Fernando Boavida

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.

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.

Why is IPSec a viable option for wireless sensor networks

Many issues still remain to be addressed in order to achieve acceptable security in wireless sensor networks (WSNs). This necessity, together with the adoption of IPv6 on WSNs being defined at the 6lowpan working group of the IETF, motivates our investigation on the feasibility of the application of IPSec on sensor nodes. IPSec is already part of IPv6, which makes it a natural candidate to be directly employed or adapted for WSNs. We discuss results obtained from practical experiments on the usage of cryptographic algorithms typically employed within IPSec in real sensor nodes. We analyze the security and performance tradeoffs involved when employing cryptography measures in WSNs, also in the context of their usage side-by-side with IPv6. The results obtained show that the adoption of a security architecture such as IPSec is viable, and also point towards the successful design and deployment of a security architecture for WSNs.

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.

Providing applications with mobile agent technology

Over the last couple of years we have been working on the development of mobile agents systems and their application to the areas of telecommunications and network management. This work has produced positive results: a competitive mobile agent platform was built, the run-time benefits of mobile agents were proved, and our industrial partners have developed practical applications that are being integrated into commercial products. However, despite the positive results, we feel that mobile agent technology is still not ready to enter the path of mainstream software development. In our perspective, one of the main reasons for this situation arises from the traditional approach to mobile agent technology. This approach, based on the familiar concept of the mobile-agent distributed platform as an extension of the operating system, focuses too much on the mobile agents and associated issues (mobility, agent lifecycle, security, coordination, etc.) and provides poor support for the development of applications where mobile agents are just one of several available technologies. Learning from past experience, we are now working on a new approach where the focus is brought back to the applications and mobile agents become just one the tools available to develop distributed systems. This provides a much lighter framework for application-based mobile agent systems. This paper presents the lessons learned from our previous project and discusses the new concept we are developing: application-centric mobile agent systems.

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.

Quality of Experience management framework for real-time multimedia applications

Real-time multimedia will be among the most important applications in next generation networks. However, efficiently managing the delivery of these applications to guarantee Quality of Experience (QoE) to end-users facing network resources limitation and heterogeneity of networks is a challenge. This paper first explores key requirements to provide QoE assurance for multimedia applications in Content Distribution Networks (CDN). A new management framework, named QoE-aware Real-time Multimedia Management (QoE2M), is then introduced to provide end-to-end quality control on real-time multimedia applications over heterogeneous networks based on a combined control of video assessment, Quality of Service (QoS) and QoE-based mapping and adaptation procedures. Validation of the QoE2M framework is also discussed.

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.

6GLAD: IPv6 Global to Link-layer ADdress Translation for 6LoWPAN Overhead Reducing

The next generation of wireless sensor networks will integrate communication systems beyond the third generation paradigm. As a result of this integration, the new communication systems will be fed by the sensor networks with information gathered from the environment, achieving context awareness. To reach the necessary end-to-end connectivity between all-IP networks and sensor networks, the IETF 6LoWPAN working group has designed an IPv6 adaptation layer for low power devices. This protocol stack provides IPv6 interoperability to the sensor networks, thus avoiding as much overhead as possible. This paper analyses and evaluates the associated IP communication overhead in each possible 6LoWPAN scenario, from intra to inter network communication. We conclude that, even the 6LoWPAN offering a light weight IP solution for link local sensor network communication, it has a relatively high overhead when data flows between different networks. In order to avoid the communication overhead when global IPv6 addressing is necessary we propose a new solution based on a 6LoWPAN global-to-link-layer address translation.

Integrating SNMP into a Mobile Agent Infrastructure

Mobile Code is an emerging paradigm that is gaining momentum in several fields of application. Network Management is a potential area for the use of this technology, provided it will be able to interoperate with well established solutions for Network Management. This paper presents the integration a classic NM protocol, like SNMP, into a platform of Mobile Agents. Our platform, called JAMES, has been developed in the context of an Eureka Project (Σ!1921) where the project partners are University of Coimbra, Siemens SA and Siemens AG. Since the main target of the platform is network management, it includes a set of SNMP services allowing mobile agents to easily interface with SNMP agents, as well as with legacy SNMP-based management applications. In the paper we present a brief overview of the general architecture of the platform and we describe in some detail the framework we used to provide for integration between mobile agent applications and SNMP.