ISRN Sensor Networks The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. An Energy Efficient Data Gathering in Dense Mobile Wireless Sensor Networks Wed, 16 Apr 2014 09:34:20 +0000 Amidst of the growing impact of wireless sensor networks (WSNs) on real world applications, numerous schemes have been proposed for collecting data on multipath routing, tree, clustering, and cluster tree. Effectiveness of WSNs only depends on the data collection schemes. Existing methods cannot provide a guaranteed reliable network about mobility, traffic, and end-to-end connection, respectively. To mitigate such kind of problems, a simple and effective scheme is proposed, which is named as cluster independent data collection tree (CIDT). After the cluster head election and cluster formation, CIDT constructs a data collection tree (DCT) based on the cluster head location. In DCT, data collection node (DCN) does not participate in sensing, which is simply collecting the data packet from the cluster head and delivering it into sink. CIDT minimizes the energy exploitation, end-to-end delay and traffic of cluster head due to transfer of data with DCT. CIDT provides less complexity involved in creating a tree structure, which maintains the energy consumption of cluster head that helps to reduce the frequent cluster formation and maintain a cluster for considerable amount of time. The simulation results show that CIDT provides better QoS in terms of energy consumption, throughput, end-to-end delay, and network lifetime for mobility-based WSNs. R. Velmani and B. Kaarthick Copyright © 2014 R. Velmani and B. Kaarthick. All rights reserved. Development and Implementation of Wireless Multigas Concentration Cloud System Tue, 04 Mar 2014 11:51:35 +0000 According to the report “Global Health Risks of 2004” issued by WHO (World Health Organization) in Geneva 2009 (WHO, 2012), the mortality rate of the diseases and cause of death which results from the smoke produced by burning solid fuel is ranked tenth, occupying 3.3% of the global amounts, and the DALYs (Disability Adjusted Life Years) is ranked the ninth, occupying 2.7% of the world. Once the pollution occurred in an insufficient ventilation location, the womankind and children will be the most directly affected; therefore, we hoped to focus the measurement environment on indoor surroundings in this paper. This paper proposes a pointing at several kinds of indoor pollutants and integrating multigas sensors, which includes carbon monoxide, carbon dioxide total volatile organic compounds, and so forth. Our paper combines gas sensors with WSN (Wireless Sensor Networks) nodes; we provide users with optional monitoring subjects for constructing and also adapt ZigBee and Wi-Fi modules to get united with uploading real-time sensor messages. Moreover, for the reason of decreasing installation cost of sensors and setting up easily, this paper builds a cloud data-viewing platform additionally, enabling users to observe air quality through the cloud server everywhere. Sheng-Chung Tien, Robert Lin, Tsung-Yu Lee, Ren-Guey Lee, and Shu-Ying Huang Copyright © 2014 Sheng-Chung Tien et al. All rights reserved. On Formal and Automatic Security Verification of WSN Transport Protocols Tue, 04 Mar 2014 08:15:00 +0000 We address the problem of formal and automated security verification of transport protocols for wireless sensor networks (WSN) that may perform cryptographic operations. The verification of this class of protocols is difficult because they typically consist of complex behavioral characteristics, such as real-time, probabilistic, and cryptographic operations. To solve this problem, we propose a probabilistic timed calculus for cryptographic protocols and demonstrate how to use this formal language for proving security or vulnerability of protocols. The main advantage of the proposed language is that it supports an expressive syntax and semantics, allowing for studying real-time, probabilistic, and cryptographic issues at the same time. Hence, it can be used to verify systems that involve these three properties in a convenient way. In addition, we propose an automatic verification method, based on the well-known PAT process analysis toolkit, for this class of protocols. For demonstration purposes, we apply the proposed manual and automatic proof methods for verifying the security of DTSN and SDTP, which are two of the recently proposed WSN transport protocols. Vinh Thong Ta, Levente Buttyán, and Amit Dvir Copyright © 2014 Vinh Thong Ta et al. All rights reserved. Capacity of Data Collection in Wireless Sensor Networks Based on Mutual Information and MMSE Estimation Mon, 17 Feb 2014 12:31:24 +0000 We investigate the properties of data collection in wireless sensor networks, in terms of both capacity and power allocation strategy. We consider a scenario in which a number of sensors observe a target being estimated at fusion center (FC) using minimum mean-square error (MMSE) estimator. Based on the relationship between mutual information and MMSE (I-MMSE), the capacity of data collection in coherent and orthogonal multiple access channel (MAC) models is derived. Considering power constraint, the capacity is derived under two scenarios: equal power allocation and optimal power allocation of both models. We provide the upper bound of capacity as a benchmark. In particular, we show that the capacity of data collection scales as Θ((1/2)log) when the number of sensors L grows to infinity. We show through simulation results that for both coherent and orthogonal MAC models, the capacity of the optimal power is larger than that of the equal power. We also show that the capacity of coherent MAC is larger than that of orthogonal MAC, particularly when the number of sensors L is large and the total power P is fixed. Ajib Setyo Arifin and Tomoaki Ohtsuki Copyright © 2014 Ajib Setyo Arifin and Tomoaki Ohtsuki. All rights reserved. Detection and Countermeasure of Node Misbehaviour in Clustered Wireless Sensor Network Sun, 29 Dec 2013 10:37:30 +0000 Wireless sensor networks are widely used in many applications like battlefield monitoring, environment monitoring, and so forth. In all of these applications the cooperation among various sensor nodes is needed to forward the data packets to the base station. However, it expends the various resources of a sensor node such as battery power, storage, and processing power. Therefore, to conserve its own resources a node may become selfish by not forwarding the data to the others. This kind of attack has serious consequences if the attacker node is the leader of a cluster. In the presence of attack the base station will not be able to get the data from the victimized cluster while resources of the member of that cluster are being consumed. In this paper we propose a scheme called window based scheme (WBS) to detect this kind of misbehavior in WSN. Our detection scheme is energy efficient because most of the computations are done at base station only. Simulation results prove that our method detects and removes the attacker effectively and efficiently. Meenakshi Tripathi, M. S. Gaur, V. Laxmi, and P. Sharma Copyright © 2013 Meenakshi Tripathi et al. All rights reserved. Balancing Energy Consumption in Clustered Wireless Sensor Networks Mon, 11 Nov 2013 08:56:25 +0000 Clustering in wireless sensor networks is an efficient way to structure and organize the network. It aims at identifying a subset of nodes within the network and binding it to a leader (i.e., cluster head). The leader becomes in charge of specific additional tasks like gathering data from all nodes in its cluster and sending them using a longer range communication to a sink. As a consequence, a cluster head exhausts its battery more quickly than regular nodes. In this paper, we present four variants of BLAC, a novel battery level aware clustering family of schemes. BLAC considers the battery level combined with another metric to elect the cluster-head. The cluster-head role is taken alternately by each node to balance energy consumption. Due to the local nature of the algorithms, keeping the network stable is easier. BLAC aims at maximizing the time with all nodes alive to satisfy the application requirements. Simulation results show that BLAC improves the full network lifetime three times more than the traditional clustering schemes by balancing energy consumption over nodes and still deliveres high data ratio. Tony Ducrocq, Michaël Hauspie, and Nathalie Mitton Copyright © 2013 Tony Ducrocq et al. All rights reserved. Faulty Sensor Node Detection Using Round Trip Time and Discrete Paths in WSNs Mon, 23 Sep 2013 08:47:22 +0000 Wireless sensor networks (WSNs) with efficient and accurate design to increase the quality of service (QoS) have become a hot area of research. Implementing the efficient and accurate WSNs requires deployment of the large numbers of portable sensor nodes in the field. The quality of service of such networks is affected by lifetime and failure of sensor node. In order to improve the quality of service, the data from faulty sensor nodes has to be ignored or discarded in the decision-making process. Hence, detection of faulty sensor node is of prime importance. In the proposed method, discrete round trip paths (RTPs) are compared on the basis of round trip delay (RTD) time to detect the faulty sensor node. RTD protocol is implemented in NS2 software. WSNs with circular topology are simulated to determine the RTD time of discrete RTPs. Scalability of the proposed method is verified by simulating the WSNs with various sensor nodes. R. N. Duche and N. P. Sarwade Copyright © 2013 R. N. Duche and N. P. Sarwade. All rights reserved. A Sub-A Ultrasonic Wake-Up Trigger with Addressing Capability for Wireless Sensor Nodes Thu, 19 Sep 2013 17:39:58 +0000 Wireless sensor nodes spend most of the time waiting either for sensed data or for packets to be routed to the sink. While on board, sensors can raise hardware interrupts to trigger the wake-up of the processor, incoming packets require the radio module to be turned on in order to be properly received and processed; thus, reducing the effectiveness of dynamic power management and exposing the node to unintended packets cause energy waste. The capability of triggering the wake-up of a node over the air would makes it possible to keep the entire network asleep and to wake up the nodes along a path to the sink whenever there is a packet to transmit. This paper presents an ultrasonic wake-up trigger for ultra-low-power wireless sensor nodes developed as a plug-in module for VirtualSense motes. The module supports a simple out-of-band addressing scheme to enable the selective wake-up of a target node. In addition, it makes it possible to exploit the propagation speed of ultrasonic signals to perform distance measurements. The paper outlines the design choices, reports the results of extensive measurements, and discusses the additional degrees of freedom introduced by ultrasonic triggering in the power-state diagram of VirtualSense. Emanuele Lattanzi, Matteo Dromedari, Valerio Freschi, and Alessandro Bogliolo Copyright © 2013 Emanuele Lattanzi et al. All rights reserved. Water-Filling Solution for Distributed Estimation of Correlated Data in WSN MIMO System Wed, 18 Sep 2013 11:16:56 +0000 We consider the distributed estimation of a random vector signal in a power constraint wireless sensor network (WSN) that follows a multiple-input and multiple-output (MIMO) coherent multiple access channel model. We design linear coding matrices based on linear minimum mean-square error (LMMSE) fusion rule that accommodates spatial correlated data. We obtain a closed-form solution that follows a water-filling strategy. We also derive a lower bound to this model. Simulation results show that when the data is more correlated, the distortion in terms of mean-square error (MSE) degrades. By taking into account the effects of correlation, observation, and channel matrices, the proposed method performs better than equal power method. Ajib Setyo Arifin and Tomoaki Ohtsuki Copyright © 2013 Ajib Setyo Arifin and Tomoaki Ohtsuki. All rights reserved. Borel Cayley Graph-Based Topology Control for Consensus Protocol in Wireless Sensor Networks Sat, 14 Sep 2013 11:01:52 +0000 Borel Cayley graphs have been shown to be an efficient candidate topology in interconnection networks due to their small diameter, short path length, and low degree. In this paper, we propose topology control algorithms based on Borel Cayley graphs. In particular, we propose two methods to assign node IDs of Borel Cayley graphs as logical topologies in wireless sensor networks. The first one aims at minimizing communication distance between nodes, while the entire graph is imposed as a logical topology; while the second one aims at maximizing the number of edges of the graph to be used, while the network nodes are constrained with a finite radio transmission range. In the latter case, due to the finite transmission range, the resultant topology is an “incomplete” version of the original BCG. In both cases, we apply our algorithms in consensus protocol and compare its performance with that of the random node ID assignment and other existing topology control algorithms. Our simulation indicates that the proposed ID assignments have better performance when consensus protocols are used as a benchmark application. Junghun Ryu, Jaewook Yu, Eric Noel, and K. Wendy Tang Copyright © 2013 Junghun Ryu et al. All rights reserved. Address Assignment in Indoor Wireless Networks Using Deterministic Channel Simulation Sun, 01 Sep 2013 13:30:54 +0000 A crucial step during commissioning of wireless sensor and automation networks is assigning high-level node addresses (e.g., floor/room/fixture) to nodes mounted at their respective location. This address assignment typically requires visiting every single node prior to, during, or after mounting. For large-scale networks it also presents a considerable logistical effort. This paper describes a new approach to automatically assign high-level addresses without visiting every node. First, the wireless channel is simulated using a deterministic channel simulation in order to obtain node-to-node estimates of path loss. Next, the channel is measured by a precommissioning test procedure on the live network. In a third step, results from measurements and simulation are condensed into graphs and matched against each other. The resulting problem, identified as weighted graph matching, is solved heuristically. Viability of the approach and its performance is demonstrated by means of a publicly available test data set, which the algorithm is able to solve flawlessly. Further points of interest are the conditions that lead to high quality address assignments. Edgar Holleis and Christoph Grimm Copyright © 2013 Edgar Holleis and Christoph Grimm. All rights reserved. Sensor Node Placement in Wireless Sensor Network Based on Territorial Predator Scent Marking Algorithm Wed, 26 Jun 2013 07:52:43 +0000 Optimum sensor node placement in a monitored area is needed for cost-effective deployment. The positions of sensor nodes must be able to provide maximum coverage with longer lifetimes. This paper proposed a sensor node placement technique that utilizes a new biologically inspired optimization technique that imitates the behaviour of territorial predators in marking their territories with their odours, known as territorial predator scent marking algorithm (TPSMA). The TPSMA deployed in this paper uses the maximum coverage objective function. A performance study has been carried out by comparing the performance of the proposed technique with the minimax and lexicographic minimax (lexmin) sensor node placement schemes in terms of coverage ratio and uniformity. Uniformity is a performance metric that can be used to estimate a WSN lifetime. Simulation results show that the WSN deployed with the proposed sensor node placement scheme outperforms the other two schemes with larger coverage ratio and is expected to provide as long lifetime as possible. Husna Zainol Abidin and Norashidah Md. Din Copyright © 2013 Husna Zainol Abidin and Norashidah Md. Din. All rights reserved. MQoSR: A Multiobjective QoS Routing Protocol for Wireless Sensor Networks Tue, 04 Jun 2013 15:11:24 +0000 With the growing demand for quality-of-service (QoS) aware routing protocol in wireless networks, QoS-based routing has emerged as an interesting research topic. Quality of service guarantee in wireless sensor networks (WSNs) is difficult and more challenging due to the fact that the available resources of sensors and the various applications running over these networks have different constraints in their nature and requirements. In this paper, we present a heuristic neighbor selection mechanism in WSNs that uses the geographic routing mechanism combined with the QoS requirements to provide multiobjective QoS routing (MQoSR) for different application requirements. The problem of providing QoS routing is formulated as link, and path-based metrics. The link-based metrics are partitioned in terms of reliability, delay, distance to sink, and energy, and the path-based metrics are presented in terms of end-to-end delay, reliability of data transmission, and network lifetime. The simulation results demonstrate that MQoSR protocol is able to achieve the delay requirements, and due to optimum path selection process, the achieved data delivery ratio is always above the required one. MQoSR protocol outperforms the existing model in the literature remarkably in terms of reliable data transmission, time data delivery, and routing overhead and underlines the importance of energy-efficient solution to enhance network lifetime. Hind Alwan and Anjali Agarwal Copyright © 2013 Hind Alwan and Anjali Agarwal. All rights reserved. Robust Data Compression for Irregular Wireless Sensor Networks Using Logical Mapping Mon, 03 Jun 2013 13:40:38 +0000 We propose RIDA, a novel robust information-driven data compression architecture for distributed wireless sensor networks. The key idea is to determine the data correlation among a group of sensors based on the data values to significantly improve compression performance rather than relying solely on spatial data correlation. A logical mapping approach assigns virtual indices to nodes based on the data content, which enables simple implementation of data transformation on resource-constrained nodes without any other information. We evaluate RIDA with both discrete cosine transform (DCT) and discrete wavelet transform (DWT) on publicly available real-world data sets. Our experiments show that 30% of energy and 80–95% of bandwidth can be saved for typical multihop data networks. Moreover, the original data can be retrieved after decompression with a low error of about 3%. In particular, for one state-of-the-art distributed data compression algorithm for sensor networks, we show that the compression ratio is doubled by using logical mapping while maintaining comparable mean square error. Furthermore, we also propose a mechanism to detect and classify missing or faulty nodes, showing accuracy and recall of 95% when half of the nodes in the network are missing or faulty. Thanh Dang, Nirupama Bulusu, and Wu-chi Feng Copyright © 2013 Thanh Dang et al. All rights reserved. Real-World Deployments of Participatory Sensing Applications: Current Trends and Future Directions Mon, 27 May 2013 11:53:56 +0000 With the advent of participatory sensing (sensors integrated with consumer electronics such as cell phones and carried by people), exciting new opportunities arise. Mobile sensors (e.g., those mounted on cars or carried by people) can provide spatial sampling diversity not possible with traditional static sensor networks. Recently, participatory sensing has attracted considerable attention of research community. In this paper, we survey existing participatory sensing deployments and discuss current trends and few possible future directions. Sameer Tilak Copyright © 2013 Sameer Tilak. All rights reserved. A 6LoWPAN Routing Optimization Mechanism for WMSN Thu, 11 Apr 2013 14:31:40 +0000 In Wireless sensor networks (WSNs), group mobility is important in many practical application scenarios, and it is inconvenient for traditional static WSNs to collect information. In this paper, we propose a WSN model based on IPv6 over Low power Wireless Personal Area Networks (6LoWPANs) in mobile sensing application scenarios. Wireless mesh sensor network (WMSN) infrastructure and Network Mobility (NEMO) protocol are deployed to ensure the continuity of the communications. The routing optimization mechanism in the nested network is then discussed. By taking mobile network partition and IP address configuration in the nested network, the corresponding signaling flow is discussed. Simulation results indicate that our mechanism is able to minimize the transmission costing, handoff delay, throughput and energy consumption of sensor nodes. Energy of each mobile router (MR) saves around 0.2 J per 3 seconds. Jing Li, Chong Shen, and Kae Hsiang Kwong Copyright © 2013 Jing Li et al. All rights reserved. Combining Kalman Filtering with ZigBee Protocol to Improve Localization in Wireless Sensor Network Thu, 21 Mar 2013 11:35:18 +0000 We propose a low-cost and low-power-consumption localization scheme for ZigBee-based wireless sensor networks (WSNs). Our design is based on the link quality indicator (LQI)—a standard feature of the ZigBee protocol—for ranging and the ratiometric vector iteration (RVI)—a light-weight distributed algorithm—modified to work with LQI measurements. To improve performance and quality of this system, we propose three main ideas: a cooperative approach, a coefficient delta () to regulate the speed of convergence of the algorithm, and finally the filtering process with the extended Kalman filter. The results of experiment simulations show acceptable localization performance and illustrate the accuracy of this method. Bouchra El Madani, Anne Paule Yao, and Abdelouahid Lyhyaoui Copyright © 2013 Bouchra El Madani et al. All rights reserved. QC2: A QoS Control Scheme with Quick Convergence in Wireless Sensor Networks Wed, 13 Mar 2013 12:04:46 +0000 In wireless sensor networks, too many or too few power-on sensors may cause the waste of resources or poor sensing efficiency; thus, controlling the number of active sensors to meet the predicted target number is the purpose of this research. However, the total number of sensors may be unstable because of the increment and damage to the sensors. It is difficult to control the number of active sensors to meet the predicted target in this condition. Previous studies proposed the Gur Game algorithm to solve this problem. However, the convergence time of the Gur Game algorithm is too long, which causes sensors to consume excessive power and waste resources. Therefore, this paper proposed the QoS Control with Quick Convergence (QC2). This method utilizes total virtual value to accelerate the convergence operation from the number of sensors to the target number. The experiment result shows that the QC2 method can cause the number of sensors to converge rapidly with the target value and that QC2 can be over a hundred times faster than the Gur Game algorithm with regard to convergence. Hao-Li Wang and Wei-Lun Hung Copyright © 2013 Hao-Li Wang and Wei-Lun Hung. All rights reserved. Prolonging the Lifetime of Two-Tiered Wireless Sensor Networks with Mobile Relays Tue, 05 Mar 2013 13:29:57 +0000 We propose a clustering scheme for wireless sensor nodes in hierarchical wireless sensor networking architectures that employs mobile relay nodes in order to achieve energy conservation and network lifetime prolongation. The key aspects of our scheme are relay node relocation and reclustering when failures are detected. The performance of the proposed approach is evaluated via simulations for various topology layouts based on the sensor node population and number of mobile relay nodes employed. The results show significant energy savings in particular for topologies with large numbers of sensors. Theodore C. Kotsilieris and George T. Karetsos Copyright © 2013 Theodore C. Kotsilieris and George T. Karetsos. All rights reserved. An Anchor-Free Localization Scheme with Kalman Filtering in ZigBee Sensor Network Thu, 28 Feb 2013 17:28:27 +0000 A localization scheme for wireless sensor networks is proposed and its performances are investigated in this paper. The proposed scheme is an anchor-free scheme, in which no geometrical information of sensor nodes is required for their localization. Thus, only local interaction among sensor nodes is used to estimate their locations. This scheme employs the link quality indicator and hop count between sensor nodes for location estimation. A weighted averaging and Kalman filtering schemes are incorporated in order to reduce the effects of the measurement errors in the obtained values of the link quality indicator. We performed experiments by implementing the proposed scheme on ZigBee sensor modules. The results of our experiments indicate that estimation could be successfully performed for networks comprising four sensor nodes. Teijiro Isokawa, Shun Motomura, Junya Ohtsuka, Hironobu Kawa, Satoshi Nakashima, Naotake Kamiura, and Nobuyuki Matsui Copyright © 2013 Teijiro Isokawa et al. All rights reserved. Cluster Head Selection in Wireless Sensor Networks under Fuzzy Environment Sun, 24 Feb 2013 13:44:03 +0000 Clustering is one of the important methods for prolonging the network lifetime in wireless sensor networks (WSNs). It involves grouping of sensor nodes into clusters and electing cluster heads (CHs) for all the clusters. CHs collect the data from respective cluster’s nodes and forward the aggregated data to base station. A major challenge in WSNs is to select appropriate cluster heads. In this paper, we present a fuzzy decision-making approach for the selection of cluster heads. Fuzzy multiple attribute decision-making (MADM) approach is used to select CHs using three criteria including residual energy, number of neighbors, and the distance from the base station of the nodes. The simulation results demonstrate that this approach is more effective in prolonging the network lifetime than the distributed hierarchical agglomerative clustering (DHAC) protocol in homogeneous environments. Puneet Azad and Vidushi Sharma Copyright © 2013 Puneet Azad and Vidushi Sharma. All rights reserved. Wireless Sensor Network and RFID Fusion Approach for Mobile Robot Navigation Mon, 21 Jan 2013 11:31:51 +0000 There are numerous applications for mobile robots that require relatively high levels of speed and precision. For many systems, these two properties are a tradeoff, as oftentimes increasing the movement speed can mean failing to detect some sensors. This research attempts to create a useful and practical system by combining a wireless sensor network with a passive radio frequency identification system. The sensor network provides fast general navigation in open areas and the radio frequency identification system provides precision navigation near static obstacles. By fusing the data from both systems, we are able to provide fast and accurate navigation for a mobile robot. Additionally, with WSN nodes and passive RFID tag mats, the system infrastructure can be easily installed in existing environments. Guillermo Enriquez, Sunhong Park, and Shuji Hashimoto Copyright © 2013 Guillermo Enriquez et al. All rights reserved. An Underwater Sensor Allocation Scheme for Noncircular Sensing Coverage Regions Thu, 17 Jan 2013 08:33:30 +0000 Intelligently allocating underwater sensors to a large area of interest whose acoustic characteristics vary throughout is a challenge, especially for an area clearance scenario. In these scenarios, there is no apparent target for an adversary to gravitate towards, such as a ship or a port. Thus, it is difficult to determine how the field designer should allocate sensors so that their deployment locations can be planned efficiently. The previously proposed Game Theory Field Design (GTFD) model can achieve an intelligent sensor allocation, using a game theoretic approach, for sensors with circular coverage regions. In practice, however, the sensing coverage of an underwater sensor will likely be noncircular due to the azimuthally dependent bathymetric phenomena and other underwater irregularities. As a result, an extension of the model is proposed for allocating sensors for the irregularly shaped sensing coverage regions. This work provides two validations of the extended GTFD model. The first is an analytical comparison with sensing coverage regions whose shape is well understood, and the second uses simulation to validate the model for the irregularly shaped regions. Erik F. Golen, Carl V. Lutzer, David S. Ross, and Nirmala Shenoy Copyright © 2013 Erik F. Golen et al. All rights reserved. Low Power Decoding of LDPC Codes Thu, 17 Jan 2013 08:27:39 +0000 Wireless sensor networks are used in many diverse application scenarios that require the network designer to trade off different factors. Two such factors of importance in many wireless sensor networks are communication reliability and battery life. This paper describes an efficient, low complexity, high throughput channel decoder suited to decoding low-density parity-check (LDPC) codes. LDPC codes have demonstrated excellent error-correcting ability such that a number of recent wireless standards have opted for their inclusion. Hardware realisation of practical LDPC decoders is a challenging area especially when power efficient solutions are needed. Implementation details are given for an LDPC decoding algorithm, termed adaptive threshold bit flipping (ATBF), designed for low complexity and low power operation. The ATBF decoder was implemented in 90 nm CMOS at 0.9 V using a standard cell design flow and was shown to operate at 250 MHz achieving a throughput of 252 Gb/s/iteration. The decoder area was 0.72 mm2 with a power consumption of 33.14 mW and a very small energy/decoded bit figure of 1.3 pJ. Mohamed Ismail, Imran Ahmed, and Justin Coon Copyright © 2013 Mohamed Ismail et al. All rights reserved. Logical Sensor Network: An Abstraction of Sensor Data Processing over Multidomain Sensor Network Mon, 31 Dec 2012 11:08:10 +0000 This paper focuses on a sensor network virtualization over multidomain sensor network and proposes an abstraction called “logical sensor network (LSN)” for sensor data processing. In the proposed abstraction, processing is a directed acyclic graph that consists of nodes and streams, which represents a small data processor and communication rules between them, respectively. We have added a notion of a trigger to this graph. A trigger represents a timing of the process execution. We have implemented the middleware named LSN-Middle to run a virtualized sensor network and proved its feasibility. Naoya Namatame, Jin Nakazawa, and Hideyuki Tokuda Copyright © 2012 Naoya Namatame et al. All rights reserved. A Comparative Analysis of Reliable and Congestion-Aware Transport Layer Protocols for Wireless Sensor Networks Sun, 30 Dec 2012 13:38:20 +0000 Design and implementation of wireless sensor Networks have gathered increased attention in recent years due to vast potential of sensor networks consisting of spatially distributed devices (motes) to cooperatively monitor physical or environmental conditions at different locations. Wireless sensor networks are built upon low cost nodes with limited battery (power), CPU clock (processing capacity), and memory modules (storage). Transport layer protocols applied to wireless sensor networks can handle the communications between the sink node and sensor nodes in upstream (sensor-to-sink) or downstream (sink-to-sensor) direction. In this paper, we present a comparative analysis of reliable and congestion aware transport layer protocols for wireless sensor networks and number of open issues that have to be carefully realized to make use of the wireless sensor networks more efficiently and to enhance their performance. We first list the characteristics of transport layer protocols. We then provide a summary of reliable and congestion aware transport layer protocols with their respective pros and cons and comparison of different protocols based on reliability, congestion control, and energy efficiency. Finally, we point out open research issues of transport layer protocols for wireless sensor networks, which need further attention to overcome the earlier mentioned challenges. Bhisham Sharma and Trilok C. Aseri Copyright © 2012 Bhisham Sharma and Trilok C. Aseri. All rights reserved. Audio Streaming with Silence Detection Using 802.15.4 Radios Mon, 10 Dec 2012 11:55:00 +0000 Short-range radios with low data rate are gaining popularity due to their abundant commercial availability. It is imperative that high-speed multimedia would be an attractive application field with these radios. Audio over 802.15.4 compliant radios is a challenging task to achieve. This paper describes a real-time implementation of audio communication using 802.15.4 radios. Silence detection and soft ADPCM are the main features of our work. Our results show that silence detection improves bandwidth optimization and audio communication performance over low bit-rate radios. A. W. Rohankar, Shantanu Pathak, Mrinal K. Naskar, and Amitava Mukherjee Copyright © 2012 A. W. Rohankar et al. All rights reserved. A Survey of Image Compression Algorithms for Visual Sensor Networks Wed, 28 Nov 2012 08:14:13 +0000 With the advent of visual sensor networks (VSNs), energy-aware compression algorithms have gained wide attention. That is, new strategies and mechanisms for power-efficient image compression algorithms are developed, since the application of the conventional methods is not always energy beneficial. In this paper, we provide a survey of image compression algorithms for visual sensor networks, ranging from the conventional standards such as JPEG and JPEG2000 to a new compression method, for example, compressive sensing. We provide the advantages and shortcomings of the application of these algorithms in VSN, a literature review of their application in VSN, as well as an open research issue for each compression standard/method. Moreover, factors influencing the design of compression algorithms in the context of VSN are presented. We conclude by some guidelines which concern the design of a compression method for VSN. Abdelhamid Mammeri, Brahim Hadjou, and Ahmed Khoumsi Copyright © 2012 Abdelhamid Mammeri et al. All rights reserved. Comparison of Residual Energy-Based Clustering Algorithms for Wireless Sensor Network Thu, 18 Oct 2012 14:12:43 +0000 Wireless sensor network swears an exceptional fine-grained interface between the virtual and physical worlds. The clustering algorithm is a kind of key technique used to reduce energy consumption. Many clustering, power management, and data dissemination protocols have been specifically designed for wireless sensor network (WSN) where energy awareness is an essential design issue. Each clustering algorithm is composed of three phases cluster head (CH) selection, the setup phase, and steady state phase. The hot point in these algorithms is the cluster head selection. The focus, however, has been given to the residual energy-based clustering protocols which might differ depending on the application and network architecture. In this paper, a survey of the state-of-the-art clustering techniques in WSNs has been compared to find the merits and demerits among themselves. It has been assumed that the sensor nodes are randomly distributed and are not mobile, the coordinates of the base station (BS) and the dimensions of the sensor field are known. Asis Kumar Tripathy and Suchismita Chinara Copyright © 2012 Asis Kumar Tripathy and Suchismita Chinara. All rights reserved. Polymer Optical Fiber Intensity-Based Sensor for Liquid-Level Measurements in Volumetric Flasks for Industrial Application Sun, 14 Oct 2012 15:04:51 +0000 A low-cost intensity-based polymer optical fiber (POF) sensor for liquid detection applied to volumetric flasks is presented. Experimental results demonstrate the viability of the POF-based sensor system in a high-accuracy liquid level measurement scenario. Moreover, a wireless mesh sensor network based on ZigBee specification protocol to address multiplexed POF-based sensor is also developed. Experimental results demonstrate the feasibility to address a high number of optical sensors in an industrial process framework by means of this low-cost wireless solution. D. S. Montero and C. Vázquez Copyright © 2012 D. S. Montero and C. Vázquez. All rights reserved.