One of the major challenges in the use of Radio Frequency Identification (RFID) on a large scale is the ability to read a large number of tags quickly. Central to solving this problem is resolving collisions that occur when multiple tags reply to the query of a reader. To this purpose several MAC protocols for passive RFID systems have been proposed. These typically build on traditional MAC schemes such as aloha and tree based protocols. Our objective is to design novel anticollision schemes able to fast identify large number of tags. We have designed protocols that overcome the limits of current solutions, proposing schemes for tag population estimation and identification. We have also proposed schemes which exploit interference cancellation for fast tag identification. We are working on solutions for mobile RFID systems. We have developed a simulator for RFID protocols, and performed experiments on performance of current RFID systems. Part of this work is performed within the Artemis CHIRON project, and in collaboration with Prof. Tom La Porta (Penn State University).
By exploiting novel HW concepts and HW/SW cross optimizations, we are developing solutions for a new generation of sensor nodes equipped with radio triggering circuits and multi-source energy harvesting. Collectively, these new technologies have the potential to change the time horizon for WSNs autonomous operations, posing the basis for energy neutral systems.
We have designed and developed solutions for structural health monitoring, mechanisms for energy prediction and management, protocols for harvesting-aware resource allocation, and harvesting-aware schemes that enable robust and reliable security support. We have also developed GreenCastalia, an open-source energy-harvesting simulation framework that allows to simulate networks of embedded devices with heterogeneous harvesting capabilities.
Underwater safe oil and gas extraction and distribution, monitoring of underwater CO2 storage infrastructures, monitoring and control of marine life, marine archaeological site monitoring, tsunami and seaquake early warning systems, border control are examples of emerging which demand for new technologies to perform pervasive real life monitoring and control of underwater areas and of underwater critical infrastructures. SENSES lab is very actively involved in the emerging field of underwater sensor networks and underwater monitoring systems. We have developed a framework for accurate simulation, emulation and test at sea of solutions for underwater acoustic communications. The developed framework has been ported on embedded devices and is combined with an architectural principle which allows to easily equip with communications capabilities a variety of platforms (buoys, underwater nodes, AUVs and mobile platforms), and to easily integrate to the nodes different sensors. Communications is performed according to different protocol stacks (including MAC and routing protocols, for underwater multi-hop communications, as well as cross layer solutions) we have developed. The group has also developed analytical frameworks and scheduling solutions for underwater sensor networks.
In this activity, we develop adaptive algorithms and protocols for Cognitive Radio Networks (CRNs). Particularly, we focus on Opportunistic Spectrum Access (OSA) techniques and optimal, integrated, cross-layer protocol designs for Cognitive Radio Ad-Hoc Networks (CRAHNs) and Wireless Sensor Networks (WSNs). As a subsystem of the cognitive radio paradigm, we consider the Wireless Spectrum Sensor Network (WSSN). Such network, not nececessarily physically separated from the CRN, provides the necessary support to perform the cooperative sensing operations which enable the implementation of the OSA approach. Our work jointly addresses the design of CRN protocols and of the WSSN signalling protocols. Within this activity we have developed a flexible simulation framework based on NS2 Miracle. Our framework takes into account physical layer aspects, such as the use of multiple frequencies and the simulation of fading effects, that are not accurately modelled by most of the existing network simulators. Our target applications include CRAHNs coexisting with traditional cellular networks operating on licensed bands as well as sensor networks coexisting with WLANs in unlicensed bands. This activity has been partially funded by the 7th Framework Programme european project ICT-SENDORA.
Application scenarios for wireless sensor networks (WSNs) and body area networks (BANs) are extremely diverse and heterogeneous, ranging from smart environment to perimeter sensing, to weather and ambient control, to healthcare, to military applications, and so on. The same diversity is valid for Underwater Acoustic Sensor Networks (UASNs), which are becoming the key enabler for a large set of application scenarios ranging from scientific exploration and commercial exploitation, to homeland security.
With so much diversity, a one-size-fits-all general design paradigm for security appears far from being effective, if even possible. Thus, our focus is on the development of new security solutions specifically tailored for BANs, WSNs and UASNs. We have developed standard based end-to-end security protocols for the IoT, context-aware decentralized Data Access control for GREEn WSNs, protection mechanims against Denial-of-Sleep attacks for Wake-up-enabled networks, security frameworks and reputation based routing protocols for UASNs.
Optimization of sensor networks performance through sink mobility
This activity stems from the observation nodes around the sink tend to transmit/receive more packets, fast deploying their available energy and isolating the sink from the rest of the network. A way to load balance energy consumption among the network nodes is via relay or sinks mobility. The activity carried out has resulted in scalable models which output sojourn times of the sink at different sites, as well as the sink movement which maximize the network lifetime. Both the single sink and the multi-sink cases have been considered. Distributed solutions which achieve performance close to the optimum have also been designed.
Design of complete, cross-layer optimized protocol stacks for terrestrial wireless sensor networks.
Three different stacks have been designed, evaluated, implemented and tested: ROME, ALBA-R and IRIS. They do not require any knowledge of the neighborhood of a node, do not require exchange of information between pairs of neighboring devices unless there is the need to transmit data traffic.
ROME is a geographic routing protocol for wireless sensor networks (WSNs) with mobile nodes. ROME design is suited to deal with communication problems in WSN scenarios with high network dynamics, such as nodal addition, nodal removal and node mobility. In addition, it retains desirable properties of protocols for static WSNs such as using cross-layer techniques for performance optimization, dealing with asynchronous nodal duty cycles, and being able to deal with connectivity dead ends.
ALBA-R is a solution for convergecasting in wireless sensor networks. ALBA-R features the crosslayer integration of geographic routing with contention-based MAC for relay selection and load balancing (ALBA) as well as a mechanism to detect and route around connectivity holes (Rainbow). ALBA and Rainbow (ALBA-R) together solve the problem of routing around a dead end without needing high-overhead techniques such as graph planarization and face routing. The protocol is fully localized and distributed, is highly adaptive to variations in traffic and to different node deployments.
IRIS is a cross-layer protocol for WSNs that integrates different desirable features: awake/asleep scheduling, interest dissemination, cross layer convergecasting, data fusion, adaptive duty cycle and estimation of the number of neighbors of each sensor node. IRISI TinyOS implementation will be made available soon.
We have also developed robust, energy-efficient interest dissemination schemes. Fireworks exploits topology graph properties to perform reliable probabilistic flooding.
Design of schemes for backbone formation in ad hoc and wireless sensor networks
The activity has focused on 1) comparing major solutions so far proposed identifying which features or approaches are required for realistic deployments. A simulation framework has been developed to perform such evaluation and has been made available to the scientific community (see sw and test-bed section of these pages); 2) designing improved solutions for backbone formation. Activities have in particular focused on the design of schemes which are resilient to nodes failures and that lead to low overhead and fast backbone reorganization.
Development of tools for managing a wireless sensor networks test-bed
Tools have been developed to monitor the performance of indoor, cabled test-beds, as well as for monitoring the performance of real-life test-beds.
We have developed a Wireless Sensor Network Test-bed Management System, called JAMES (JAva test-bed ManagEment System). JAMES is a complete system to remotely manage a pool of federated test-beds, schedule tests, gather and analyze results, supporting fair comparative performance evaluation of different protocols and of a protocol in various settings.
Implementation of schemes for enabling communications in personal area networks. In particular schemes for scatternet formation, intra e inter-piconet scheduling, for routing in a personal area network have been designed and integrated in a complete protocol stack, evaluating the end to end system performance. Activities have also been devoted to porting solutions for PANs in commercial devices, identifying limits of several implementations of the standard in commercial devices (which result in degraded performance). A Bluetooth ns2 extension have been developed by the group, Bluebrick.