despite of offering better round-trip times and throughputs, cloud appears to consistently lose large amounts of the data that it is required to send to the clients. In this paper, we first give a concise survey on the research efforts in this area. Our survey findings show that the networking research community has converged to the common understanding that a measurement infrastructure is insufficient for the optimal operation and future growth of the cloud. Despite many proposals on building an network measurement infrastructure from the research community, we believe that it will not be in the near future for such an infrastructure to be fully deployed and operational, due to both the scale and the complexity of the network. We explore this problem, and offer deduction that might explain this erratic behavior. We also suggest a set of technologies to identify and manage cloud traffic using IP header DS field, QoS protocols and some high speed edge routers. Our solutions assume that cloud is being assessed via basic public network.

The Sensor Network Localization problem deals with estimating the geographical location of all nodes in Wireless Sensor Network. The focus is on those node sensors to be equipped with GPS, but it is often too expensive to include GPS receiver in all sensor nodes. In the proposed localization method, sensor networks with non-GPS nodes derive their location from limited number of GPS nodes. The nodes are capable of measuring received signal strength and the need for a framework that could benefit from the interactions of nodes with mixed types of sensors for WSN.In this paper, localization is achieved by incorporating Mobility Models with Hidden Markov Model (HMM). Scenario based mobility models like Random walk, Random Waypoint, Reference Point Group mobility (RPGM)and Semi-Markov Smooth mobility (SMS) model are used with Hidden Markov Model to estimate error, energy, control overhead, with respect to node density, time and transmission range.

In the field of networking, the specialist area of

Network Security

consists of the provisions made in an underlying computer network infrastructure, policies adopted by the network administrator to protect the network and the network-accessible resources from unauthorized access, and consistent and continuous monitoring and measurement of its effectiveness (or lack) combined together.

The terms Network Security and Information Security are often used interchangeably. Network Security is generally taken as providing protection at the boundaries of an organization by keeping out intruders (hackers). Information Security, however, explicitly focuses on protecting data resources from malware attack or simple mistakes by people within an organization by use of Data Loss Prevention (DLP) techniques. One of these techniques is to compartmentalize large networks with internal boundaries. Employees have to cross these boundaries and be authenticated when attempting to access protected information.

Ongoing research work shows that homogeneous sensor networks have poor security, connectivity, performance and scalability. Heterogeneous sensor network (HSN) consists of physically different types of sensor nodes. The feasibility of implementing Elliptic Curve Diffe-Helmen (ECC) in HSN is simulated in this approach. Under dynamic condition of sensor node, implementation of grid-based coordinate route driven scheme has been proposed. This route driven scheme is highly adaptable for public key management scheme for HSN. It also compares the energy and throughput efficiency for dynamic position of sensor nodes. The proposed method is compared with the existing routing techniques like AODV and DSR. The proposed method dramatically increases network lifetime based on the elected coordinator nodes and the size of the grid area.

Grid monitoring involves the monitoring of the available resources and the network. Monitoring the resource metrics helps the grid middleware to decide which job to be submitted to which resource. The resource metrics is not enough for deciding a job to be submitted in a resource. A study and analysis of the network metrics also do equally contribute to the decision making while submitting a job.

Wireless Sensor and Actor Networks (WSANs) are composed of heterogeneous nodes referred to as sensors and actors. Sensors are low-cost, low-power, multi-functional devices that communicate untethered in short distances. Actors collect and process sensor data and perform appropriate actions on the environment. Hence,actors are resource-rich devices equipped with higher processing and transmission capabilities, and longer battery life.In WSANs, the collaborative operation of the sensors enables the distributed sensing of a physical phenomenon. After sensors detect an event in the deployment field, the event data is distributively processed and transmitted to the actors, which gather, process, and eventually reconstruct the event data. WSANs can be considered a distributed control system designed to react to sensor information with an effective and timely action. For this reason, in WSANs it is important to provide real-time coordination and communication to guarantee timely execution of the right actions and energy efficiency of the networking protocols is also a major concern, since sensors are resource-constrained devices. We propose an energy efficient routing protocol for wireless sensor and actor networks to cope with these challenges keeping in mind the resource constraints of the network and the early response by the actor nodes for delay sensitive applications with number of transmissions as less as possible. Our protocol is based on clustering (virtual grid) and Voronoi region concept.

In this paper a new (2, 2) visual cryptographic technique has been proposed, where the aspect ratio and the dimension of the secrete image/share with respect to source image remains constant during the process. In the VCTGLI technique grey level of some pixels of the input image has been inverted using random function to generate shares, instead of generating new pixels for shares. The scheme may be more secured and easy to implement like other techniques of visual cryptography.

To expound the effectiveness of the technique the obtained results are compared with the technique of Naor and Shamir [1], Yue and Chiang [2] and Jena and Jena [3] where it has been shown that VCTGLI gives better performance.

This paper presents an approach to the recognition of speech signal using frequency spectral information with Mel frequency for the improvement of speech feature representation in a HMM based recognition approach. A frequency spectral information is incorporated to the conventional Mel spectrum base speech recognition approach. The Mel frequency approach exploits the frequency observation for speech signal in a given resolution which results in resolution feature overlapping resulting in recognition limit. Resolution decomposition with separating frequency is mapping approach for a HMM based speech recognition system. The Simulation results show a improvement in the quality metrics of speech recognition with respect to computational time, learning accuracy for a speech recognition system.

One of the most critical issues in distributed system is security. The ideal solution to this concern is to have an environment that is fully trusted by all its entities. Our proposed approach is truly unique and fully comprehensive incorporating fuzzy logic for subjective concepts and integrating various trust related characteristics. The trust values(TV) calculated between the entities are stored in a global data store. This TV can be used as a basis for future transactions of the entity concerned. Since the global data store contains the trust value of all the users of the environment, these trust values are more accurate than that which has been calculated through recommendations. This also obviates the necessity for entities to know each other beforehand, which is a prerequisite in the case of recommendations. Also the security issues related with the global trust scheme is analyzed and an efficient solution to it using fuzzy logic has been proposed.

Test-suite reduction can provide us with a smaller set of test cases that preserve the original coverageoften a dramatically smaller set. One potential drawback with test suite reduction is that this might affect the quality of the test suite in terms of fault finding the problem and determine its effect when testing. Based on observations from our previous experimental studies on test suite reduction, we believe there is a need for optimized test suite with increase in fault detection. We examine the effectiveness of a test suite reduction process based on a combination of both concept analysis and Genetic algorithm. We also suggest a method for handling the tie between the groups in the lattice which will yield the cases that are most suitable for covering the requirements at that level. Our experimental study suggests that integrating concept analysis and Genetic algorithm has a positive impact on the effectiveness of the resulting test suites.

We investigate the use of dominating-set neighbor elimination as an integral part of the distribution of route requests using the Ad hoc On-demand Distance Vector (AODV) protocol as an example of on-demand routing protocols. We use detailed simulations to show that simply applying dominant pruning (DP) to the distribution of route requests in AODV results in pruning too many route requests in the presence of mobility and cross-traffic. Accordingly, we introduce several heuristics to compensate the effects of DP and show that the resulting AODV with Dominating Set heuristics (AODV-DS) has comparable or better delivery ratio, network load, and packet latency than the conventional AODV. AODV-DS exhibits over 70% savings on RREQ traffic than conventional AODV, and in some situations, AODV-DS may have a lower control overhead using Hello packets than conventional AODV without Hellos.

DoS attacks are still remaining unsolved mystery in internet. Though various methods such as change point detection, classifier method, packet marking, use of efficient filters and gateways have been proposed to mitigate DoS attacks, all these methods lack in enough accuracy in detection and hence the false alarm. The proposed work performs network traffic monitoring by way of analyzing the generated traffic signal and determines the traffic wavelet coefficients using continuous wavelet transform and based on the wavelet coefficients and energy distribution in successive time intervals, inference of attack occurrence is confirmed. In this paper, DoS attack detection is performed using three types of wavelet functions and the efficiency of different wavelets in the attack detection is compared.

In the 3

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generation long-haul optical backbone networks, an optical signal is not transmitted end-to-end solely in the optical domain due to several physical layer impairments affecting the optical fiber transmission system; intermediate 3R regeneration is essential after an optical lightpath transmits for a long distance. This study focuses on the impact of regenerators on the network design problem. We also propose a cost-conscious 3R-regeneration based Routing and Wavelength Assignment (RWA) scheme that reduces the network cost without any compromise in the network performance by allocating optimal number of regenerators in the network. The different network parameters (like blocking probability, number of regenerators, wavelengths per fiber, etc) computed on a practical subnet using this new scheme show the effectiveness of our heuristic. Our results also provide information on the system specifications required to achieve efficient network performance at an optimal cost, under different network design scenarios.

It is an established fact that we are facing difficulties in the attendance management. Presently the attendance in most of the organizations is marked manually on paper which is an error-prone process. Specifically, in educational institutions, a significant amount of time of both students and staff is wasted while marking the attendance manually. Further, there are additional malpractices like proxy and bunking which make this system flawed. To counter these problems, we propose a system

TATTEND

which achieves full transparency and it maintains the regular and accurate updating of the attendance in the database. The three technologies have been integrated to achieve a full-proof system for effective attendance marking. The concept is innovative and a fully automated one. The three technologies include the use of RFID, IR Motion Sensor and an Electronic Deadbolt.

Multi-constrained Quality of Service (QoS) routing is to find a feasible path that satisfies multiple constraints simultaneously, which is a big challenge for Mobile Ad hoc Networks (MANETs) where the topology may change constantly. Most of the conventional protocols are designed to concentrate on either maximizing the throughput or decreasing the end-to-end delay. These single constrained QoS routing protocols have inherent shortcomings in real time applications where the communication requires meeting stringent requirements on delay, delay-jitter, cost and other QoS metrics. In this paper we propose an agent based Multi-Constrained QoS aware multicast routing scheme based on MAODV (MC_MAODV) which uses a set of static and mobile agent. It depicts QoS multicast model with multiple constraints which may deal with bandwidth reservation, delay constraint and packet loss to multicast session. Here the mobile agents are used to find multicast routes, create the backbone for a reliable multicasting and to adapt to dynamic topology. Multi-path strategy is introduced to reduce the time consumption of rerouting when the link fails due to node mobility. Also, the source node can utilize the best path for the data transmission to meet multiple QoS requirements. Extensive simulations have been conducted to evaluate the performance of MC_MAODV using Network Simulator (NS-2). The simulation results show that the proposed scheme performs better than traditional MAODV in terms of improving packet delivery ratio and minimizing end-to-end delay.

In this paper an efficient approach is presented to design and implement a high speed RRC pulse shaping filter for digital up converter (DUC) section of

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oftware

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efined

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adios (SDR). The implementation is based on efficient utilization of embedded DSP48E slices of the target device to enhance the speed of complex multipliers used in implementation of pulse shaping filters. It is an efficient method because the use of DSP48E slices not only increases the speed but also saves the general purpose resources on the target device. The root raised cosine (RRC) filter is designed and simulated in direct and transposed form with Matlab and Xilinx AccelDSP, synthesized with Xilinx Synthesis Tool (XST), and implemented on Virtex-5 based XC5VSX50T FPGA device. The proposed transposed structure can operate at an estimated frequency of 146.5 MHz as compared to 69.1 MHz in case of direct form structure by consuming almost same embedded DSP48E slices to provide cost effective solution for mobile and wireless communication systems.

Intrusion Detection Systems are one of the emerging areas of Information Security research. They can be implemented using Soft computing techniques. This paper, focuses on multi class classification process whose performance can be significantly enhanced by selecting an optimal subset of input features that is used for training in multi layer feed forward network thereby reducing the false alarm rate. A feed forward network called the back propagation network is trained to classify data as being normal or intrusive. Five training functions are used and analysis is done to decide which training function gives an optimal performance. In addition, the selection of a subset will reduce the dimensionality of the data samples and eliminate the redundancy and ambiguity introduced by some attributes. The user classifier can then operate only on the selected features to perform the learning process. Experiments are performed using kddcup99 dataset. The optimality of the obtained feature subset is then tested and a classification rate of 86% is obtained.

In control engineering, any system that takes some input signals, processes it and gives output signals, e.g. an electrical transformer, a mechanical lever, a car’s hydraulic brake system, a country’s economy, population of a country etc., can be treated like a black – box plant. Any given plant should be stable and also should perform well in terms of speed, accuracy and other properties. If it does not behave so, another system called controller is designed which is used in conjunction with the plant. In this paper, we propose an alternative, easy-to-use algebraic method to find the transfer function of the controller with better accuracy than graphical methods like root locus and bode plot. Our algorithm has complexity O(n^3).

The health care environment is rife with issues that are urgently in need of solutions that can readily be addressed using appropriate tools for decision support. Recent developments in RFID technology facilitate this process through continuous provision of instantaneous item-level information. We consider an existing decision support framework and instantiate this framework using an example from the health care domain using RFID-generated item-level information. We illustrate the process by developing a health care knowledge-based system and evaluate its performance.

We propose an algorithm called

OptMeshTrans

to determine a sequence of stable meshes that connect the source nodes and receiver nodes of a multicast session in Mobile Ad hoc Networks (MANETs).

OptMeshTrans

uses the following greedy strategy: Whenever a mesh connecting a set of source nodes to a set of receiver nodes is required, we choose the mesh, called the Stable-Static-Mesh, which exists for the longest time. In this pursuit, we determine a long-living minimum edge Steiner tree connecting the source nodes to the receiver nodes and the Stable-Static-Mesh is an extension of this Steiner tree by including in the mesh, all the edges that exist between the constituent nodes of the tree. When such a Stable-Static-Mesh gets disconnected, leading to the absence of a path from any source to any receiver node, we use the above greedy principle to construct another long-living mesh. The sequence of long-living Stable-Static-Meshes determined over the duration of the multicast session time is called a Stable-Mobile-Mesh. The lifetime of the meshes determined using algorithm

OptMeshTrans

forms the benchmark for maximum mesh lifetime in multicast routing. Simulation results indicate that the lifetime of the meshes determined using the classical mesh-based On-Demand Multicast Routing Protocol (ODMRP) is significantly lower than the optimal lifetime of the stable meshes determined using

OptMeshTrans

.

Mobile ad hoc network is a set of mobile nodes connecting with each other without physical infrastructure and centralized computing. Factors such as variable wireless link quality, propagation path loss, fading, multiuser interference, power expended, and topological changes, become relevant issues. Quality of Service (QoS) is a set of service requirements that needs to be met by the network while transporting a packet stream from a source to its destination. QoS support for Mobile Adhoc Networks (MANETs) is a challenging task due to the dynamic topology and limited resources. The clustering algorithm presents a logical topology to the routing algorithm, and it accepts feedback from routing algorithm in order to adjust that logical topology and make clustering decisions. In this algorithm we have introduced a new metric, next hop availability, which is a combination of two metrics. It maximizes path availability and minimizes travel time of packets and therefore offers a good balance between selection of fast paths and a better use of network resources. In the conclusion it provides simulation result of DWCA Algorithm performed on network simulator.

This paper aims towards a critical retrospection of some of the most bugging limitations of cluster formation and cluster head selection. Based on this, a new Weighted Adaptive Clustering Algorithm (WACA) has been proposed. The proposed methodology is aimed at reducing the transmission overhead, total required time and increasing the stability of the formed cluster. WACA can dynamically adapt itself to the frequently changing topology of ad-hoc network.

The continuous miniaturization of hardware components has contributed greatly to developement of wireless sensor nodes, that have greater computing capabilities. One major drawback of these sensor nodes, however, is that they have to operate in diverse environments without adequate maintenance in terms of power recharging. Thus reducing the amount of computation, and data transmission in such cases is of paramount importance. In this paper, we look at an approach in which a publish/subscribe based middleware arcitecture can be made both context and topography aware. We aim at decomposing complex queries, coming from the subscribers, and distributing the subqueries depending on the topography of the network. We also implement a feedback mechanism, which fine tunes this redistribution, at runtime. The redistribution is context aware (ie, dependant on the collected data and the computational power of the individual sensors), and is aimed at allowing the individual nodes to share greater computaional responsibilities. The ultimate aim is to minimize the computaion and data transmission load on each individual node.

Wireless Mesh Networks(WMNs) are emerging and low-cost next generation wireless networks. WMNs are able to provide communication for all types of networks with its backbone composed of low mobile or stationary Mesh Routers(MR). In WMNs, most of the traffic is generated by either Mobile Clients(MC) or Mesh Points(MP). MRs and MCs are two different mobile nodes in WMNs with different resources. Due to low mobility at MR level, proactive scenario performs well and proactive approach effectively utilizes the resources. The main constraint is at mobile client side, which have less resources and high mobility. So at this level reactive scenario performs well and it helps to utilize less resources in a good way.

In On-demand Table-driven approach, based on the topology proactive or reactive routing is used. At backbone level, the topology information is collected and maintained in the form of routing tables. At MC level, one-hop neighbors information is collected. Rouitng is mainly between the gateways(MP) and MCs, MPs use table-driven approach to communicate MCs and MCs use on-demand approach to communicate with MPs or MCs. MRs are intermediate routers, topology information are collected and provide instant route to either MPs or MCs. On-demand Table-driven approach reduces end to end delay,routing overhead and packet loss ratio.

In this paper, an efficient QoS scheduling strategy is proposed for IEEE 802.16 BWA systems that satisfies both throughput and delay guarantee to the applications such as video and audio streaming, online gaming, video conferencing, Voice over IP (VoIP), File Transfer Protocol (FTP) and Web Browsing. The proposed QoS scheduling strategy is compared with an existing QoS scheduling scheme proposed in literature in recent past. Simulation results show that the proposed scheduling architecture can provide a tight QoS guarantee for all types of traffic as defined in the standard hence maintain fairness and helps to eliminate starvation of lower priority class services.

Voice over IP is expected to be in practice in the next generation communication networks. The target of this paper is to analyse its performance in the next generation networks. Among the most competing networks like WiMAX, Wifi, etc., WiMAX having higher bandwidth accommodates more users but with degraded performance. Hence, an integrated network using WiMAX backbone and WLAN hotspots has been developed and VoIP has been setup using SIP. Since, OPNET 14.5.A provides a real life simulation environment, it is chosen as the simulation tool. Quality of the service is critically analysed with parameters like jitter, MOS and delay for various voice codecs. Finally, it is concluded that the WiMAX-WLAN integrated network provides improved and optimal performance over WLAN and WiMAX network with respect to network capacity and quality of service.

Mobile ad hoc networks (MANET) are formed when two or more nodes come within the communication range of each other. Since the wireless range is very short, all the nodes in the network have to extend their complete co-operation for efficient functioning of the network. This paper proposes a generalized trust framework for any ad hoc routing protocol to curb selfish and malicious nodes in a MANET. The trust relationships existing between the nodes determine the routing path to be taken for data transfer. The trust framework is combined with any MANET routing algorithm. The performance analysis of this framework is currently done with two reactive protocols. Jointly, they form a trusted network to curb various attacks originating in the ad hoc network. This type of a trusted framework established in a MANET, would be most suited for tactical environments.

It is very tough to use today’s Internet efficiently on poles, disasters or in the environments which are characterized by very long delay paths and frequent network partitions. DTN is a new area of research to improve network communication when connectivity is periodic, intermittent, and/or prone to disruptions. Delay Tolerant Networks (DTNs) is used to interconnect devices in regions in which an end-to-end connection may never be present. It is based on store and forward principle as to make communication possible, intermediate nodes stores the data and forward it as the opportunity arises. In a DTN, however, an end-to-end path may be unavailable at all times, routing is performed to achieve eventual delivery by employing long-term storage at the intermediate nodes. This paper surveys the area of routing in delay tolerant networks and presents a system for classifying the proposed routing strategies.

In a mobile computing environment, clients can access data irrespective of their physical location. Data is shared among multiple clients and can be updated by each client independently. This leads to inconsistency of the data. Due to limitations of mobile computing environment traditional techniques cannot be used. Several concurrency control techniques are proposed in literature to prevent data inconsistency. In this paper we first analyze the existing scheme of concurrency control without locking and justify its Performance limitations. A new scheme is proposed which adaptively set the validity period of the cached data items based on the number of data items required and current load of the database server. Experimental results show performance benefits and increase in commit rate of the transactions

abstract

environment.

Node clustering is a widely used approach to address the scalability issue of large-scale mobile ad hoc networks(MANETs). It eases the implementation of routing and resource management by constructing an abstract hierarchy of the flat network architecture of MANETs. Its effectiveness however depends largely on the clusters stability which is measured by the lifetime of the clusters. The aim of this paper is to propose a fully distributed clustering algorithm that addresses the stability of mobile nodes in terms of neighborhood associativity and remaining energy. The algorithm maximizes the cluster lifetime by choosing those nodes as clusterheads which have the highest neighborhood associativity and remaining energy. It also tries to minimize the number of clusters in the network by giving priority to higher degree nodes. Simulation results show that the algorithm identifies clusters that are stable with respect to cluster lifetime and the frequency of reaffiliations of mobile nodes.

High speed wireless data transmission requires systems to operate with high spectral efficiency in wideband channels The physical layer should facilitate multiuser/multirate transmissions to support a number of users and applications with diverse needs. Orthogonal Frequency Division Multiple Access (OFDMA) is a multiple access technique that can accommodate many users with widely varying applications, data rates and Quality of Service requirements with increased spectral efficiency. OFDMA is attractive due to the fact that it exploits the computational efficiency associated with frequency domain equalization (FDE). This paper presents analysis of transmission of multiple data rates by using Orthogonal Variable Spreading Factor (OVSF) codes in an OFDMA system with frequency domain equalization. The performance of the system is analyzed using bit error rate (BER), for Vehicular A and Pedestrian B channel models.

In mobile ad hoc networks (MANET) ,computation devices are battery powered. Limited energy in battery constrains the computation and communication of each device. Hence services like sharing a data or information among users becomes a challenging issue in critical environments like military applications, rescue operations etc. To overcome this, we have proposed a replication model which replicates shared data in suitable nodes. It addresses how data sharing can be done effectively by periodically checking the remaining energy of each node that holds the replica. If the remaining energy falls below a threshold level, replica can be relocated to appropriate nodes that has the maximum energy. Therefore our proposal ensures file availability, improves the network life time, decreases query response time, increases energy utilization, decreases number of packet drops due to battery depletion of a node.

The Wired Equivalent Privacy (WEP) protocol protection technique suggested for ad hoc network falls short of the objective of data privacy, data integrity and authentication. Various security standards such as IEEE 802.11i, WAP, IEEE 802.1X were suggested to address the security issues in 802.11. Despite their efficiency, these standards do not provide any security approach for monitoring the authentication in a distributed architecture. In this paper we present a self monitored security approach for self-monitoring of key authentication for security protocol in ad hoc networks for the efficient monitoring of the authentication issue in ad hoc network. The processing overhead for the suggested approach is evaluated for a threshold based cryptographic approach.

The Transmission Control Protocol (TCP) was designed to provide reliable end-to-end delivery of data over unreliable networks. In practice, most TCP deployments have been carefully designed in the context of wired networks. Ignoring the properties of wireless Ad-hoc Networks can lead to TCP implementations with poor performance. In a wireless network, however packet losses occur more often due to unreliable wireless links than due to congestion. When using TCP over wireless links, each packet loss on the wireless link results in congestion control measures being invoked at the source. This causes severe performance degradation. If there is any packet loss in wireless networks, then the reason for that has to be found out and then only congestion control mechanism has to be applied. This work shows the performance of TCP with Adaptive Pacing (TCP-AP) and Link Random Early Discard (LRED) as queuing model over Single and Multiple TCP flows in multihop transmission when the source and destination nodes are in mobile nature. The adaptive pacing technique seeks to improve spatial reuse. The LRED technique seeks to react earlier to link overload. This paper consists of simulated environment results under three different network scenarios. Simulations are done with the use of NS2.

Security in infrastructure-less networks like MANETs (Mobile Ad Hoc Networks) has proven to be a challenging task. Multipath routing protocols were initially proposed in order to design robust and secure networks. These protocols improve network performance in terms of delay, throughput, reliability and life time. It is hard to find a single protocol that can improve all these performance parameters. In this paper we propose a secure prioritized trust based multi path routing protocol. It ensures reliable communication with low overhead and minimum delay. This is realized by discovering and selecting reliable path based on the trust information. We take the advantage of multiple paths to increase reliability and robustness of data through context aware routing. Results show the effectiveness of our protocol.

IEEE 802.11 wireless networks have gained ever greater popularity nowadays. Handoff is a critical issue in IEEE 802.11 based wireless networks and latency in the handoff process is a major concern.

In this paper, we propose to reduce handoff latency for IEEE 802.11 wireless networks with Neighbor Graphs (NG) pre-scanning mechanisms. IEEE 802.11 uses 11 channels of which the channels 1, 6 and 11 do not mutually overlap. So these channels are expected to have a lower carrier-to-interference ratio (CI) compared to the other channels present under the same base station, which increases the channel’s availability during handoff. Based on the NG pre-scanning mechanism, when handoff criterions have been met, we design an algorithm to first scan the channels 1, 6 and 11, if present under the next Access Point (AP), to reduce the scanning delay. We also introduce pre-authentication mechanism, which will effectively reduce the message processing delay.

The Congestion in Wireless Sensor Networks is significantly higher and thus severely affects the network performance leading to increased data loss and end to end delay. In a normal scenario a static sink collects data from the entire network but this approach results in high traffic load in the sink’s vicinity. To alleviate this problem a mobile sink is introduced in addition to already existing static sink for data collection from the network. Since the mobile sink travels through the network area, the sensor nodes deliver the data whenever the mobile sink comes near its vicinity. By this hybrid sink approach method along with efficient data collection algorithm not only reduces bottleneck around the static sink but also decreases end to end delay. This hybrid sink approach where a combination of a static sink and a mobile sink could be useful in delay sensitive applications. Analysis and simulation results show that Hybrid sink approach along with efficient data collection algorithm performs significantly better than a static sink.

A mobile ad-hoc network (MANET) is a self-configuring network of mobile nodes. MANETs are hindred by intermittent network connections, restricted power supplies, and limited computing resources. These restrictions raise several new challenges for data access applications with the respect to data availability and access efficiency. Data caching addresses these challenges in MANETs to improve the efficiency of information access.

Cooperative caching

improves system performance because it allows sharing and coordination of cached data among multiple mobile users in the network. This paper aims to classify and compare existing cooperative caching strategies for MANETs based on their performance metrics such as query latency and cache hit ratio.

On-demand ad hoc routing protocols broadcast control packets to establish route to destination nodes. In ad hoc networks that are formed by many mobile nodes, they generate a high number of broadcast packets, thereby causing contention, packet collision and battery power wastage in the mobile nodes. We propose an efficient route establishment method to decrease the transmission of control packets by using a neighborhood vector and controlled flooding technique. The goals are to: i) discover the shortest path with minimal control overhead, and ii) minimize the total resources consumed in message delivery. Through simulation, we demonstrate that our proposed method is especially efficient in dense ad hoc networks. In our proposed method, the number of control packets is decreased without lowering the success ratio of path discoveries according to the number of adjacent nodes. Furthermore, our proposed method adapts to the normal network conditions. The simulation results show [Section 3.4] that the proposal technique save up to 70% of control packets when the network is denser.

Wireless Sensor Networks (WSN) are networks of low cost nodes with minimal power consumption, processing capabilities and maintenance, that can be used for wide area environmental monitoring. This paper discusses the main innovations, challenges, solutions and deployment experiences in designing a Lightweight Management Framework (LMF) for a real-time, 24/7 operational, heterogeneous network. The network must reliably deliver data continuously from a set of deep earth probe sensors in a remote hilly rainforest area to a data management, analysis, and visualization center at the University campus hundreds of miles away. This framework provides the ability to incorporate different heterogeneous networks such as 802.15.4, 802.11b/g, VSAT, GPRS, GSM, Internet and also proprietary wireless sensor network and hardware architectures. It also handles various network failures, data corruption, packet loss, and congestion problems. The data is analyzed to determine the factor of safety of the landslide prone area using landslide simulation software, stream data in real-time to the internet, and give automatic warnings. The architecture has been implemented in a real-time wireless sensor network deployed in the Western Ghats of Kerala, India to detect landslides. The architecture is operational in the deployment site since February 2008 and was used to issue landslide warnings during the July 2009 monsoon.

The accuracy of event detection is a key ingredient in wireless sensor network. It can be achieved with multi-sensor information fusion. In this paper, a fusion framework for Fire detection application using Dasarathy model is proposed .The proposed framework performs fusion with sensed data using two algorithms namely Dempster-Shafer and Fuzzy logic. The final decision about the detection of fire is decided in the sink. Further, a imprecision compensator module is also designed to minimize the imprecision present in the sensed data which results in enhancement of accuracy in fire detection. Performance of the proposed fusion framework is simulated and analyzed in MATLAB in terms of accuracy.

This paper proposes a distributed localization algorithm based on Received Signal Strength (RSS) that consists of two phases, distance estimation phase and coordinate estimation phase. In distance estimation phase the distance of the unknown node is computed based on the RSS measurements using log normal shadowing path loss model and ITU indoor attenuation model. The distance error is minimized by one-dimensional Kalman filter and the number of iterations of the filter is limited using Cramer Rao Bound value. In the second phase, the coordinates of the unknown node is estimated by lateration technique whose accuracy is improved by min-max algorithm. The RSS value is experimentally obtained in real-time indoor environment using zigbee series 1 RF module. The proposed algorithm is simulated and analyzed in MATLAB version 7. From the simulation results it is found that the proposed localization algorithm performs more efficient in terms of computational cost and accuracy.

The Web Services are interdependent among themselves in distributed environment. Offering such interdependency is a challenging task due to geographical distance of nodes in an distributed environment which results in high data accessing delay. This paper contributes an Publish/Subscribe Replication Middleware for distributed web services. This technique achieves replication of data dynamically upon the incoming transaction request from the client. This middleware framework offers: Replication services to achieve interdependency, Heterogeneity and security issues among web services. This method achieves interdependency by improving the data accessing delay and avoids reading of stale replicas. When compared to the systems with out replication/using any traditional techniques to achieve interdependency the proposed model is proved efficient through the implementation.

As organizations, both business and research-development continue to search better ways to exploit knowledge capital accumulated on the diversified Web; it fosters the need of collaboration among people with similar interest & expertise. In this paper we focus on the problem of discovering people who have particular interests or expertise. The standard approach is to build interest group lists from explicitly registered data. However, doing so assumes one knows what lists should be built, and who ought to be included in each list. We present an alternative approach, which can support a finer grained and dynamically adaptive notion of shared interests. Our approach deduces shared interest relationships between people based on interest similarity calculated by the means of entries written on their blog. Using this approach, a user could search for people by requesting a list of people whose interests are similar to several people known to have the interest in question.

Federated Identity Management is a version of Single Sign-On where each device, system, and application queries a centralized database for authentication and authorization information. Federated Identity Management systems are tasked with enabling authentication and authorization data across organizational boundaries. Federated Identity Management system, authentication data can be passed across security domains from within a company to its business partners. This can enable Single Sign-On to extend past organizational boundaries. Federated Identity Management is often abbreviated

FIM

.

In this paper a novel approach to make discovery and subsequent integration of semantic repositories, like ontologies, as seamlees and automatic as possible is presented. Reuse of semantic repositories has many advantages and it has been acknowledged time and again that it is a process which can only be partially or semi automatically be achieved. We discuss the nature of semantic repositories, the challenges and issues still to be resolved and finally the proposed framework.

The constantly increasing performances of e-commerce services or telecommunication services of web services mean web model can replace more and more web applications. In design, the goal is not to just replace the solution but also to improve it by adding new functionality. To interpret the dynamic behavior of a model is crucial for being able to modify, maintain, and improve it. Model represents a complete exposition of their focus; although there may be dependencies on other aspects of the architecture: these dependencies are usually well defined. We interpret a model in two folds. Firstly, a model which is derived before implementation of a business process is defined as pre-model. Second one is post-model which is derived after implementation. Deriving Post-Model from business execution logs is one of the challenging issues in current age. In this survey, we will present different approaches of model discovery from event logs. The idea is to generalize the process discovery problem and find out research challenges.

The aim of this paper is to predict the Learning Disabilities (LD) of school-age children using decision tree. Decision trees are powerful and popular tool for classification and prediction in Data mining. Different rules extracted from the decision tree are used for prediction of learning disabilities. LDs affect about 10 percent of all children enrolled in schools. The problems of children with specific learning disabilities have been a cause of concern to parents and teachers for some time. This paper highlights the data mining technique – decision tree, used for classification and extraction of rules for prediction of learning disabilities. As per the formulated rules, LD in any child can be identified.

This paper presents a method for resolution of ambiguity of place names and its evaluation over the Geological Corpus. We discussed the methods for generating co-occurrence models (co-occurrence matrix and cooccurrence graph) for the purpose of place name disambiguation. A graph based disambiguation algorithm is introduced to resolve the ambiguities such as synonyms and polynyms in place names. Using the neighborhoods in the cooccurrence graph, the query can be expanded with related place names after disambiguation. Experimental results on a Geological corpus (IITKGPGEOCORP) show that query expansion with place disambiguation outperforms the baseline method.

The protocol between a web service and its client may lead to semantically inconsistent results if the ontologies used by the server and client are different. Given that the web is growing in a mostly uncoordinated way, it is unrealistic to expect that web services will adhere to standardized ontologies in near future. In this paper we show that if the client publishes its ontology and presents the protocol it intends to follow with a web service, then the web server can perform a semantic verification step to determine formally whether any of the possible executions of the protocol may lead to a semantic conflict arising out of the differences in their ontologies. We believe that this an approach which enables a web-server to automatically verify the semantic compatibility of a client with the service it offers before it actually allows the client to execute the protocol. We model the ontologies as graphs and present a graph based search algorithm to determine whether the protocol can possibly reach a conflict state.

A testing process involves testing the given program with the designed test cases. A testing objective has to be defined before testing the program. The test cases depend upon the testing objective of the program. As new test cases are generated over time due to software modifications, test suite sizes may grow significantly. Because of time and resource constraints for testing, test suite minimization techniques are needed to remove those test cases from a suite that, due to code modifications over time have become redundant with respect to the coverage of testing requirements for which they were generated. For reducing the cost of the test execution only efficient test cases should be taken into consideration. Existing algorithms like GRE reduces the test suite by removing redundancy that may sometimes can significantly diminish the fault detection effectiveness (FDE) of suites. We present the modified GRE heuristic with selective redundancy (GSRE) for test suite reduction that attempts to use additional coverage information of test cases to selectively retain some additional test cases in the reduced suites that are partially redundant with respect to the testing criteria used for suite minimization, with the goal of improving the FDE retention of the test suites. Our experiments show that our GSRE approach can significantly improve the FDE retention of test suites without severely affecting the extent of suite size reduction.

In this paper, mobility time is studied by using the changes in the received signal strenth indicator (RSSI). RSSI values are used to define mobility, non-mobility or unclear times. The experiments are conducted to investigate mobility and non-mobility times and also the poster experiment is used to determine rating ratios of posters.

The Next Generation Networks (NGN) aims to integrate for IP-based telecom infrastructures and provide most advance & high speed emerging value added services. NGN capable to provide higher innovative services, these services will able to integrate communication and Web service into a single platform. IP Multimedia Subsystem, a NGN leading technology, enables a variety of NGN-compliant communications services to interoperate while being accessed through different kinds of access networks, preferably broadband. IMS–NGN services essential by both consumer and corporate users are by now used to access services, even communications services through the web and web-based communities and social networks, It is key for success of IMS-based services to be provided with efficient web access, so users can benefit from those new services by using web-based applications and user interfaces, not only NGN-IMS User Equipments and SIP protocol. Many Service are under planning which provided only under convergence of IMS & Web 2.0. Convergence between Web 2.0 and NGN-IMS creates and serves new invented innovative, entertainment and information appealing as well as user centric services and applications. These services merge features from WWW and Communication worlds. On the one hand, interactivity, ubiquity, social orientation, user participation and content generation, etc. are relevant characteristics coming from Web 2.0 services. Parallel IMS enables services including multimedia telephony, media sharing (video-audio), instant messaging with presence and context, online directory, etc. all of them applicable to mobile, fixed or convergent telecom networks. With this paper, this paper brings out the benefits of adopting web 2.0 technologies for telecom services. As the services are today mainly driven by the user’s needs, and proposed the concept of unique customizable service interface.

Wireless Sensor Network (WSN) is generally observed as a service layer for providing context information to Pervasive Computing applications. Acquiring this vital context information using WSN demands special skill-sets from the developer and is tightly coupled with the application requirements. The developer needs to evaluate several combination of services like routing, localization, time synchronization, security protocols to fulfill the application requirements. In this paper we justify the need and propose a system architecture of an Adaptive Framework for WSN Application (AFWA) that hosts the application workflow from development to deployment. This framework provides a flexibility for opting the required services based on the application needs and abstracts the application developer from the intricacies of WSN system components.

In this paper we discuss different wireless routing algorithms. We compare the efficiency of those routing algorithms. The basic criterion for the comparison is to determine the time to reach a message from source to destination. In this paper we have also shown that the most efficient WSN routing algorithm may not perform best in case of every application. Different routing algorithms are suitable for different application areas. We also discuss about the limitations of WSN.

There exist several open source 6LoWPAN stacks for researchers to experiment with. However, they often lack sufficient and in-depth description of the internal operation, which makes extending the stacks difficult for many of us. This paper provides detailed documentation of the internal logic of an implemented and working 6LoWPAN stack, Nanostack (v1.1). We present first the main architecture of the stack and subsequently describe the path followed by a packet transiting the different layers. The logic in each one of the layers is explained with exception of the ICMP layer. Finally at the end of the paper we observe Nanostack from user’s perspective and discuss features and problems that we noticed in the stack.

This paper presents a fair comparison of Low energy adaptive clustering hierarchy (LEACH) and ant colony applied on LEACH on the basis of the death of first node in the wireless sensor network (WSN) and data transfer. The simulation results show that when the ant colony algorithm is applied on the existing LEACH protocol the results show significant improvement in the network lifetime by delaying the death of first node in the WSN and thus increasing the efficiency of the system.

Mobility in tandem with energy efficiency in wireless sensor network endows with significant challenges for routing. Sensor nodes have limited energy supply and minimizing the power consumption is crucial in Mobile Wireless Sensor Network (MWSN). This paper proposes a novel hybrid multipath energy aware routing protocol for MWSN called Energy Efficient Mobile Wireless Sensor Network Routing Protocol (E

2

MWSNRP). The Energy Aware (EA) selection mechanism and the Maximal Nodal Surplus Energy estimation technique employed in this algorithm improve its energy performance. The ‘readiness’ concept of EA selection prolongs the network lifetime. The hybrid routing concept applied in this algorithm presents the advantages of both the reactive and proactive routing. An evaluation methodology and simulation environment to verify the operation of this algorithm is presented here. Simulation results can demonstrate that the proposed scheme can outperform the existing routing protocols in terms of energy efficiency, network lifetime and packet delivery ratio.

In a ubiquitous environment, e.g. smart home, a user is surrounded by a network of sensor nodes all around and also on his body or clothing. We modeled such a sensor network as a services network where the nodes exchange services for collaborating and smart decision taking. As the user moves around performing activities, the surrounding network also changes as wireless inter-node connections are made or broken. The challenge is to re-discover the network quickly and transparently to the user.

We used a two-step approach. First, Proximal Neighborhood Discovery identified nodes that formed the network. Second, Optimal Service Discovery determined, for each such network node, who were the best service provider nodes from the same network. We modeled this as an optimization problem and solved using a new and efficient algorithm.

We implemented the algorithm using nesC and simulated using TOSSIM interference-model. The results showed appreciable improvements over conventional approaches.

Scheduling workflow tasks is a key issue in the workflow management system. Workflow Scheduling is defined as allocating suitable resources to workflow tasks in order to satisfy objective functions specified by users. This paper presents a task scheduling algorithm called LCPR algorithm for workflow tasks in heterogeneous computing environment. This algorithm focuses mainly on the tasks that are tightly coupled or that have high dependency with other tasks. This paper evaluates the algorithm with other workflow algorithms and found that LCPR gives better performance in terms of execution time and response time of the job.

Ubiquitous computing technology is expected to become very small and reasonably cheap in the future, large amounts of electronic items can be deployed almost everywhere. Localization of sensor nodes is important in many respects in wireless sensor networks. First, it informs the remote end user of the precise location within a network where the specific “event’ of interest took place. Second, in case of node failure, identification can be made for the network area within the sensor network which is affected. Similarly, the known location of sensor node helps in coming up with efficient routing paths to the sink, which is mobile, is used to track the event driven sensor nodes in the path of the event, thus conserving energy and time. In wireless sensor networks, the capabilities of individual sensor nodes are extremely limited and therefore collaboration is required with minimum energy expense.

As Information without location is meaningless in sensor networks, Localization plays an important role in coming up with an efficient inter-node collaboration. With this scheme, the ordinary sensor nodes do not need to spend energy on neighboring interaction for localization. The localization mechanism has been implemented in TOSSIM. The simulation results show that our scheme performed better than other range-based schemes.

With the increase improvement in VLSI design and progressive complication of circuits, an efficient technique for test pattern generation is necessary with the intension of reducing number of faults and with use of testability measures. Using the fault equivalence method, the number of faults are reduced. The line justification and error propagation is used to find the test vectors for reduced fault set with the aid of controllability and observability. The programs are developed for fault equivalence method, controllability observability and finally for automatic test pattern generation using object oriented language C++. ISCAS 85 C17 circuit is used for analysis purpose. Standard ISCAS (International Symposium on Circuits And Systems) netlist format is used. The stuck at fault model is considered. The complete ATPG based on controllability and observability for reduced fault set is discussed in this paper.

In this paper, we propose a new All Digital Phase Locked Loop (ADPLL) for SOC applications. The proposed ADPLL can be designed with any standard cell library. The ADPLL has been implemented using standard cells of 0.6μm CMOS process from CADENCE TOOLS. The designed ADPLL operates in the range between 12.5 MHz to 100MHz with phase error of less than 10ns. Portability over different processes is ensured in the new ADPLL. The complexity in the design process is reduced. The time for redesign considerably decreases making it suitable for SOC applications.

Advances in the field of Integrated Circuits (ICs) has resulted in high density Very Large Scale Integrated (VLSI) chips comprising of both digital and analog components onto a single chip. Consequently, testing of these ICs with analog and digital components are challenging and time consuming. Moreover, the techniques available for testing analog components when compared to digital are less and also difficult. This paper describes a approach of utilizing Field Programmable Gate Arrays (FPGAs) for fault diagnosis of analog circuits describing the technique of Reconfigurable Computing Systems (RCS). The paper provides a brief about Fault diagnosis, FPGAs and utilization of FPGAs for RCS followed with the approach of the research. In summary the paper provides a brief about utilizing a digital hardware to perform testing of analog cicuits.

The increasing demand of personal health monitoring products with long battery life had forced designers to use of those circuits which consumes low power. Operational Transconductance Amplifier (OTA) operating in subthreshold (weak inversion) region introduces a versatile solution for the realization of low power VLSI building blocks. This paper demonstrates a modified OTA with high linearity and better performance achieved by using High-swing improved-Wilson current mirror for low power and low-frequency applications. The achieved linearity is about ± 1.9 volt and unity gain bandwidth (UGB) of 342.30 KHz. The OTA is operated at power supply of 0.9 volt and consumes power in range of nanowatts. The OTA simulation has been performed in a standard TSMC 0.18 micrometer technology on BSIM 3v3 model using ELDO Simulator.