Wireless sensor and actor networks: research challenges

Wireless sensor and actor networks (WSANs) refer to a group of sensors and actors linked by wireless medium to perform distributed sensing and acting tasks. The realization of wireless sensor and actor networks (WSANs) needs to satisfy the requirements introduced by the coexistence of sensors and actors. In WSANs, sensors gather information about the physical world, while actors take decisions and then perform appropriate actions upon the environment, which allows a user to effectively sense and act from a distance. In order to provide effective sensing and acting, coordination mechanisms are required among sensors and actors. Moreover, to perform right and timely actions, sensor data must be valid at the time of acting. This paper explores sensor-actor and actor-actor coordination and describes research challenges for coordination and communication problems.     

Wireless sensor networks: Enabling technology for ambient intelligence

Wireless sensor networks are one of the most rapidly evolving research and development fields for microelectronics. Their applications are countless, and the market potentials are huge. However, many technical hurdles have to be overcome to achieve a widespread diffusion of wireless sensor network technology. This paper summarizes the trends of evolution in wireless sensor network nodes, focusing on hardware architectures and fabrication technology. We describe four generations of sensor networks (obtrusive, parasitic, symbiotic and bio-inspired), moving from the recent past to the future. We outline the key research challenges and the common themes in the field.     

无线传感器网络中目标追踪策略

协同信息处理是无线传感器网络研究的难点。以跟踪单目标为基础,提出了一种基于对策论的协同机制,对网络节点建立群组方式进行目标跟踪,动态地分配任务,随时更新群组成员,同步信息整合与数据传递,在实验中让基于对策论与已有的基于实例的协同机制进行对比。实验结果证明,采用基于对策论方式进行目标跟踪准确率明显提高,网络能量消耗大幅度降低,信息传递流畅,满足了网络节点的动态扩展性与适应性。     

Underwater acoustic sensor networks: research challenges

Underwater sensor nodes will find applications in oceanographic data collection, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance applications. Moreover, unmanned or autonomous underwater vehicles (UUVs, AUVs), equipped with sensors, will enable the exploration of natural undersea resources and gathering of scientific data in collaborative monitoring missions. Underwater acoustic networking is the enabling technology for these applications. Underwater networks consist of a variable number of sensors and vehicles that are deployed to perform collaborative monitoring tasks over a given area.In this paper, several fundamental key aspects of underwater acoustic communications are investigated. Different architectures for two-dimensional and three-dimensional underwater sensor networks are discussed, and the characteristics of the underwater channel are detailed. The main challenges for the development of efficient networking solutions posed by the underwater environment are detailed and a cross-layer approach to the integration of all communication functionalities is suggested. Furthermore, open research issues are discussed and possible solution approaches are outlined.     

无线传感器网络数据的迭代凸优化重构

为提高弱相关性网络数据压缩感知的可靠性和有效性,提出一种基于迭代凸优化的网络数据重构方法.该方法利用多次凸优化算法共同重构相关性较弱的网络数据,在每次运行凸优化算法后,对已重构出的数据向量元素进行加权以降低权值,而使其他的数据向量元素在下次凸优化中得到重构.与以往的压缩感知重构方法相比,迭代凸优化重构可在网络数据相关性较弱的情况下保证重构准确度.仿真实验验证了所提方法的正确性.     

Controlled sink mobility for prolonging wireless sensor networks lifetime

This paper demonstrates the advantages of using controlled mobility in wireless sensor networks (WSNs) for increasing their lifetime, i.e., the period of time the network is able to provide its intended functionalities. More specifically, for WSNs that comprise a large number of statically placed sensor nodes transmitting data to a collection point (the sink), we show that by controlling the sink movements we can obtain remarkable lifetime improvements. In order to determine sink movements, we first define a Mixed Integer Linear Programming (MILP) analytical model whose solution determines those sink routes that maximize network lifetime. Our contribution expands further by defining the first heuristics for controlled sink movements that are fully distributed and localized. Our Greedy Maximum Residual Energy (GMRE) heuristic moves the sink from its current location to a new site as if drawn toward the area where nodes have the highest residual energy. We also introduce a simple distributed mobility scheme (Random Movement or RM) according to which the sink moves uncontrolled and randomly throughout the network. The different mobility schemes are compared through extensive ns2-based simulations in networks with different nodes deployment, data routing protocols, and constraints on the sink movements. In all considered scenarios, we observe that moving the sink always increases network lifetime. In particular, our experiments show that controlling the mobility of the sink leads to remarkable improvements, which are as high as sixfold compared to having the sink statically (and optimally) placed, and as high as twofold compared to uncontrolled mobility. Stefano Basagni holds a Ph.D. in electrical engineering from the University of Texas at Dallas (December 2001) and a Ph.D. in computer science from the University of Milano, Italy (May 1998). He received his B.Sc. degree in computer science from the University of Pisa, Italy, in 1991. Since Winter 2002 he is on faculty at the Department of Electrical and Computer Engineering at Northeastern University, in Boston, MA. From August 2000 to January 2002 he was professor of computer science at the Department of Computer Science of the Erik Jonsson School of Engineering and Computer Science, The University of Texas at Dallas. Dr. Basagni’s current research interests concern research and implementation aspects of mobile networks and wireless communications systems, Bluetooth and sensor networking, definition and performance evaluation of network protocols and theoretical and practical aspects of distributed algorithms. Dr. Basagni has published over four dozens of referred technical papers and book chapters. He is also co-editor of two books. Dr. Basagni served as a guest editor of the special issue of the Journal on Special Topics in Mobile Networking and Applications (MONET) on Multipoint Communication in Wireless Mobile Networks, of the special issue on mobile ad hoc networks of the Wiley’s Interscience’s Wireless Communications & Mobile Networks journal, and of the Elsevier’s journal Algorithmica on algorithmic aspects of mobile computing and communications. Dr. Basagni serves as a member of the editorial board and of the technical program committee of ACM and IEEE journals and international conferences. He is a senior member of the ACM (including the ACM SIGMOBILE), senior member of the IEEE (Computer and Communication societies), and member of ASEE (American Society for Engineering Education). Alessio Carosi received the M.S. degree “summa cum laude” in Computer Science in 2004 from Rome University “La Sapienza.” He is currently a Ph.D. candidate in Computer Science at Rome University “La Sapienza.” His research interests include protocols for ad hoc and sensor networks, underwater systems and delay tolerant networking. Emanuel Melachrinoudis received the Ph.D. degree in industrial engineering and operations research from the University of Massachusetts, Amherst, MA. He is currently the Director of Industrial Engineering and Associate Chairman of the Department of Mechanical and Industrial Engineering at Northeastern University, Boston, MA. His research interests are in the areas of network optimization and multiple criteria optimization with applications to telecommunication networks, distribution networks, location and routing. He is a member of the Editorial Board of the International Journal of Operational Research. He has published in journals such as Management Science, Transportation Science, Networks, European Journal of Operational Research, Naval Research Logistics and IIE Transactions. Chiara Petrioli received the Laurea degree “summa cum laude” in computer science in 1993, and the Ph.D. degree in computer engineering in 1998, both from Rome University “La Sapienza,” Italy. She is currently Associate Professor with the Computer Science Department at Rome University “La Sapienza.” Her current work focuses on ad hoc and sensor networks, Delay Tolerant Networks, Personal Area Networks, Energy-conserving protocols, QoS in IP networks and Content Delivery Networks where she contributed around sixty papers published in prominent international journals and conferences. Prior to Rome University she was research associate at Politecnico di Milano and was working with the Italian Space agency (ASI) and Alenia Spazio. Dr. Petrioli was guest editor of the special issue on “Energy-conserving protocols in wireless Networks” of the ACM/Kluwer Journal on Special Topics in Mobile Networking and Applications (ACM MONET) and is associate editor of IEEE Transactions on Vehicular Technology, the ACM/Kluwer Wireless Networks journal, the Wiley InterScience Wireless Communications & Mobile Computing journal and the Elsevier Ad Hoc Networks journal. She has served in the organizing committee and technical program committee of several leading conferences in the area of networking and mobile computing including ACM Mobicom, ACM Mobihoc, IEEE ICC,IEEE Globecom. She is member of the steering committee of ACM Sensys and of the international conference on Mobile and Ubiquitous Systems: Networking and Services (Mobiquitous) and serves as member of the ACM SIGMOBILE executive committee. Dr. Petrioli was a Fulbright scholar. She is a senior member of IEEE and a member of ACM. Z. Maria Wang received her Bachelor degree in Electrical Engineering with the highest honor from Beijing Institute of Light Industry in China, her M.S. degree in Industrial Engineering/Operations Research from Dalhousie University, Canada and her Ph.D. in Industrial Engineering/Operations Research from Northeastern University, Boston. She served as a R&D Analyst for General Dynamics. Currently MS. Wang serves as an Optimization Analyst with Nomis Solutions, Inc.     

Relay sensor placement in wireless sensor networks

This paper addresses the following relay sensor placement problem: given the set of duty sensors in the plane and the upper bound of the transmission range, compute the minimum number of relay sensors such that the induced topology by all sensors is globally connected. This problem is motivated by practically considering the tradeoff among performance, lifetime, and cost when designing sensor networks. In our study, this problem is modelled by a NP-hard network optimization problem named Steiner Minimum Tree with Minimum number of Steiner Points and bounded edge length (SMT-MSP). In this paper, we propose two approximate algorithms, and conduct detailed performance analysis. The first algorithm has a performance ratio of 3 and the second has a performance ratio of 2.5. Xiuzhen Cheng is an Assistant Professor in the Department of Computer Science at the George Washington University. She received her MS and PhD degrees in Computer Science from the University of Minnesota - Twin Cities in 2000 and 2002, respectively. Her current research interests include Wireless and Mobile Computing, Sensor Networks, Wireless Security, Statistical Pattern Recognition, Approximation Algorithm Design and Analysis, and Computational Medicine. She is an editor for the International Journal on Ad Hoc and Ubiquitous Computing and the International Journal of Sensor Networks. Dr. Cheng is a member of IEEE and ACM. She received the National Science Foundation CAREER Award in 2004. Ding-Zhu Du received his M.S. degree in 1982 from Institute of Applied Mathematics, Chinese Academy of Sciences, and his Ph.D. degree in 1985 from the University of California at Santa Barbara. He worked at Mathematical Sciences Research Institutea, Berkeley in 1985-86, at MIT in 1986-87, and at Princeton University in 1990-91. He was an associate-professor/professor at Department of Computer Science and Engineering, University of Minnesota in 1991-2005, a professor at City University of Hong Kong in 1998-1999, a research professor at Institute of Applied Mathematics, Chinese Academy of Sciences in 1987-2002, and a Program Director at National Science Foundation of USA in 2002-2005. Currently, he is a professor at Department of Computer Science, University of Texas at Dallas and the Dean of Science at Xi’an Jiaotong University. His research interests include design and analysis of algorithms for combinatorial optimization problems in communication networks and bioinformatics. He has published more than 140 journal papers and 10 written books. He is the editor-in-chief of Journal of Combinatorial Optimization and book series on Network Theory and Applications. He is also in editorial boards of more than 15 journals. Lusheng Wang received his PhD degree from McMaster University in 1995. He is an associate professor at City University of Hong Kong. His research interests include networks, algorithms and Bioinformatics. He is a member of IEEE and IEEE Computer Society. Baogang Xu received his PhD degree from Shandong University in 1997. He is a professor at Nanjing Normal University. His research interests include graph theory and algorithms on graphs.     

无线传感器网络及其MAC层协议

无线传感器网络（WSN）是当今信息领域的一大研究热点，在军事、环境、医疗护理和智能家居等方面有着广阔的应用前景，引起了世界各国的广泛关注。首先介绍了无线传感器网络的相关理论知识，然后对无线传感器网络目前所采用的典型的MAC协议按类型进行了介绍。     

Dynamic proxy tree-based data dissemination schemes for wireless sensor networks

In wireless sensor networks, efficiently disseminating data from a dynamic source to multiple mobile sinks is important for the applications such as mobile target detection and tracking. The tree-based multicasting scheme can be used. However, because of the short communication range of each sensor node and the frequent movement of sources and sinks, a sink may fail to receive data due to broken paths, and the tree should be frequently reconfigured to reconnect sources and sinks. To address the problem, we propose a dynamic proxy tree-based framework in this paper. A big challenge in implementing the framework is how to efficiently reconfigure the proxy tree as sources and sinks change. We model the problem as on-line constructing a minimum Steiner tree in an Euclidean plane, and propose centralized schemes to solve it. Considering the strict energy constraints in wireless sensor networks, we further propose two distributed on-line schemes, the shortest path-based (SP) scheme and the spanning range-based (SR) scheme. Extensive simulations are conducted to evaluate the schemes. The results show that the distributed schemes have similar performance as the centralized ones, and among the distributed schemes, the SR scheme outperforms the SP scheme.     

UWB radio module design for wireless sensor networks

In this paper, we describe an impulse-based ultra wideband (UWB) radio system for wireless sensor network (WSN) applications. Different architectures have been studied for base station and sensor nodes. The base station node uses coherent UWB architecture because of the high performance and good sensitivity requirements. However, to meet complexity, power and cost constraints, the sensor module uses a novel non-coherent architecture that can autonomously detect the UWB signals. The radio modules include a transceiver block, a baseband processing unit and a power management block. The transceiver block includes a Gaussian pulse generator, a multiplier, an integrator and timing circuits. For long range applications, a wideband low noise amplifier (LNA) is included in the transceiver of the sensor module, whereas in short range applications it is simply eliminated to further reduce the power consumption. In order to verify the proposed system concept, circuit level implementation is studied using 1.5 V 0.18 μm CMOS technology. Finally, the UWB radio modules have been designed for implementation in liquid-crystal-polymer (LCP) based System-on-Package (SoP) technology for low power, low cost and small size integration. A small low cost, double-slotted, Knight’s helm antenna is embedded in the LCP substrate, which shows stable characterization and a return loss better than ?10 dB over the UWB band.     

Self-propagating mal-packets in wireless sensor networks: Dynamics and defense implications

Self-propagating mal-packets have become an emergent threat against information confidentiality, integrity, and service availability in wireless sensor networks. While playing an important role for people to interact with surrounding environment, wireless sensor networks suffer from growing security concerns posed by mal-packets because of sensor networks’ low physical security, lack of resilience and robustness of underlying operating systems, and the ever-increasing complexity of deployed applications.In this paper, we study the propagation of mal-packets in 802.15.4 based wireless sensor networks. Based on our proposed mal-packet self-propagation models, we use TOSSIM, a simulator for wireless sensor networks, to study their propagation dynamics. We also present a study of the feasibility of mal-packet defense in sensor networks. Specifically, we apply random graph theory and percolation theory to investigate the immunization of highly-connected nodes, i.e., nodes with high degrees of connectivity. Our goal is to partition the network into as many separate pieces as possible, thus preventing or slowing down the mal-packet propagation. We study the percolation thresholds of different network densities and the effectiveness of immunization in terms of connection ratio, remaining link ratio, and distribution of component sizes. We also present an analysis of the distribution of component sizes.     

Spatial channel reuse in wireless sensor networks

Wireless sensor networks (WSN) are formed by network-enabled sensors spatially randomly distributed over an area. Because the number of nodes in the WSNs is usually large, channel reuse must be applied, keeping co-channel nodes sufficiently separated geographically to achieve satisfactory SIR level. The most efficient channel reuse configuration for WSN has been determined and the worst-interference scenario has been identified. For this channel reuse pattern and worst-case scenario, the minimum co-channel separation distance consistent with an SIR level constraint is derived. Our results show that the two-hop co-channel separations often assumed for sensor and ad hoc networks are not sufficient to guarantee communications. Minimum co-channel separation curves given various parameters are also presented. The results in this paper provide theoretical basis for channel spatial reuse and medium access control for WSN s and also serve as a guideline for how channel assignment algorithms should allocate channels. Furthermore, because the derived co-channel separation is a function of the sensor transmission radius, it also provides a connection between network data transport capacity planning and network topology control which is administered by varying transmission powers. Xiaofei Wang is born on July 31st, 1974, in Jilin, People’s Republic of China. He received the M.S. degree in Electrical Engineering from Delft University of Technology, Delft, The Netherlands in 1992, and the Ph.D. degree in Electrical and Computer Engineering from Cornell University, Ithaca, New York in 2005. From 1997 to 1998, he was selected as one of the twenty best master graduate candidates in all fields to participate in the Japan Prizewinners Programme, an international leadership exchange program established by the Dutch Ministry of Culture, Science and Education. From 1998 to 1999, he worked as a researcher at the Department of Electrical Engineering and Applied Mathematics of Delft University of Technology in the areas of Secondary Surveillance Radar and Ground Penetrating Radar. His research interests include wireless sensor networks, wireless mesh networks, wireless networking, error control coding, communication theory and information theory. He is currently working at Qualcomm Incorporated in San Diego, CA. Toby Berger was born in New York, NY on September 4, 1940. He received the B.E. degree in electrical engineering from Yale University, New Haven, CT in 1962, and the M.S. and Ph.D. degrees in applied mathematics from Harvard University, Cambridge, MA in 1964 and 1966, respectively. From 1962 to 1968 he was a Senior Scientist at Raytheon Company, Wayland, MA. From 1968 through 2005 he he held the position of Irwin and Joan Jacobs Professor of Engineering at Cornell University, Ithaca, NY where in 2006 he became a professor in the ECE Deportment of the University of Virginia, Charlottesville, VA. Professor Berger’s research interests include information theory, random fields, communication networks, wireless communications, video compression, voice and signature compression and verification, neuroinformation theory, quantum information theory, and coherent signal processing. Berger has served as editor-in-chief of the IEEE Transactions on Information Theory and as president of the IEEE Information Theory Group. He has been a Fellow of the Guggenheim Foundation, the Japan Society for Promotion of Science, the Ministry of Education of the People’s Republic of China and the Fulbright Foundation. In 1982 he received the Frederick E. Terman Award of the American Society for Engineering Education, he received the 2002 Shannon Award from the IEEE Information Theory Society and has been designated the recipient of the IEEE 2006 Leon K. Kirchmayer Graduate Teaching Award. Berger is a Fellow and Life Member of the IEEE, a life member of Tau Beta Pi, and an avid blues harmonica player.     

Asynchronous particle filter for tracking using non-synchronous sensor networks

This paper deals with the problem of tracking using a sensor network when the sensors are not synchronised. We propose a new algorithm called the asynchronous particle filter that, with much less computational burden than the traditional particle filter, has a slightly poorer performance. Thus, it is a good solution to real-time applications with non-synchronised sensors when high performance is required. The low computational burden of the method lies in the fact that we do not predict and update the state every time a measurement is collected. Its high performance is due to the fact that we account for the time instant at which each measurement was taken.     

Indoor localization based on wireless sensor networks

Indoor localization systems are becoming very popular because they enable the creation of very interesting location-based applications. This paper provides a short introduction about localization systems based on a sensor network and the actual state of the art. Important topics related to indoor localization like the necessary infrastructure, available technologies and their expected accuracy are treated. Additionally, the results of previous work referred to the performance evaluation of localization algorithms are shortly described. Finally, some ideas related to further investigations are presented.     

Secure data aggregation without persistent cryptographic operations in wireless sensor networks

In-network data aggregation is an essential operation to reduce energy consumption in large-scale wireless sensor networks. With data aggregation, however, raw data items are invisible to the base station and thus the authenticity of the aggregated data is hard to guarantee. A compromised sensor node may forge an aggregation value and mislead the base station into trusting a false reading. Due to the stringent constraints of energy supply and computing capability on sensor nodes, it is challenging to detect a compromised sensor node and keep it from cheating, since expensive cryptographic operations are unsuitable for tiny sensor devices. This paper proposes a secure aggregation tree (SAT) to detect and prevent cheating. Our method is essentially different from other existing solutions in that it does not require any cryptographic operations when all sensor nodes work honestly. The detection of cheating is based on the topological constraints in the aggregation tree. We also propose a weighted voting scheme to determine a misbehaving node and a secure local recovery scheme to avoid using the misbehaving node.     

EKAES: An efficient key agreement and encryption scheme for wireless sensor networks

Wireless sensor networks are being deployed for some practical applications and their security has received considerable attention.It is an important challenge to find out suitable key agreement and encryption scheme for wireless sensor networks due to limitations of the power,computation capability and storage resources.In this paper,an efficient key agreement and encryption scheme for wireless sensor networks is presented.Results of analysis and simulations among the proposed scheme and other schemes show that the proposed scheme has some advantages in terms of energy consumption,computation requirement,storage requirement and security.     

Accelerating signature-based broadcast authentication for wireless sensor networks

In wireless sensor networks (WSNs), broadcast authentication is a crucial security mechanism that allows a multitude of legitimate users to join in and disseminate messages into the networks in a dynamic and authenticated way. During the past few years, several public-key based multi-user broadcast authentication schemes have been proposed to achieve immediate authentication and to address the security vulnerability intrinsic to μTESLA-like schemes. Unfortunately, the relatively slow signature verification in signature-based broadcast authentication has also incurred a series of problems such as high energy consumption and long verification delay. In this contribution, we propose an efficient technique to accelerate the signature verification in WSNs through the cooperation among sensor nodes. By allowing some sensor nodes to release the intermediate computation results to their neighbors during the signature verification, a large number of sensor nodes can accelerate their signature verification process significantly. When applying our faster signature verification technique to the broadcast authentication in a 4 × 4 grid-based WSN, a quantitative performance analysis shows that our scheme needs 17.7-34.5% less energy and runs about 50% faster than the traditional signature verification method. The efficiency of the proposed technique has been tested through an experimental study on a network of MICAz motes.     

Energy balanced data propagation in wireless sensor networks

We study the problem of energy-balanced data propagation in wireless sensor networks. The energy balance property guarantees that the average per sensor energy dissipation is the same for all sensors in the network, during the entire execution of the data propagation protocol. This property is important since it prolongs the network’:s lifetime by avoiding early energy depletion of sensors. We propose a new algorithm that in each step decides whether to propagate data one-hop towards the final destination (the sink), or to send data directly to the sink. This randomized choice balances the (cheap) one-hop transimssions with the direct transimissions to the sink, which are more expensive but “bypass” the sensors lying close to the sink. Note that, in most protocols, these close to the sink sensors tend to be overused and die out early. By a detailed analysis we precisely estimate the probabilities for each propagation choice in order to guarantee energy balance. The needed estimation can easily be performed by current sensors using simple to obtain information. Under some assumptions, we also derive a closed form for these probabilities. The fact (shown by our analysis) that direct (expensive) transmissions to the sink are needed only rarely, shows that our protocol, besides energy-balanced, is also energy efficient. This work has been partially supported by the IST/FET/GC Programme of the European Union under contract numbers IST-2001-33135 (CRESCCO) and 6FP 001907 (DELIS). A perliminary version of the work appeared in WMAN 2004 [11]. Charilaos Efthymiou graduated form the Computer Engineering and Informatics Department (CEID) of the University of Patras, Greece. He received his MSc from the same department with advisor in S. Nikoletseas. He currently continuous his Ph.D studies in CEID with advisor L. Kirousis. His research interest include Probabilistic Techniques and Random Graphs, Randomized Algorithms in Computationally Hard Problems, Stochastic Processes and its Applications to Computer Science. Dr. Sotiris Nikoletseas is currently a Senior Researcher and Managing Director of Research Unit 1 (“Foundations of Computer Science, Relevant Technologies and Applications”) at the Computer Technology Institute (CTI), Patras, Greece and also a Lecturer at the Computer Engineering and Informatics Department of Patras University, Greece. His research interests include Probabilistic Techniques and Random Graphs, Average Case Analysis of Graph Algorithms and Randomized Algorithms, Fundamental Issues in Parallel and Distributed Computing, Approximate Solutions to Computationally Hard Problems. He has published scientific articles in major international conferences and journals and has co-authored (with Paul Spirakis) a book on Probabilistic Techniques. He has been invited speaker in important international scientific events and Universities. He has been a referee for the Theoretical Computer Science (TCS) Journal and important international conferences (ESA, ICALP). He has participated in many EU funded R&D projects (ESPRIT/ALCOM-IT, ESPRIT/GEPPCOM). He currently participates in 6 Fifth Framework projects: ALCOM-FT, ASPIS, UNIVERSAL, EICSTES (IST), ARACNE, AMORE (IMPROVING). Jose Rolim is Full Professor at the Department of Computer Science of the University of Geneva where he leads the Theoretical Computer Science and Sensor Lab (TCSensor Lab). He received his Ph.D. degree in Computer Science at the University of California, Los Angeles working together with Prof. S. Greibach. He has published several articles on the areas of distributed systems, randomization and computational complexity and leads two major projects on the area of Power Aware Computing and Games and Complexity, financed by the Swiss National Science Foundation. Prof. Rolim participates in the editorial board of several journals and conferences and he is the Steering Committee Chair and General Chair of the IEEE Distributed Computing Conference in Sensor Systems.     

Strategies and techniques for node placement in wireless sensor networks: A survey

The major challenge in designing wireless sensor networks (WSNs) is the support of the functional, such as data latency, and the non-functional, such as data integrity, requirements while coping with the computation, energy and communication constraints. Careful node placement can be a very effective optimization means for achieving the desired design goals. In this paper, we report on the current state of the research on optimized node placement in WSNs. We highlight the issues, identify the various objectives and enumerate the different models and formulations. We categorize the placement strategies into static and dynamic depending on whether the optimization is performed at the time of deployment or while the network is operational, respectively. We further classify the published techniques based on the role that the node plays in the network and the primary performance objective considered. The paper also highlights open problems in this area of research.     

Clamp-and-Forget: A self-sustainable non-invasive wireless sensor node for smart metering applications

Measuring and managing the power consumption of household appliances, as well as that of industrial machineries, is becoming more and more important to improve the distribution and usage of the electrical energy and to reduce the energy bill. We present the design of a non-invasive wireless current meter which can measure AC current up to $60A_{\mathit{RMS}}$ exploiting a small clamp-on inductive sensor. The novelty of the design is a subsystem consisting of a harvesting circuit designed to extract energy from the same current transducer used for measurements. Experiments have been conducted to validate the approach, to assess the accuracy of the sensing system and deviations due to the energy harvester, and to determine the condition which permits us to achieve the energy neutrality and thus, a self-sustainable smart meter.