International Journal of Distributed Sensor Networks The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Wireless HDLC Protocol for Energy-Efficient Large-Scale Linear Wireless Sensor Networks Thu, 17 Apr 2014 17:15:40 +0000 Wireless sensor networks (WSNs) have been widely recognized as a promising technology that can enhance various aspects of infrastructure monitoring. Typical applications, such as sensors embedded in the outer surface of a pipeline or mounted along the supporting structure of a bridge, feature a large-scale linear sensor arrangement. In this paper, we propose a new bidirectional wireless communication scheme, based on the high-level data link control (HDLC) standard, for devices with short-range transmission capabilities for linear sensor topology. By applying for the first time a standard data layer along with a time division multiple access (TDMA)-based medium access control (MAC) and time synchronization technique specifically designed for the linear topology, we address the interoperability problem with guaranteed energy efficiency and data link performance in linear sensor topology. The proposed Wireless HDLC supports half-duplex communication, point to point (peer to peer), and multipoint networking. Daniel Mihai Toma, Joaquin del Rio, and Antoni Mànuel Copyright © 2014 Daniel Mihai Toma et al. All rights reserved. A Flow-Partitioned Unequal Clustering Routing Algorithm for Wireless Sensor Networks Thu, 17 Apr 2014 17:12:55 +0000 Energy efficiency and energy balance are two important issues for wireless sensor networks. In previous clustering routing algorithms, multihop transmission, sleep scheduling, and unequal clustering are always used to improve energy efficiency and energy balance. In these algorithms, only the cluster heads share the burden of data forwarding in each round. In this paper, we propose a flow-partitioned unequal clustering routing (FPUC) algorithm to achieve better energy efficiency and energy balance. FPUC consists of two phases: clustering and routing. In the clustering phase, the competition radius is computed according to the node density and the distance from sensor nodes to the sink. The sensor nodes that have more residual energy and larger overlapping degree have higher probability to be selected as cluster heads. In the routing phase, each cluster head first finds the gateway nodes and then distributes the data flow to each of its gateway nodes depending on residual energy. After that, each gateway node forwards the data to the next hop with minimum cost. Two metrics called network lifetime and coverage lifetime are used to compare the performance of FPUC with that of the existing ones. Simulation results show that FPUC can achieve longer network lifetime and coverage lifetime than previous algorithms. Jian Peng, Xiaohai Chen, and Tang Liu Copyright © 2014 Jian Peng et al. All rights reserved. A Packet Loss Concealment Technique Improving Quality of Service for Wideband Speech Coding in Wireless Sensor Networks Thu, 17 Apr 2014 17:10:38 +0000 A packet loss concealment (PLC) algorithm is proposed to improve the quality of decoded speech when packet losses occur in a wireless sensor network. The proposed algorithm is mainly based on artificial bandwidth extension (ABE) from narrowband to wideband. It consists of three main functions: packet loss concealment in the narrowband, ABE in the modified discrete cosine transform (MDCT) domain, and smoothing of wideband MDCT coefficients with those of the last good frame. The performance of the proposed PLC algorithm is implemented by replacing the PLC algorithm employed in the ITU-T Recommendation G.729.1. The experimental results show that the proposed PLC algorithm provides significantly better speech quality than the PLC in the ITU-T G.729.1. Nam In Park, Jin Ah Kang, Seong Ro Lee, and Hong Kook Kim Copyright © 2014 Nam In Park et al. All rights reserved. Lightweight Secure Directed Diffusion for Wireless Sensor Networks Thu, 17 Apr 2014 16:54:17 +0000 We propose a lightweight secure routing scheme for wireless sensor networks, which provides authenticity and integrity in the routing process with relative low overhead by extending directed diffusion protocol with secure measures. We analyze the security capabilities and performance of our scheme; besides, we execute a simulation and the performance results are encouraging. Eric Ke Wang, Yuming Ye, and Xiaofei Xu Copyright © 2014 Eric Ke Wang et al. All rights reserved. Sensor Grid Middleware Metamodeling and Analysis Thu, 17 Apr 2014 13:46:51 +0000 Sensor grid is a platform that combines wireless sensor networks and grid computing with the aim of exploiting the complementary advantages of the two systems. Proper integration of these distinct systems into effective, logically single platform is challenging. This paper presents an approach for practical sensor grid implementation and management. The proposed approach uses a metamodeling technique and performance analysis and tuning as well as a middleware infrastructure that enable practical sensor grid implementation and management. The paper presents our implementation and analysis of the sensor grid. Srimathi Chandrasekaran, Eunmi Choi, Jemal H. Abawajy, and Rajesh Natarajan Copyright © 2014 Srimathi Chandrasekaran et al. All rights reserved. A Data Gathering Method Based on a Mobile Sink for Minimizing the Data Loss in Wireless Sensor Networks Thu, 17 Apr 2014 11:45:06 +0000 The sensor nodes near to the fixed sink node suffer from the quickly exhausted energy. For this, many methods have been researched to distribute the energy consumption into all wireless sensor nodes using a mobile sink. Since the mobile sink changes its location in the network continuously, it has limited time to communicate with the sensor nodes and needs the time to move to each sensor node. Therefore, before the mobile sink approaches the sensor node, the node can collect huge data by event occurrence. It causes the memory overflow of the sensor node and then the data loss. We propose a novel data gathering method based on a mobile sink considering the data loss in wireless sensor networks. The proposed scheme actively sends the stored data to the mobile sink by considering the amount of collected data in the cluster header and the mobile patterns of the sink node. By doing so, it minimizes the data loss of each sensor node. To show the superiority, we compare it with the existing scheme. Our experimental results show that our proposed scheme minimizes the data loss and has similar network lifetime over the existing scheme based on a mobile sink. Junho Park, Kyoungsoo Bok, Dongook Seong, Sanglae Kim, and Jaesoo Yoo Copyright © 2014 Junho Park et al. All rights reserved. Indoor Location Based VOD Service Using Smart Phone Sensors Thu, 17 Apr 2014 10:15:59 +0000 A smart phone is the best device on which a location based VOD service (ILBVS) runs, because a smart phone has PC level computing power and storage capacity, and it is a personal belonging that the owner always carries. Thus, this paper proposes an efficient way of implementing an ILBVS as a smart phone app. ILBVS cannot be realized unless the system can estimate the user’s location. We use a dead-reckoning indoor positioning method that determines user’s location using smart phone sensors. Another necessary ingredient of ILBVS is a map that is the most important element of the LBS’s user interface. We obtain the floor map from the floor map repository. The most important contribution made by this paper is the method of guessing what the user is most interested in at the current moment. With this method, we implement an example ILBVS. Jaegeol Yim and Young-Ho Park Copyright © 2014 Jaegeol Yim and Young-Ho Park. All rights reserved. PSFCS: Robust Emergency Communications Supporting High Mobility Based on WiMAX MMR Networks Wed, 16 Apr 2014 17:25:58 +0000 Nowadays public safety networks are widely deployed to support highly reliable wireless communications in case of emergency. The adoption of standardized systems such as WiMAX for emergency communications represents a significant advance in the off-the-shelf technologies for error detection and error correction. Since it is difficult to fully eliminate the Doppler effect under high speed moving environment, we propose an enhanced CRC-based error correction scheme that carries as much extra segmented frame Check Sequence (FCS) information as subblocks of emergency multicast/broadcast service (MBS) frame, called progressive and selective frame check sequence (PSFCS). In a mobile multihop relay (MMR) environment, a high-mobility mobile station might receive an emergency MBS frame more than once, so the PSFCS could be cross-referenced by duplicated frames received. Therefore the PSFCS achieves a significant performance improvement over the legacy FCS scheme in terms of error detection and correction of emergency MBS frames in a WiMAX MMR network operating in transparent mode. The experimental results show that the goodput and utilization of high-mobility mobile stations can be improved remarkably. Wen-Kang Jia, Chia-Yao Chen, and Yaw-Chung Chen Copyright © 2014 Wen-Kang Jia et al. All rights reserved. Multisensor Based Neutral Function Identification of Solenoid Valve Wed, 16 Apr 2014 14:15:58 +0000 Condition monitoring of hydraulic systems has been using automatic control in industrial system. In this paper, a sensor network based intelligent control is proposed for efficient solenoid valve identification. The detection system learns to detect the change of output pressure of multipoints that represent a more complicated task. Linear correlation analysis is introduced for feature extraction, which allows for a significant reduction in the dimension of original data without compromising the change detection performance. Implemented as an agent identifying the valve types under measurement, the support vector machine classifier achieves a significant high accuracy in identification and an increase in deployment efficiency. Experimental results prove that the system is feasible for application designs and could be implemented on technological platforms. Yanqing Guo, Yongling Fu, Xiaoye Qi, and Chun Cao Copyright © 2014 Yanqing Guo et al. All rights reserved. Autonomous Position Estimation of a Mobile Node Based on Landmark and Localization Sensor Wed, 16 Apr 2014 14:09:06 +0000 This study proposes an efficient position estimation method for localizing a mobile node in indoor environment. Although several conventional methods have been successfully applied for position estimation, they have some drawbacks such as low extendibility in an indoor space, intensive computation, and estimation errors. We propose a precise estimation approach based on a localization sensor and artificial landmarks. In our approach, a mobile node autonomously measures the location of landmarks attached to the ceiling with a localization sensor while moving across the landmarks and building a landmark map. And then, the node estimates its location under the ceiling using the map. In this process, we use a landmark histogram and a Kalman filter to reduce estimation errors. Several experiments performed using a mobile robot successfully demonstrated the feasibility of our proposed approach. Se-Jun Park, Jeong-Sik Park, Yong-Ho Seo, and Tae-Kyu Yang Copyright © 2014 Se-Jun Park et al. All rights reserved. Underwater Wireless Sensor Networks Wed, 16 Apr 2014 07:01:11 +0000 Dongkyun Kim, Juan Carlos Cano, Wei Wang, Floriano De Rango, and Kun Hua Copyright © 2014 Dongkyun Kim et al. All rights reserved. An Improved Group-Based Neighbor Discovery Algorithm for Mobile Sensor Networks Tue, 15 Apr 2014 16:36:18 +0000 Wireless sensor networks have been widely used in a variety of commercial and military applications, which often require neighbor nodes to establish connection quickly. Due to high mobility of nodes, it is a challenging issue to reduce discovery delay. Most discovery designs are based on pairwise and fixed duty cycle, in which discovery is passively achieved when two nodes wake up at the same time. In order to further improve the efficiency of neighbor discovery in mobile sensor networks, this paper proposes an improved group-based neighbor discovery algorithm (IGND) which dynamically adjusts the nodes’ active time based on spatial properties. This paper describes the network model and the algorithm implementation in detail. Simulation results show that the improved algorithm has a good effect in reducing discovery latency and promoting discovery efficiency. Qiang Niu, Weiwei Bao, and Shixiong Xia Copyright © 2014 Qiang Niu et al. All rights reserved. Sensor Resource Sharing Approaches in Sensor-Cloud Infrastructure Tue, 15 Apr 2014 16:29:43 +0000 Generally, wireless sensor networks have been designed to support predefined application services. The tight coupling between a network and application limits the usability of sensor data. To increase the utilities of wireless sensor networks, sensor-cloud infrastructure has been proposed to provide an open and flexible platform to gather, store, use, and share data from heterogeneous sensors. In this paper, we introduce sensor-cloud infrastructure and present not only comprehensive technical issues like sensor description and publish/subscribe middleware but also applications using sensor-cloud infrastructure. When the issues are tackled in the development of sensor-cloud system, the attractiveness of new applications and services will considerably be increased for end users. Yujin Lim and Jaesung Park Copyright © 2014 Yujin Lim and Jaesung Park. All rights reserved. Semisupervised Location Awareness in Wireless Sensor Networks Using Laplacian Support Vector Regression Tue, 15 Apr 2014 16:17:32 +0000 Supervised machine learning has been widely used in context-aware wireless sensor networks (WSNs) to discover context descriptions from sensor data. However, collecting a lot of labeled training data in order to guarantee good performance requires much cost and time. For this reason, the semisupervised learning has been recently developed due to its superior performance despite using only a small amount of the labeled data. In this paper, we extend the standard support vector regression (SVR) to the semisupervised SVR by employing manifold regularization, which we call Laplacian SVR (LapSVR). The LapSVR is compared with the standard SVR and the semisupervised least square algorithm that is another recently developed semisupervised regression algorithm. The algorithms are evaluated for location awareness of multiple mobile robots in a WSN. The experimental results show that the proposed algorithm yields more accurate location estimates than the other algorithms. Jaehyun Yoo and H. Jin Kim Copyright © 2014 Jaehyun Yoo and H. Jin Kim. All rights reserved. Using Traffic Light Signal to Enhance Intersection Foreground Detection Based on Video Sensor Networks Tue, 15 Apr 2014 14:05:10 +0000 Foreground detection plays an important role in the traffic surveillance applications, especially in urban intersections. Background subtraction is an efficient approach to segment the background and foreground with static cameras from video sensor networks. But when modelling the background, most statistical techniques adjust the learning rate only based on the changes from video sequences, which is a crucial parameter controlling the updating speed. This causes a slow adaptation to sudden environmental changes. For example, a stopped car fuses into background before moving again, and it lowers the segmentation performance. This paper proposes an efficient way to address the problem by accounting for the physical world signal in traffic junctions. It assigns an adaptive learning rate to each pixel by integrating traffic light signal obtained from sensor networks.Combined with abundant physical world signals, background subtraction method is able to adapt itself to the outside world changes instantly. We test our approach in real urban traffic intersection; experimental results show that the new method increases the accuracy of detection and has a promising future. Rong Ding, Shunli Wang, and Xu Liu Copyright © 2014 Rong Ding et al. All rights reserved. Activity Graph Feature Selection for Activity Pattern Classification Tue, 15 Apr 2014 14:01:38 +0000 Sensor-based activity recognition is attracting growing attention in many applications. Several studies have been performed to analyze activity patterns from an activity database gathered by activity recognition. Activity pattern classification is a technique that predicts class labels of people such as individual identification, nationalities, and jobs. For this classification problem, it is important to mine discriminative features reflecting the intrinsic patterns of each individual. In this paper, we propose a framework that can classify activity patterns effectively. We extensively analyze activity models from a classification viewpoint. Based on the analysis, we represent activities as activity graphs by combining every combination of daily activity sequences in meaningful periods. Frequent patterns over these activity graphs can be used as discriminative features, since they reflect people’s intrinsic lifestyles. Experiments show that the proposed method achieves high classification accuracy compared with existing graph classification techniques. Kisung Park, Yongkoo Han, and Young-Koo Lee Copyright © 2014 Kisung Park et al. All rights reserved. Implementation and Evaluation of Large-Scale Video Surveillance System Based on P2P Architecture and Cloud Computing Tue, 15 Apr 2014 11:27:46 +0000 Video surveillance system (VSS) is increasingly becoming important part in daily life. For traditional VSS, each camera stores streaming data to a centralized server. It will create a great volume of video data for a large VSS and may raise some issues in keeping daily video data to centralized server, such as limited bandwidth and storage insufficiency of server and lower reliability and scalability. In order to solve the problem, we have proposed an architecture for VSS based on well-developed peer-to-peer technique and emerging cloud computing. In this paper, we implement a large-scale VSS (LVSS) and propose an evaluation framework based on the proposed architecture. We implement the LVSS exploits inherent characteristics of P2P and cloud computing to provide an economic, scalable, reliable, and efficient approach to store streaming video. We conducted some experiments to evaluate effectiveness and efficiency of the system. The result shows that the proposed architecture outperforms traditional VSS in terms of effectiveness, efficiency, reliability, and scalability. Win-Tsung Lo, Yue Shan Chang, Ruey-Kai Sheu, Chao-Tung Yang, Tong-Ying Juang, and Yu-Sheng Wu Copyright © 2014 Win-Tsung Lo et al. All rights reserved. Associated Clustering Strategy for Wireless Sensor Network Tue, 15 Apr 2014 08:14:05 +0000 We consider the soil moisture monitoring problem and propose a WSN associated clustering strategy based on spatiotemporal data correlation, which ensures that the nodes within each cluster can share a good data correlation and consequently makes the cluster head do the data fusion more efficiently. As a result, the energy of each node will be saved and the lifetime of the whole sensor network will be extended. In the associated clustering strategy, the different clusters can be divided by the correlation characteristics of nodes data, which is based on a dynamic model and a correlation characteristics model after the correlation coefficient analysis. Simulation results show that our proposed associated clustering strategy works very well in soil moisture measurement. Moreover, as compared with the traditional random clustering, the associated clustering strategy based on data correlation achieves better performance for each cluster, and will be more efficient in data fusion at the cluster heads. Yajuan Sun, Huanzhao Wang, Kewang Zhang, and Xudong Yang Copyright © 2014 Yajuan Sun et al. All rights reserved. Proposed M-Payment System Using Near-Field Communication and Based on WSN-Enabled Location-Based Services for M-Commerce Tue, 15 Apr 2014 06:59:16 +0000 Advances in mobile communication and information technology have resulted in wireless sensor network (WSN) systems in which mobile phones (smart phones) can be used to conduct a wide variety of commercial, social, entertainment, and file-sharing transactions. In particular, mobile commerce (m-commerce) allows users to conduct payment, business, and service transactions over portable mobile devices. This trend has been enhanced by the development of near-field communication (NFC) technology and the increased market for NFC-embedded (smart phones). NFC technology is a standards-based wireless communication technology that allows data to be exchanged between devices located a few centimeters apart, such as radio-frequency identification (RFID tags and readers). To refine the m-commerce process in the NFC-based mobile environment, we study NFC and location-based services propose a WSN-hosted m-payment system based on these technologies. Sun-Kuk Noh, Seong-Ro Lee, and DongYou Choi Copyright © 2014 Sun-Kuk Noh et al. All rights reserved. Integration of Energy Harvester for Self-Powered Wireless Sensor Network Nodes Mon, 14 Apr 2014 16:07:24 +0000 This paper reports an energy harvester suitable for self-powered wireless sensor network (WSN) nodes consisting of a piezoelectric cantilever, an energy harvesting circuit, and a storage capacitor. Having the same size as a credit card, the proposed WSN nodes can be easily integrated into various applications, such as motor and air conditioning equipment. The WSN node is powered by an integrated bimorph piezoelectric generator that harvests energy from ambient vibration. The paper has developed a method to optimize the harvester parameters to attune it to the dominant vibration frequency. Tests carried out on the proposed harvester show that the proposed design can meet the energy requirements of a WSN node and achieve an efficiency of 79%. Lijuan Chen, Xiaohui Xu, Pingliang Zeng, and Jianqiang Ma Copyright © 2014 Lijuan Chen et al. All rights reserved. A Novel 3D Indoor Localization Scheme Using Virtual Access Point Mon, 14 Apr 2014 12:44:20 +0000 The global positioning system (GPS) is a popular choice for accurate location sensing and is often used in navigation systems. However, GPS fails to operate inside buildings because satellite signals are blocked. Thus, GPS cannot be used for localization indoors. Moreover, it is difficult to distinguish between the different floors. Research to overcome this problem using the ultrawideband (UWB), radio frequency identification (RFID), and infrared ray (IR) has been conducted. These methods, however, have drawbacks, such as the need for an additional communication module and database. Wireless local area network (WLAN) access point (AP) is widely installed at various locations, and using these WLAN APs can be a viable alternative. The proposed system in this paper indicates the location information in the service set identifier (SSID) of virtual AP. Therefore, merely by scanning the WLAN signals, mobile users can detect their location indoors. Taekook Kim and Eui-Jik Kim Copyright © 2014 Taekook Kim and Eui-Jik Kim. All rights reserved. Ubiquitous Data-Centric Sensor Networks Mon, 14 Apr 2014 09:00:32 +0000 Ting Yang, Peng-Yung Woo, Zhaoxia Wang, Javid Taheri, Chin Hoong Choor, and Guoqiang Hu Copyright © 2014 Ting Yang et al. All rights reserved. Side Information Generation for Distributed Video Coding Using Spatiotemporal Joint Bilinear Upsampling Mon, 14 Apr 2014 08:02:29 +0000 Distributed video coding presents a viable solution for power-constrained multimedia communication. However, its relatively low coding efficiency compared to the conventional video coding schemes remains a challenging issue. The rate-distortion performance of distributed video coding is highly dependent on the quality of side information generated at the decoder and various techniques have been proposed to improve the side information quality in block-based and frame-based distributed video coding architectures. In this paper, a robust spatiotemporal joint bilateral upsampling based side information generation method is proposed. The proposed side information generation method is based on a block-based low-complexity distributed video coding architecture with adaptive block coding mode classification. A partially reconstructed Wyner-Ziv (WZ) frame with skip and key blocks is downsampled and spatiotemporal error concealment and joint bilateral upsampling are used to generate the side information. Simulation results show that the proposed method improves the quality of side information significantly while keeping low computational complexity. Wenhui Liu, Krishna Rao Vijayanagar, and Joohee Kim Copyright © 2014 Wenhui Liu et al. All rights reserved. Protocol and Architecture to Bring Things into Internet of Things Sun, 13 Apr 2014 13:00:31 +0000 The Internet of Things (IoT) concept proposes that everyday objects are globally accessible from the Internet and integrate into new services having a remarkable impact on our society. Opposite to Internet world, things usually belong to resource-challenged environments where energy, data throughput, and computing resources are scarce. Building upon existing standards in the field such as IEEE1451 and ZigBee and rooted in context semantics, this paper proposes CTP (Communication Things Protocol) as a protocol specification to allow interoperability among things with different communication standards as well as simplicity and functionality to build IoT systems. Also, this paper proposes the use of the IoT gateway as a fundamental component in IoT architectures to provide seamless connectivity and interoperability among things and connect two different worlds to build the IoT: the Things world and the Internet world. Both CTP and IoT gateway constitute a middleware content-centric architecture presented as the mechanism to achieve a balance between the intrinsic limitations of things in the physical world and what is required from them in the virtual world. Said middleware content-centric architecture is implemented within the frame of two European projects targeting smart environments and proving said CTP’s objectives in real scenarios. Ángel Asensio, Álvaro Marco, Rubén Blasco, and Roberto Casas Copyright © 2014 Ángel Asensio et al. All rights reserved. A Novel Mobile Localization Method for Distributed Sensor Network with Non-Line-of-Sight Error Mitigation Sun, 13 Apr 2014 00:00:00 +0000 Mobile localization using distributed sensor network has attracted significant research interest in recent years. One of the main challenges for mobile location estimation is the presence of the non-line-of-sight (NLOS) propagation. It results in erroneous measurements containing NLOS error due to the reflection and diffraction. The NLOS error could seriously reduce the localization accuracy. This paper presents a novel mobile localization method for distributed sensor network in NLOS propagation scenarios. The aim of the method is to mitigate the NLOS error and enhance the localization accuracy. The transition between the LOS and NLOS is described by two-state Markov model. The interacting multiple model frame is employed to estimate the position of unknown node. The probability data association algorithm is used to filter the estimated location. The simulation results show that the proposed method outperforms the traditional filter method in NLOS scenarios. Nan Hu, Hao Wu, Chengdong Wu, and Yuan Gao Copyright © 2014 Nan Hu et al. All rights reserved. Prediction-Based Filter Updating Policies for Top- Monitoring Queries in Wireless Sensor Networks Sun, 13 Apr 2014 00:00:00 +0000 Processing top- query in an energy-efficient manner is an important topic in wireless sensor networks. Redundant data transmitting between base station and sink node is avoided by installing filters on sensor nodes; thus, communication overhead between base station and sensor nodes is decreased. However, existing algorithms such as FILA, and DAFM consume much energy when updating the filter window. In this paper, we propose a new top- algorithm named PreFU which is based on prediction models to update window parameters of filters. PreFU can predict the next step sensor values based on time series predicting models which can be built by historical data. By estimating the cost of updating window parameters based on predicted sensor values, updates of filter window parameters can be reduced. Thus, the cost of updating window parameters is decreased. Experimental results show that our PreFU algorithm is more energy-efficient than existing algorithms while guaranteeing the accuracy of top- query results. Jiping Zheng, Hui Zhang, Baoli Song, Haixiang Wang, and Yongge Wang Copyright © 2014 Jiping Zheng et al. All rights reserved. Geometric Range-Free Localization Algorithm Based on Optimal Anchor Node Selection in Wireless Sensor Networks Thu, 10 Apr 2014 17:40:37 +0000 In range-free localization scheme of wireless sensor networks, estimating the distance to the anchor nodes having the actual location is common to compute the position of unknown node. Since the range-free scheme is based on the topology information, the accuracy of distance estimation is considerably affected by node density or node deployment. In this paper, we propose a geometric range-free localization algorithm which estimates the unknown positions geometrically by topological information without considering the distance estimation. To achieve this, we propose an optimal anchor node selection algorithm which selects the anchor nodes connected topologically well for the geometrical location estimation. Simulation results show that the proposed algorithm offers considerably an improved performance compared to the other existing studies. Hyunjae Woo and Chaewoo Lee Copyright © 2014 Hyunjae Woo and Chaewoo Lee. All rights reserved. Consensus Target Tracking in Switching Wireless Sensor Networks with Outliers Thu, 10 Apr 2014 17:25:22 +0000 The problem of consensus-based distributed tracking in wireless sensor networks (WSNs) with switching network topologies and outlier-corrupted sensor observations is considered. First, to attack the outlier-corrupted measurements, a robust Kalman filtering (RKF) scheme with weighted matrices on innovation sequences is introduced. The proposed RKF possesses high robustness against outliers while having similar computational burden as traditional Kalman filter. Then, each node estimates the network-wide agreement on target state using only communications between one-hop neighbors. In order to improve the convergent speed of the consensus filter in case of switching topologies, an adaptive weight update strategy is proposed. Note that the proposed algorithm relaxes the requirement of Gaussian noise statistics in contrast to the decentralized/distributed Kalman filters. Besides, unlike the existing consensus-based filters, we do not need to perform consensus filtering on the covariance matrices, which will reduce the computational and communicational burden abundantly. Finally, simulation examples are included to demonstrate the robustness of the proposed RKF and effectiveness of adaptive consensus approach. Yan Zhou, Dongli Wang, Yonghong Lan, and Qingzhen Wen Copyright © 2014 Yan Zhou et al. All rights reserved. Design and Implementation of File Deduplication Framework on HDFS Thu, 10 Apr 2014 12:32:03 +0000 File systems are designed to control how files are stored and retrieved. Without knowing the context and semantics of file contents, file systems often contain duplicate copies and result in redundant consumptions of storage space and network bandwidth. It has been a complex and challenging issue for enterprises to seek deduplication technologies to reduce cost and increase the storage efficiency. To solve such problem, researchers proposed in-line or offline solutions for primary storages or backup systems at the subfile or whole-file level. Some of the technologies are used for file servers and database systems. Fewer studies focus on the cloud file system deduplication technologies at the application level, especially for the Hadoop distributed file system. It is the goal of this paper to design a file deduplication framework on Hadoop distributed file system for cloud application developers. The architecture, interface, and implementation experiences are also shared in this paper. Ruey-Kai Sheu, Shyan-Ming Yuan, Win-Tsung Lo, and Chan-I Ku Copyright © 2014 Ruey-Kai Sheu et al. All rights reserved. An Energy-Efficient Outlier Detection Based on Data Clustering in WSNs Thu, 10 Apr 2014 12:11:19 +0000 Sensor nodes in wireless sensor networks are prone to malfunction because they are exposed to the nearby environment directly. Consequently, wrong sensor readings occurred from sensor nodes and these readings are called an outlier. Commonly, since an outlier deviates from normal sensor readings and it can bring about some problems, various techniques to detect the outliers have been proposed. In this paper, we propose an efficient outlier detection technique based on data clustering. In order to decide the width of the cluster that consists of the sensor readings, we applied the Pigeonhole Principle and then detected the outliers based on clusters. In experiments, we demonstrate the efficiency of our proposed technique compared to other outlier detection techniques. Hongyeon Kim and Jun-Ki Min Copyright © 2014 Hongyeon Kim and Jun-Ki Min. All rights reserved.