Roberto Beraldi

Sapienza University of Rome | la sapienza · Department of Computer, Automatic and Management Engineering "Antonio Ruberti"

Fog Computing is a widely adopted paradigm that allows distributing the computation in a geographic area. This makes it possible to implement time-critical applications and opens the study to a series of solutions that permit smartly organizing the traffic among a set of fog nodes, which constitute the core of the Fog Computing paradigm. As a typic...

Fog and Edge Computing are two paradigms specifically suitable for real-time and time-critical applications, which are usually distributed among a set of nodes that constitutes the core idea of both Fog and Edge Computing. Since nodes are heterogeneous and subject to different traffic patterns, distributed scheduling algorithms are in charge of mak...

When dealing with distributed applications in Edge or Fog computing environments, the service latency that the user experiences at a given node can be considered an indicator of how much the node itself is loaded with respect to the others. Indeed, only considering the average CPU time or the RAM utilisation, for example, does not give a clear depi...

Recently, the emerging interdisciplinary research in biosensing has been increasing, due to the advances in 3D printing technology. In this article, we demonstrate the feasibility of the novel smartphone-based 3D printed design with the aid of an Android application intended solely to measure the concentration of multiple biomarker samples based on...

Recently, the emerging interdisciplinary research in biosensing has been increasing, due to the advances in 3D printing technology. In this article, we demonstrate the feasibility of the novel smartphone-based 3D printed design with the aid of an Android application intended solely to measure the concentration of multiple biomarker samples based on...

The knowledge of environmental depth is essential in multiple robotics and computer vision tasks for both terrestrial and underwater scenarios. Moreover, the hardware on which this technology runs, generally IoT and embedded devices, are limited in terms of power consumption, and therefore, models with a low-energy footprint are required to be desi...

In Edge and Fog Computing environments, it is usual to design and test distributed algorithms that implement scheduling and load balancing solutions. The operation paradigm that usually fits the context requires the users to make calls to the closer node for executing a task, and since the service must be distributed among a set of nodes, the serve...

When deploying a distributed application in the Fog or Edge computing environments, the average service latency among all the involved nodes can be an indicator of how much a node is loaded with respect to the other. Indeed, only considering the average CPU time, or the RAM utilisation, for example, does not give a clear depiction of the load situa...

The distributed nature of edge computing infrastructures requires a significant effort to avoid overload conditions due to uneven distribution of incoming load from sensors placed over a wide area. While optimization algorithms operating offline can address this issue in the medium to long term, sudden and unexpected traffic surges require an onlin...

Fog Computing is today a wide used paradigm that allows to distribute the computation in a geographic area. This not only makes possible to implement time-critical applications but opens the study to a series of solutions which permit to smartly organise the traffic among a set of Fog nodes, which constitute the core of the Fog Computing paradigm....

The computing continuum model is a widely accepted and used approach that make possible the existence of applications that are very demanding in terms of low latency and high computing power. In this three-layered model, the Fog or Edge layer can be considered as the weak link int he chain, indeed the computing nodes whose compose it are generally...

In this paper, colorimetric analysis for biochemical samples has been realized, by developing an easy-to-use smartphone colorimetric sensing android application that can measure the molar concentration of the biochemical liquid analyte. The designed application can be used for on-site testing and measurement. We examined three different biochemical...

Smart cities represent an archetypal example of infrastructures where the fog computing paradigm can express its potential: we have a large set of sensors deployed over a large geographic area where data should be pre-processed (e.g., to extract relevant information or to filter and aggregate data) before sending the result to a collector that may...

In this paper, we consider a load balancing protocol based on the power of random choices that is adapted to a fog deploy in which several independent fog nodes equipped with a set of servers or VM are serving the same geographical area. The protocol is based on a simple but effective mechanism based on a threshold of $T$ . When a fog node receiv...

In this paper, we propose and report a study of a low latency resource sharing protocol for Fog Computing. The protocol has its root in the power-of-random choices family of randomization protocol. The protocol, dubbed LLg (T ) is designed to cope with a not homogeneous set of nodes and dealing with a communication latency comparable with the task...

The fog computing paradigm brings together storage, communication, and computation resources closer to users' end-devices. Therefore, fog servers are deployed at the edge of the network, offering low latency access to users. With the expansion of such fog computing services, different providers will be able to deploy multiple resources within a res...

Modern large-scale internet applications represent today a fundamental source of information for millions of users. The larger is the user base, the more difficult it is to control the quality of data that is spread from producers to consumers. This can easily hamper the usability of such systems as the amount of low quality data received by consum...

Modern large-scale internet applications, like the ubiquitous social networks, represent today a fundamental source of information for millions of users. The larger is the user base, the more difficult it is to control the quality of data that is spread from producers to consumers. This can easily hamper the usability of such systems as the amount...

In the last ten years, recommendation systems evolved from novelties to powerful business tools, deeply changing the internet industry. Collaborative Filtering (CF) represents a widely adopted strategy today to build recommendation engines. The most advanced CF techniques (i.e. those based on matrix factorization) provide high quality results, but...

Financial organizations communicate with each other using ISO 8583 or its derivatives to complete the request and response cycle of card originated transactions originated from an ATM, POS, or the web. ISO 8583 is a broad standard. Its implementations slightly vary due to the flexibility available within the standard. This paper discusses the probl...

In the last ten years, recommendation systems evolved from novelties to powerful business tools, deeply changing the internet industry. Collaborative Filtering (CF) represents today’s a widely adopted strategy to build recommendation engines. The most advanced CF techniques (i.e. those based on matrix factorization) provide high quality results, bu...

The publish/subscribe paradigm is gaining attention for the development of several applications in wide area networks (WANs) due to its intrinsic time, space, and synchronization decoupling properties that meet the scalability and asynchrony requirements of those applications. However, while the communication in a WAN may be affected by the unpredi...

We present a study of a content delivery protocol exploiting a group of dynamically and intermittently connected mobile networks forming an abstract cloud service. An external user gets the content through temporary contacts with nodes of the cloud. The information to be delivered can, for example, be the electronic edition of a free daily newspape...

We consider the data delivery problem in delay tolerant networks, where a data content is located in a fixed source need to be delivered to a specific destination. We assume nodes have limited storage and computational capabilities. In this paper, we initially, explore the data delivery problem, for both unbiased and biased contact models. Based on...

Mobile applications require more and more resources to be able to execute tasks on a single device, despite the fact that mobile devices are getting better capabilities. This has been addressed through several proposals for efficient computation offloading from mobile devices to remote cloud resources or closely located computing resources known as...

Traffic density estimates on maps not only assist drivers to decide routes that are time and fuel economical due to less congestions and but also help in preventing accidents that may occur due to the lack of not being able to see far ahead. In this paper, we propose a protocol that exploit vehicle-to-vehicle ad hoc communication for the estimation...

Publish/subscribe is a well known and powerful distributed programming paradigm with many potential applications. Publish/subscribe content dissemination techniques based on opportunistic networking and network coding-based epidemic routing are key techniques for optimizing network resources, simplifying network architecture, and providing a platfo...

In the last few years telco providers are striving to migrate their services from the traditional Public Switch Telephone Network to so called Next Generation Networks (NGNs) based on standard IP connectivity. This switch is expected to produce a cost degression of 50% for CAPital EXpenditure, while OPerating EXpences remains fairly stable due to n...

We propose an efficient software architecture for private collaborative event processing, enabling information sharing and processing among administratively and geographically disjoint organizations over the Internet. The architecture is capable of aggregating and correlating events coming from the organizations in near real-time, while preserving...

The design of large-scale critical infrastructures demands for innovative data dissemination services, able to jointly provide reliability and timeliness guarantees. Current middleware solutions do not address both these aspects. Indeed, fault tolerance is typically achieved at the cost of severe performance fluctuations, or timeliness is always ob...

Data aggregation, in its most basic definition, is the ability to summarize information. Data aggregation is highly relevant to distributed systems, which collect and process information from many sources, like Internet-scale information systems, and peer-to-peer data management systems. Several architectures and techniques have been recently explo...

Many interoperable software systems atop of large-scale critical infrastructures are based on the publish/subscribe paradigm. They are developed using data dissemination middleware services, which are required to provide reliability and timeliness in multicast communications. The literature of event dissemination and the market of publish/subscribe...

Context and motivations. Publish/subscribe systems have commonly been divided in two large families on the basis of their event-selection model [2]: topicbased and content-based systems. The former trade reduced subscription expressiveness with simpler implementations and higher performance. Conversely, the latter allow to accurately map published...

Consider a group of peers, an ideal random peer sampling service should return a peer, which is a uniform independent random sample of the group. This paper focuses on the implementation and analysis of a peer sampling service based on symmetric view shuffling, where each peer is equipped with a local view of size c, representing a uniform random s...

Up to now Service Oriented Architectures and Event Driven Architectures have been considered as competing parties striving to conquer the crown of the standard paradigm for the implementation of complex distributed applications. Todays we are witnesses of large efforts to merge both paradigms and give birth to a new generation of middleware platfor...

Random walk (RW) is simple to implement and has a better termination control. The Markov chain analysis informs that RW eventually visits all vertices of a connected graph. Due to such nice properties, RW is often proposed for information dissemination or collection from all or part of a large scale unstructured network. The random walker, which ca...

Random walk (RW) based algorithms are often proposed to solve many problems in wireless networks. The implementation of such algorithms are usually done at the application layer so that many characteristics of the wireless transmissions are not exploited. In this paper, we show that we can greatly reduce the energy requirements to perform a RW by b...

Telco providers are in the phase of migrating their services from PSTN to so called Next Generation Networks (NGNs) based on standard IP connectivity. This switch is expected to produce a cost degression of 50% for CAPEX, while OPEX remains fairly stable due to network management and energy costs. At the same time we are expecting a big increase of...

We present a new protocol for information dissemination in intermittently connected networks. The objective of the protocol is to disseminate a piece of information, a podcast episode in our scenario, to a subset of nodes of the network by exploiting the random opportunistic contacts occurring among them. To allow for minimum coordination among nod...

Coolstreaming is one of the first and currently most popular collaborative content distribution system working over the Internet. Such a system has demonstrated how live video streaming can be delivered by exploiting the peer-to-peer (p2p) paradigm. In this paper we propose W-Coolstreaming, a porting of Coolstreaming tailored to work over a mobile...

Consider a group of peers, an ideal random peer sampling service should return a peer, which is an unbiased independent random sample of the group. This paper focuses on peer sampling service based on view shuffling (aka gossip-based peer sampling), where each peer is equipped with a local view of size c. This view should correspond to a uniform ra...

Service discovery in mobile ad hoc networks (MANETs) is a challenging issue. The nodes in a MANETs offer spontaneous and variable connectivity. Also the proximity of a given service as well as the kind and the number of services vary unpredictably with time. Traditional directory based architectural solutions can hardly cope with such a dynamic env...

This book constitutes the thoroughly refereed post-conference proceedings of the thirs International ICST conference on Autonomic Computing and Communication Systems, Autonomics 2009, held in Cyprus Univesity of Technology, Limassol, Cyprus, in September 2009. The 11 revised full papers out of 26 submitted and hosted 5 invited talks, covering vario...

Au sein d'un ensemble de noeuds, un service d'échantillonnage aléatoire idéal se doit de retourner un pointeur vers un noeud, correspondant à un échantillon indépendant sans biais du groupe considéré. Cet article porte sur un service d'échantillonnage issue de la notion de mélange de vues. Chaque noeud possède une vision locale du système, constitu...

Purpose The purpose of this paper is to show how a swarm of robots can cooperate to achieve a common task, in a totally distributed and autonomous way, by exploiting powerful clues contained in some devices that are distributed in the environment. This system exploits a coordination mechanism that is twofold, using radio frequency identification (R...

Publish/subscribe is a well know and powerful distributed program- ming paradigm with many potential applications. In this paper we consider the central problem of any pub/sub implementation, namely the problem of event dis- semination, in the case of a Wireless Mesh Network. We propose a protocol based on non-trivial forwarding mechanisms that emp...

In the last few years there has been a growing interest in small, low-power hardware platforms that integrate sens- ing, processing and wireless communication capabilities that can be adopted to quickly deploy powerful wireless sensor networks. Applications for WSNs often apply the event- based interaction paradigm for communication among par- tici...

In this paper we propose an adaptive random walk for wireless networks. The lifetime of the walk is varied in such a way that at least a given fraction of nodes is covered, in expectation. The only parameter of the random walk, alpha, depends on the nominal network size N and on the required coverage. For sizes lower than N the required coverage is...

Low latency data delivery is an important requirement for achieving effective monitoring through wireless sensor networks. When sensor nodes employ duty cycling, sending a message along the shortest path, however, does not necessarily result in minimum delay. In this paper we firstly study the lowest latency path problem, i.e., the characteristics...

Random walks can be conveniently exploited for implementing probabilistic algorithms to solve many searching problems arised by distributed applications, for example, service discovery, p2p file sharing, etc. In this paper we consider random walks executed on uniform wireless networks and study how to reduce the expected number of walk steps requir...

A recurrent problem when designing distributed applications is to search for a node with known property. File searching in peer-to-peer (P2P) applications, resource discovery in service-oriented architectures (SOAs), and path discovery in routing can all be cast as a search problem. Random walk-based search algorithms are often suggested for tackli...

The last progress in the pervasive computing field has led to the distribution of knowledge and computational power in the environment, rather than condensing it in a single, powerful entity. This allows agents to behave like insects in a swarm, that can fulfil a task communicating directly or indirectly among them. Following this vision of ambient...

Because service discovery enables cooperation among many resource-constrained mobile devices, it's a key research area in mobile ad hoc networks (manets). This comprehensive study analyzes service discovery protocols (SDPs) in multihop manets. The authors start with a general framework and then go into detail on the building blocks of multihop mane...

This paper considers a random walk-based search algorithm in which the random walk occasionally makes longer jumps. The algorithm is tailored to work over wireless networks with uniform node distribution. In a classical random walk each jump has the same mean length. On the contrary, in the proposed algorithm a node may decide to double the expecte...

In a world that is giving prominence to ubiquitous computing, a classical standalone robot, though as complex, specialised and efficient as it may be, is not suitable for a distributed environment. The aim is to have knowledge and computing power diffused in the environment, exploiting the collaboration of simple, flexible and cost-effective robots...

Random walk (RW) based search algorithms are often suggested to solve a search problem, namely the need to locate a node with a given property in a network, e.g., a node providing a service. In order for this solution to be efficient, the number of steps the walker makes before hitting the target node should be low. This can be achieved exploiting...

In this paper we present a novel probabilistic protocol for path discovery in Mobile Ad Hoc Networks (MANETs). The protocol implements what we call a polarized gossiping algorithm. While in the classical gossip algorithm each node forwards a message with the same probability, our proposal is characterized by a variable gossiping probability, which...

The completely decoupled interaction model offered by the publish/subscribe communication paradigm perfectly suits the interoperability needs of todays large-scale, dy- namic, peer-to-peer applications. The unmanaged envi- ronments, where these applications are expected to work, pose a series of problems (potentially wide number of par- tipants, lo...

Recently many scalable and efficient solutions for event dissemination in publish/subscribe (pub/sub) systems have appeared in the literature. This dissemination is usually done over an overlay network of brokers and its cost can be measured as the number of messages sent over the overlay to allow the event to reach all intended subscribers. Effici...

In this paper we tackle the problem of service discovery in mobile wireless networks by exploiting an informed random walk based search, which is implemented directly atop the data link layer. The algorithm can be used both to discover a service and route data packets back to the requesting node, without any routing layer support. The information d...

Point-to-point transmissions represent a fundamental primitive in any communication network. Despite many proposals have appeared in the literature, providing an efficient implementation of such an abstraction in Mobile Ad Hoc Networks (MANETs) still remains an open issue.This paper proposes a probabilistic protocol for unicast packet delivery in a...

The overall goal of the MAIS framework is to support services that are capable of adapting their behavior to changing requirements, environments, user profiles and platforms, in order to provide the user with a suitable quality of service (QoS) [112, 181, 292]. To accomplish this goal, both the front-end and the back-end MAIS environment exploit kn...

In this paper we present a gossip based protocol for path discovery in Mobile Ad Hoc Networks (MANETs). While in the classical gossip algorithm each node for- wards a packet with the same probability, our proposal is characterized by a variable gossiping