International Journal of Distributed Sensor Networks The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Fast and Energy Efficient Multihop D2D Routing Scheme Wed, 04 May 2016 09:44:21 +0000 Device-to-device (D2D) communications are expected to offload cellular networks and enhance public safety. In addition to the capability of direct communication between devices, the capability of delivering data over multihops in an ad hoc manner by autonomous decision of each device is highly desired to expand application areas of D2D communications. To address this issue, we propose a fast and energy efficient D2D multihop routing method using the geographic locations of nodes. To expedite data delivery while saving transmission powers of nodes, we devise the next hop selection method considering the congestion levels of potential next hops. In addition, we devise a detour scheme to move around a routing hole that is encountered when a node cannot find a neighbor that is closer to the destination of a packet than itself. We also propose management procedures so that each node acquires the locations of destinations and its neighboring nodes. Through extensive simulations, we validate the proposed method by comparing the performance of the proposed method with those of maximum progress method (MaxP), cost over progress method (CoP), and congestion-aware forwarder selection method (CAFS). Even though the number of hops obtained by the proposed method is larger than those obtained by MaxP and CAFS, our method is superior to them in terms of the probability of successfully delivering packets to destinations and total amount of energy consumption. We also show that our method can reduce end-to-end delay considerably compared with CoP. Jaesung Park Copyright © 2016 Jaesung Park. All rights reserved. Optimizing Data Access for Wind Farm Control over Hierarchical Communication Networks Tue, 03 May 2016 10:28:43 +0000 We investigate a centralized wind farm controller which runs periodically. The controller attempts to reduce the damage a wind turbine sustains during operation by estimating fatigue based on the wind turbine state. The investigation focuses on the impact of information access and communication networks on the controller performance. We start by investigating the effects of a communication network that introduces delays in the information access for the central controller. The control performance as measured by accumulated fatigue is shown to be significantly impacted by communication delays and also by the choice of the time instances at which sensor information is accessed. In order to optimize the latter, we introduce an information quality metric and a mathematical model based on Markov chains, which are compared performance-wise to a heuristic approach for finding this parameter. This information quality metric is called mismatch probability, mmPr, and is used to express quantitatively the information accuracy in a given scenario. Lastly, measurements of different communication technologies have been performed in order to carry out the analysis in a practically relevant scenario with respect to the communication network delays. These measurements are done in regard to packet loss and communication delays, and the simulations are rerun using either the traces from the measurements or scenarios constructed from the delay parameters. Jacob Madsen, Mislav Findrik, Tatiana Madsen, and Hans-Peter Schwefel Copyright © 2016 Jacob Madsen et al. All rights reserved. A Novel Energy-Efficient k-Coverage Algorithm Based on Probability Driven Mechanism of Wireless Sensor Networks Sat, 30 Apr 2016 11:26:05 +0000 In the process of fulfilling -coverage over target nodes, a large quantity of redundant data may be produced, which will cause network congestion, reduce communication efficiency, impair coverage quality, and exhaust network energy quickly. To solve this problem, the paper proposes an Energy-Efficient k-Coverage Algorithm (EEKCA), which attempts to construct a network coverage model by utilizing the relative positions of nodes. Through analyzing the model, the coverage expectations for nodes in the monitored area and the minimum number of nodes required for full coverage are computed. As for power consumption, the paper presents an energy shifting function between working nodes and neighboring nodes, by use of which the scheduling for low-energy node is completed, balancing the energy consumption over the entire network and optimizing network resources. Finally, simulation results suggest that the proposed algorithm not only can improve the coverage quality of network but also can prevent the rapid depletion of node energy, thus achieving the goal of extending network lifetime. Chuanfeng Li, Zeyu Sun, Huihui Wang, and Houbing Song Copyright © 2016 Chuanfeng Li et al. All rights reserved. CooperSense: A Cooperative and Selective Picture Forwarding Framework Based on Tree Fusion Sat, 30 Apr 2016 08:39:48 +0000 Mobile crowd photographing has become a major crowd sensing paradigm, which allows people to use cameras on smart devices for local sensing. In MCP, pictures taken by different people in close proximity or time period can be highly similar and different MCP tasks have diverse constraints or needs to deal with such duplicate data. In order to save the network cost and improve the transmitting efficiency, pictures will be preselected by mobile clients and then uploaded to the server in an opportunistic manner. In this paper, CooperSense, a multitask MCP framework for cooperative and selective picture forwarding, was designed. Based on the sensing context of pictures and task constraints, CooperSense structures sequenced pictures into a hierarchical context tree. When two participants encounter, their mobile clients will just exchange their context trees and at the same time automatically accomplish forwarding high-quality pictures to each other via a tree fusion mechanism. Via virtual or real pruning and grafting, mobile clients learn which picture should be sent to the encounter and which one should be abandoned. Our experimental results indicate that the transmission and storage cost of CooperSense are much lower comparing with the traditional Epidemic Routing (ER) method, while their efficiency is almost the same. Huihui Chen, Bin Guo, and Zhiwen Yu Copyright © 2016 Huihui Chen et al. All rights reserved. Wireless Sensor Network of Typical Land Surface Parameters and Its Preliminary Applications for Coarse-Resolution Remote Sensing Pixel Tue, 26 Apr 2016 14:23:13 +0000 How to obtain the “truth” of land surface parameter as reference value to validate the remote sensing retrieved parameter in heterogeneous scene and coarse-resolution pixel is one of the most challenging topics in environmental studies. In this paper, a distributed sensor network system named CPP-WSN was established to capture the spatial and temporal variation of land surface parameters at coarse-resolution satellite pixel scale around the Huailai Remote Sensing Station, which locates in the North China Plain. The system consists of three subnetworks that are RadNet, SoilNet, and VegeNet. Time series observations of typical land surface parameters, including UVR, PAR, SWR, LWR, albedo, and land surface temperature (LST) from RadNet, multilayer soil moisture and soil temperature from SoilNet, and fraction of vegetation cover (FVC), clumping index (CI), and leaf area index (LAI) from VegeNet, have been obtained and shared on the web. Compared with traditional single-point measurement, the “true” reference value of coarse pixel is obtained by averaging or representativeness-weighted averaging the multipoint measurements acquired using the sensor network. The preliminary applications, which validate several remote sensing products with CPP-WSN data, demonstrate that a high quality ground “truth” dataset has been available for remote sensing as well as other applications. Baocheng Dou, Jianguang Wen, Xiuhong Li, Qiang Liu, Jingjing Peng, Qing Xiao, Zhigang Zhang, Yong Tang, Xiaodan Wu, Xingwen Lin, Dongqin You, Hua Li, Li Li, Yelu Zeng, Erli Cai, and Jialin Zhang Copyright © 2016 Baocheng Dou et al. All rights reserved. Alternative Approach for Combination of Fingers in Underwater Acoustic Communication Wed, 20 Apr 2016 06:29:11 +0000 An underwater acoustic communication channel is time varying and has multipath propagation with bottom and surface reflection. A rake receiver has time diversity effects in multipath propagation environments. We have to recognize the correct path for a rake receiver, as this affects communication performance in the underwater acoustic channel. In this paper, we propose a more reliable rake receiver based on BER (bit error rate) of training sequence duration. We conducted simulations and lake trials to evaluate the performance of the proposed method. When the channel coding technique was not applied, the uncoded BER performances of the proposed method, the conventional method, and the nonrake method in the lake trial were 0.016, 0.088, and 0.141, respectively. Ji-Hong Son, Eun-Hye Jeon, Ki-Man Kim, Dong-Won Lee, and Tae-Doo Park Copyright © 2016 Ji-Hong Son et al. All rights reserved. A Novel Real Time Framework for Cluster Based Multicast Communication in Vehicular Ad Hoc Networks Tue, 19 Apr 2016 08:02:39 +0000 In a vehicular ad hoc network (VANET), the vehicles communicate with each other to develop an intelligent transport system (ITS) which provides safety and convenience while driving. The major challenge of VANET is that the topology changes dynamically due to the high speed and unpredictable mobility of vehicles resulting in an inefficient real time message dissemination, especially in emergency scenarios such as in the accident event where it can cause high level of destruction. To the best of our knowledge, there is no such mechanism in existing literature which can handle real time multicast communication in VANET for both urban and highway scenarios. In this paper, we propose a novel real time vehicular communication (RTVC) framework which consists of a VANET cluster scheme (VCS) and VANET multicast routing (VMR) to achieve efficient vehicle communication within both urban and highway scenarios. The RTVC framework develops stable communication links and achieves high throughput with low overhead despite high mobility by combining the multicast routing with a unique cluster based scheme. In VCS, the cluster head (CH) is elected upon cluster threshold value (CTV) to disseminate the messages within the cluster members (CMs) and to other cluster heads by intercluster communication, which reduces the network overhead. In addition, the vehicles cluster head election (VCHE) procedure is proposed to reduce the number of CHs and CMs switches which results in lower overhead of maintaining the clusters. Moreover, another novelty of the framework is that the CTV of VCHE can be adjusted by speed adjustment factor (SAF) to achieve the desired cluster stability depending upon the required VANET application. The simulation results illustrate that the proposed framework has achieved the goal of stable, efficient, and real time communication despite highly dynamic environment of VANET. Waqar Farooq, Muazzam Ali Khan, and Saad Rehman Copyright © 2016 Waqar Farooq et al. All rights reserved. Design and Verification of a High-Precision Wireless Strength Testing Node for Aircraft Structure Mon, 18 Apr 2016 14:17:04 +0000 Wireless sensor network provides a good solution for the state monitoring of large-scale structures. Compared to traditional approaches, it can greatly reduce the amount of devices wiring and the weight of the monitoring system. However, research of aviation structure monitoring application based wireless sensor networks is still in the initiation of the exploration stage. In particular, the developed wireless strain sensor node of WSN cannot be used in aviation structure because of low precision and other problems. In this paper, a high-precision and multichannel wireless strain sensor node of WSN is designed in detail. The wireless strain sensor node is composed of power module, multichannel strain sensing acquisition module, data-processing module, and wireless communication module. In addition, its special design of encapsulation makes it shock-proof and possess anti-interference property. To verify the functionality of the designed wireless sensor node for structural strength testing capability, several evaluation experiments are completed on a test piece of real aircraft. The experimental results show that the developed system has good performance in monitoring structural strain. Jian Wu, Xingmei Cui, Hongbing Sun, and Yunpeng Xu Copyright © 2016 Jian Wu et al. All rights reserved. Analysis of Secure TCP/IP Profile in 61850 Based Substation Automation System for Smart Grids Mon, 18 Apr 2016 11:26:24 +0000 Smart grid is the term used to describe modern power grids. It aims at achieving efficient, sustainable, economic, and secure delivery of electricity supplies. In order to achieve these goals, communication between different components within the grid and control centers is required. In a rapidly growing world, the demands for substation automation are increasing. Recently, two trends have been changing Substation Automation Systems: IEC 61850 and the need for cybersecurity. IEC 61850 specifies very strict performance requirements for message transfer time. The security for the smart grid must be designed to satisfy both performance and reliability requirements. In this paper, we address a study about secure communication in the substation real-time environment, complying with the IEC 61850 specifications. We mainly focus on analyzing the proposed Secure TCP/IP profile for MMS, testing different cipher suite combinations and examining whether by applying TLS we can still achieve the strict performance requirements of IEC 61850 or not. As a result of the study, we propose a list of cipher suite combinations that should be used. The importance of this study lies mainly on future scenarios, because IEC 61850 is thought to support smart metering communications. Omar Khaled, Andrés Marín, Florina Almenares, Patricia Arias, and Daniel Díaz Copyright © 2016 Omar Khaled et al. All rights reserved. Directional Probability Perceived Nodes Deployment Based on Particle Swarm Optimization Sun, 17 Apr 2016 13:29:07 +0000 Node deployment is the key problem of wireless sensor network technology. For a directional sensor network, the perceived probability model reflects the quality of the network. The problem of the probability node deployment is too little of the distribution of the nodes asymmetrical. In this paper, we study the probability model of directional perceived nodes and propose an improved deterministic deployment algorithm based on particle swarm optimization to increase perceived probability. By analyzing the coverage probability of the monitoring area with different deployment models to obtain more serviceable environmental data of the monitoring areas, experimental results demonstrate that, compared with random deployment, sixteen percent is improved by the proposed algorithm. Junguo Zhang, Yutong Lei, Chen Chen, and Fantao Lin Copyright © 2016 Junguo Zhang et al. All rights reserved. Implementation of True IoT Vision: Survey on Enabling Protocols and Hands-On Experience Sun, 17 Apr 2016 12:15:19 +0000 Internet of Things (IoT) is expected to become a driver in an emerging era of interconnected world through the advanced connectivity of smart devices, systems, and services. IoT goes beyond a broad range of Machine-to-Machine (M2M) communication technologies and covers a wide variety of networking protocols. There exist solutions like MQTT or SIP collecting data from sensors, CoAP for constrained devices and networks, or XMPP for interconnecting devices and people. Also there is a plethora of standards and frameworks (OSGi, AllJoyn) bringing closer the paradigm of IoT vision. However, the main constraint of most existing platforms is their limited mutual interoperability. To this end, we provide a comprehensive description of protocols suitable to support the IoT vision. Further, we advocate an alternative approach to already known principles and employ the SIP protocol as a container for M2M data. We provide description of data structures and practical implementation principles of the proposed structures (JSON and Protocol Buffers are discussed in detail) transmitted by SIP as a promising enabler for efficient M2M communication in the IoT world. Our reported findings are based on extensive hands-on experience collected after the development of advanced M2M smart home gateway in cooperation with the operator Telekom Austria Group. Pavel Masek, Jiri Hosek, Krystof Zeman, Martin Stusek, Dominik Kovac, Petr Cika, Jan Masek, Sergey Andreev, and Franz Kröpfl Copyright © 2016 Pavel Masek et al. All rights reserved. Sum-Power Minimization in Multiuser Single-DF-Relay Networks with Direct Links Thu, 14 Apr 2016 11:35:47 +0000 Forming cooperation through relay’s assistance is a promising method to realize green communication by reducing transmission power. In this paper, for multiuser single-DF-relay wireless networks with direct links, the optimal power allocation strategy that minimizes system-sum-power consumption is investigated. Based on the principle that minimizing system-sum-power consumption is equivalent to maximizing system energy efficiency, users are classified into two parts after comparing the channel gains between source-destination link and relay-destination link. The optimal power allocation strategy of one part is determined directly, and minimizing the system-sum-power consumption of the other part is converted into minimizing source-sum-power consumption, which can be solved easily through Karush-Kuhn-Tucker (KKT) condition. Through numerical simulations, we further justified the effectiveness of our scheme compared to existing works. Shiguo Wang, Haixia Peng, and Xianru Liu Copyright © 2016 Shiguo Wang et al. All rights reserved. Advances on Software Defined Sensor, Mobile, and Fixed Networks Thu, 14 Apr 2016 11:20:18 +0000 Luis Javier García Villalba, Jun Bi, Anura P. Jayasumana, and Ana Lucila Sandoval Orozco Copyright © 2016 Luis Javier García Villalba et al. All rights reserved. Belief Propagation-Based Cognitive Routing in Maritime Ad Hoc Networks Thu, 14 Apr 2016 10:54:01 +0000 Cognitive routing for maritime wireless ad hoc networks is proposed in this paper to find a stable path between source and destination. This is ship-to-ship communication where two ships can communicate when they not only have consensus on a common idle channel but also are in the transmission range of each other. We apply belief propagation algorithm for collaborative spectrum sensing. Every user (ship) exchanges its local decisions with its neighbors to compute the final belief about the state of the channel. These beliefs are applied for estimating the link duration for total number of hops between source and destination. Then, a path is selected which maximizes the path duration among all the paths in the network to reach the destination. We apply both flood-based and geographical routing protocols to find a route between source and destination for different scenarios. We simulate our scheme for different ocean settings and evaluate path durations for different number of ships. The results report a significant increase in path duration as the number of nodes increases in the network. In addition, we verify that path duration increases with an increase in probability of primary user being idle via extensive simulations. Hence, our scheme provides stable path selection for communication among users onboard. Huma Ghafoor, Youngtae Noh, and Insoo Koo Copyright © 2016 Huma Ghafoor et al. All rights reserved. Smart Energy Efficient Device-to-Multidevice Cooperative Clustering for Multicasting Content Thu, 14 Apr 2016 07:39:13 +0000 A number of nodes that are interested in the same content can be grouped into a cluster and the cluster head can be used to relay the content received from the base station (BS) to the cluster members using device-to-multidevice (D2MD) communication. However, the data rate of such multicast communication depends on the worst channel among the cluster members and the cluster head. The rate can be enhanced by increasing the transmit power; however, this approach may deteriorate energy efficiency (EE) performance of the system. In this paper, we propose transmitting the content from more than one cluster head simultaneously. A novel algorithm is proposed that selects the cluster heads to improve the data rate of the multicast communication while keeping the total transmit power from the cluster heads constant. The cluster members receive power from all the cluster heads within the cluster and hence the received signal to noise power ratio improves. The improved received power makes communication at higher data rates possible, thus reducing the total transmission time. Hence, the energy requirement per bit will reduce. Simulation results show that 19% of reduction in energy per bit is possible by using more than one cluster head within the cluster. Mateen Ashraf, Woon-Young Yeo, Miae Woo, and Kyung-Geun Lee Copyright © 2016 Mateen Ashraf et al. All rights reserved. A Distance-Based Maximum Likelihood Estimation Method for Sensor Localization in Wireless Sensor Networks Thu, 14 Apr 2016 05:51:19 +0000 Node localization is an important supporting technology in wireless sensor networks (WSNs). Traditional maximum likelihood estimation based localization methods (MLE) assume that measurement errors are independent of the distance between the anchor node and a target node. However, such an assumption may not reflect the physical characteristics of existing measurement techniques, such as the widely used received signal strength indicator. To address this issue, we propose a distance-based MLE that considers measurement errors that depend on distance values in this paper. The proposed distance-based MLE is formulated as a complicated nonlinear optimization problem. An exact solution is developed based on first-order optimal condition to improve the efficiency of search. In addition, a two-dimensional search method is also presented. Simulation experiments are performed to demonstrate the effectiveness of this localization. The simulation results show that the distance-based localization method has better localization accuracy compared to other range-based localization methods. Jing Xu, Jingsha He, Yuqiang Zhang, Fei Xu, and Fangbo Cai Copyright © 2016 Jing Xu et al. All rights reserved. Sensor-Web Systems, Applications, and Services Tue, 12 Apr 2016 12:56:07 +0000 M. Anwar Hossain, Jemal H. Abawajy, Raúl García-Castro, Wen-Huang Cheng, and Dewan Tanvir Ahmed Copyright © 2016 M. Anwar Hossain et al. All rights reserved. Adaptive Resource Scheduling for Dual Connectivity in Heterogeneous IoT Cellular Networks Mon, 11 Apr 2016 14:30:49 +0000 As massive distributed sensor devices are integrated into Internet for Internet of things (IoT) and generate tremendous data from simple measurement to rich multimedia information, wireless cellular networks like LTE are enforced to deploy more small cells to accommodate data from the countless IoT devices. In 3GPP Rel-12 specification, dual connectivity helps deploying the small cell eNBs by separating a control and data plane to a macro and small cell, respectively. The dual connectivity also improves per-user throughput and mobility robustness. Meanwhile, dynamic TDD configuration in the Rel-12 can enhance radio resource utilization of TDD-based small cells even though intercell interference can be worse than legacy static configuration within a small cell cluster. In this paper, we propose a heterogeneous cellular IoT network architecture using the aforementioned two small cell features, as well as scheduling algorithms for load balancing in the dual connectivity and for dynamic TDD configuration to mitigate interference in the small cell cluster. We evaluate proposed algorithms using LTE system level simulator and show that our approach improves network throughput. Wooseong Kim Copyright © 2016 Wooseong Kim. All rights reserved. ELDP: Extended Link Duration Prediction Model for Vehicular Networks Mon, 11 Apr 2016 09:41:58 +0000 Link duration between two vehicles is considered an important quality of service metric in designing a network protocol for vehicular networks. There exist many works that study the probability density functions of link duration in a vehicular network given various vehicle mobility models, for example, the random waypoint model. None of them, however, provides a practical solution to estimating the link duration between two vehicles on the road. This is in part because link duration between vehicles is affected by many factors including the distance between vehicles, their turning directions at intersections, and the impact of traffic lights. Considering these factors, we propose the extended link duration prediction (ELDP) model which allows a vehicle to accurately estimate how long it will be connected to another vehicle. The ELDP model does not assume that vehicles follow certain mobility models; instead, it assumes that a vehicle’s velocity follows the Normal distribution. We validate the ELDP model in both highway and city scenarios in simulations. Our detailed simulations illustrate that relative speed between vehicles plays a vital role in accurately predicting link duration in a vehicular network. On the other hand, we find that the turning directions of a vehicle at intersections have subtle impact on the prediction results. Xiufeng Wang, Chunmeng Wang, Gang Cui, Qing Yang, and Xuehai Zhang Copyright © 2016 Xiufeng Wang et al. All rights reserved. A Bioinspired Fair Resource-Allocation Algorithm for TDMA-Based Distributed Sensor Networks for IoT Mon, 11 Apr 2016 07:31:38 +0000 Many studies on distributed resource-allocation algorithms have been conducted recently because of the increasing number of network nodes and the rapidly changing network environments in the Internet of Things (IoT). In this paper, we propose the multihop DESYNC algorithm, which is a bioinspired Time Division Multiple Access- (TDMA-) based distributed resource-allocation scheme for distributed sensor networks. We define a detailed frame structure for the proposed multihop DESYNC algorithm and a firing message, which acts as a reference for resource allocation. In addition, operating procedures for resource allocation and collision detection avoidance under multihop DESYNC are explained. Simulations show that multihop DESYNC effectively resolves the hidden-node problem and that it fairly shares resources among nearby nodes in multihop networks. Moreover, it achieves better performance than the CSMA/CA algorithm in terms of channel reuse gain and average throughput. Young-Jae Kim, Hyun-Ho Choi, and Jung-Ryun Lee Copyright © 2016 Young-Jae Kim et al. All rights reserved. A Trusted and Energy Efficient Approach for Cluster-Based Wireless Sensor Networks Sun, 10 Apr 2016 12:51:06 +0000 How to improve both security and energy efficiency is one of the most prominent issues in wireless sensor networks (WSNs). In this paper, we present a trusted and energy efficient approach for cluster-based WSNs. The approach offers (i) trusted hardware module design; (ii) energy-efficient clustering algorithm; and (iii) network operation. In the cluster-based WSNs, every cluster head is equipped with a designed trusted hardware module (TM) to improve security. Then, for improving the energy efficiency of the network, a trusted hardware based energy efficient clustering (TEEC) algorithm is proposed to select appropriate cluster heads. In the network operation, we use TEEC algorithm to perform clustering and apply TMs to achieve security functions. The analysis shows that our approach does well in resisting the attacks such as data confidentiality attack, data integrity attack, and compromise node attack. In addition, experimental results show that the TEEC algorithm makes more balanced clusters with the variance value of loads around 50% and prolongs the life cycle of the network at least 10% compared to traditional methods. Tianshu Wang, Gongxuan Zhang, Xichen Yang, and Ahmadreza Vajdi Copyright © 2016 Tianshu Wang et al. All rights reserved. Side Trip Multipath Routing Protocol for Spatial Node Failure in Data-Gathering WSNs Sun, 10 Apr 2016 12:16:03 +0000 In severe disaster environments, data-gathering wireless sensor networks possibly suffer from spatial node failure due to external factors such as land slide and river overflow. In order to enhance tolerance to spatial node failure, this paper proposes not only a multipath data gathering protocol called “Side Trip (ST)” scheme but also an improved version of ST scheme called “Side Trip with Network Coding (STNC)” scheme. In the ST scheme, a node establishes a secondary path which passes through nodes almost the same hop count away from the sink in order to spatially separate the path from the primary path and enhance spatial node-failure tolerance. In the STNC scheme, redundant packets from different source nodes are network-coded into an encoded packet in order to reduce the number of redundant packets and the impact on the system lifetime. We compare the ST scheme, STNC scheme, and two existing multipath protocols (i.e., H-SPREAD (Hybrid-Secure Protocol for REliable dAta Delivery) scheme and SMRP (Subbranch Multipath Routing Protocol) scheme) by means of a self-developed simulator. Simulation results show that STNC scheme and ST scheme enhance tolerance to node-failure compared to H-SPREAD scheme and SMRP scheme with no significant impact on system lifetime. Keisuke Fujita, Yumi Takaki, Chikara Ohta, and Hisashi Tamaki Copyright © 2016 Keisuke Fujita et al. All rights reserved. The Quality of Sampling from Geographic Networks Thu, 07 Apr 2016 08:31:04 +0000 We empirically investigate the factors affecting the quality of information obtained by randomly sampling nodes from a network embedded in two-dimensional space. The motivation for this work is that wireless and other physical networks do in fact have embedding of their nodes in space, although analyses of random walks on such networks often only consider the link structure while ignoring node locations. Of independent interest is the measure we propose to evaluate the quality of sampling: the rate of decrease in the area of the largest empty circle remaining. John Matta, Gunes Ercal, and William Stimson Copyright © 2016 John Matta et al. All rights reserved. QoS Aware Middleware Support for Dynamically Reconfigurable Component Based IoT Applications Thu, 07 Apr 2016 08:11:09 +0000 Sensor web systems, cyber-physical systems, and the so-called Internet of Things are concepts that share a set of common characteristics. The nature of such systems is highly dynamic and very heterogeneous and issues such as interoperability, energy consumption, or resource management must be properly managed to ensure the operation of the applications within the required quality of service level. In this context, base technologies such as component based software engineering or Service Oriented Architecture can play a central role. Model driven development and middleware technologies also aid in the design, development, and operation of such systems. This paper presents a middleware solution that provides runtime support for the complete lifecycle management of a system consisting of several concurrent applications running over a set of distributed infrastructure nodes. The middleware builds up on top of a general purpose component model and is driven by a quality of service aware self-configuration algorithm that provides stateful reconfiguration capabilities in face of both internal (application triggered) and external (application unaware) reconfiguration events. The platform has been deployed over an automated warehouse supervision system that serves as a case study. Aitor Agirre, Jorge Parra, Aintzane Armentia, Elisabet Estévez, and Marga Marcos Copyright © 2016 Aitor Agirre et al. All rights reserved. Urban Impedance Computing Based on Check-In Records Thu, 07 Apr 2016 06:20:51 +0000 Urban impedance is an important consideration in assessments of transportation and land-use systems. This work leverages check-in records obtained from mobile social networks to build a fine-grained but inexpensive urban impedance model. Check-in records and road networks are collected and used to calculate and adjust the various parameters of the model, including path length, number and angle of turns, number and direction of junctions, and population density. Check-in records can filter functional locations and supply the time factor, thereby providing excellent advantages over traditional models that do not employ this data type. The proposed model is more accurate than traditional impedance models, as verified by experiments using Sina Weibo data in Tianjin City. Zhiyong Yu, Yuzhong Chen, Songpan Zheng, Yao Shen, Zhiwen Yu, and Jordan Pascual Copyright © 2016 Zhiyong Yu et al. All rights reserved. Trail-Using Ant Behavior Based Energy-Efficient Routing Protocol in Wireless Sensor Networks Wed, 06 Apr 2016 12:01:07 +0000 Swarm Intelligence (SI) observes the collective behavior of social insects and other animal societies. Ant Colony Optimization (ACO) algorithm is one of the popular algorithms in SI. In the last decade, several routing protocols based on ACO algorithm have been developed for Wireless Sensor Networks (WSNs). Such routing protocols are very flexible in distributed system but generate a lot of additional traffic and thus increase communication overhead. This paper proposes a new routing protocol reducing the overhead to provide energy efficiency. The proposed protocol adopts not only the foraging behavior of ant colony but also the trail-using behavior which has never been adopted in routing. By employing the behaviors, the protocol establishes and manages the routing trails energy efficiently in the whole network. Simulation results show that the proposed protocol has low communication overhead and reduces up to 55% energy consumption compared to the existing ACO algorithm. Soon-gyo Jung, Byungseok Kang, Sanggil Yeoum, and Hyunseung Choo Copyright © 2016 Soon-gyo Jung et al. All rights reserved. Computational Intelligence in Wireless Sensor and Ad Hoc Networks Thu, 31 Mar 2016 11:36:52 +0000 Sergio Toral, Ciprian Dobre, Bernabé Dorronsoro, Mesut Günes, and Daniel G. Reina Copyright © 2016 Sergio Toral et al. All rights reserved. -Augmented Tree for Robust Data Collection in Advanced Metering Infrastructure Tue, 29 Mar 2016 13:56:30 +0000 Tree multicast configuration of smart meters (SMs) can maintain the connectivity and meet the latency requirements for the Advanced Metering Infrastructure (AMI). However, such topology is extremely weak as any single failure suffices to break its connectivity. On the other hand, the impact of a SM node failure can be more or less significant: a noncut SM node will have a limited local impact compared to a cut SM node that will break the network connectivity. In this work, we design a highly connected tree with a set of backup links to minimize the weakness of tree topology of SMs. A topology repair scheme is proposed to address the impact of a SM node failure on the connectivity of the augmented tree network. It relies on a loop detection scheme to define the criticality of a SM node and specifically targets cut SM node by selecting backup parent SM to cover its children. Detailed algorithms to create such AMI tree and related theoretical and complexity analysis are provided with insightful simulation results: sufficient redundancy is provided to alleviate data loss at the cost of signaling overhead. It is however observed that biconnected tree provides the best compromise between the two entities. Joseph Kamto, Lijun Qian, Wei Li, and Zhu Han Copyright © 2016 Joseph Kamto et al. All rights reserved. Handover Management of Net-Drones for Future Internet Platforms Tue, 29 Mar 2016 12:54:47 +0000 The advent of the Internet of things (IoT) is changing the way how we interact with the physical world. However, the current Internet suffers from exponential increase in bandwidth demand. In order to resolve the bandwidth issue, we can consider aerial networks by unmanned aerial vehicles (UAV) or the so-called drones for establishing a three-dimensional mobile network in an ad hoc manner. By deploying a network from the sky, we can use the otherwise idle wireless medium and high mobility free from ground obstacles. Aerial networks are especially effective for supporting the temporary surge of population as well as disaster areas because building an additional network infrastructure requires extensive time. In this paper, we propose an efficient handover mechanism for aerial networks in the three-dimensional space, which significantly differs from the conventional two-dimensional schemes. The proposed scheme adjusts the height of a drone and the distance between the drones. To this end, we use the seamless handover success probability and the false handover initiation probability in order to evaluate the optimal coverage decision algorithm. To the best of our knowledge, the proposed scheme is the first attempt for resolving handover of net-drones in the three-dimensional space. Kyung-Nam Park, Jin-Hyeok Kang, Byeong-Moon Cho, Kyung-Joon Park, and Hwangnam Kim Copyright © 2016 Kyung-Nam Park et al. All rights reserved. A Type of Energy Hole Avoiding Method Based on Synchronization of Nodes in Adjacent Annuluses for Sensor Network Mon, 28 Mar 2016 09:15:53 +0000 For the purpose of balancing energy consumption of nodes in Wireless Sensor Networks (WSNs for short), a type of energy hole avoiding method based on synchronization of nodes in adjacent annuluses (SNAA for short) is proposed in this paper. The circular network is divided into virtual annuluses with the same width. Nodes are deployed nonuniformly and their number increases in geometric progression from the outer annuluses to the inner ones which could effectively reduce the work load on nodes near the center. Moreover, each node could find its optimal parent by considering the residual energy of each candidate as well as the distance between the two nodes in adjacent annuluses. And on the basis of synchronization of nodes between adjacent annuluses during their transmitting and receiving phases, a sleep scheduling strategy is also proposed to further reduce the energy consumption of nodes in idle listening mode. Simulation results show that SNAA has a superior performance on energy consumption balance compared to the algorithm proposed (Liu et al., 2013; Wu et al., 2008) and it could also mitigate the energy hole problem in WSNs. Chao Sha, Huan Chen, Chen Yao, Yao Liu, and Ru-chuan Wang Copyright © 2016 Chao Sha et al. All rights reserved.