André Rodrigues

Diagnostic Tools for Wireless Sensor Networks: A Comparative Survey

The availability of tools to diagnose Wireless Sensor Network (WSN) failures is a key success factor for this type of networks as already demonstrated by several long-running deployments. By nature, WSNs are resource-constrained, fragile, complex to analyse, and failure-prone. Naturally, with the growing number of installations, it is becoming fundamental to efficiently diagnose failures as soon as possible, in order to deal with the underlying causes. In accordance with this, from 2005 onwards, the offer of diagnostic tools has been increasing, as the other base technologies (e.g. networking, operating system, localisation, synchronisation) become reasonably stable. The purpose of this survey is to provide an overview of existing post-deployment WSN diagnostic tools, by briefly presenting their functionality, architecture and constraints, in order to enable a basic understating of each tool. The survey also includes a multi-dimensional comparative analysis of the various tools, based on a proposed classification scheme and evaluation criteria, as well as an identification of the main open research issues. Although the number of diagnostic tools is high and considerable work has been done in this area, we conclude that there are still several challenges concerning post-deployment WSN diagnostic tools, regarding scope, flexibility, generality, mobility and security. Moreover, there is a need for mature, native diagnostic-oriented functionality in WSN platforms and operating systems.

Mobility management in IP-based Wireless Sensor Networks

Mobility is one of the most important issues in next generation networks. As wireless sensor networks are becoming the next elements of the future Internet, it is crucial to study new models that also support mobility of these nodes. This paper presents and studies three paradigms to support mobility in sensor nodes. This study is supported by prototyping. As a result a set of proposals are proposed and discussed. The work presented in this paper proposes the use of IP in wireless sensor networks as a unifying protocol and it is in compliance with the IETF 6LowPAN group.

Multicast in Wireless Sensor Networks The next step

Multicast potentially optimises bandwidth consumption and node resources, when several users simultaneously participate in a communication session. Nevertheless, contrary to the expectations, IP multicast has not experienced widespread deployment, with the exception of IPTV. On the other hand, emerging wireless sensor network (WSN) applications could greatly benefit from multicast and constitute another field where multicast can be an effective and efficient technique. The question is: do multicast advantages hold in WSN scenarios? This paper discusses and evaluates the use of multicast in wireless sensor networks. A WSN platform with IP support and multicast is being developed. Concurrently, simulation studies were performed in order to assess the usefulness of multicast in WSNs. The results clearly point to the benefits of the use of this technique in processing and energy-restricted environments such as this one

A Taxonomy of Faults for Wireless Sensor Networks

Over the last decade, Wireless Sensor Networks (WSN) went from being a promising technology to the main enabler of countless Internet of Things applications in all types of areas. In industry, WSNs are now used for monitoring and controlling industrial processes, with the benefits of low installation costs, self-organization, self-configuration, and added functionality. Nevertheless, despite the fact that base WSN technologies are quite stable and subject to standardization, they have kept one of their main characteristics: fault-proneness. As a result, in recent years considerable effort has been made in order to provide mechanisms that increase the availability, reliability and maintainability of this type of networks. In this context, a whole range of techniques such as fault detection, fault identification and fault diagnosis used in other research fields are now being applied to WSNs. Unfortunately, this has not led to a consistent, comprehensive WSN fault taxonomy that can be used to characterize and/or classify faults. Neglecting the importance of WSN fault characterization (e.g., when using supervised algorithms for anomaly detection) may lead to bad classifiers and, consequently, bad fault handling procedures and/or tools. In this paper, we start by reviewing base fault management concepts and techniques that can be applied to WSNs. We then proceed to propose and present a comprehensive WSN fault taxonomy that can be used not only in general purpose WSNs but also in Industrial WSNs. Finally, the proposed taxonomy is validated by applying it to an extensive set of faults described in the literature.

iSenior—A Support System for Elderly Citizens

Health and safety monitoring of elderly citizens are key to the improvement of their quality of life, by enabling them to be more independent. This was the general motivation for developing the iSenior system presented in this paper. iSenior is a wireless embedded system solution for people living in rest homes that retain their mobility and, thus, move around the facilities and can even go outside. iSenior is a cyber-physical system solution that currently supports a set of functions like monitoring, alerting, and requesting assistance. The system has been implemented and is under field evaluation in a real world deployment. The aim of this paper is to provide information on the main features of the system, including architecture, implementation details, and performance evaluation.

Hermes: A versatile platform for wireless embedded systems

This paper presents Hermes, a new modular platform that can be used in a variety of scenarios, including the role of body area network coordinator, enabling temperature, movement and heartbeat sensing, local and remote communication, and indoor and outdoor localization. Hermes is based on two main modules that can operate as a single system in a coordinated fashion or individually, depending on the application scenario. One of the modules uses a Telos-inspired architecture, with new processing, communication, sensing, storage and energy subsystems, and executing TinyOS. The other module is designed around a PIC 24F MCU, also supporting communication, sensing, storage, and executing a custom operating system. Both modules have expansion capabilities. The main innovative aspects of the implemented platform are its modularity and its capability to provide device abstraction, which considerably eases application development. The paper addresses the platform motivation, requirements, hardware architecture, implementation details, and performance evaluation.

An Automated Application-Independent Approach to Anomaly Detection in Wireless Sensor Networks

As Wireless Sensor Networks (WSN) gain momentum in what concerns applications and deployment, monitoring is becoming crucial in order to guarantee that anomalies are promptly detected. Unfortunately, current WSN monitoring solutions have several limitations, such as being tailored for specific applications, requiring dedicated or specific hardware, consuming precious energy and/or processing resources, or relying on manual or offline intervention. In this paper we propose an approach to anomaly detection in WSNs that addresses these limitations. The approach is based on two very simple metrics, a logging tool, and a data-mining algorithm, thus leading to the following key characteristics: very low resource consumption, application independency, very good potential for multi-WSN monitoring, and automation and simplification of the detection process. The proposed approach was validated by implementation, which showed that it is quite effective in detecting several typical anomalies.

iHorse — A WSN-based equine monitoring system

Horses played a key role in the history of mankind, having been instrumental in the rise and fall of great empires. In modern days, they are still very important assets, from economical, operational or even sentimental points of view. Their importance is, thus, the main motivation for developing the iHorse equine monitoring system presented in this paper. iHorse is a deployed, fully-operational, commercially-available, wireless-sensor-network-based system and application, developed and tested over a three-year period. The aim of this paper is to provide information on the main features of the system, including its architecture, implementation details and performance data. The paper also discusses the lessons learnt throughout the system development and deployment phases.

FoTSeC — Human Security in Fog of Things

Today’s devices, which make up the Internet of Things (IoT) and Cyber-Physical Systems (CPS), are becoming increasingly more heterogeneous, mobile and intelligent. They represent an untapped computational resource that is available on site. By taking advantage of these devices we reduce the need for distant service providers: direct communication with neighbour devices becomes key for handling local tasks and information. Thus, the traditional cloud is “descending” to the network edge and becoming “diffused” among the client devices in both mobile and wired networks. Since single individuals are now becoming walking sensor networks, with many types of devices (smart-shirts, smartphones, smart glasses, smart watches…), human behavior begins to have a significant impact on the availability of resources. This means that security risks rise tremendously in these distributed clouds.The objective of this paper is to present an analysis of security in the future Internet - an Internet that integrates the concepts of Fog of Things (FoT) and Human in the Loop (HiTL). This paper also describes our model and the platform that we implemented for the evaluation tests.

A connection-mode network service relay functional specification

Functional standardization activities in ISO and in regional workshops are currently addressing end-system profiles and network layer relay profiles for the interconnection of several types of subnetworks. In order to achieve end-system interconnectivity, connection-mode network layer relays appear as one of the key pieces of the Open Systems Interconnection puzzle. In this paper the authors present a connection-mode relay functional specification being input to the European Workshop for Open Systems, discuss the relevant profile options, and identify some issues that will require future attention and discussion.