Riccardo Tomasi

The VIRTUS Middleware: An XMPP Based Architecture for Secure IoT Communications

Before a wider adoption of the Internet of Things (IoT) vision occurs, many urgent technological and social challenging issues still need to be addressed, including device interoperability, systems autonomy, privacy and security concerns, which could have a significant impact on several aspects of everyday-life or potential end-user. Due to the very large number of technologies normally in place within the IoT paradigm, some type of middleware layer is employed to enforce seamless integration of devices and data within the same information network. Within such middleware, data must be exchanged respecting strict protection constraints. Both the networking and security issues have driven the design and the development of the VIRTUS Middleware, an IoT middleware relying on the open XMPP protocol to provide secure event- driven communications within an IoT scenario. Leveraging the standard security features provided by XMPP, the middleware offers a reliable and secure communication channel for distributed applications, protected with both authentication (through TLS protocol) and encryption (SASL protocol) mechanisms. The proposed architecture provides the possibility to isolate an instance of VIRTUS, allowing the exchange of data only within a private network. This paper presents an overview of VIRTUS, providing an overall platform description and details regarding its security features.

Event-Driven User-Centric Middleware for Energy-Efficient Buildings and Public Spaces

In this paper, the design of an event-driven user-centric middleware for monitoring and managing energy consumption in public buildings and spaces is presented. The main purpose is to increase energy efficiency in buildings and public spaces, thus reducing consumption. To achieve this, the proposed service-oriented middleware has been designed to be event based, also exploiting the user behavior patterns of people who live and work in buildings. Furthermore, it allows an easy integration of heterogeneous technologies in order to enable a hardware-independent interoperability between them. Moreover, a heating ventilation and air conditioning (HVAC) control strategy has been developed, and the whole infrastructure has been deployed in a real-world case study consisting of a historical building. Finally, the results will be presented and discussed.

Hybrid WSN and RFID indoor positioning and tracking system

Wireless sensor networks (WSNs), consisting of a large number of nodes to detect ambient environment, are widely deployed in a predefined area to provide more sophisticated sensing, communication, and processing capabilities, especially concerning the maintenance when hundreds or thousands of nodes are required to be deployed over wide areas at the same time. Radio frequency identification (RFID) technology, by reading the low-cost passive tags installed on objects or people, has been widely adopted in the tracing and tracking industry and can support an accurate positioning within a limited distance. Joint utilization of WSN and RFID technologies is attracting increasing attention within the Internet of Things (IoT) community, due to the potential of providing pervasive context-aware applications with advantages from both fields. WSN-RFID convergence is considered especially promising in context-aware systems with indoor positioning capabilities, where data from deployed WSN and RFID systems can be opportunistically exploited to refine and enhance the collected data with position information. In this papera, we design and evaluate a hybrid system which combines WSN and RFID technologies to provide an indoor positioning service with the capability of feeding position information into a general-purpose IoT environment. Performance of the proposed system is evaluated by means of simulations and a small-scale experimental set-up. The performed analysis demonstrates that the joint use of heterogeneous technologies can increase the robustness and the accuracy of the indoor positioning systems.

Bringing the Internet of Things along the manufacturing line: A case study in controlling industrial robot and monitoring energy consumption remotely

The Internet of Things (IoT) concept attracts considerable interest from the academia and industry. This paper provides a set of proof-of-concept prototype descriptions, based on such IoT exploitation, which aim at gathering real-time data along the manufacturing processes that enables a responsive production management and maintenance, including energy consumption and water usage monitoring at each stage of a production cycle. The presented work takes advantage of the ebbits platform, which provides a middleware infrastructure for integrating industrial sensors, devices and emerging wireless technology in the physical world, transforming them into web services that enable seamless integration into mainstream business system such as MES and ERP.

Frequency agility in IPv6-Based wireless personal area networks (6LoWPAN)

This paper presents a demonstrator of a multi-hop 6LoWPAN provided with frequency-agility extensions. A reference architecture is presented along with the basic components introduced to build a distributed spectrum sensing and interference resolution service in a multi-hop environment. Moreover, a frequency-agility management plane is proposed for the 6LoWPAN communication stack. The proposed solution is implemented in a small-scale network adopting TinyOS and an open-source implementation of 6LoWPAN protocol stack. The resulting demonstrator proves the capability of the proposed system to characterize the spectrum occupancy state in a multi-hop environment. In addition, it shows the ability of the network to reallocate to the best available channel in case a critical level of interference is detected on the current operating channel.

Distributed spectrum sensing and channel selection in opportunistic wireless personal area networks

This demonstrator showcases a distributed spectrum sensing and channel selection service running on a small-scale IEEE 802.15.4 opportunistic WPAN network. This service can provide spectrum awareness to the network itself or to other co-located networks. In case an interfering signal is detected the network devices are able to identify less used spectrum portions such that the network can reallocate to the best available channel. The channel occupancy can be observed in real-time via a graphical user interface.

On spectrum sensing duration in cognitive wireless sensor networks

Frequency agility is considered as an indispensable feature of next-generation wireless sensor networks (WSNs), which will have to cope with highly interfered environments due to the increasing diffusion of wireless devices operating in unlicensed bands. In this paper we investigate some design aspects related to spectrum sensing in “cognitive” WSNs, relating the duration of sensing time to the probability of error in channel selection and analyzing the tradeoff between sensing duration and average throughput. Results are based on a realistic model, consistent with previous experimental works and existing testbeds.

Leveraging BIM Interoperability for UWB-Based WSN Planning

Wireless sensor networks (WSNs) are a key part of the Internet of Things vision which aims at bridging together the physical and the digital worlds in several application domains. In the building automation field, WSNs are widely adopted for energy optimization, safety and security purposes, and could greatly benefit from existing information already available in preexisting building information models (BIMs). Such BIMs are normally developed during the building design phase and reused continuously during the construction and operation phases of the building life-cycle. In current deployments, however, due to lack of interoperability such information (e.g., walls geometry, materials, and so on) must often be recollected and reinputed by WSN commissioning specialists. Open development and planning tools and methodologies can play a key role in fostering interoperability and convergence of BIM and WSN systems. This paper aims at demonstrating how increased interoperability between WSN development-support tools and BIM systems could provide advantages to developers, integrators, domain specialist, and BIM users. The methodology is validated by applying a newly proposed tool exploiting BIM interoperability to support the planning of the topology of a WSN based on ultrawideband technologies. The proposed approach is evaluated through a small-scale experimentation held in a historical building in Torino (Italy).

Leveraging Social System Networks in Ubiquitous High-Data-Rate Health Systems

Social system networks with high data rates and limited storage will discard data if the system cannot connect and upload the data to a central server. We address the challenge of limited storage capacity in mobile health systems during network partitions with a heuristic that achieves efficiency in storage capacity by modifying the granularity of the medical data during long intercontact periods. Patterns in the connectivity, reception rate, distance, and location are extracted from the social system network and leveraged in the global algorithm and online heuristic. In the global algorithm, the stochastic nature of the data is modeled with maximum likelihood estimation based on the distribution of the reception rates. In the online heuristic, the correlation between system position and the reception rate is combined with patterns in human mobility to estimate the intracontact and intercontact time. The online heuristic performs well with a low data loss of 2.1%-6.1%.

Hy-Sim: model based hybrid simulation framework for WSN application development

Bridging the physical world with the virtual one often broadens the possibilities of accelerating and easing embedded system design. This is even more true for WSNs, where generally the developed applications need to be tested and executed in hundreds to thousands of nodes. Often times, it is hard to manage test beds that have huge number of nodes. The most common solution is to rely on simulation frameworks that allow the developers to create virtual sensor nodes and then provides levels of abstraction to specify the applications which will be executed on the nodes. The foremost drawback of this kind of simulation is the absence of direct interfaces with the physical environment. Hence in this paper we propose a hybrid simulation framework for WSN application development that interconnects a virtual network with the physical network and then allows one to simulate the networks as a whole. Moreover, the developers model WSN applications by using high level abstractions which could be used for multi-platform automatic code generation (in TinyOS and Ember ZigBee platforms).