Jorge Sá Silva

An energy-efficient ant-based routing algorithm for wireless sensor networks

Wireless Sensor Networks are characterized by having specific requirements such as limited energy availability, low memory and reduced processing power. On the other hand, these networks have enormous potential applicability, e.g., habitat monitoring, medical care, military surveillance or traffic control. Many protocols have been developed for Wireless Sensor Networks that try to overcome the constraints that characterize this type of networks. Ant-based routing protocols can add a significant contribution to assist in the maximisation of the network lifetime, but this is only possible by means of an adaptable and balanced algorithm that takes into account the Wireless Sensor Networks main restrictions. This paper presents a new Wireless Sensor Network routing protocol, which is based on the Ant Colony Optimization metaheuristic. The protocol was studied by simulation for several Wireless Sensor Network scenarios and the results clearly show that it minimises communication load and maximises energy savings.

Security for the Internet of Things: A Survey of Existing Protocols and Open Research Issues

The Internet of Things (IoT) introduces a vision of a future Internet where users, computing systems, and everyday objects possessing sensing and actuating capabilities cooperate with unprecedented convenience and economical benefits. As with the current Internet architecture, IP-based communication protocols will play a key role in enabling the ubiquitous connectivity of devices in the context of IoT applications. Such communication technologies are being developed in line with the constraints of the sensing platforms likely to be employed by IoT applications, forming a communications stack able to provide the required power-efficiency, reliability, and Internet connectivity. As security will be a fundamental enabling factor of most IoT applications, mechanisms must also be designed to protect communications enabled by such technologies. This survey analyzes existing protocols and mechanisms to secure communications in the IoT, as well as open research issues. We analyze how existing approaches ensure fundamental security requirements and protect communications on the IoT, together with the open challenges and strategies for future research work in the area. This is, as far as our knowledge goes, the first survey with such goals.

The GINSENG system for wireless monitoring and control: Design and deployment experiences

Todays industrial facilities, such as oil refineries, chemical plants, and factories, rely on wired sensor systems to monitor and control the production processes. The deployment and maintenance of such cabled systems is expensive and inflexible. It is, therefore, desirable to replace or augment these systems using wireless technology, which requires us to overcome significant technical challenges. Process automation and control applications are mission-critical and require timely and reliable data delivery, which is difficult to provide in industrial environments with harsh radio environments. In this article, we present the GINSENG system which implements performance control to allow us to use wireless sensor networks for mission-critical applications in industrial environments. GINSENG is a complete system solution that comprises on-node system software, network protocols, and back-end systems with sophisticated data processing capability. GINSENG assumes that a deployment can be carefully planned. A TDMA-based MAC protocol, tailored to the deployment environment, is employed to provide reliable and timely data delivery. Performance debugging components are used to unintrusively monitor the system performance and identify problems as they occur. The article reports on a real-world deployment of GINSENG in an especially challenging environment of an operational oil refinery in Sines, Portugal. We provide experimental results from this deployment and share the experiences gained. These results demonstate the use of GINSENG for sensing and actuation and allow an assessment of its ability to operate within the required performance bounds. We also identify shortcomings that manifested during the evaluation phase, thus giving a useful perspective on the challenges that have to be overcome in these harsh application settings.

Mobility in Wireless Sensor Networks — Survey and Proposal

Abstract Targeting an increasing number of potential application domains, wireless sensor networks (WSN) have been the subject of intense research, in an attempt to optimize their performance while guaranteeing reliability in highly demanding scenarios. However, hardware constraints have limited their application, and real deployments have demonstrated that WSNs have difficulties in coping with complex communication tasks – such as mobility – in addition to application-related tasks. Mobility support in WSNs is crucial for a very high percentage of application scenarios and, most notably, for the Internet of Things. It is, thus, important to know the existing solutions for mobility in WSNs, identifying their main characteristics and limitations. With this in mind, we firstly present a survey of models for mobility support in WSNs. We then present the Network of Proxies (NoP) assisted mobility proposal, which relieves resource-constrained WSN nodes from the heavy procedures inherent to mobility management. The presented proposal was implemented and evaluated in a real platform, demonstrating not only its advantages over conventional solutions, but also its very good performance in the simultaneous handling of several mobile nodes, leading to high handoff success rate and low handoff time.

A Survey on Human-in-the-Loop Applications Towards an Internet of All

Our tools and appliances are becoming increasingly more intelligent and interconnected, giving birth to an “Internet of Things” that can be used to support new types of cyber-physical systems (CPSs). While many CPSs are human-centric applications where humans are an essential part of the system, unfortunately, most of these systems still consider the human as an external and unpredictable element to the control loop. In order for these systems to better serve human needs, future CPSs will need to bolster a closer tie with the human element, through Human-in-the-Loop controls that take into consideration human intents, psychological states, emotions and actions inferred through sensory data. This area is a natural confluence of multidisciplinary focus but currently lacks a general understanding of the underlying requirements, principles and theory. As far as we know, this survey is the first effort towards extending the fields knowledge through an in-depth research of the state-of-the-art and a critical overview of the current taxonomic efforts in the area of Human-in-the-Loop CPSs. On top of this research, a novel taxonomic exercise focused on the general roles of the human component together with a requirement analysis, are presented.

Security in the integration of low-power Wireless Sensor Networks with the Internet

The integration of low-power wireless sensing and actuating devices with the Internet will provide an important contribution to the formation of a global communications architecture encompassing Wireless Sensor Networks (WSN), and to enable applications using such devices designed to bring unprecedented convenience and economical benefits to our life. Such applications also take place in the context of our current vision on an Internet of Things (IoT), which promises to encompass heterogeneous devices and communication technologies, including WSN. Due to the characteristics of the devices in WSN and to the requirements of applications, low-power wireless communications are employed and the functionalities supported must be carefully balanced against the limited resources at the disposal of applications. Low-power communication technologies are also currently being designed with the purpose of supporting the integration of WSN with the Internet and, as in isolated WSN environments, security will be a fundamental enabling factor of future applications using Internet-integrated WSN. Although various surveys currently exist addressing security mechanisms for WSN environments, our goal is to analyze how security may be addressed as an enabling factor of the integration of low-power WSN with the Internet, in the context of its contribution to the IoT. We analyze the current research and industry proposals supporting this integration, together with the security solutions and mechanisms designed in its context. Our discussion is supported by an analysis on the attack and threat model against Internet-integrated WSN, and on the security requirements to consider in this context. We believe that a survey with such goals may provide an important contribution to readers interested in embracing this important area of research and ours is, as far as our knowledge goes, the first article with such goals.

A proposal for proxy-based mobility in WSNs

Inability to meet the key requirement of efficient mobility support is becoming a major impairment of wireless sensor network (WSN). Many critical WSN applications need not only reliability, but also the ability to adequately cope with the movement of nodes between different sub-networks. Despite the work of IETFs 6lowPAN WG and work on the use of MIPv6 (and many of its variants) in WSNs, no practical mobility support solution exists for this type of networks. In this paper we start by assessing the use of MIPv6 in WSNs, considering soft and hard handoff, showing that, although feasible in small networks, MIPv6 complexity leads to long handoff time and high energy consumption. In order to solve these problems, we propose a proxy-based mobility approach which, by relieving resource-constrained sensor nodes from heavy mobility management tasks, drastically reduces time and energy expenditure during handoff. The evaluation of both MIPv6 and the proposed solution is done by implementation and simulation, with a varying number of nodes, sinks and mobility strategies.

Robust dynamic user authentication scheme for wireless sensor networks

In recent years, wireless sensor networks (WSNs) have been widely used in different domains. For instance, WSNs can be deployed in insecure and unattended environments. In this regard, user authentication is a critical issue for WSNs. In this paper, we propose a user authentication protocol in WSNs, which is variation of strong-password based solution proposed by Wong et al. The proposed protocol is evaluated and compared with the previous schemes.

Mobility in WSNs for critical applications

Recent critical application sectors of sensor networks like military, health care, and industry require the use of mobile sensor nodes, something that poses unique challenges in aspects like handoff delay, packet loss, and reliability. In this paper we propose a novel mobility model that handles those challenges effectively by providing on-time mobility detection and handoff triggering. In that way soft handoffs and controlled disconnections are assured. The proposed solution uses cross-layer information from the MAC and Network layers. Our solution was implemented and evaluated in an experimental testbed, in the context of the European FP7 GINSENG project.

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.