The development of intelligent Industrial Internet of Things (IIoT) systems promises to revolutionize operational and maintenance practices, driving improvements in operational efficiency. Anomaly detection within IIoT architectures plays a crucial role in preventive maintenance and spotting irregularities in industrial components. However, due to limited message and processing capacity, traditional Machine Learning (ML) faces challenges in deploying anomaly detection models in resource-constrained environments like LoRaWAN. On the other hand, Federated Learning (FL) solves this problem by enabling distributed model training, addressing privacy concerns, and minimizing data transmission. This study explores using FL for anomaly detection in industrial and civil construction machinery architectures that use IIoT prototypes with LoRaWAN communication. The process leverages an optimized autoencoder neural network structure and compares federated models with centralized ones. Despite uneven data distribution among machine clients, FL demonstrates effectiveness, with a mean F1 score (of 94.77), accuracy (of 92.30), TNR (of 90.65), and TPR (92.93), comparable to centralized models, considering airtime of Trainning messages of 52.8 min. Local model evaluations on each machine highlight adaptability. At the same time, the performed analysis identifies message requirements, minimum training hours, and optimal round/epoch configurations for FL in LoRaWAN, guiding future implementations in constrained industrial environments.

The evolution of the Internet of Things (IoT), progressing from a hyper-connected world of seamless device interaction to a paradigm that emphasizes the human factor as a central component, is driven by approaches like human-in-the-loop IoT (HITL-IoT). This shift enables the development of innovative systems in various environments. For example, in the context of a smart city, which comprises diverse solutions aimed at enhancing citizens’ quality of life and urban service efficiency, HITL-IoT approaches are employed to promote sustainability. Given the strong human involvement in these systems, challenges related to personal data protection, transparency, and participation must be addressed. Additionally, ensuring interoperability among different smart city entities is crucial for the coexistence and synergy of these solutions. This article presents a model that incorporates contemporary technologies like Blockchain and LoRa to integrate citizen-centric IoT privacy preservation solutions, fostering the vision of smart and sustainable cities. To demonstrate the feasibility of the proposed model, a prototype was designed, implemented, and deployed in a realistic scenario. Assessment results include metrics, such as latency, throughput, and communication aspects of the components.

New concepts based on the Internet of Things propose the integration of the human factor as a key component of novel interconnected ecosystems, to offer them new services and features. However, the data acquisition process, carried out by the devices that allow the deployment of these new paradigms, leads to concerns about what kind of information these entities are able to collect and/or infer. In fact, in most cases, users are not aware that their information is being gathered, nor can they properly control these data flows. Nowadays, the European Union’s General Data Protection Regulation calls for the adoption of transparent practices comprising, inter alia, adequate notification mechanisms, proper consent management schemes, and the development of models to empower the user as an active participant, with full control over the data flows, along with privacy preservation techniques. In this specific context, the aim of this manuscript is to present a review of existing user-centric privacy preservation models. This is, as far as we know, one of the few papers that addresses this particular privacy preserving dimension within an IoT context. Finally, the paper identifies and summarizes open issues, including a discussion of research opportunities in this area.

Citizens are a crucial factor in the sustainability of the cities because they are one of the pillars for balancing their environment. Smart city projects can offer citizens an opportunity to understand how they contribute to their city’s sustainability. Furthermore, an interactive smart city system can create synergies that benefit both the citizens and the city itself. This paper presents the Green Bear smart city platform, an IoT Human-in-the-Loop system that uses LoRaWAN nodes to gather information on city green spaces, bike lanes, and recycling depots. A user-centered mobile application that allows for active user participation, feedback, and incentivization is used to close the loop with humans. This system allows citizens to evaluate their participation in aspects that improve the city’s sustainability through a gamification scheme, obtaining points for different activities in the city’s public spaces and personal activities to improve their quality of life. This solution is being implemented in the city of Coimbra, Portugal. After an overview of the system, the paper describes each main system module. The Green Bear prototype was subject to functional and technological assessment, and the results are presented and discussed.

While the traditional Internet of Things (IoT) relies on electronic sensors/actuators, today's IoT involves a variety of sensors, comprising not only physical, electronic-based devices but also virtual and even human social sensors/actuators. In this context, how can we efficiently and effectively manage different types of IoT data sources? In this article, we propose a solution to manage different types of sensors/actuators and analyze which management protocols are best in terms of performance. The proposal is based on open and broadly adopted technologies in IoT, with emphasis on the FIWARE middleware. We showed that the management of the heterogeneity of the sensing/actuating IoT devices is feasible, by presenting functionalities related to real use cases. We took advantage of the implemented prototype to compare the performances of lightweight machine to machine (LwM2M) and ultralight device management services in FIWARE. In addition to demonstrating the viability of the proposed approach, the obtained results point to mixed advantages/disadvantages of one protocol over the other.

The last decade has witnessed a paradigm change in Industrial Control Systems (ICS), from closed, isolated systems to fully-connected, Internet-capable systems. At the same time, new wireless technologies, mainly coming from the Internet of Things domain, emerged. IEEE 802.15.4 wireless-based standards like WirelessHART, ISA100.11a, ZigBee, and WIA-PA are increasingly used for monitoring industrial processes. Nevertheless, along with this paradigm change, some new threats appeared that menace current industrial infrastructures and economies (e.g., Stuxnet, Mariposa, Slammer). Additionally, in order to keep up with the requirements of new Industry 4.0 applications, sensor nodes software and hardware are becoming more complex and, thus, more prone to faults. In this paper, using a monitoring architecture proposed in our previous work, we injected and subsequently proceeded to detect representative firmware and hardware anomalies (namely, buffer overflow attacks, SPI faults, under-voltage, and high temperature faults) that can be used by attackers to cause major losses or even damage industrial control systems. We evaluated the performance of several machine learning techniques commonly used to detect anomalies (i.e. OCSVM, kNN, AutoEnconder), in order to determine if they could be useful to detect such faults. The obtained results demonstrate that simple and broad scope classifiers, using features that consume little resources, can be developed to detect such faults.

Industrial Control Systems are now exploring the use of Internet of Things technologies not only to make them fitter to their job but also to explore the advantages that come from connecting them to the Internet. Nevertheless, with this paradigm shift, new threats appear, of which the stuxnet worm is just an example, and Intrusion Detection Systems architectures and solutions were and still are being considered. However, most existing projects concentrate on high level system aspects and thus neglect security aspects at wireless communication standards level, such as WirelessHART (the standard with largest market share), choosing not to address security solutions to common, known attacks identified by the community. In this paper, using a monitoring architecture proposed in our previous work, we will monitor a WirelessHART testbed, and at the same time, conduct network attacks from an outsider perspective. As main contributions this paper presents a new exhaustion attack for WirelessHART that, until now, to the best of our knowledge, has not been yet described. Additionally, the presented work proves that using classifiers like One Class Support Vector Machines (OSVM), and our monitoring architecture we are capable to detect the new exhaustion attack and more common attacks like jamming and collision.

Use of wireless sensor networks (WSNs) in conjunction with mobile devices is growing on a daily basis. Mobile phones are not only personal devices that provide communication services, but also versatile and resourceful elements in the Internet of Things (IoT). Nevertheless, despite the referred growth, one key aspect for real-world IoT deployments is still largely overlooked: reliability. In this respect, there is a clear gap between theoretical models and real implementations, as no practical reliability mechanisms are in place for IoT. Proposing, studying, and providing IoT reliability solutions is, thus, fundamental for the massive deployment of IoT technology across all sectors of society. In this context, the main purpose of this paper is to propose, explore, and assess reliability mechanisms for IoT scenarios, based on the use of redundant routes and devices that take advantage of mobile devices, as key elements of IoT. These mechanisms were evaluated in a variety of failure scenarios, both theoretically and through implementations constructed with real, off-the-shelf equipment, showing their good capability to maintain effective communication even in the presence of link failures.

Cloud computing has been pointed out as one of the pillars of the Internet of Things, providing this emerging infrastructure with unlimited resources and easing its deployment. However, cloud computing relies on remote, mainly centralized resource provisioning, which poses substantial problems in the support of time-critical and location-aware IoT applications. Fog computing, on the other hand, recently emerged as an intermediate solution to solve the mentioned cloud computing limitations, but its embryonic status still prevents it from being used in real developments. In this paper we present a fog computing characterization and assess the feasibility of its use in a worst-case scenario, which we name opportunistic fog network. Subsequently, as a first step towards its effective use and deployment in an IoT scenario, we propose a fog computing network architecture, constituted by virtual clusters running on peer-to-peer overlays, capable of abstracting the complexity of lower layers. Opportunistic fog computing can benefit from thousands of end-devices moving in urban areas everyday, providing connectivity and processing resources to every crowded spot, and promoting green computing by allowing a more efficient local resource usage and by decreasing remote communications to the cloud. Furthermore, opportunistic fog computing overcomes cloud computing drawbacks whenever a set of independent and heterogeneous end-devices agree to share their own resources.

Welcome to Coimbra—home to the oldest university in Portugal and one of the oldest in the world, dating back from 1290—and welcome to the IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WoWMoM), the intellectual hub and melting pot of ideas from researchers and practitioners interested in all aspects of wireless, mobile, and multimedia pervasive communications. Sponsored by the IEEE Computer Society and its Technical Committee on Computer Communications (TCCC), and co-sponsored by Missouri University of Science and Technology and the University of Coimbra, the 17th WoWMoM is held in Coimbra, Portugal, in the iconic Quinta das Lágrimas Hotel. During its history, the reputation of WoWMoM has rapidly grown and it has become one of the premier conferences in the field of wireless, mobile, and multimedia networking.

Over the last years, Wireless Sensor Networks (WSN) went from being a promising technology for countless industrial applications to a de facto technology used in todays' applications. WSNs have been gaining momentum over costly wired technologies, offering low installation costs, self-organization, and added functionality. As a consequence of their enormous potential, WSNs were subject to standardization and some industrial standards and open source solutions like WirelessHART, Zigbee, ISA100, IEEE802.15.4 and OpenWSN were announced. However, despite considerable efforts to provide mechanisms that increase the availability, reliability, security and maintainability of this type of networks, WSNs have kept one of their main characteristics: fault-proneness. As a result, the offer of post-deployment diagnostic tools has been increasing in the last decade in order to diagnose WSN failures as soon as possible. Nevertheless, current WSN diagnostic tools still have many limitations and cannot be considered “ready to use” in real-world scenarios. In this paper we present an autonomous diagnostic tool that addresses these limitations in a real industrial Internet of Things (IIoT) scenario. Our tool is based on simple metrics, a logging tool, a data-mining algorithm, and available network metrics, and it monitors the condition of the sensor nodes firmware, hardware and the network itself. The proposed demonstration was tested and validated using the WirelessHART IIoT standard.

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.

This paper presents a performance evaluation in the context of the Aggregation Service (AgS). The AgS is a P2P overlay-tier whose purpose is to aggregate the services and service components maintained by service providers in a P2P Service Overlay Network (SON). The performance evaluation takes into account two metrics: (1) the average path length, and (2) the response time. Both of them are used in the comparison of two environments: (1) AgS and (2) a P2P SON without AgS. Additionally, the searching performance in the environment with AgS is compared with a P2P SON that uses Gnutella as the searching mechanism. The simulation results clearly show an improvement in the performance of the search operations when the AgS is used to the detriment of the searches performed without it. The results also show AgS is better suited for use in small overlays.

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.

This paper presents a mechanism to improve the efficiency of service searching in large-scale multi-domain environments composed of service providers organized in a P2P Service Overlay Network (SON). This mechanism relies on a P2P overlay-tier whose purpose is to aggregate the services and service components maintained by service providers in the P2P SON. We name this mechanism Aggregation Service (AgS). It comprises the service and service components publishing and allows the separation between the service providers and the search schema. The average search path length was used as metric for the AgS assessment through simulation. The simulation results clearly show an improvement in search operations when the proposed Aggregation Service is used, when compared to searches performed without it.

Wireless sensor networks are low cost networks constituted by modest devices with limited resources, whose main function is monitoring. Based on the low price of these devices, it will be cheap to deploy a large amount of nodes to monitor a large area. However, to provide an efficient ad hoc network using these limited devices, new and optimized algorithms should be proposed. Most of the current work about WSNs are based on simulation studies and do not take in consideration engineering processes. This paper presents a multi-sink node alternative to multi-hop solutions. The proposed solution also provides a new system for the discovery of devices and services over IPv6, allowing nodes to be automatically incorporated in the nearest WSN. This paper also presents a paradigm to efficiently provide mobility, granting a fast handover of nodes between different WSNs, without loosing the connection.

Ubiquitous broadband Internet access is an important requirement to satisfy user demands and support a new set of real time services and applications. IEEE 802.16, as a broadband wireless access technology, can significantly contribute in this area. It is able to provide high throughput over large distances, with intrinsic QoS support, in line-of-Sight and Non- line-of-Sight environments. This paper discusses a network architecture, based on IEEE 802.16 d compliant equipments, which is able to support real-time services with QoS integration through dynamic configuration of the 802.16 channel, using the NSIS framework. Tests have been carried out to evaluate the QoS performance of the defined architecture, demonstrating that it is perfectly capable of handling and supporting real time services, using dynamic configuration of the 802.16 channel, without introducing an excessive cost in the network.

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.

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.

Multihoming smart routing plays a significant role in improving the performance of Internet access of IP network customers through dynamic path switching. On the other hand, inter-domain traffic engineering becomes indispensable for IP network providers, in order for them to meet their traffic objectives. Unfortunately, this ability of both parties to choose their own routing policies does not necessary lead to the best routing in the Internet. A major challenge of the research on traffic engineering and Internet routing architectures is to accommodate this tussle. However, little is known about the interactions between Inter-domain smart routing and traffic engineering. In this paper, we analyse such interactions through intuitive descriptions and a simulation model. In our evaluations, we observed that the overall stability can benefit from combining Inter-domain adaptive smart routing and traffic engineering. However, we also observed that the effectiveness of Inter-domain traffic engineering can be negatively affected by interdomain routing changes performed by smart routing.

In this paper we describe a Java middleware, the SENSACT API, which enables the construction - and connection through a Bluetooth network - of a network of sensors and actuators for the purpose of enabling its use in mobile pervasive augmented reality games. The system enables sensors and actuators to be deployed and subsequently connected to a central coordinating device, the game device, that has a compatible middleware API, the Status Transmission Framework Version 2.0 PAN API. The presented middleware package was subject to functional as well as performance tests using Sun Microsystems Java Wireless Toolkit 2.3 Beta version, which showed that the proposed API is adequate for small sensor/actuator networks.

In this paper we present results from an experimental study addressing the use of mobile agents in the retrieval of management information. We compare several agent-based models for distributed collection and processing of management data, focusing on performance but also considering network traffic and setup costs. This study reveals that in many situations the performance of mobile agent systems is mainly determined by distribution, rather than locality. Furthermore, it shows that despite its importance in the flexibility and adaptability of the management system, agent mobility does not increase the system performance.

At the Communications and Telematics Laboratory of the University of Coimbra is being developed a router prototype with the aim to provide QoS to different traffic classes. One of the most important mechanisms of this router is the IP packet scheduler. It is well known that the common scheduling discipline of current routers (first come first serve) makes them useless when QoS is needed-a different type of scheduler must be used. Our first idea to overcome this problem was to use a simple, open, and available scheduler, easy to adapt to the system we wanted to implement. We thought of the WFQ discipline, and, as we are using a testbed of Intel machines running FreeBSD OS, we admitted that the WFQ/ALTQ implementation would be an interesting choice. Nevertheless, a broad set of tests carried out at our laboratory proved the contrary. Most important, these tests guided us to a deep knowledge of the problems, and causes, that can weaken the effectiveness of IP schedulers. Given the importance of that surplus information, we decided to implement our own scheduler. The idea was to take advantage of a pragmatic view of scheduling activities to construct a scheduler with the best possible characteristics (but also very simple) able to reach very good performance levels. This paper presents the scheduler that resulted from our attempts. The proposed scheduler was subject to a set of tests that proved its ability to effectively differentiate traffic classes. The results of these tests are also presented and analyzed.

This paper presents a study carried out on a weighted fair queuing implementation for Unix routers-the WFQ implementation of the ALTQ project. It shows the WFQ/ALTQ weaknesses and explains why we cannot expect an interesting behavior from a system using such a scheduler. The conclusions here presented are supported by a set of tests using UDP traffic only. With a tool developed in our laboratory, we were able to show that changing the classes' weights does not necessarily result on a different quality of service for each of the existing classes. To achieve this differentiation, the lengths of the queues which serve the scheduler (one for each class) must be increased beyond reasonable values. We found that the low-level dynamics of FreeBSD systems practically turns WFQ schedulers useless. The same is applicable to any other work-conserving discipline. Thus, an important conclusion of this paper, is that one must design very carefully the platforms that support work conserving disciplines in order to expect adequate behaviors from those systems, in terms of QoS provision.

The article proposes and evaluates some extensions to the CORBA event service, based on the use of the light-weight reliable multicast protocol (LRMP). These extensions address some limitations of the CORBA Event Service, namely multicasting, reliability and total ordering. The extensions were developed and tested in a prototype environment created for this purpose, and are transparent and fully compatible with the standard OMG event service, enabling the user to decide on the use of standard IIOP or IP multicasting.