Integrating Wireless Sensor Networks and Mobile Ad-hoc NETworks for enhanced value-added services

In some situations where the standard telecommunication infrastructure is not available, Mobile Ad hoc NETworks (MANETs) can be deployed to provide the required communication. These networks are established "on the fly" without a need for prior communication organization and are composed of autonomous mobile devices, such as cell phones, PDAs or laptops. In similar conditions, such as in emergency response operations, integrating MANETs and Wireless Sensor Networks (WSNs) can notably enhance the MANET participant's end-user experience. WSNs sense and aggregate ambient information, such as physiological, environmental or physical data related to a nearby phenomenon. The integration, which provides end-user availability to WSN required information, is feasible via gateways. However, when the ambient information collected by WSNs is intended for applications residing in MANETs, centralized and fixed gateways are not practicably feasible. This is mainly due to ad-hoc nature, lack of centralized control and constraints on the end-user devices that are used in MANETs. These devices are usually limited in power and capacity and cannot host centralized gateways. In this thesis we exploit the integration of WSN and MANET in order to provide novel value-added services which enhance the end-user experience of MANET participants. Motivating scenarios are introduced, background information is presented, requirements are derived and the state of the art regarding the integration of WSN with existing networks, including MANETs, is evaluated. Based on the evaluation, none of the existing solutions satisfies all of our derived requirements. Therefore, we propose an overall two-level overlay architecture to integrate WSNs (with mobile sinks) and MANETs. This architecture is based on the distributed gateway and applications which form the P2P overlays. Overlays are application-layer networks which are created on top of the exiting MANET. To interconnect gateway and application overlays we derive corresponding requirements and evaluate the existing approaches. Since none of these approaches fulfills all of our requirements, we propose protocols, mechanisms and design corresponding modules for the interconnection of overlays. Finally we refine our overall architecture based on the interconnection aspects. As a proof of concept, we implement a prototype for the inter-overlay information exchange. This implementation is based on SIP extensions and uses two existing P2P middlewares. We also simulate our prototype using Oversim simulation tool and collect experimental results. Based on these results, we can see that our architecture is a valid and promising approach for interconnecting different P2P overlays and can be deployed to provide the overall solution for WSN and MANET integrated system

A Distributed SIP P2P telephony system

Since the telephone was invented, it has revolutionalized the telecommunications and enabled people to talk to each other over long distances. Through the years, the telephone has been greatly improved and many new models have been developed to serve the different needs of the diversified set of users. Peer-to-peer systems inherently have high scalability, robustness and fault tolerance because there is no centralized server and the network self-organizes itself. These features can be used in order to construct peer-to-peer internet telephony systems where there is no central server and with a lower cost than the current internet telephony systems. In this thesis, we propose a fully distributed peer-to-peer architecture, called SIP2P, for the Session Initiation Protocol (SIP). Peers connect directly to other peers, constructing an overlay network of peers which communicate to each other in order to provide the same services as the central server in the conventional SIP. The nodes that define the overlay not only act as an ordinary SIP user agent but they can also perform all together the role of the SIP proxy, SIP register and the SIP location service. The behavior of the conventional SIP servers is distributed over all the nodes participating in the overlay. An implementation of the SIP2P system concludes the thesis in order to validate and evaluate its distributed desig

Prospects of peer-to-peer SIP for mobile operators

Tämän diplomityön tarkoituksena on esitellä kehitteillä oleva Peer-to-Peer Session Initiation Protocol (P2PSIP), jonka avulla käyttäjät voivat itsenäisesti ja helposti luoda keskenään puhe- ja muita multimediayhteyksiä vertaisverkko-tekniikan avulla. Lisäksi tarkoituksena on arvioida P2PSIP protokollan vaikutuksia ja mahdollisuuksia mobiilioperaattoreille, joille sitä voidaan pitää uhkana. Tästä huolimatta, P2PSIP:n ei ole kuitenkaan tarkoitus korvata nykyisiä puhelinverkkoja. Työn alussa esittelemme SIP:n ja vertaisverkkojen (Peer-to-Peer) periaatteet, joihin P2PSIP-protokollan on suunniteltu perustuvan. SIP mahdollistaa multimedia-istuntojen luomisen, sulkemisen ja muokkaamisen verkossa, mutta sen monipuolinen käyttö vaatii keskitettyjen palvelimien käyttöä. Vertaisverkon avulla käyttäjät voivat suorittaa keskitettyjen palvelimien tehtävät keskenään hajautetusti. Tällöin voidaan ylläpitää laajojakin verkkoja tehokkaasti ilman palvelimista aiheutuvia ylläpito-kustannuksia. Mobiilioperaattorit ovat haasteellisen tilanteen edessä, koska teleliikennemaailma on muuttumassa yhä avoimemmaksi. Tällöin operaattoreiden asiakkaille aukeaa mahdollisuuksia käyttää kilpailevia Internet-palveluja (kuten Skype) helpommin ja tulevaisuudessa myös itse muodostamaan kommunikointiverkkoja P2PSIP:n avulla. Tutkimukset osoittavat, että näistä uhista huolimatta myös operaattorit pystyvät näkemään P2PSIP:n mahdollisuutena mukautumisessa nopeasti muuttuvan teleliikennemaailman haasteisiin. Nämä mahdollisuudet sisältävät operaattorin oman verkon optimoinnin lisäksi vaihtoehtoisten ja monipuolisempien palveluiden tarjoamisen asiakkailleen edullisesti. Täytyy kuitenkin muistaa, että näiden mahdollisuuksien toteuttamisten vaikutusten ei tulisi olla ristiriidassa operaattorin muiden palveluiden kanssa. Lisäksi tulisi muistaa, että tällä hetkellä keskeneräisen P2PSIP-standardin lopullinen luonne ja ominaisuudet voivat muuttaa sen vaikutuksia.The purpose of this thesis is to present the Peer-to-Peer Session Initiation Protocol (P2PSIP) being developed. In addition, the purpose of this thesis is to evaluate the impacts and prospects of P2PSIP to mobile operators, to whom it can be regarded as a threat. In P2PSIP, users can independently and easily establish voice and other multimedia connections using peer-to-peer (P2P) networking. However, P2PSIP is not meant to replace the existing telephony networks of the operators. We start by introducing the principles of SIP and P2P networking that the P2PSIP is intended to use. SIP enables to establish, terminate and modify multimedia sessions, but its versatile exploitation requires using centralized servers. By using P2P networking, users can decentralize the functions of centralized servers by performing them among themselves. This enables to maintain large and robust networks without maintenance costs resulted of running such centralized servers. Telecommunications market is transforming to a more open environment, where mobile operators and other service providers are challenged to adapt to the upcoming changes. Subscribers have easier access to rivalling Internet-services (such as Skype) and in future they can form their own communication communities by using P2PSIP. The results show that despite of these threats, telecom operators can find potential from P2PSIP in concurrence in adaptation to the challenges of the rapidly changing telecom environment. These potential roles include optimization of the network of the operator, but as well roles to provide alternative and more versatile services to their subscribers at low cost. However, the usage of P2PSIP should not conflict with the other services of the operator. Also, as P2PSIP is still under development, its final nature and features may change its impacts and prospects

Efficient service discovery in wide area networks

Living in an increasingly networked world, with an abundant number of services available to consumers, the consumer electronics market is enjoying a boom. The average consumer in the developed world may own several networked devices such as games consoles, mobile phones, PDAs, laptops and desktops, wireless picture frames and printers to name but a few. With this growing number of networked devices comes a growing demand for services, defined here as functions requested by a client and provided by a networked node. For example, a client may wish to download and share music or pictures, find and use printer services, or lookup information (e.g. train times, cinema bookings). It is notable that a significant proportion of networked devices are now mobile. Mobile devices introduce a new dynamic to the service discovery problem, such as lower battery and processing power and more expensive bandwidth. Device owners expect to access services not only in their immediate proximity, but further afield (e.g. in their homes and offices). Solving these problems is the focus of this research. This Thesis offers two alternative approaches to service discovery in Wide Area Networks (WANs). Firstly, a unique combination of the Session Initiation Protocol (SIP) and the OSGi middleware technology is presented to provide both mobility and service discovery capability in WANs. Through experimentation, this technique is shown to be successful where the number of operating domains is small, but it does not scale well. To address the issue of scalability, this Thesis proposes the use of Peer-to-Peer (P2P) service overlays as a medium for service discovery in WANs. To confirm that P2P overlays can in fact support service discovery, a technique to utilise the Distributed Hash Table (DHT) functionality of distributed systems is used to store and retrieve service advertisements. Through simulation, this is shown to be both a scalable and a flexible service discovery technique. However, the problems associated with P2P networks with respect to efficiency are well documented. In a novel approach to reduce messaging costs in P2P networks, multi-destination multicast is used. Two well known P2P overlays are extended using the Explicit Multi-Unicast (XCAST) protocol. The resulting analysis of this extension provides a strong argument for multiple P2P maintenance algorithms co-existing in a single P2P overlay to provide adaptable performance. A novel multi-tier P2P overlay system is presented, which is tailored for service rich mobile devices and which provides an efficient platform for service discovery

The design of efficient and secure P2PSIP systems

Doktorgradsavhandling i informasjons- og kommunikasjonsteknologi, Universitetet i Agder, Grimstad, 201

The state of peer-to-peer network simulators

Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

A DHT-based Peer-to-peer Architecture for Distributed Internet Applications

La tecnologia peer-to-peer é divenuta popolare soprattutto per applicazioni di file-sharing come Napster, Gnutella, Kazaa ed eMule, che sono state la componente principale del traffico di Internet per diversi anni. La tecnologia peer-to-peer, tuttavia, non é solo relativa al file-sharing. Molte applicazioni, utilizzate da milioni di utenti ogni giorno, come Skype, sono applicazioni basate sul paradigma peer-to-peer. Il paradigma peer-to-peer (P2P) é un modello di comunicazione in cui una moltitudine di dispositivi indipendenti ed eterogenei interagiscono come pari (peer). In una rete P2P pura, ogni nodo implementa le funzionalità sia di client che di server, e ciascun peer può instaurare una sessione di comunicazione in qualsiasi momento. I nodi sono disposti in un'overlay network, costruita sopra ad una rete esistente, come Internet. Molte applicazioni peer-to-peer sono basate su una particolare classe di reti peer-to-peer: le Distributed Hash Tables (DHT). Le DHT sono reti peer-to-peer strutturate che forniscono un servizio di memorizzazione e recupero di informazioni simile ad una classica hash table, in cui le chiavi sono mappate a valori, in modo scalabile, flessibile ed auto-configurante. Questa tesi riporta i risultati della ricerca sull'applicazione delle tecnologie peer-to-peer al di là del file sharing. Il lavoro é stato concentrato in primo luogo sullo studio ed analisi delle implementazioni esistenti di reti peer-to-peer, specialmente le Distributed Hash Tables, e le proposte per protocolli peer-to-peer definite dall'IETF P2PSIP Working Group. La principale attività di ricerca é stata la definizione di un'architettura peer-to-peer, chiamata Distributed Location Service (DLS), che permette di instaurare connessioni dirette tra gli estremi di una comunicazione senza la necessità di dipendere da server centralizzati. Il Distributed Location Server é un servizio peer-to-peer basato su DHT che può essere utilizzato per memorizzare e recuperare informazioni relative a dove e come accedere alle risorse, eliminando il bisogno di dipendere (parzialmente) dal sistema DNS e da servizi di localizzazione centralizzati, come il SIP Location Service. Le informazioni di accesso sono memorizzate nel DLS come coppie chiave-valore, che sono mantenute da una moltitudine di nodi che partecipano alla DHT su cui si basa il DLS. Il DLS é stato implementato come un framework, definendo un set di interfacce standard per la comunicazione tra i componenti del DLS, al fine di consentire la massima flessibilità sui componenti, come l'algoritmo di DHT e il protocollo di comunicazione in uso, in quanto nessuna ipotesi é stata formulata al riguardo nella definizione dell'architettura del DLS. L'algoritmo di DHT Kademlia e il protocollo di comunicazione dSIP sono stati implementati ed integrati nel framework DLS per creare applicazioni basate su DLS al fine di dimostrare la praticabilità dell'approccio DLS. Queste applicazioni dimostrative sono state realizzate altresì con l'intento di mostrare che il peer-to-peer non può essere ridotto al solo file sharing, ma che applicazioni di comunicazione real-time, come il VoIP, file system distribuiti, e Social Netowrks possono essere realizzati utilizzando come base un'architettura peer-to-peer. Sebbene l'attività di ricerca sia stata condotta in maniera indipendente dall'IETF P2PSIP Working Group, il Distributed Location Service si é rivelato molto simile alla proposta ufficiale, chiamata RELOAD, con la quale condivide diversi concetti ed idee. Un altro aspetto studiato é stato il problema del bootstrapping nelle reti peer-to-peer. Quando un nodo intende unirsi ad una rete P2P esistente, esso deve contattare un nodo che appartiene già all'overlay P2P, il quale ammetterà il nuovo nodo. Tipicamente, la scoperta di un nodo che partecipa già all'overlay avviene attraverso meccanismi quali l'utilizzo di cache, liste di nodi pre-configurate e l'interrogazione di server centralizzati. Sebbene questi approcci abbiano funzionato finora, essi non appartengono alla filosofia peer-to-peer, in cui la decentralizzazione, la scalabilità e l'auto-configurazione sono aspetti cruciali. Si é quindi definito e validato un approccio basato su Multicast, il cui scopo é quello di ottenere un servizio caratterizzato da scalabilità ed auto-configurazione.Peer-to-peer technology has become popular primarily due to file sharing applications, such as Napster, Gnutella, Kazaa, and eMule, which have been the dominant component of usage of Internet bandwidth for several years. However, peer-to-peer technology is not all about file sharing. Many famous applications used by millions of users every day, such as Skype, are applications based on the peer-to-peer paradigm. The peer-to-peer (P2P) paradigm is a communication model in which multiple independent and heterogeneous devices interact as equals (peers). In a pure P2P network each node implements functions of both client and server, and either peer can initiate a communication session at any moment. Nodes are arranged on an overlay network, built on top of an existing network, such as the Internet. Many peer-to-peer applications are based on a particular class of peer-to-peer networks: Distributed Hash Tables (DHT). DHTs are structured peer-to-peer networks which provide a service of information storage and retrieval similar to a regular hash table where keys are mapped to values, in a scalable, flexible, and self-organizing fashion. This thesis reports the results of the research activity on applying peer-to-peer technology beyond file sharing. The work has been focused first on the study and analysis of existing peer-to-peer network implementations, especially on Distributed Hash Tables, and the proposals for peer-to-peer protocols presented by the IETF P2PSIP Working Group. The main research activity has been the definition of a peer-to-peer architecture, called Distributed Location Service (DLS), which allows the establishment of direct connections among the endpoints of a communication without the need of central servers. The Distributed Location Service is a DHT-based peer-to-peer service which can be used to store and retrieve information about where resources can be accessed, thus eliminating the need to rely (partially) on the DNS system and on central location servers, such as SIP Location Services. Access information is stored in the DLS as key-to-value mappings, which are maintained by a number of nodes that participate in the DHT overlay the DLS is built upon. The DLS has been implemented as a framework, by defining a standard set of interfaces between the components of the DLS, in order to allow maximum flexibility on components such as the DHT algorithm and communication protocol in use, as no assumption has been made in the definition of the DLS architecture. The Kademlia DHT algorithm and the dSIP communication protocol have been implemented and integrated in the DLS framework in order to create real-world DLS-based application to show the feasibility of the DLS approach. These demonstrative DLS-based applications have been realized with the intent to show that peer-to-peer is not just about file sharing, but real-time communication applications, such as VoIP, distributed file systems, and Online Social Networks, can also be built on top of a peer-to-peer architecture. Even though the research activity has been conducted independently from the IETF P2PSIP Working Group, the Distributed Location Service has been eventually found quite similar to the official proposal, named RELOAD, with whom it shares several concepts and ideas. Another aspect that was studied is the issue of bootstrapping in peer-to-peer networks. When a node wants to join an existing P2P network, it needs to gather information about one node that already belongs to the P2P overlay network which will then admit the new node. Typically, the discovery of a node that is already participating in the overlay is made through mechanisms such as caching, pre-configured list of nodes, or the use of central servers. Even though these approaches have worked so far, they are not in the true philosophy of peer-to-peer networks, where decentralization, scalability, and self-organization are critical features. A Multicast-based approach has therefore been defined and validated, with the goal of achieving true scalability and self-organization

Enabling technologies for decentralized interpersonal communication

In the recent years the Internet users have witnessed the emergence of Peer-to-Peer (P2P) technologies and applications. One class of P2P applications is comprised of applications that are targeted for interpersonal communication. The communication applications that utilize P2P technologies are referred to as decentralized interpersonal communication applications. Such applications are decentralized in a sense that they do not require assistance from centralized servers for setting up multimedia sessions between users. The invention of Distributed Hash Table (DHT) algorithms has been an important, but not an inclusive enabler for decentralized interpersonal communication. Even though the DHTs provide a basic foundation for decentralization, there are still a number of challenges without viable technological solutions. The main contribution of this thesis is to propose technological solutions to a subset of the existing challenges. In addition, this thesis also presents the preliminary work for the technological solutions. There are two parts in the preliminary work. In the first part, a set of DHT algorithms are evaluated from the viewpoint of decentralized interpersonal communication, and the second part gives a coherent presentation of the challenges that a decentralized interpersonal communication application is going to encounter in mobile networks. The technological solution proposals contain two architectures and two algorithms. The first architecture enables an interconnection between a decentralized and a centralized communication network, and the second architecture enables the decentralization of a set of legacy applications. The first algorithm is a load balancing algorithm that enables good scalability, and the second algorithm is a search algorithm that enables arbitrary searches. The algorithms can be used, for example, in DHT-based networks. Even though this thesis has focused on the decentralized interpersonal communication, some of the proposed technological solutions also have general applicability outside the scope of decentralized interpersonal communication

Enabling technologies for decentralized interpersonal communication

In the recent years the Internet users have witnessed the emergence of Peer-to-Peer (P2P) technologies and applications. One class of P2P applications is comprised of applications that are targeted for interpersonal communication. The communication applications that utilize P2P technologies are referred to as decentralized interpersonal communication applications. Such applications are decentralized in a sense that they do not require assistance from centralized servers for setting up multimedia sessions between users. The invention of Distributed Hash Table (DHT) algorithms has been an important, but not an inclusive enabler for decentralized interpersonal communication. Even though the DHTs provide a basic foundation for decentralization, there are still a number of challenges without viable technological solutions. The main contribution of this thesis is to propose technological solutions to a subset of the existing challenges. In addition, this thesis also presents the preliminary work for the technological solutions. There are two parts in the preliminary work. In the first part, a set of DHT algorithms are evaluated from the viewpoint of decentralized interpersonal communication, and the second part gives a coherent presentation of the challenges that a decentralized interpersonal communication application is going to encounter in mobile networks. The technological solution proposals contain two architectures and two algorithms. The first architecture enables an interconnection between a decentralized and a centralized communication network, and the second architecture enables the decentralization of a set of legacy applications. The first algorithm is a load balancing algorithm that enables good scalability, and the second algorithm is a search algorithm that enables arbitrary searches. The algorithms can be used, for example, in DHT-based networks. Even though this thesis has focused on the decentralized interpersonal communication, some of the proposed technological solutions also have general applicability outside the scope of decentralized interpersonal communication