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Special Issue "Towards Energy-Neutral WSN Architectures: Energy Harvesting and Other Enabling Technologies"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Sensor Networks".

Deadline for manuscript submissions: closed (30 September 2015)

Special Issue Editor

Guest Editor
Dr. Davide Brunelli

DII, University of Trento, I-38123 Trento, Italy
Website | E-Mail
Interests: Development of new techniques of Energy Scavenging for embedded electronic systems; Exploring interaction and design issues in embedded personal device and wireless sensor network; Development and optimization of low-power and low-cost Wireless Sensor Networks (WSN) for Climate and Environmental Monitoring; Development of algorithms for position analysis and tracking in indoor environments; Ubiquitous computing oriented to the cooperation through mobile devices and development of applications for portable systems

Special Issue Information

Dear Colleagues,

Smart and distributed sensing systems are one of the technological cornerstones of the Internet of Things (IoT), wearable electronic devices, future transportation, environmental monitoring and smart cities. Today, one of the major challenges of using smart wireless sensors in real deployments is related to energy consumption and guaranteeing adequate lifetime. Energy harvesting and deep–low power management are making significant strides forward, and innovative solutions in terms of on-board hardware for energy scavenging, energy adaptive algorithms, and power management policies of the nodes in the network are the ultimate frontiers.

To open the door to unlimited and uninterrupted operation (zero-energy networks), the organizers solicit novel and previously unpublished technical articles which describe advances in sensing systems with zero-energy expenditure from conventional power supply (i.e., batteries and plugs).

Potential topics include, but are not limited to:

•           Advancements on circuits of energy harvesting for embedded systems;

•           Power management algorithms for energy harvesting sensing systems;

•           Architectures for energy-neutral sensing systems;

•           Discovery protocols for energy neutral systems;

•           Resilient energy-neutral sensors;

•           Sharing transducers for sensing and scavenging;

•           Middleware support and services which support interoperability between zero-energy networks;

•           Remote activation and Wake-up (wake-up from radio, sound and other mechanisms);

•           Resource management for energy neutral operations;

•           Operating systems for perpetual devices;

•           Network-wide distributed energy management (e.g. WSN routing);

•           Online measurement and Forecasting algorithms of energy intake and consumption;

•           Simulation tools and modelling of future energy autonomous sensing systems;

•           IoT—Internet of (battery-less) things;

•           Practical deployments and implementation experiences;

•           Standards and interoperability of energy-neutral sensing infrastructures.

Authors are invited to contact the guest editor, prior to submission, if they are uncertain whether their work falls within the general scope of this Special Issue.

Dr. Davide Brunelli
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • energy harvesting
  • deep-low power management
  • Internet of Things
  • wireless smart sensors

Published Papers (23 papers)

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Open AccessArticle A High-Efficiency Wind Energy Harvester for Autonomous Embedded Systems
Sensors 2016, 16(3), 327; doi:10.3390/s16030327
Received: 29 September 2015 / Revised: 20 February 2016 / Accepted: 24 February 2016 / Published: 4 March 2016
Cited by 6 | PDF Full-text (3677 KB) | HTML Full-text | XML Full-text
Abstract
Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is
[...] Read more.
Energy harvesting is currently a hot research topic, mainly as a consequence of the increasing attractiveness of computing and sensing solutions based on small, low-power distributed embedded systems. Harvesting may enable systems to operate in a deploy-and-forget mode, particularly when power grid is absent and the use of rechargeable batteries is unattractive due to their limited lifetime and maintenance requirements. This paper focuses on wind flow as an energy source feasible to meet the energy needs of a small autonomous embedded system. In particular the contribution is on the electrical converter and system integration. We characterize the micro-wind turbine, we define a detailed model of its behaviour, and then we focused on a highly efficient circuit to convert wind energy into electrical energy. The optimized design features an overall volume smaller than 64 cm3. The core of the harvester is a high efficiency buck-boost converter which performs an optimal power point tracking. Experimental results show that the wind generator boosts efficiency over a wide range of operating conditions. Full article
Open AccessArticle Design of New Power Management Circuit for Light Energy Harvesting System
Sensors 2016, 16(3), 270; doi:10.3390/s16030270
Received: 30 September 2015 / Revised: 12 February 2016 / Accepted: 18 February 2016 / Published: 23 February 2016
Cited by 2 | PDF Full-text (3644 KB) | HTML Full-text | XML Full-textRetraction
Abstract
Nowadays, it can be observed that Wireless Sensors Networks (WSN) are taking increasingly vital roles in many applications, such as building energy monitoring and control, which is the focus of the work in this paper. However, the main challenging issue with adopting WSN
[...] Read more.
Nowadays, it can be observed that Wireless Sensors Networks (WSN) are taking increasingly vital roles in many applications, such as building energy monitoring and control, which is the focus of the work in this paper. However, the main challenging issue with adopting WSN technology is the use of power sources such as batteries, which have a limited lifetime. A smart solution that could tackle this problem is using Energy Harvesting technology. The work in this paper will be focused on proposing a new power management design through harvesting indoor light intensity. The new approach is inspired by the use of the Fractional Open Circuit Voltage based Maximum Power Point tracking (MPPT) concept for sub mw Photo Voltaic (PV) cells. The new design adopts two main features: First, it minimizes the power consumed by the power management section; and second, it maximizes the MPPT-converted output voltage and consequently improves the efficiency of the power conversion in the sub mw power level. The new experimentally-tested design showed an improvement of 81% in the efficiency of MPPT conversion using 0.5 mW input power in comparison with the other presented solutions that showed less efficiency with higher input power. Full article
Open AccessArticle Realtime Gas Emission Monitoring at Hazardous Sites Using a Distributed Point-Source Sensing Infrastructure
Sensors 2016, 16(1), 121; doi:10.3390/s16010121
Received: 14 September 2015 / Revised: 14 January 2016 / Accepted: 14 January 2016 / Published: 20 January 2016
PDF Full-text (7127 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant’s critical areas; each sub-net includes a
[...] Read more.
This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant’s critical areas; each sub-net includes a gateway unit wirelessly connected to the WSN nodes, hence providing an easily deployable, stand-alone infrastructure featuring a high degree of scalability and reconfigurability. Furthermore, the system provides automated calibration routines which can be accomplished by non-specialized maintenance operators without system reliability reduction issues. Internet connectivity is provided via TCP/IP over GPRS (Internet standard protocols over mobile networks) gateways at a one-minute sampling rate. Environmental and process data are forwarded to a remote server and made available to authenticated users through a user interface that provides data rendering in various formats and multi-sensor data fusion. The platform is able to provide real-time plant management with an effective; accurate tool for immediate warning in case of critical events. Full article
Open AccessArticle Energy-Efficient Control with Harvesting Predictions for Solar-Powered Wireless Sensor Networks
Sensors 2016, 16(1), 53; doi:10.3390/s16010053
Received: 18 November 2015 / Revised: 30 December 2015 / Accepted: 30 December 2015 / Published: 4 January 2016
Cited by 10 | PDF Full-text (1890 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks equipped with rechargeable batteries are useful for outdoor environmental monitoring. However, the severe energy constraints of the sensor nodes present major challenges for long-term applications. To achieve sustainability, solar cells can be used to acquire energy from the environment. Unfortunately,
[...] Read more.
Wireless sensor networks equipped with rechargeable batteries are useful for outdoor environmental monitoring. However, the severe energy constraints of the sensor nodes present major challenges for long-term applications. To achieve sustainability, solar cells can be used to acquire energy from the environment. Unfortunately, the energy supplied by the harvesting system is generally intermittent and considerably influenced by the weather. To improve the energy efficiency and extend the lifetime of the networks, we propose algorithms for harvested energy prediction using environmental shadow detection. Thus, the sensor nodes can adjust their scheduling plans accordingly to best suit their energy production and residual battery levels. Furthermore, we introduce clustering and routing selection methods to optimize the data transmission, and a Bayesian network is used for warning notifications of bottlenecks along the path. The entire system is implemented on a real-time Texas Instruments CC2530 embedded platform, and the experimental results indicate that these mechanisms sustain the networks’ activities in an uninterrupted and efficient manner. Full article
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Open AccessArticle Energy Efficient Moving Target Tracking in Wireless Sensor Networks
Sensors 2016, 16(1), 29; doi:10.3390/s16010029
Received: 15 September 2015 / Revised: 10 December 2015 / Accepted: 21 December 2015 / Published: 2 January 2016
Cited by 3 | PDF Full-text (273 KB) | HTML Full-text | XML Full-text
Abstract
Moving target tracking in wireless sensor networks is of paramount importance. This paper considers the problem of state estimation for L-sensor linear dynamic systems. Firstly, the paper establishes the fuzzy model for measurement condition estimation. Then, Generalized Kalman Filter design is performed
[...] Read more.
Moving target tracking in wireless sensor networks is of paramount importance. This paper considers the problem of state estimation for L-sensor linear dynamic systems. Firstly, the paper establishes the fuzzy model for measurement condition estimation. Then, Generalized Kalman Filter design is performed to incorporate the novel neighborhood function and the target motion information, improving with an increasing number of active sensors. The proposed measurement selection approach has some advantages in time cost. As such, if the desired accuracy has been achieved, the parameter initialization for optimization can be readily resolved, which maximizes the expected lifespan while preserving tracking accuracy. Through theoretical justifications and empirical studies, we demonstrate that the proposed scheme achieves substantially superior performances over conventional methods in terms of moving target tracking under the resource-constrained wireless sensor networks. Full article
Open AccessArticle Self-Powered WSN for Distributed Data Center Monitoring
Sensors 2016, 16(1), 57; doi:10.3390/s16010057
Received: 12 November 2015 / Revised: 24 December 2015 / Accepted: 29 December 2015 / Published: 2 January 2016
Cited by 1 | PDF Full-text (18193 KB) | HTML Full-text | XML Full-text
Abstract
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental
[...] Read more.
Monitoring environmental parameters in data centers is gathering nowadays increasing attention from industry, due to the need of high energy efficiency of cloud services. We present the design and the characterization of an energy neutral embedded wireless system, prototyped to monitor perpetually environmental parameters in servers and racks. It is powered by an energy harvesting module based on Thermoelectric Generators, which converts the heat dissipation from the servers. Starting from the empirical characterization of the energy harvester, we present a power conditioning circuit optimized for the specific application. The whole system has been enhanced with several sensors. An ultra-low-power micro-controller stacked over the energy harvesting provides an efficient power management. Performance have been assessed and compared with the analytical model for validation. Full article
Open AccessArticle A Multi-Hop Energy Neutral Clustering Algorithm for Maximizing Network Information Gathering in Energy Harvesting Wireless Sensor Networks
Sensors 2016, 16(1), 26; doi:10.3390/s16010026
Received: 17 August 2015 / Revised: 17 December 2015 / Accepted: 23 December 2015 / Published: 26 December 2015
Cited by 4 | PDF Full-text (3581 KB) | HTML Full-text | XML Full-text
Abstract
Energy resource limitation is a severe problem in traditional wireless sensor networks (WSNs) because it restricts the lifetime of network. Recently, the emergence of energy harvesting techniques has brought with them the expectation to overcome this problem. In particular, it is possible for
[...] Read more.
Energy resource limitation is a severe problem in traditional wireless sensor networks (WSNs) because it restricts the lifetime of network. Recently, the emergence of energy harvesting techniques has brought with them the expectation to overcome this problem. In particular, it is possible for a sensor node with energy harvesting abilities to work perpetually in an Energy Neutral state. In this paper, a Multi-hop Energy Neutral Clustering (MENC) algorithm is proposed to construct the optimal multi-hop clustering architecture in energy harvesting WSNs, with the goal of achieving perpetual network operation. All cluster heads (CHs) in the network act as routers to transmit data to base station (BS) cooperatively by a multi-hop communication method. In addition, by analyzing the energy consumption of intra- and inter-cluster data transmission, we give the energy neutrality constraints. Under these constraints, every sensor node can work in an energy neutral state, which in turn provides perpetual network operation. Furthermore, the minimum network data transmission cycle is mathematically derived using convex optimization techniques while the network information gathering is maximal. Simulation results show that our protocol can achieve perpetual network operation, so that the consistent data delivery is guaranteed. In addition, substantial improvements on the performance of network throughput are also achieved as compared to the famous traditional clustering protocol LEACH and recent energy harvesting aware clustering protocols. Full article
Open AccessArticle Service-Aware Clustering: An Energy-Efficient Model for the Internet-of-Things
Sensors 2016, 16(1), 9; doi:10.3390/s16010009
Received: 1 October 2015 / Revised: 29 November 2015 / Accepted: 8 December 2015 / Published: 23 December 2015
Cited by 3 | PDF Full-text (973 KB) | HTML Full-text | XML Full-text
Abstract
Current generation wireless sensor routing algorithms and protocols have been designed based on a myopic routing approach, where the motes are assumed to have the same sensing and communication capabilities. Myopic routing is not a natural fit for the IoT, as it may
[...] Read more.
Current generation wireless sensor routing algorithms and protocols have been designed based on a myopic routing approach, where the motes are assumed to have the same sensing and communication capabilities. Myopic routing is not a natural fit for the IoT, as it may lead to energy imbalance and subsequent short-lived sensor networks, routing the sensor readings over the most service-intensive sensor nodes, while leaving the least active nodes idle. This paper revisits the issue of energy efficiency in sensor networks to propose a clustering model where sensor devices’ service delivery is mapped into an energy awareness model, used to design a clustering algorithm that finds service-aware clustering (SAC) configurations in IoT settings. The performance evaluation reveals the relative energy efficiency of the proposed SAC algorithm compared to related routing algorithms in terms of energy consumption, the sensor nodes’ life span and its traffic engineering efficiency in terms of throughput and delay. These include the well-known low energy adaptive clustering hierarchy (LEACH) and LEACH-centralized (LEACH-C) algorithms, as well as the most recent algorithms, such as DECSA and MOCRN. Full article
Open AccessArticle An Intelligent Weather Station
Sensors 2015, 15(12), 31005-31022; doi:10.3390/s151229841
Received: 20 October 2015 / Revised: 20 November 2015 / Accepted: 25 November 2015 / Published: 10 December 2015
Cited by 6 | PDF Full-text (5666 KB) | HTML Full-text | XML Full-text
Abstract
Accurate measurements of global solar radiation, atmospheric temperature and relative humidity, as well as the availability of the predictions of their evolution over time, are important for different areas of applications, such as agriculture, renewable energy and energy management, or thermal comfort in
[...] Read more.
Accurate measurements of global solar radiation, atmospheric temperature and relative humidity, as well as the availability of the predictions of their evolution over time, are important for different areas of applications, such as agriculture, renewable energy and energy management, or thermal comfort in buildings. For this reason, an intelligent, light-weight, self-powered and portable sensor was developed, using a nearest-neighbors (NEN) algorithm and artificial neural network (ANN) models as the time-series predictor mechanisms. The hardware and software design of the implemented prototype are described, as well as the forecasting performance related to the three atmospheric variables, using both approaches, over a prediction horizon of 48-steps-ahead. Full article
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Open AccessArticle An Inductorless Self-Controlled Rectifier for Piezoelectric Energy Harvesting
Sensors 2015, 15(11), 29192-29208; doi:10.3390/s151129192
Received: 23 June 2015 / Revised: 7 October 2015 / Accepted: 13 November 2015 / Published: 19 November 2015
Cited by 3 | PDF Full-text (2775 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a high-efficiency inductorless self-controlled rectifier for piezoelectric energy harvesting. High efficiency is achieved by discharging the piezoelectric device (PD) capacitance each time the current produced by the PD changes polarity. This is achieved automatically without the use of delay lines,
[...] Read more.
This paper presents a high-efficiency inductorless self-controlled rectifier for piezoelectric energy harvesting. High efficiency is achieved by discharging the piezoelectric device (PD) capacitance each time the current produced by the PD changes polarity. This is achieved automatically without the use of delay lines, thereby making the proposed circuit compatible with any type of PD. In addition, the proposed rectifier alleviates the need for an inductor, making it suitable for on-chip integration. Reported experimental results show that the proposed rectifier can harvest up to 3.9 times more energy than a full wave bridge rectifier. Full article
Open AccessArticle An Open Source Low-Cost Wireless Control System for a Forced Circulation Solar Plant
Sensors 2015, 15(11), 27990-28004; doi:10.3390/s151127990
Received: 25 August 2015 / Revised: 29 October 2015 / Accepted: 30 October 2015 / Published: 5 November 2015
Cited by 8 | PDF Full-text (2345 KB) | HTML Full-text | XML Full-text
Abstract
The article describes the design phase, development and practical application of a low-cost control system for a forced circulation solar plant in an outdoor test cell located near Milan. Such a system provides for the use of an electric pump for the circulation
[...] Read more.
The article describes the design phase, development and practical application of a low-cost control system for a forced circulation solar plant in an outdoor test cell located near Milan. Such a system provides for the use of an electric pump for the circulation of heat transfer fluid connecting the solar thermal panel to the storage tank. The running plant temperatures are the fundamental parameter to evaluate the system performance such as proper operation, and the control and management system has to consider these parameters. A solar energy-powered wireless-based smart object was developed, able to monitor the running temperatures of a solar thermal system and aimed at moving beyond standard monitoring approaches to achieve a low-cost and customizable device, even in terms of installation in different environmental conditions. To this end, two types of communications were used: the first is a low-cost communication based on the ZigBee protocol used for control purposes, so that it can be customized according to specific needs, while the second is based on a Bluetooth protocol used for data display. Full article
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Open AccessArticle A Hybrid Lifetime Extended Directional Approach for WBANs
Sensors 2015, 15(11), 28005-28030; doi:10.3390/s151128005
Received: 4 September 2015 / Accepted: 14 September 2015 / Published: 5 November 2015
Cited by 4 | PDF Full-text (1052 KB) | HTML Full-text | XML Full-text
Abstract
Wireless Body Area Networks (WBANs) can provide real-time and reliable health monitoring, attributing to the human-centered and sensor interoperability properties. WBANs have become a key component of the ubiquitous eHealth (electronic health) revolution that prospers on the basis of information and communication technologies.
[...] Read more.
Wireless Body Area Networks (WBANs) can provide real-time and reliable health monitoring, attributing to the human-centered and sensor interoperability properties. WBANs have become a key component of the ubiquitous eHealth (electronic health) revolution that prospers on the basis of information and communication technologies. The prime consideration in WBAN is how to maximize the network lifetime with battery-powered sensor nodes in energy constraint. Novel solutions in Medium Access Control (MAC) protocols are imperative to satisfy the particular BAN scenario and the need of excellent energy efficiency in healthcare applications. In this paper, we propose a hybrid Lifetime Extended Directional Approach (LEDA) MAC protocol based on IEEE 802.15.6 to reduce energy consumption and prolong network lifetime. The LEDA MAC protocol takes full advantages of directional superiority in energy saving that employs multi-beam directional mode in Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) and single-beam directional mode in Time Division Multiple Access (TDMA) for alternative in data reservation and transmission according to the traffic varieties. Moreover, the impacts of some inherent problems of directional antennas such as deafness and hidden terminal problem can be decreased owing to that all nodes generate individual beam according to user priorities designated. Furthermore, LEDA MAC employs a Dynamic Polled Allocation Period (DPAP) for burst data transmissions to increase the network reliability and adaptability. Extensive analysis and simulation results show that the proposed LEDA MAC protocol achieves extended network lifetime with improved performance compared with IEEE 802.15.6. Full article
Open AccessArticle A Novel Wireless Power Transfer-Based Weighed Clustering Cooperative Spectrum Sensing Method for Cognitive Sensor Networks
Sensors 2015, 15(11), 27760-27782; doi:10.3390/s151127760
Received: 27 July 2015 / Revised: 24 October 2015 / Accepted: 26 October 2015 / Published: 30 October 2015
Cited by 3 | PDF Full-text (819 KB) | HTML Full-text | XML Full-text
Abstract
In a cognitive sensor network (CSN), the wastage of sensing time and energy is a challenge to cooperative spectrum sensing, when the number of cooperative cognitive nodes (CNs) becomes very large. In this paper, a novel wireless power transfer (WPT)-based weighed clustering cooperative
[...] Read more.
In a cognitive sensor network (CSN), the wastage of sensing time and energy is a challenge to cooperative spectrum sensing, when the number of cooperative cognitive nodes (CNs) becomes very large. In this paper, a novel wireless power transfer (WPT)-based weighed clustering cooperative spectrum sensing model is proposed, which divides all the CNs into several clusters, and then selects the most favorable CNs as the cluster heads and allows the common CNs to transfer the received radio frequency (RF) energy of the primary node (PN) to the cluster heads, in order to supply the electrical energy needed for sensing and cooperation. A joint resource optimization is formulated to maximize the spectrum access probability of the CSN, through jointly allocating sensing time and clustering number. According to the resource optimization results, a clustering algorithm is proposed. The simulation results have shown that compared to the traditional model, the cluster heads of the proposed model can achieve more transmission power and there exists optimal sensing time and clustering number to maximize the spectrum access probability. Full article
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Open AccessArticle SITRUS: Semantic Infrastructure for Wireless Sensor Networks
Sensors 2015, 15(11), 27436-27469; doi:10.3390/s151127436
Received: 4 June 2015 / Revised: 13 October 2015 / Accepted: 19 October 2015 / Published: 29 October 2015
Cited by 2 | PDF Full-text (778 KB) | HTML Full-text | XML Full-text
Abstract
Wireless sensor networks (WSNs) are made up of nodes with limited resources, such as processing, bandwidth, memory and, most importantly, energy. For this reason, it is essential that WSNs always work to reduce the power consumption as much as possible in order to
[...] Read more.
Wireless sensor networks (WSNs) are made up of nodes with limited resources, such as processing, bandwidth, memory and, most importantly, energy. For this reason, it is essential that WSNs always work to reduce the power consumption as much as possible in order to maximize its lifetime. In this context, this paper presents SITRUS (semantic infrastructure for wireless sensor networks), which aims to reduce the power consumption of WSN nodes using ontologies. SITRUS consists of two major parts: a message-oriented middleware responsible for both an oriented message communication service and a reconfiguration service; and a semantic information processing module whose purpose is to generate a semantic database that provides the basis to decide whether a WSN node needs to be reconfigurated or not. In order to evaluate the proposed solution, we carried out an experimental evaluation to assess the power consumption and memory usage of WSN applications built atop SITRUS. Full article
Open AccessArticle Piezoelectric Energy Harvesting in Internal Fluid Flow
Sensors 2015, 15(10), 26039-26062; doi:10.3390/s151026039
Received: 31 August 2015 / Revised: 2 October 2015 / Accepted: 8 October 2015 / Published: 14 October 2015
Cited by 3 | PDF Full-text (8028 KB) | HTML Full-text | XML Full-text
Abstract
We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two
[...] Read more.
We consider piezoelectric flow energy harvesting in an internal flow environment with the ultimate goal powering systems such as sensors in deep oil well applications. Fluid motion is coupled to structural vibration via a cantilever beam placed in a converging-diverging flow channel. Two designs were considered for the electromechanical coupling: first; the cantilever itself is a piezoelectric bimorph; second; the cantilever is mounted on a pair of flextensional actuators. We experimentally investigated varying the geometry of the flow passage and the flow rate. Experimental results revealed that the power generated from both designs was similar; producing as much as 20 mW at a flow rate of 20 L/min. The bimorph designs were prone to failure at the extremes of flow rates tested. Finite element analysis (FEA) showed fatigue failure was imminent due to stress concentrations near the bimorph’s clamped region; and that robustness could be improved with a stepped-joint mounting design. A similar FEA model showed the flextensional-based harvester had a resonant frequency of around 375 Hz and an electromechanical coupling of 0.23 between the cantilever and flextensional actuators in a vacuum. These values; along with the power levels demonstrated; are significant steps toward building a system design that can eventually deliver power in the Watts range to devices down within a well. Full article
Open AccessArticle Energy Efficient Medium Access Control Protocol for Clustered Wireless Sensor Networks with Adaptive Cross-Layer Scheduling
Sensors 2015, 15(9), 24026-24053; doi:10.3390/s150924026
Received: 11 March 2015 / Revised: 21 July 2015 / Accepted: 21 July 2015 / Published: 18 September 2015
Cited by 1 | PDF Full-text (728 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an Energy Efficient Medium Access Control (MAC) protocol for clustered wireless sensor networks that aims to improve energy efficiency and delay performance. The proposed protocol employs an adaptive cross-layer intra-cluster scheduling and an inter-cluster relay selection diversity. The scheduling is
[...] Read more.
This paper presents an Energy Efficient Medium Access Control (MAC) protocol for clustered wireless sensor networks that aims to improve energy efficiency and delay performance. The proposed protocol employs an adaptive cross-layer intra-cluster scheduling and an inter-cluster relay selection diversity. The scheduling is based on available data packets and remaining energy level of the source node (SN). This helps to minimize idle listening on nodes without data to transmit as well as reducing control packet overhead. The relay selection diversity is carried out between clusters, by the cluster head (CH), and the base station (BS). The diversity helps to improve network reliability and prolong the network lifetime. Relay selection is determined based on the communication distance, the remaining energy and the channel quality indicator (CQI) for the relay cluster head (RCH). An analytical framework for energy consumption and transmission delay for the proposed MAC protocol is presented in this work. The performance of the proposed MAC protocol is evaluated based on transmission delay, energy consumption, and network lifetime. The results obtained indicate that the proposed MAC protocol provides improved performance than traditional cluster based MAC protocols. Full article
Open AccessArticle Adaptive Data Gathering in Mobile Sensor Networks Using Speedy Mobile Elements
Sensors 2015, 15(9), 23218-23248; doi:10.3390/s150923218
Received: 6 August 2015 / Revised: 6 September 2015 / Accepted: 7 September 2015 / Published: 15 September 2015
Cited by 8 | PDF Full-text (711 KB) | HTML Full-text | XML Full-text
Abstract
Data gathering is a key operator for applications in wireless sensor networks; yet it is also a challenging problem in mobile sensor networks when considering that all nodes are mobile and the communications among them are opportunistic. This paper proposes an efficient data
[...] Read more.
Data gathering is a key operator for applications in wireless sensor networks; yet it is also a challenging problem in mobile sensor networks when considering that all nodes are mobile and the communications among them are opportunistic. This paper proposes an efficient data gathering scheme called ADG that adopts speedy mobile elements as the mobile data collector and takes advantage of the movement patterns of the network. ADG first extracts the network meta-data at initial epochs, and calculates a set of proxy nodes based on the meta-data. Data gathering is then mapped into the Proxy node Time Slot Allocation (PTSA) problem that schedules the time slots and orders, according to which the data collector could gather the maximal amount of data within a limited period. Finally, the collector follows the schedule and picks up the sensed data from the proxy nodes through one hop of message transmissions. ADG learns the period when nodes are relatively stationary, so that the collector is able to pick up the data from them during the limited data gathering period. Moreover, proxy nodes and data gathering points could also be timely updated so that the collector could adapt to the change of node movements. Extensive experimental results show that the proposed scheme outperforms other data gathering schemes on the cost of message transmissions and the data gathering rate, especially under the constraint of limited data gathering period. Full article
Open AccessArticle Energy-Efficient Transmissions for Remote Wireless Sensor Networks: An Integrated HAP/Satellite Architecture for Emergency Scenarios
Sensors 2015, 15(9), 22266-22290; doi:10.3390/s150922266
Received: 9 July 2015 / Revised: 31 August 2015 / Accepted: 1 September 2015 / Published: 3 September 2015
Cited by 11 | PDF Full-text (507 KB) | HTML Full-text | XML Full-text
Abstract
A typical application scenario of remote wireless sensor networks (WSNs) is identified as an emergency scenario. One of the greatest design challenges for communications in emergency scenarios is energy-efficient transmission, due to scarce electrical energy in large-scale natural and man-made disasters. Integrated high
[...] Read more.
A typical application scenario of remote wireless sensor networks (WSNs) is identified as an emergency scenario. One of the greatest design challenges for communications in emergency scenarios is energy-efficient transmission, due to scarce electrical energy in large-scale natural and man-made disasters. Integrated high altitude platform (HAP)/satellite networks are expected to optimally meet emergency communication requirements. In this paper, a novel integrated HAP/satellite (IHS) architecture is proposed, and three segments of the architecture are investigated in detail. The concept of link-state advertisement (LSA) is designed in a slow flat Rician fading channel. The LSA is received and processed by the terminal to estimate the link state information, which can significantly reduce the energy consumption at the terminal end. Furthermore, the transmission power requirements of the HAPs and terminals are derived using the gradient descent and differential equation methods. The energy consumption is modeled at both the source and system level. An innovative and adaptive algorithm is given for the energy-efficient path selection. The simulation results validate the effectiveness of the proposed adaptive algorithm. It is shown that the proposed adaptive algorithm can significantly improve energy efficiency when combined with the LSA and the energy consumption estimation. Full article
Open AccessArticle An Energy-Efficient Spectrum-Aware Reinforcement Learning-Based Clustering Algorithm for Cognitive Radio Sensor Networks
Sensors 2015, 15(8), 19783-19818; doi:10.3390/s150819783
Received: 25 May 2015 / Revised: 30 July 2015 / Accepted: 31 July 2015 / Published: 13 August 2015
Cited by 9 | PDF Full-text (1622 KB) | HTML Full-text | XML Full-text
Abstract
It is well-known that clustering partitions network into logical groups of nodes in order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio through cooperative sensing. While the topic of energy efficiency has been well investigated in conventional wireless
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It is well-known that clustering partitions network into logical groups of nodes in order to achieve energy efficiency and to enhance dynamic channel access in cognitive radio through cooperative sensing. While the topic of energy efficiency has been well investigated in conventional wireless sensor networks, the latter has not been extensively explored. In this paper, we propose a reinforcement learning-based spectrum-aware clustering algorithm that allows a member node to learn the energy and cooperative sensing costs for neighboring clusters to achieve an optimal solution. Each member node selects an optimal cluster that satisfies pairwise constraints, minimizes network energy consumption and enhances channel sensing performance through an exploration technique. We first model the network energy consumption and then determine the optimal number of clusters for the network. The problem of selecting an optimal cluster is formulated as a Markov Decision Process (MDP) in the algorithm and the obtained simulation results show convergence, learning and adaptability of the algorithm to dynamic environment towards achieving an optimal solution. Performance comparisons of our algorithm with the Groupwise Spectrum Aware (GWSA)-based algorithm in terms of Sum of Square Error (SSE), complexity, network energy consumption and probability of detection indicate improved performance from the proposed approach. The results further reveal that an energy savings of 9% and a significant Primary User (PU) detection improvement can be achieved with the proposed approach. Full article
Open AccessArticle Cooperative Energy Harvesting-Adaptive MAC Protocol for WBANs
Sensors 2015, 15(6), 12635-12650; doi:10.3390/s150612635
Received: 19 February 2015 / Accepted: 7 May 2015 / Published: 28 May 2015
Cited by 18 | PDF Full-text (541 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in
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In this paper, we introduce a cooperative medium access control (MAC) protocol, named cooperative energy harvesting (CEH)-MAC, that adapts its operation to the energy harvesting (EH) conditions in wireless body area networks (WBANs). In particular, the proposed protocol exploits the EH information in order to set an idle time that allows the relay nodes to charge their batteries and complete the cooperation phase successfully. Extensive simulations have shown that CEH-MAC significantly improves the network performance in terms of throughput, delay and energy efficiency compared to the cooperative operation of the baseline IEEE 802.15.6 standard. Full article
Open AccessArticle An Energy-Efficient Underground Localization System Based on Heterogeneous Wireless Networks
Sensors 2015, 15(6), 12358-12376; doi:10.3390/s150612358
Received: 25 March 2015 / Accepted: 8 May 2015 / Published: 26 May 2015
Cited by 3 | PDF Full-text (1676 KB) | HTML Full-text | XML Full-text
Abstract
A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners’ should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on
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A precision positioning system with energy efficiency is of great necessity for guaranteeing personnel safety in underground mines. The location information of the miners’ should be transmitted to the control center timely and reliably; therefore, a heterogeneous network with the backbone based on high speed Industrial Ethernet is deployed. Since the mobile wireless nodes are working in an irregular tunnel, a specific wireless propagation model cannot fit all situations. In this paper, an underground localization system is designed to enable the adaptation to kinds of harsh tunnel environments, but also to reduce the energy consumption and thus prolong the lifetime of the network. Three key techniques are developed and implemented to improve the system performance, including a step counting algorithm with accelerometers, a power control algorithm and an adaptive packets scheduling scheme. The simulation study and experimental results show the effectiveness of the proposed algorithms and the implementation. Full article
Open AccessArticle An Energy-Efficient Transmission Scheme for Real-Time Data in Wireless Sensor Networks
Sensors 2015, 15(5), 11628-11652; doi:10.3390/s150511628
Received: 18 March 2015 / Revised: 13 May 2015 / Accepted: 14 May 2015 / Published: 20 May 2015
Cited by 5 | PDF Full-text (2790 KB) | HTML Full-text | XML Full-text
Abstract
The Internet of things (IoT) is a novel paradigm where all things or objects in daily life can communicate with other devices and provide services over the Internet. Things or objects need identifying, sensing, networking and processing capabilities to make the IoT paradigm
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The Internet of things (IoT) is a novel paradigm where all things or objects in daily life can communicate with other devices and provide services over the Internet. Things or objects need identifying, sensing, networking and processing capabilities to make the IoT paradigm a reality. The IEEE 802.15.4 standard is one of the main communication protocols proposed for the IoT. The IEEE 802.15.4 standard provides the guaranteed time slot (GTS) mechanism that supports the quality of service (QoS) for the real-time data transmission. In spite of some QoS features in IEEE 802.15.4 standard, the problem of end-to-end delay still remains. In order to solve this problem, we propose a cooperative medium access scheme (MAC) protocol for real-time data transmission. We also evaluate the performance of the proposed scheme through simulation. The simulation results demonstrate that the proposed scheme can improve the network performance. Full article

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Open AccessLetter Implicit Block ACK Scheme for IEEE 802.11 WLANs
Sensors 2016, 16(2), 167; doi:10.3390/s16020167
Received: 19 September 2015 / Revised: 21 December 2015 / Accepted: 30 December 2015 / Published: 28 January 2016
PDF Full-text (222 KB) | HTML Full-text | XML Full-text
Abstract
The throughput of IEEE 802.11 standard is significantly bounded by the associated Medium Access Control (MAC) overhead. Because of the overhead, an upper limit exists for throughput, which is bounded, including situations where data rates are extremely high. Therefore, an overhead reduction is
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The throughput of IEEE 802.11 standard is significantly bounded by the associated Medium Access Control (MAC) overhead. Because of the overhead, an upper limit exists for throughput, which is bounded, including situations where data rates are extremely high. Therefore, an overhead reduction is necessary to achieve higher throughput. The IEEE 802.11e amendment introduced the block ACK mechanism, to reduce the number of control messages in MAC. Although the block ACK scheme greatly reduces overhead, further improvements are possible. In this letter, we propose an implicit block ACK method that further reduces the overhead associated with IEEE 802.11e’s block ACK scheme. The mathematical analysis results are presented for both the original protocol and the proposed scheme. A performance improvement of greater than 10% was achieved with the proposed implementation. Full article
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