Tools and Technologies for eParticipation and eVoting, Trust and Security: provisions and instruments, eDemocracy and eParticipation Challenges, Risk Assessment, Cryptographic Protocol, Security Architecture
Abstract: In this paper, we survey the current state-of-the-art in middleware and systems for Wireless Sensor Networks (WSN). We provide a discussion on the definition of WSN middleware, design issues associated with it, and the taxonomies commonly used to categorize it. We also present a categorization of a number of such middleware platforms, using middleware functionalities and challenges which we think will play a crucial role in developing software for WSN in the near future. Finally, we provide a short discussion on WSN middleware trends.
Abstract: Implementation of a commercial application to a
grid infrastructure introduces new challenges in managing the
quality-of-service (QoS) requirements, most stem from the fact
that negotiation on QoS between the user and the service provider
should strictly be satisfied. An interesting commercial application
with a wide impact on a variety of fields, which can benefit from
the computational grid technologies, is three–dimensional (3-D)
rendering. In order to implement, however, 3-D rendering to a
grid infrastructure, we should develop appropriate scheduling
and resource allocation mechanisms so that the negotiated (QoS)
requirements are met. Efficient scheduling schemes require
modeling and prediction of rendering workload. In this paper
workload prediction is addressed based on a combined fuzzy
classification and neural network model. Initially, appropriate
descriptors are extracted to represent the synthetic world. The
descriptors are obtained by parsing RIB formatted files, which
provides a general structure for describing computer-generated
images. Fuzzy classification is used for organizing rendering
descriptor so that a reliable representation is accomplished which
increases the prediction accuracy. Neural network performs
workload prediction by modeling the nonlinear input-output
relationship between rendering descriptors and the respective
computational complexity. To increase prediction accuracy, a
constructive algorithm is adopted in this paper to train the neural
network so that network weights and size are simultaneously
estimated. Then, a grid scheduler scheme is proposed to estimate
the queuing order that the tasks should be executed and the
most appopriate processor assignment so that the demanded
QoS are satisfied as much as possible. A fair scheduling policy is
considered as the most appropriate. Experimental results on a real
grid infrastructure are presented to illustrate the efficiency of the
proposed workload prediction — scheduling algorithm compared
to other approaches presented in the literature.
Abstract: Large-scale sensor networks, monitoring an environment at close range with high spatial and temporal resolutions are expected to play an important role in various applications, e.g., assessing the ``health'' of machines; environmental, medical, food-safety, and habitat monitoring; inventory control, building automation, etc. Ensuring the security of these complex and yet resource-constrained systems has emerged as one of the most pressing challenges for researchers. In this paper (i) we present the major threats and some characteristic countermeasures, (ii) we propose a way to classify existing systems for intrusion detection in wireless sensor networks and (iii) we present a new approach for decentralized energy efficient intrusion detection that can be used to improve security from both external and internal adversaries.
Abstract: Usage and exploitation of the Internet is a critical requirement for managing and distributing valuable digital assets. This requirement introduces a great number of threats for commercial (or not) organizations that may cause huge data and financial losses, harm their reputation as well as people's trust on them. In this paper we present the research challenges for secure digital asset management over the web by proposing a model that provides data safety and secure user interaction on especially demanding on-line collaboration environments.
Abstract: This paper presents an overview of Quality of Service (QoS) differentiation mechanisms proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple the benefits of both circuit and packet switching for the “on demand” use of capacity in the future optical Internet. In such a case, QoS support imposes some important challenges before this technology is deployed. This paper takes a broader view on QoS, including QoS differentiation not only at the burst but also at the transport levels for OBS networks. A classification of existing QoS differentiation mechanisms for OBS is given and their efficiency and complexity are comparatively discussed. We provide numerical examples on how QoS differentiation with respect to burst loss rate and transport layer throughput can be achieved in OBS networks.
Abstract: We study the problem of secure routing in wireless sensor networks where the sensors and the sink can move during the execution of remote monitoring applications and communication is not necessarily directed towards the sink. We present a new routing protocol that builds upon a collection of mechanisms so that the integrity and confidentiality of the information reported to the controlling authorities is secured. The mechanisms are simple to implement, rely only on local information and require O(1) storage per sensor. The protocol adapts to mobility and security challenges that may arise throughout the execution of the application. We take special care for wireless sensor networks that monitor dynamically changing environments and applications that require its operation for extended periods of time. APSR can detect when the current network conditions are about to change and becomes ready for adaption to the new conditions. We demonstrate how to deal with inside and outside attacks even when the network is adapting to internal and/or external events.
Abstract: An ever growing emphasis is put nowadays in developing personalized journey planning and renewable mobility services in smart cities. These services combine means of scheduled-based public transport and electric vehicles or bikes, using crowdsourcing techniques for collecting real-time traffic information and for assessing the recommended routes. The goal is to develop an information system that will allow the fast, real-time computation of best routes.
The main challenges in developing such an information system are both technological and algorithmic. The technological challenge concerns the collection, storage, management, and updating of a huge volume of transport data that are usually time-dependent, and the provision (through these data) of personalized renewable mobility services in smartphones. This challenge is typically confronted by creating a cloud infrastructure that on the one hand will support the storage, management, and updating of data, while on the other hand it will handle the necessary data feed to the smartphone applications for providing the users with the requested best routes.
The algorithmic challenge concerns the development of innovative algorithms for the efficient provision of journey planning services in smartphones, based on data they will receive from the cloud infrastructure. These services guarantee the computation of realistic and useful best routes, as well as the updating of the precomputed (route and timetable) information, in case of delays of scheduled public transport vehicles, so that the users can online update their routes to destination. The goal is to develop an algorithmic basis for supporting modern renewable mobility services (information systems), such as "mobility on demand'' (where the next leg of a journey is decided in real-time) and "door-to-door'' personalized mobility, in urban scheduled-based public transport environments. Scheduled-based public transport information systems should not only compute in real-time end-user queries requesting best routes, but also to update the timetable information in case of delays.
The core algorithmic issues of mobility and journey planning (regarding the computation of optimal routes under certain criteria) in scheduled-based public transport systems concern the efficient solution of the fundamental earlier arrival (EA) problem (compute a journey from station S to station T minimizing the overall traveling time required to complete the journey), the minimum number of
transfers (MNT) problem (compute a journey from station S to station T minimizing the number of times a passenger is required to change vehicle), and the efficient updating of timetable information system in case of vehicle delays. The EA and MNT problems have been extensively studied in the literature under two main approaches: the array-based modeling (where the timetable is represented as an array) and the graph-based modeling (where the timetable is represented as a graph). Experimental results have shown so far that the array-based approaches are faster in terms of query time than graph-based ones, as they are able to better exploit data locality and do not rely on priority queues. On the other hand, the array-based approaches have not been theoretically or experimentally studied as far as the efficient updating of timetable information, in case of delays, is concerned.
In this thesis, new graph-based models are being developed that solve efficiently the aforementioned fundamental algorithmic mobility problems in urban scheduled-based public transport information systems, along with a mobile application (journey planner) running on Android-based smartphones that includes a service for the evaluation of the recommended routes by the users. In particular:
(a) An extensive comparative evaluation was conducted on graph-based dynamic models that represent big data volumes regarding their suitability for representing timetable information. The study confirmed that the realistic time-expanded model is the most suitable for representing timetable information.
(b) Two new graph-based models have been developed for representing timetable information (in a timetable information system), the reduced time-expanded model and the dynamic timetable model (DTM), both of which are more space-efficient with respect to the realistic time-expanded model. For both of the new models, new efficient algorithms were developed for fast answering of EA and MNT queries, as well as for updating the timetable information representation in case of delays.
(c)An experimental evaluation was conducted with the new graph-based models and their associated query and update algorithms on a set of 14 real-world scheduled-based transportation systems, including the metropolitan areas of Berlin, Athens, London, Rome, and Madrid. The experimental results showed that the query algorithms of the reduced time-expanded model are superior to those of the DTM model, while the reverse is true regarding the update algorithms. In addition, the experimental study showed that the query algorithms of the new graph-based models compete favorably with those of the best array-based models.
(d) A mobile, cloud-based, journey planner (information system) was developed whose core algorithmic engine builds upon the new graph-based models. The mobile application is accompanied by a service that allows the users to assess the recommended journeys. The journey planner demonstrates the practicality of the new graph-based models and their associated query and update algorithms.
Abstract: Urban road networks are represented as directed graphs, accompanied by a metric which assigns cost functions (rather than scalars) to the arcs, e.g. representing time-dependent arc-traversal-times. In this work, we present oracles for providing time-dependent min-cost route plans, and conduct their experimental evaluation on a real-world data set (city of Berlin). Our oracles are based on precomputing all landmark-to-vertex shortest travel-time functions, for properly selected landmark sets. The core of this preprocessing phase is based on a novel, quite efficient and simple oneto-all approximation method for creating approximations of shortest travel-time functions. We then propose three query algorithms, including a PTAS, to efficiently provide mincost route plan responses to arbitrary queries. Apart from the purely algorithmic challenges, we deal also with several
implementation details concerning the digestion of raw traffic data, and we provide heuristic improvements of both the preprocessing phase and the query algorithms. We conduct an extensive, comparative experimental study with all query algorithms and six landmark sets. Our results are quite encouraging, achieving remarkable speedups (at least by two orders of magnitude) and quite small approximation guarantees, over the time-dependent variant of Dijkstra¢s algorithm.
Abstract: We examine multi-player pervasive games that rely on the
use of ad-hoc mobile sensor networks. The unique feature in
such games is that players interact with each other and their
surrounding environment by using movement and presence
as a means of performing game-related actions, utilizing sen-
sor devices. We brie
y discuss the fundamental issues and
challenges related to these type of games and the scenar-
ios associated with them. We have also developed a frame-
work, called Fun in Numbers (FinN) that handles a number
of these issues, such as such as neighbors discovery, local-
ization, synchronization and delay-tolerant communication.
FinN is developed using Java and is based on a multilayer ar-
chitecture, which provides developers with a set of templates
and services for building and operating new games.
Abstract: Purpose – To examine broadband competition and broadband penetration in a set of countries that employ the same regulation framework. To define the policy and strategy required to promote broadband in weak markets that do not employ alternative infrastructures.
Design/methodology/approach – Study penetration and competition level statistics from 2002 to 2005 in a set of countries with different infrastructures deployed, services provided as well as in their social-economic structures but employing the same regulation framework. Measure the level of inter-platform and intra-platform competition as well as the availability of bitstream access versus the incumbents' shares.
Findings – The paper concludes that a mature broadband market is the one that exhibits a high penetration ratio in combination with a high competition level. Bitstream access can counterbalance the inexistence of alternative broadband infrastructures, especially in weak markets. In particular the availability of numerous bitstream access types in combination with the proper price differentiation can fuel broadband adoption in relatively weak broadband markets.
Originality/value – The paper challenges the general rule that only platform (also known as facility) based competition guarantees long-term growth of the broadband market. Bitstream and resale access do not lag local loop unbundling and can be used in weak markets that do not employ alternative infrastructures to fuel competition in the relevant markets. Different policies and strategies must be followed, in that case, on behalf of the local NRA.
Abstract: Ever-increasing bandwidth demands and higher flexibility are the main challenges for the next generation optical core networks. A new trend in order to address these challenges is to consider the impairments of the lightpaths during the design of optical networks. In our work, we focus on translucent optical networks, where some lightpaths are routed transparently, whereas others go through a number of regenerators. We present a cost analysis of design strategies, which are based either on an exact Quality of Transmission (QoT) validation or on a relaxed one and attempt to reduce the amount of regenerators used. In the exact design strategy, regenerators are required if the QoT of a candidate lightpath is below a predefined threshold, assuming empty network conditions. In the relaxed strategy, this predefined threshold is lower, while it is assumed that the network is fully loaded. We evaluate techno-economically the suggested design solutions and also show that adding more flexibility to the optical nodes has a large impact to the total infrastructure cost.
Abstract: Pervasive games are a new type of digital games that combines game and physical reality within the gameplay. This novel game type raises unprecedented research and design challenges for developers and urges the exploration of new technologies and methods to create high quality game experiences and design novel and compelling forms of content for the players. This chapter follows a systematic approach to explore the landscape of pervasive gaming. First, the authors approach pervasive games from a theoretical point of view, defining the four axes of pervasive games design, introducing the concept of game world persistency, and describing aspects of spatially/temporally/socially expanded games. Then, they present ten pervasive game projects, classified in five genres based on their playing environment and features. Following that, the authors present a comparative view of those projects with respect to several design aspects: communication and localization, context and personal awareness aspects, information model, player equipment, and game space visualization. Last, the authors highlight current trends, design principles, and future directions for pervasive games development.
Abstract: In this paper, we discuss key findings, technological challenges and socioeconomic opportunities in Smart City era. Most of the conclusions were gathered during SmartSantander project, an EU project that is developing a city-scale testbed for IoT and Future Internet experimentation, providing an integrated framework for implementing Smart City services.
Abstract: The domain of smart cities is currently burgeoning, with a lot of potential for scientific and socio-economic innovation gradually being revealed. It is also becoming apparent that cross-discipline research will be instrumental in designing and building smarter cities, where IoT technology is becoming omnipresent. SmartSantander is an FP7 project that built a massive
city-scale IoT testbed aiming to provide both a tool for the research community and a functional system for the local government to implement operational city
services. In this work, we present key smart cities projects, main application domains and representative smart city frameworks that reflect the latest advances in the smart cities domain and our own experience through SmartSantander. The project has deployed 51.910 IoT endpoints, offering a massive infrastructure to the community, as well as functional system services and a number of end-user applications. Based on these aspects, we identify and
discuss a number of key scientific and technological challenges. We also present an overview of the developed system components and applications, and
discuss the ways that current smart city challenges were handled in the project.
Abstract: We present key aspects (hardware, software, topology, networking) of SenseWall, an experimental sensor network test-bed we have created for the implementation and engineering of distributed sensor network algorithms. We then describe how SenseWall has been in particular used to implement two recent state of the art algorithms for energy balanced sensor data propagation. We elaborate on the issues and challenges created by the restrictions and particularities of the experimental test-bed and how we dealt with them. We also carry out a detailed performance evaluation comparing the energy balance protocols to two baseline protocols that include only either single hop or direct data transmissions.
Abstract: We discuss key findings and technological challenges related to SmartSantander, an EU project that is developing a city-scale experimental facility for Internet of Things and Future Internet experimentation. The main goal of the project is to design and construct a city scale lab for experimentation and provide an integrated framework for implementing Smart City services.
Abstract: Green Awareness in Action (GAIA) is introducing game challenges to the school community, where real-world sensor data produced inside school buildings are used,
aiming to increase awareness and reduce energy consumption. An initial small-scale in-school evaluation trial of the games¢ deployment is reported here.
Abstract: In this book chapter we will consider key establishment protocols for wireless sensor networks.
Several protocols have been proposed in the literature for the establishment of a shared group key for wired networks.
The choice of a protocol depends whether the key is established by one of the participants (and then transported to the other(s)) or agreed among the participants, and on the underlying cryptographic mechanisms (symmetric or asymmetric). Clearly, the design of key establishment protocols for sensor networks must deal with different problems and challenges that do not exist in wired networks. To name a few, wireless links are particularly vulnerable to eavesdropping, and that sensor devices can be captured (and the secrets they contain can be compromised); in many upcoming wireless sensor networks, nodes cannot rely on the presence of an online trusted server (whereas most standardized authentication and key establishment protocols do rely on such a server).
In particular, we will consider five distributed group key establishment protocols. Each of these protocols applies a different algorithmic technique that makes it more suitable for (i) static sensor networks, (ii) sensor networks where nodes enter sleep mode (i.e. dynamic, with low rate of updates on the connectivity graph) and (iii) fully dynamic networks where nodes may even be mobile. On the other hand, the common factor for all five protocols is that they can be applied in dynamic groups (where members can be excluded or added) and provide forward and backward secrecy. All these protocols are based on the Diffie-Hellman key exchange algorithm and constitute natural extensions of it in the multiparty case.
Abstract: Abstract— Numerous smart city testbeds and system deployments have surfaced around the world, aiming to provide services over unified large heterogeneous IoT infrastructures. Although we have achieved new scales in smart city installations and systems, so far the focus has been to provide diverse sources of data to smart city services consumers, while neglecting to provide ways to simplify making good use of them. We believe that knowledge creation in smart cities through data annotation, supported in both an automated and a crowdsourced manner, is an aspect that will bring additional value to smart cities. We present here our approach, aiming to utilize an existing smart city deployment and the OrganiCity software ecosystem. We discuss key challenges along with characteristic use cases, and report on our design and implementation, along with preliminary results.
Abstract: Although we have reached new levels in smart city installations and systems, efforts so far have focused on providing diverse sources of data to smart city services consumers while neglecting to provide ways to simplify making good use of them. In this context, one first step that will bring added value to smart cities is knowledge creation in smart cities through anomaly detection and data annotation, supported in both an automated and a crowdsourced manner. We present here LearningCity, our solution that has been validated over an existing smart city deployment in Santander, and the OrganiCity experimentation-as-a-service ecosystem. We discuss key challenges along with characteristic use cases, and report on our design and implementation, together with some preliminary results derived from combining large smart city datasets with machine learning.
Abstract: Internet of Things technologies are considered the next big
step in Smart Building installations. Although such technologies have
been widely studied in simulation and experimental scenarios it is not so
obvious how problems of real world installations should be dealt with. In
this work we deploy IoT devices for sensing and control in a multi-office
space and employ technologies such as CoAP, RESTful interfaces and
Semantic Descriptions to integrate them with the Web. We report our
research goals, the challenges we faced, the decisions we made and the
experience gained from the design, deployment and operation of all the
hardware and software components that compose our system.
Abstract: The promises inherent in users coming together to form data
sharing network communities, bring to the foreground new problems formulated
over such dynamic, ever growing, computing, storage, and networking
infrastructures. A key open challenge is to harness these highly
distributed resources toward the development of an ultra scalable, efficient
search engine. From a technical viewpoint, any acceptable solution
must fully exploit all available resources dictating the removal of any
centralized points of control, which can also readily lead to performance
bottlenecks and reliability/availability problems. Equally importantly,
however, a highly distributed solution can also facilitate pluralism in informing
users about internet content, which is crucial in order to preclude
the formation of information-resource monopolies and the biased visibility
of content from economically-powerful sources. To meet these challenges,
the work described here puts forward MINERVA{\^a}{\"i}¿½{\"i}¿½, a novel search
engine architecture, designed for scalability and efficiency. MINERVA{\^a}{\"i}¿½{\"i}¿½
encompasses a suite of novel algorithms, including algorithms for creating
data networks of interest, placing data on network nodes, load balancing,
top-k algorithms for retrieving data at query time, and replication algorithms
for expediting top-k query processing. We have implemented the
proposed architecture and we report on our extensive experiments with
real-world, web-crawled, and synthetic data and queries, showcasing the
scalability and efficiency traits of MINERVA{\^a}{\"i}¿½{\"i}¿½.
Abstract: Recommender Systems (RSs) have been extensively utilized as a means of reducing the information overload and offering travel recommendations to tourists. The emerging mobile RSs are tailored to mobile device users and promise to substantially enrich tourist experiences, recommending rich multimedia content, context-aware services, views/ratings of peer users, etc. New developments in mobile computing, wireless networking, web technologies and social networking leverage massive opportunities to provide highly accurate and effective tourist recommendations that respect personal preferences and capture usage, personal, social and environmental contextual parameters. This article follows a systematic approach in reviewing the state-of-the-art in the field, proposing a classification of mobile tourism RSs and providing insights on their offered services. It also highlights challenges and promising research directions with respect to mobile RSs employed in tourism.
Abstract: We present here, Fun in Numbers, a framework for developing multiplayer pervasive games that rely on the use of ad hoc mobile sensor networks. The unique feature in such games is that players interact with each other and their surrounding environment by using movement and presence as a means of performing game-related actions, utilizing sensor devices. We present the fundamental issues and challenges related to these type of games and the scenarios associated with them is provided. Our framework is developed using Java and is based on a multilayer architecture, which provides developers with a set of templates and services for building and operating new games. Our framework handles a number of challenging fundamental and practical issues, such as synchronization, network congestion, delay-tolerant communication and neighbors discovery. We also present our platform and identify issues that arise in pervasive games which utilize sensor network nodes. The implemented games show how to use non-conventional user interface methods to breathe new life into familiar concepts, like the multiplayer games played out in open space.
Abstract: In this work, we explore context-aware application scenarios that become possible utilizing semantically-rich information derived from real-world mobility and presence traces. Traces produced by people carrying personal mobile devices, capturing social and contextual interactions, serve as enables for Future Internet applications. We discuss the fundamental concepts, technical issues and related research challenges. We propose a reference architecture for setting up a system that collects such traces in a Smart City environment. We present the algorithms used to process the traces and infer interactions and interests for the observed populations. We conduct two 3-day trial deployments: one in an office environment and the other in the context of a Smart Conference application. We discuss our findings regarding the system's capability to track interactions and the overall efficacy of the application.
Abstract: We present and discuss challenges and solutions posed by the design of an
adaptable network infrastructure of tiny artifacts. Such artifacts are characterized by
severe limitations in computational power, communications capacity and energy;
nevertheless they must realize a communication infrastructure able to deliver
services to the end-users in a very dynamic and challenging environment. Namely
we present one unifying scenario for the activities of the FRONTS project
(www.fronts.cti.gr). The aim of the unifying scenario is to show how the results
achieved in the project can be exploited to build such a communication
infrastructure.
Abstract: With a rapidly aging population, the health-care community will
soon face a severe medical personnel shortage. It is imperative that automated
health monitoring technologies be developed to help meet this
shortage. In this direction, we are developing Ayushman, a health monitoring
infrastructure and testbed. The vision behind its development
is two-fold: first, to develop a wireless sensor-based automated health
monitoring system that can be used in diverse situations, from homebased
care, to disaster situations, without much customization; second,
to provide a testbed for implementing and testing communication protocols
and systems. Ayushman provides a collection of services which
enables it to perform this dual role. It possess a hierarchical cluster
topology which provides a fault-tolerant and reliable system by ensuring
that each tier in the hierarchy is self-contained and can survive on its
own in case of network partition. Ayushman is being implemented using
off-the-shelf and diverse hardware and software components, which
presents many challenges in system integration and operational reliability.
This is an ongoing project at the IMPACT lab at Arizona State
University1, and in this paper, we present our system¢s architecture and
some of our experiences in the development of its initial prototype.
Abstract: This Volume contains the 11 papers corresponding to poster and demo presentations
accepted to the 7th ACM/IEEE International Symposium on Modeling,
Analysis and Simulation ofWireless and Mobile Systems (MSWiM 04),
that is held October 4-6, 2004, in Venice, Italy.
MSWiM 2004 (http://www.cs.unibo.it/mswim2004/) is intended to provide
an international forum for original ideas, recent results and achievements on
issues and challenges related to mobile and wireless systems.
A Call for Posters was announced and widely disseminated, soliciting posters
that report on recent original results or on-going research in the area of wireless
and mobile networks. Prospective authors were encouraged to submit interesting
results on all aspects of modeling, analysis and simulation of mobile and
wireless networks and systems. The scope and topics of the Posters Session
were the same as those included in the MSWiM Call for Papers (see above).
Poster presentations were meant to provide authors with early feedback on
their research work and enable them to present their research and exchange
ideas during the Symposium.
All submissions to the call for posters as well as selected papers submitted
to MSWiM 04 were considered and reviewed. The review process resulted in
accepting the set of 11 papers included in this Volume. Accepted posters will
also be on display during the Symposium.
The set of papers in this Proceedings covers a wide range of important topics
in wireless and mobile computing, including channel allocation in wireless
networks, quality of service provisioning in IEEE 802.11 wireless LANs, IP
mobility support, energy conservation, routing in mobile adhoc networks, resource
sharing, wireless access to the WWW, sensor networks etc. The performance
evaluation techniques used include both analysis and simulation.
We hope that the poster papers included in this Volume will facilitate a fruitful
and lively discussion and exchange of interesting and creative ideas during
the Symposium.
We wish to thank the MSWiM Steering Committee Chair Azzedine Boukerche
and the Program Co-Chairs ofMSWiM 04 Carla-Fabiana Chiasserini and
Lorenzo Donatiello for their valuable help in the selection procedure. Also, the
MSWiM 04 Publicity Co-Chairs Luciano Bononi, Helen Karatza and Mirela
Sechi Moretti Annoni Notare for disseminating the Call for Posters.
We wish to warmly thank the Poster Proceedings Chair Ioannis Chatzigiannakis
for carefully doing an excellent job in preparing the Volume you now
hold in your hands.
Abstract: Efficient query processing in traditional database
management systems relies on statistics on base data. For centralized systems, there is a rich body of research results on such statistics, from simple aggregates to more elaborate synopses such as sketches and histograms. For Internet-scale distributed systems, on the other hand, statisticsmanagement still poses major challenges. With the work in this paper we aim to endow peer-to-peer data management over structured
overlays with the power associated with such statistical information, with emphasis on meeting the scalability challenge.
To this end, we first contribute efficient, accurate, and decentralized algorithms that can compute key aggregates such as Count, CountDistinct, Sum, and Average. We show how to construct several types of histograms, such as simple Equi-Width, Average Shifted Equi-Width, and Equi-Depth histograms. We present a full-fledged open-source implementation
of these tools for distributed statistical synopses,
and report on a comprehensive experimental performance evaluation, evaluating our contributions in terms of efficiency, accuracy, and scalability.
Abstract: In this work, we discuss multiplayer pervasive
games that rely on the use of ad hoc mobile sensor networks.
The unique feature in such games is that players interact
with each other and their surrounding environment by using
movement and presence as a means of performing game-related
actions, utilizing sensor devices. We discuss the fundamental
issues and challenges related to these type of games and the
scenarios associated with them. We also present and evaluate
an example of such a game, called the “Hot Potato”, developed
using the Sun SPOT hardware platform. We provide a set of
experimental results, so as to both evaluate our implementation
and also to identify issues that arise in pervasive games which
utilize sensor network nodes, which show that there is great
potential in this type of games.
Abstract: Peer-to-peer sharing systems are becoming
increasingly popular and an exciting new class of
innovative, internet-based data management
systems. In these systems, users contribute their
own resources (processing units and storage
devices) and content (i.e., documents) to the P2P
community. We focus on the management of
content and resources in such systems. Our goal
is to harness all available resources in the P2P
network so that the users can access all available
content efficiently. Efficiency is taken both from
(i) the point of view of the system, in that we
strive to ensure fair load distribution among all
peer nodes, and (ii) from the point of view of the
users, in that we strive to ensure low user-request
response times.
We propose a novel architecture for this new
class of applications, which differs drastically
from what is either found currently in existing
products or proposed in academia. We contribute
and study novel solutions that achieve our goals,
while at the same time addressing the formidable
challenges due to the autonomy of peers, their
heterogeneous processing and storage capacities,
their different content contributions, the huge
system scale, and the highly dynamic system
environment.
Abstract: In this paper, we discuss the integration of Wireless
Sensor Networks (WSN) and smart objects with the Web. We present a set of research challenges which we believe are the most important ones rising from this integration and propose a prototype system, Uberdust, which addresses such challenges. Uberdust is a brokerage web service for connecting smart objects to the Internet of Things, providing storage, sharing and discovery of real-time and historical data from smart objects, devices & building installations around the world via the Web. Our system provides high-level language-independent APIs so IoT application developers may choose their favorite programming or scripting languages.
Abstract: The interpolation method, originally developed in statistical physics, transforms distributions of random CSPs to distributions of much simpler problems while bounding the change in a number of associated statistical quantities along the transformation path. After a number of further mathematical developments, it is now known that, in principle, the method can yield rigorous unsatisfiability bounds if one “plugs in an appropriate functional distribution”. A drawback of the method is that identifying appropriate distributions and plugging them in leads to major analytical challenges as the distributions required are, in fact, infinite dimensional objects. We develop a variant of the interpolation method for random CSPs on arbitrary sparse degree distributions which trades accuracy for tractability. In particular, our bounds only require the solution of a 1-dimensional optimization problem (which typically turns out to be very easy) and as such can be used to compute explicit rigorous unsatisfiability bounds.
Abstract: In this work, we discuss various aspects of the application of pervasive technologies inside an urban setting. In the last decade we have seen the emergence of a multitude of closely-related pervasive technologies that have only recently started to materialize on a grand scale, such as wireless sensor networks, RFID and NFC. We discuss the arising research challenges associated with such converging fields and we also provide a survey of the state-of-the-art related application scenaria, which we believe set their near-future applied context. Finally, we provide a more analytic discussion on three discrete systems that belong to this category of applications and give insight to the current state-of-the-art work in this field.
Abstract: The Internet of Things (IoT) and smart cities are two of the most popular directions the research community is pursuing very actively. But although we have made great progress in many fields, we are still trying to figure out how we can utilize our smart city and IoT infrastructures, in order to produce reliable, economically sustainable solutions that create public value, and even more so in the field of education.
GAIA1, a Horizon2020 EC-funded project, has developed an IoT infrastructure across school buildings in Europe. Its primary aim has been to raise awareness about energy consumption and sustainability, based on real-world sensor data produced inside the school buildings where students and teachers live and work. Today's students are the citizens of tomorrow, and they should have the skills to understand and respond to challenges like climate change. Currently, 25 educational building sites participate in GAIA, located in Sweden, Italy, and Greece. An IoT infrastructure [1] is installed in these buildings, monitoring in real-time their power consumption, as well as several indoor and outdoor environmental parameters.