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    Gaia Maselli

    This paper presents our experiences in developing and evaluating a low cost videogame controller that exploits RFID backscattering for battery-free operation. Specifically, we develop a system to gather data from a paper-made device,... more
    This paper presents our experiences in developing and evaluating a low cost videogame controller that exploits RFID backscattering for battery-free operation. Specifically, we develop a system to gather data from a paper-made device, named JoyPaper, while it interacts with a videogame console. JoyPaper is home-made device that can be built by everyone and enables consumers to playing at every moment without caring about power charging: the device is ready to work as soon as the console is on. Our experiments show that JoyPaper's performance is comparable to that of a commercial controller in terms of latency and it is able to transfer up to 1 kbps.
    Fast and reliable identification of Radio Frequency Indentification (RFID) tags by means of anticollision (MAC) protocols has been a problem of substantial interest for more than a decade. However, improvements in identification rate have... more
    Fast and reliable identification of Radio Frequency Indentification (RFID) tags by means of anticollision (MAC) protocols has been a problem of substantial interest for more than a decade. However, improvements in identification rate have been slow, as most solutions rely on sequential approaches that try to avoid collisions, which have limited margin for performance improvement. Recently, there has been growing interest in concurrent techniques that exploit the structure of collisions to recover tag IDs. While these techniques promise substantial improvements in speed, a key question that remains unaddressed is how to deal with noise or interference that might introduce errors in the recovery process at the reader. Our goal in this paper is to consider a noisy wireless channel and add robustness to concurrent RFID identification techniques. We propose a new protocol, called CIRF (Concurrent Identification of RFids), which uses multiple antennas to add robustness to noise and levera...
    The emerging demand for smart building systems has significantly stimulated the research on management platforms for sensor and actuator networks. In the last few years, several solutions have been proposed for this kind of networks,... more
    The emerging demand for smart building systems has significantly stimulated the research on management platforms for sensor and actuator networks. In the last few years, several solutions have been proposed for this kind of networks, spanning from research to commercial systems. However, single devices operate based on proprietary protocols, making interoperability a significant issue. To achieve a thorough understanding of the performance of these systems in field experiments are needed. This paper proposes SMARTEEX, a software tool to test smart building solutions. SMARTEEX is the first proposal that provides a virtual network to test different architectures for smart environments, running experiments with real and/or simulated smart devices. Our performance evaluation demonstrates that using SMARTEEX it is possible to compare for example a cloud-based with an SDN-based architecture.
    In developing countries, crop field productivity is particularly vulnerable to spreading diseases, including viruses and fungi. This is mostly due to the lack of skilled plant pathologists as well as to the scarce fund and poor... more
    In developing countries, crop field productivity is particularly vulnerable to spreading diseases, including viruses and fungi. This is mostly due to the lack of skilled plant pathologists as well as to the scarce fund and poor infrastructure (e.g., roads, power and water lines) availability. The PlantVillage project through its mobile application named Nuru provides an AI digital assistant to recognize plants and their diseases through image analysis. Through the use of Nuru endowed smartphones, farmers can participate in a mobile crowd-sensing framework to improve their crop production. The crowd sensing framework also contributes to early detection of the outbreak of spreading diseases across geographical regions, and consequent adoption of appropriate countermeasures to ensure food security. As devices are often granted in a limited number by countries' government or charities, we propose a Farmer to Farmer (F2F) cooperation to achieve the required Quality of Information (QoI) for the system. In particular, only a selected crew of farmers receive smartphones to monitor their own farm as well as some other farmers' one. We formulate two variants of the problem of mobile device deployment and task assignment and propose related solutions. We evaluate the proposed approaches through simulations and apply them to a test-bed in Kenya.
    Libro di testo per corso di Reti di Elaboratori per laurea in Informatica e Ingegneria Informatic
    We expose a new security leak for smartphone users, which allows to stole user personal data by accessing the mobile operator user page when auto-login is employed. We show how any "apparently" genuine app can steal these data... more
    We expose a new security leak for smartphone users, which allows to stole user personal data by accessing the mobile operator user page when auto-login is employed. We show how any "apparently" genuine app can steal these data from some mobile operators, affecting more than 80% of Italian mobile smartphones.
    Recent years have witnessed the design and development of several smart devices that are wireless and battery-less. These devices exploit RFID backscattering-based computation and transmissions. Although singular devices can operate... more
    Recent years have witnessed the design and development of several smart devices that are wireless and battery-less. These devices exploit RFID backscattering-based computation and transmissions. Although singular devices can operate efficiently, their coexistence needs to be controlled, as they have widely varying communication requirements, depending on their interaction with the environment. The design of efficient communication protocols able to dynamically adapt to current device operation is quite a new problem that the existing work cannot solve well. In this article, we propose a new communication protocol, called ReLEDF, that dynamically discovers devices in smart buildings and their active and nonactive status and when active their current communication behavior (through a learning-based mechanism) and schedules transmission slots (through an Earliest Deadline First-- (EDF) based mechanism) adapt to different data transmission requirements. Combining learning and scheduling...
    Has now become more important than ever to guarantee an always present connectivity to users, especially in emergency scenarios. However, in case of a disaster, network infrastructures are often damaged, with consequent connectivity... more
    Has now become more important than ever to guarantee an always present connectivity to users, especially in emergency scenarios. However, in case of a disaster, network infrastructures are often damaged, with consequent connectivity disruption, isolating users when are more in need for information and help. Drones may supply with a recovery network, thanks to their capabilities to provide network connectivity on the fly. However, users typically need special devices or applications to reach these networks, reducing their applicability and adoption. To tackle this problem we present DANGER, a framework able to create a mesh network of drones, which can be reached by any WiFi smartphone. DANGER is highly flexible and does not require any special application: all connected devices can chat, with voice and videos, through a simple web-application. The DANGER network is completely distributed, can work even partitioned or in case of drones failures.
    The fast and unconstrained mobility of Flying Ad-hoc NETworks (FANETs) brings about the need to develop solutions for packet routing in a highly dynamic topology scenario. Previous works in this direction aim at extending protocols... more
    The fast and unconstrained mobility of Flying Ad-hoc NETworks (FANETs) brings about the need to develop solutions for packet routing in a highly dynamic topology scenario. Previous works in this direction aim at extending protocols designed for Mobile Ad-hoc NETworks (MANETs) to the more challenging domain of FANETs. Unlike previous approaches, we aim at exploiting the device controllable mobility to facilitate network routing. We propose MAD (Movement Assisted Delivery): a packet routing protocol specifically tailored for networks of aerial vehicles. MAD enables adaptive selection of the most suitable relay nodes for packet delivery, resorting to movement-assisted delivery upon need, which is supported by a reinforcement learning approach. By means of extensive simulations we show that MAD outperforms previous solutions in all the considered performance metrics including average packet delay, delivery ratio, and communication overhead, at the expense of a moderate loss in average device availability.
    In the latest years, there has been a growing interest in autonomous drone delivery. This is due to the increasing demand for efficient delivery services, and to the concurrent inability of existing ground based systems to provide... more
    In the latest years, there has been a growing interest in autonomous drone delivery. This is due to the increasing demand for efficient delivery services, and to the concurrent inability of existing ground based systems to provide guaranteed availability, and delivery time. However, the cost for implementing a centralized drone-based delivery service can only be afforded by large commercial organizations. To face this issue we propose Druber, a fully distributed service based on a fleet of coordinated drones, belonging to multiple owners. With Druber, delivery of a parcel is provided by several drones, with intermediate pit stops for battery replacement or drone-to-drone parcel handovers. The use of a federated approach eliminates the need of a single company investment and guarantees a quickly deployable, highly scalable, and inexpensive architecture. Nevertheless, it introduces a problem of trust: can users rely on private drone owners? To guarantee a trustable service Druber leverages blockchain features to develop and control the entire delivery chain. Our evaluation shows an impressive advantage of our platform with respect to existing ground based services in terms of service cost and parcel delivery time, at the expense of a negligible delay for the management of blockchain operations.
    Fleets of cooperative drones are a powerful tool in monitoring critical scenarios requiring early anomaly discovery and intervention. Due to limited energy availability and application requirements, drones may visit target points in... more
    Fleets of cooperative drones are a powerful tool in monitoring critical scenarios requiring early anomaly discovery and intervention. Due to limited energy availability and application requirements, drones may visit target points in consecutive trips, with recharging and data offloading in between. To capture timeliness of intervention and prioritize early coverage, we propose the new notion of Weighted Progressive Coverage, which is based on the definition of time dependent weights. Weighted progressive coverage generalizes classic notions of coverage, as well as a new notion of accumulative coverage specifically designed to address trip scheduling. We show that weighted progressive coverage maximization is NP-hard and propose an efficient polynomial algorithm, called Greedy and Prune (GaP), with guaranteed approximation. By means of simulations we show that GaP performs close to the optimal solution and outperforms a previous approach in all the considered performance metrics, including coverage, average inspection delay, energy consumption, and computation time, in a wide range of application scenarios. Through prototype experiments we also confirm the theoretical and simulation analysis, and demonstrate the applicability of our algorithm in real scenarios.
    Although smart environments are a key component of the Internet of Things (IoT), it is also clear that billions connected doors, washing machines, ovens and others will ultimately raise security and privacy concerns. Early work in this... more
    Although smart environments are a key component of the Internet of Things (IoT), it is also clear that billions connected doors, washing machines, ovens and others will ultimately raise security and privacy concerns. Early work in this area, as well as most of commercial solutions, has adopted a centralized client/server approach, neglecting the multitude of risks that are induced by an unfair control of the server side. This has made the adoption of a decentralized and trust-less framework quintessential to guarantee devices security. Nevertheless, decentralized proposals are hardly applicable due to costs, slowness and privacy issues. In this paper, we make the use of blockchain practical for smart environments by designing HyBloSE, a secure-by-design and lightweight blockchain-based framework, able to run on low-power devices without additional hardware. HyBloSE is built by using Delegated Proof of Authority and a Moving Window Blockchain. We evaluate HyBloSE through a network emulator and real experiments with different Raspberry Pi platforms. Results show that HyBloSE guarantees a higher security level in terms of resiliency to internal and external attacks compared to centralized solutions, with overhead below 0.38s per operation and less than $4 per month for unlimited operations. Furthermore, we show how Proof of Authority is more adapt then Proof of Work in IoT private scenarios.
    Abstract In this paper we investigate interference cancellation to faster identify tags in RFID networks. We explore how interference cancellation can be applied to ALOHA and tree-based identification schemes, its limitations, the extent... more
    Abstract In this paper we investigate interference cancellation to faster identify tags in RFID networks. We explore how interference cancellation can be applied to ALOHA and tree-based identification schemes, its limitations, the extent of achievable improvements, and ...
    ABSTRACT We consider the problem of efficient tag identification in RFID networks. Among the solutions recently proposed for tag identification, a variant of the framed slotted ALOHA protocol, called tree slotted ALOHA (TSA), has been... more
    ABSTRACT We consider the problem of efficient tag identification in RFID networks. Among the solutions recently proposed for tag identification, a variant of the framed slotted ALOHA protocol, called tree slotted ALOHA (TSA), has been shown to achieve the lowest identification delay and highest time system efficiency. However, in case of a large number of tags, this protocol produces an estimate of the tag population size which still differs from the actual number of tags, and utilizes a non-optimal method for deciding the frame size. In this paper we address the issues of more precise tag number estimation and achieving optimal frame sizing by proposing a new protocol, the binary spitting TSA (BSTSA) protocol. Through thorough NS2-based simulations we show that BSTSA considerably outperforms all previous protocols, achieving 80% time system efficiency vs. the 50% achieved by TSA, and reduces the length of the tag identification process of up to 40% with respect to TSA.
    ABSTRACT We present a distributed, integrated medium access control, scheduling, routing and congestion/rate control protocol stack for Cognitive Radio Ad Hoc Networks (CRAHNs) that dynamically exploits the available spectrum resources... more
    ABSTRACT We present a distributed, integrated medium access control, scheduling, routing and congestion/rate control protocol stack for Cognitive Radio Ad Hoc Networks (CRAHNs) that dynamically exploits the available spectrum resources left unused by primary licensed users, maximizing the throughput of a set of multi-hop flows between peer nodes. Using a Network Utility Maximization (NUM) formulation, we devise a distributed solution consisting of a set of sub-algorithms for the different layers of the protocol stack (MAC, flow scheduling and routing), which result from a natural decomposition of the problem into sub-problems. Specifically, we show that: 1) The NUM optimization problem can be solved via duality theory in a distributed way, and 2) the resulting algorithms can be regarded as the CRAHN protocols. These protocols combine back-pressure scheduling with a CSMA-based random access with exponential backoffs. Our theoretical findings are exploited to provide a practical implementation of our algorithms using a common control channel for node coordination and a wireless spectrum sensor network for spectrum sensing. We evaluate our solutions through ns-2 MIRACLE-based simulations. Our results show that the proposed protocol stack effectively enables multiple flows among cognitive radio nodes to coexist with primary communications. The CRAHN achieves high utilization of the spectrum left unused by the licensed users, while the impact on their communications is limited to an increase of their packet error rate that is below 1%.
    In mobile ad hoc networks, protocols are distributed and rely on the cooperative participation of all nodes in the network. Since the wireless technology implies node resource constraints, it may not be convenient for a node to relay... more
    In mobile ad hoc networks, protocols are distributed and rely on the cooperative participation of all nodes in the network. Since the wireless technology implies node resource constraints, it may not be convenient for a node to relay requests on behalf of others. Also, malicious nodes may intentionally damage network functioning by not cooperating. Thus, cooperative algorithms make the system vulnerable to users as well as to malicious and selfish misbehavior. Lack of cooperation may severely degrade the performance of the ad hoc system; noncooperative nodes may partition the network, and well-behaving nodes can be overburdened by the consequent deviation of most of the traffic on to them, leading to possible congestion events. We address the issues of performance and reliability in packet forwarding. Our approach is based on reliability estimators taking into account not only selfish and malicious misbehavior, but also situations of congestion and lossy links. We aim at increasing network throughput and avoiding unreliable routes, thus increasing network "performability" (performance and reliability).

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