Wireless Sensor Network Testbeds Research Articles

Self-Organizing Multilateration of an Unknown Number of Transmitters

Wireless Sensor Networks (WSNs) that classify the source of detected radio signals require mobile transmitters, physical (PHY) and link layer meta data, and packet sniffing capabilities. These signal classifiers are restricted by assumptions that may be difficult to realize in adversarial Signal of Opportunity (SOP) localization settings, and they do not jointly localize transmitters. In this paper, we present a novel framework that self-organizes to classify and jointly localize sets of stationary transmitters emitting SOP. The framework leverages the underlying Gaussian distribution associated with multilateration estimates via the use of Unsupervised Learning (UL) techniques. Inference of spatial multilateration features allows for the joint estimation of classification outcomes with respect to several unknown parameters, including the number of transmitters, source transmitters for each signal, the underlying multilateration distribution, and the transmitter locations. The proposed framework was evaluated in a two-dimensional trilateration experiment. Signals transmitted by vehicular Tire Pressure Monitoring System (TPMS) wireless beacons were observed by a custom-built WSN test bed to produce Received Signal Strength Indicators (RSS) features. We used a trained Convolutional Neural Network (CNN) to make location estimates from the RSS feature data. An Anderson-Darling test showed that these CNN estimates were statistically indistinguishable from those of a normal distribution. The spatial trilateration estimates were clustered to identify six of the eight TPMS transmitters with a 75% cluster detection rate, which was the result of every statistically different spatial and RSS population as determined by a Kruskal-Wallis (KW) test. The source transmitter of every signal was classified with a 76.4% indicator variable accuracy (93.7% when removing statistically identical RSS populations) and the detected source transmitters were localized with an average of 1.72 m variance and 1.19 m bias within a roughly 15 m square whose perimeter is made up of receivers.

Design and implementation of a low cost experimental testbed for wireless sensor networks

As wireless sensor networks (WSNs) become essential part of modern day infrastructure, researchers have presented loads of algorithms and models aimed at optimizing several aspects of the technology. These models are often developed and analyzed in simulated environments. The obvious need to experiment and confirm the actual performance of these algorithms and models on the field or in a more realistic environment is hampered in many cases by the high cost of advanced sensor node available in the market. This study therefore presents an inexpensive WSN test bed designed and constructed from an ESP8266EX Wi-Fi module. An experiment was conducted and results revealed that ESP8266EX based sensor nodes have a wider network coverage compared to the Arduino sensors based test bed. The proposed test bed was used to compare the performances in terms of power management of two WSN routing algorithms; normal Low Energy Adaptive Clustering Hierarchy (LEACH) and Cluster Head Assisted Routing (CHAR). Results show that the rate at which batteries depleted in LEACH and CHAR are 50% and 10% respectively; and this indicates that batteries depleted faster in LEACH than CHAR; therefore it can be stated that there is an improvement in energy conservation in CHAR over LEACH. It was also observed that CHAR produced a more even and gradual battery depletion rate leading to a longer network life of 20 rounds more than normal LEACH. http://dx.doi.org/10.4314/njt.v37i1.30

A WSN Testbed for Teaching Purposes

A WSN (Wireless Sensor Network) testbed or remote laboratory is a WSN deployed in a controlled environment that allows users to perform experiments remotely. Users can remotely access the WSN to configure and program the nodes, and retrieve the results produced by the experiments. There are a large number of WSN testbeds intended for scientific research, but have not been implemented WSN testbeds for teaching objectives. Testbeds for teaching aims have different requirements with respect to testbeds for scientific research. In this paper, a WSN testbed oriented to teaching objetives is proposed, aimed at students with low WSN and programming knowledge.

Interval type 2 fuzzy localization for wireless sensor networks

Indoor localization in wireless sensor networks (WSN) is a challenging process. This paper proposes a new approach to solve the localization problematic. A fuzzy linguistic localization scheme is proposed. Based on interval type 2 fuzzy logic (IT2FL), a signal processing of the radio signal strength indicator (RSSI) minimizes the uncertainty in RSSI measurements from anchors caused by the indoor obstacles. The fuzzy system subdivides the map on fuzzy sets described by a new fuzzy location indicator (FLI). Fluctuations on RSS fingerprints are then reduced thanks to the IT2FL in the input side and the FLI in the output side. Experimentations were done in the Cynapsys indoor environment on a WSN test bed. The experimental results prove higher success rate in position estimations thanks to the FLI concept and the superiority of interval type 2 fuzzy logic to handle signal fluctuations.

A Brief Review of Network and Sensor Virtualization for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) are more vigorously being used with applications relating to the Internet of Things (IoT). They are used for a variety of applications, but are frequently deployed keeping in view a specific objective. Sensor network virtualization may be classified as network and sensor virtualization. Virtualization comes with numerous challenges in the form of segregating various networks, hardware and associated software in the system. This research paper touches upon the past and current research directions associated with virtualization, various design targets, layouts and numerous testbeds have also been looked into. The paper also highlights the current challenges and future avenues associated to expedite research on virtualization. Keywords: Internet of things (IoT), Network virtualization, Sensor virtualization, Virtualization, Wireless sensor network (WSN), WSN testbeds.

Wireless sensor network based monitoring system for a large-scale indoor space: data process and supply air allocation optimization

Wireless sensor network (WSN) for building applications has been considered by many HVAC experts as an efficient tool to promote building energy efficiency and indoor thermal comfort. This paper, therefore, proposes a strategy of using WSN to monitor the temperature distribution in a large-scale indoor space, which aims to (i) improve the quality of the measurements transmitted by wireless signals, (ii) identify the temperature distribution pattern of the large-scale space, and (iii) optimize the allocation of supply air rated flow rate to multiple supply air terminals that serve the space according to the identified temperature distribution pattern. The developed strategy is illustrated by applying it to a real WSN test bed, installed in a typical large-scale space in Hong Kong. Results are presented and discussed, which shows that the phenomenon of temperature uneven distribution was commonly existent in a large-scale space and the developed strategy was able to efficiently improve the quality of measurements by WSN and improve the temperature homogeneity in the large-scale space.

Experimental Research Testbeds for Large-Scale WSNs: A Survey from the Architectural Perspective

Wireless sensor networks (WSNs) have a significant potential in diverse applications. In contrast to WSNs in a small-scale setting, the real-world adoption of large-scale WSNs is quite slow particularly due to the lack of robustness of protocols at all levels. Upon the demanding need for their experimental verification and evaluation, researchers have developed numerous WSN testbeds. While each individual WSN testbed contributes to the progress with its own unique innovation, still a missing element is an analysis on the overall system architecture and methodologies that can lead to systematic advances. This paper seeks to provide a framework to reason about the evolving WSN testbeds from the architectural perspective. We define three core requirements for WSN testbeds, which are scalability, flexibility, and efficiency. Then, we establish a taxonomy of WSN testbeds that represents the architectural design space by a hierarchy of design domains and associated design approaches. Through a comprehensive literature survey of existing prominent WSN testbeds, we examine their best practices for each design approach in our taxonomy. Finally, we qualitatively evaluate WSN testbeds for their responsiveness to the aforementioned core requirements by assessing the influence by each design approach on the core requirements and suggest future directions of research.

Find the Weakest Link: Statistical Analysis on Wireless Sensor Network Link-Quality Metrics

Routing protocol plays an important role in data communication. A wireless sensor network (WSN) is usually deployed in scenarios where efficient and energy-aware routing protocols are desired. In wireless sensors, the radio-frequency (RF) modules consume most of the energy. Routing metrics are important in determining paths and maintaining the quality of service in routing protocols. The most efficient metrics need to send packets to maintain link-quality measurement using the RF module. In this article, two prominent link-quality metrics-received signal strength indication (RSSI) and link-quality indication (LQI)-are introduced; the symmetry of RSSI and LQI in two directions has been studied, and relations between the expected transmission count (ETX), RSSI, and LQI as link-quality metrics have been analyzed. The evaluation in this article is based on a series of WSN test beds in real scenarios. The collected data from the test beds show symmetry in the RSSI in both directions as well as a significant correlation between the RSSI and distance, making RSSI a suitable link-quality metric for use in routing protocols for devices that work in limited-resources scenarios.

CMKMS

Purpose – The paper aims to address wireless sensor network (WSN) security by proposing new cluster-based mobile key management scheme (CMKMS). The growing demands of WSNs in variety of real-time and mission-critical applications increase the challenges in terms of energy efficiency, security and mobility. The security is important to avoid malicious attacks and improve the energy efficiency, while mobility helps to improve the reachability of network. The CMKMS algorithm focuses on the management and maintenance of keys under cluster-based mobile WSN network. Design/methodology/approach – The paper studied the related work in the area of key management and compared the different key management algorithms according to the technique used. The comparative study shows that the available key management algorithms are efficient in terms of security, but they are not scaleable enough to the changing conditions of network and do not work efficiently under node mobility. The research uses cluster-based approach for improving scalability, where cluster head (CH) acts as a key manager. The work developed by considering both static and mobile CH. Findings – The CMKMS considers two phases, first for key maintenance which establishes the two private keys, home key for own cluster and foreign key when node moves from one cluster to another. The second phase maintains the keys when CH moves from one cluster to another. The proposed algorithm improves the efficiency of key management algorithm in terms of security, mobility, energy efficiency and scalability of network. The simulation of scheme in different realistic situation shows that proposed solution shows less computational overheads, energy consumption and delay as compared with state-of-art solution. Research limitations/implications – The research is validated using computer-based simulation, which limits the testing of research by considering external environmental conditions. Therefore, research can be further test using WSN test bed. Practical implications – The research address the issues in key management, developed the scaleable, and node mobility supportable key management algorithms, for addressing the demands of growing WSN applications. Originality/value – This paper accomplish the security of WSN using scaleable and mobility-supported key management algorithms.

Wireless Sensor Networks Testbeds and State-of-the-Art Multimedia Sensor Nodes

In recent years, Wireless Sensor Networks (WSNs) attracted researchers' attention. This has led to advancements made in both hardware design and software components. The research at the hardware level has resulted in a variant of WSN called Wireless Multimedia Sensor Networks (WMSNs). WSNs have application in battlefields, industrial process monitoring, and environmental monitoring, to name but a few. Furthermore, WMSNs have the potential for real-time object detection and recognition. It can be used to locate misplaced items, assisted living, helping people with cognitive impairme nts, species detection, and providing real-time images for many other surveillance-based applications. Thus, such networks need to operate in a diverse environment. Researchers invariably test their designed algorithms and protocols using simulation tools. Simulators do not accurately model the environment in which such networks are deployed. Therefore, there exists many WSNs and WMSNs testbeds. These testbeds enable researchers and programmers to validate the performance of their algorithms and protocols on a physical network. In this paper, we provide a detailed description of various state-of-the-art WSN testbeds. We have evaluated these state-of-the-art testbeds on a set of metrics. Furthermore, we survey the state-of-the-art in wireless multimedia sensor nodes hardware along with their eminent features.

WSN4QoL: A WSN-Oriented Healthcare System Architecture

People worldwide are getting older and this fact has pushed the need for designing new, more pervasive, and possibly cost effective healthcare systems. In this field, distributed and networked embedded systems, such as wireless sensor networks (WSNs), are the most appealing technology to achieve continuous monitoring of aged people for their own safety, without affecting their daily activities. This paper proposes recent advancements in this field by introducing WSN4QoL, a Marie Curie project which involves academic and industrial partners from three EU countries. The project aims to propose new WSN-based technologies to meet the specific requirements of pervasive healthcare applications. In particular, in this paper, the system architecture is presented to cope with the challenges imposed by the specific application scenario. This includes a network coding (NC) mechanism and a distributed localization solution that have been implemented on WSN testbeds to achieve efficiency in the communications and to enable indoor people tracking. Preliminary results in a real environment show good system performance that meet our expectations.

A Survey on Testbeds and Experimentation Environments for Wireless Sensor Networks

Research results in wireless sensor networks are primarily gained from simulations and theoretical considerations. Currently, the community begins to realize that the results need to be validated in testbeds. Testbeds can be also used to directly gather knowledge with sensor network experiments on real hardware and a real environmental context. This survey gives an overview of different approaches to build testbeds and experimentation environments regarding different research foci. We discuss emerging testbed requirements and present existing solutions of the community. The overview is complemented with a discussion of common design decisions concerning architectures and experimentation support in current testbeds. A look on future trends and developments in wireless sensor network testbeds concludes this paper. This survey is intended to help researchers to attain own results in real-world experiments with wireless sensor networks. The reader gains a comprehensive overview on existing testbeds and practical knowledge documented in the referenced literature. The survey is laying the foundation for design decisions while developing an own testbed using the examples of described approaches.

User and Machine Authentication and Authorization Infrastructure for Distributed Wireless Sensor Network Testbeds

The intention of an authentication and authorization infrastructure (AAI) is to simplify and unify access to different web resources. With a single login, a user can access web applications at multiple organizations. The Shibboleth authentication and authorization infrastructure is a standards-based, open source software package for web single sign-on (SSO) across or within organizational boundaries. It allows service providers to make fine-grained authorization decisions for individual access of protected online resources. The Shibboleth system is a widely used AAI, but only supports protection of browser-based web resources. We have implemented a Shibboleth AAI extension to protect web services using Simple Object Access Protocol (SOAP). Besides user authentication for browser-based web resources, this extension also provides user and machine authentication for web service-based resources. Although implemented for a Shibboleth AAI, the architecture can be easily adapted to other AAIs.

Wavelet-based Burst Event Detection and Localization in Water Distribution Systems

In this paper we present techniques for detecting and locating transient pipe burst events in water distribution systems. The proposed method uses multiscale wavelet analysis of high rate pressure data recorded to detect transient events. Both wavelet coefficients and Lipschitz exponents provide additional information about the nature of the signal feature detected and can be used for feature classification. A local search method is proposed to estimate accurately the arrival time of the pressure transient associated with a pipe burst event. We also propose a graph-based localization algorithm which uses the arrival times of the pressure transient at different measurement points within the water distribution system to determine the actual location (or source) of the pipe burst. The detection and localization performance of these algorithms is validated through leak-off experiments performed on the WaterWiSe@SG wireless sensor network test bed, deployed on the drinking water distribution system in Singapore. Based on these experiments, the average localization error is 37.5 m. We also present a systematic analysis of the sources of localization error and show that even with significant errors in wave speed estimation and time synchronization the localization error is around 56 m.

NetEye: a user‐centered wireless sensor network testbed for high‐fidelity, robust experimentation

SUMMARYExperimentation infrastructures for wireless sensor networks (WSNs) have been widely adopted over the past decade for high‐fidelity validation and rapid prototyping of applications and for discovering and modeling phenomena that have led to improvements in analysis and simulation capabilities. Nonetheless, the community is still looking for more heterogeneous WSN testbeds for purposes such as federation, experiment regression analysis, and improved testbed availability. In addition, most existing WSN testbeds lack robustness and predictability in the presence of failures, and they do not provide user‐friendly support for scientific experimentation (e.g., quick repetition of experiments). We develop the NetEye testbed as a high‐fidelity, robust WSN experimentation infrastructure that provides the ease of scientific experimentation. Consisting of 130 TelosB motes with IEEE 802.15.4 radios and 15 Linux laptops with IEEE 802.11a/b/g radios, NetEye provides a WSN deployment that enables high‐fidelity experimentation with single‐hop as well as multihop WSN networking, and the lab‐scale deployment mimics network properties of building‐scale and outdoor WSN deployments. Building upon the authors’ experience in developing and using WSN testbeds in the past years, NetEye also has enhanced features that enables easy, robust scientific experimentation. In particular, NetEye provides users with a simple, powerful web portal, which streamlines users’ experience in the whole lifecycle of scientific experimentation (e.g., experiment scheduling, status monitoring, and data exfiltration). NetEye employs a stable, fault‐tolerant state machine to improve the robustness of the testbed in the presence of failures. NetEye also develops a health monitoring service NetEye Doctor that monitors hardware and software status; the real‐time health monitoring information about the testbed is seamlessly integrated with the lifecycle of experiment scheduling, experiment status monitoring, and experiment data analysis for both robust experimentation and for informed experiment analysis. To address the log‐data congestion problem in long‐running, large scale experiments, NetEye employs a TDMA (Time Division Multiple Access) mechanism to ensure reliability in exfiltrating experiment data to users. To facilitate quick, repetitive scientific experimentation, NetEye also speeds up the mote programming cycle through fast job status transition and multi‐thread‐based mote programming. NetEye has been successfully running for over 3.5 years, and it has been integrated with the federated WSN experimental infrastructure KanseiGenie. NetEye is widely used by researchers from USA and Asia, and more than 10 experiments are executed through NetEye per day on average. Copyright © 2012 John Wiley & Sons, Ltd.

Development of a Testbed for Wireless Underground Sensor Networks

Wireless Underground Sensor Networks (WUSNs) constitute one of the promising application areas of the recently developed wireless sensor networking techniques. WUSN is a specialized kind of Wireless Sensor Network (WSN) that mainly focuses on the use of sensors that communicate through soil. Recent models for the wireless underground communication channel are proposed but few field experiments were realized to verify the accuracy of the models. The realization of field WUSN experiments proved to be extremely complex and time-consuming in comparison with the traditional wireless environment. To the best of our knowledge, this is the first work that proposes guidelines for the development of an outdoor WUSN testbed with the goals of improving the accuracy and reducing of time for WUSN experiments. Although the work mainly aims WUSNs, many of the presented practices can also be applied to generic WSN testbeds.

A Secure Remote Authentication, Operation and Management Infrastructure for Distributed Wireless Sensor Network Testbeds

In this paper we propose an infrastructure for a secure remote authentica- tion, management and operation system for a distributed global wireless sensor net- work testbed. We base the design of the architecture on an existing well-established, widely deployed and frequently used authentication and authorization system devel- oped to simplify inter-organizational access to web-resources. The proposed infras- tructure addresses the main challenges of a interconnected distributed sensor net- work testbed, such as secure remote availability, multi-user access, confidentiality and integrity. The paper further describes our perspective of a testbed workflow management and operation system aiming to provide a simple and comprehensive interface for remote wireless sensor network configuration and experimentation.

Chowkidar

Wireless sensor network (WSN) testbeds are useful because they provide a way to test applications in an environment that makes it easy to deploy experiments, configure them statically or dynamically, and gather performance information. However, WSNs are typically composed of low-cost devices and tend to be unreliable, with failures a common phenomenon. Accurate knowledge of network health status, including nodes and links of each type, is critical for correctly configuring applications on WSN testbeds and for interpreting the data collected from them. In this article we present a stabilizing protocol, Chowkidar, that provides accurate and efficient network health monitoring in WSNs. Our approach adapts the well-known problem of message-passing rooted spanning tree construction and its use in propagation of information with feedback (PIF) for the case of a WSN. The Chowkidar protocol is initiated upon demand; that is, it does not involve ongoing maintenance, and it terminates with accurate results, including detection of failure and restart during the monitoring process. Chowkidar is distinguished from others in two important ways. Given the resource constraints of WSNs, it is message-efficient in that it uses only a few messages per node. Also, it tolerates ongoing node and link failure and node restart, in contrast to requiring that faults stop during convergence. We have implemented the Chowkidar protocol as part of enabling a network health status service that is tightly integrated with a remotely accessible wireless sensor network testbed, Kansei, at The Ohio State University. We present experimental results from this testbed that validate the correctness and performance of Chowkidar. We also report on initial experiences and lessons learnt from the integration of Chowkidar with Kansei, including feedback from both testbed users and administrators who have found Chowkidar to be a useful tool for improving the accuracy and efficiency of testbed experimentation and maintenance, and the need for well-defined policies to address issues such as minimizing interference with concurrently running experiments. Finally, we discuss extensions that enhance the functionality and usability of Chowkidar.