Proof-of-Concept Implementation of the Ahoy Discovery Protocol for Ad-hoc Networks

The context discovery protocol Ahoy has been proposed ear- lier for resource-limited fully-distributed ad-hoc networks. Ahoy has been proven as an efficient context discovery pro- tocol, which generates only little network traffic, in both static and dynamic ad-hoc networks. In this report, we im- plement the prototype of Ahoy and test it on UNIX-like platforms. We show the possibility to implement Ahoy in the real world

Context discovery using attenuated Bloom filters in ad-hoc networks

A novel approach to performing context discovery in ad-hoc networks based on the use of attenuated Bloom filters is proposed in this paper. In order to investigate the performance of this approach, a model has been developed. This document describes the model and its validation. The model has been implemented in Matlab, and some results are also shown in this document. Attenuated Bloom filters appear to be a very promising approach for context discovery in ad hoc networks

Context discovery using attenuated Bloom codes: model description and validation

A novel approach to performing context discovery in ad-hoc networks based on the use of attenuated Bloom filters is proposed in this report. In order to investigate the performance of this approach, a model has been developed. This document describes the model and its validation. The model has been implemented in Matlab, and results are also shown in this document. Attenuated Bloom filters appear to be a very promising approach for context discovery in ad hoc networks compared to conventional solutions. The results show that using attenuated Bloom filters in context discovery can well save traffic load in a fully distributed ad hoc network in practical situations

Optimization of Critical Data Synchronization via Link Overlay RNG in Mobile Ad Hoc Networks

International audienceIn practice, ad hoc networks are still too unreliable for standard mobile and vehicular communications. It is thus important to complement current protocols in this context, with schemes guaranteeing the exchange of critical data when needed. A promising approach in this realm is to use an overlay subgraph, over which critical messages are exchanged and acknowledged in a peer to peer fashion. Overlay nodes' local databases remain thus synchronized over time, at least concerning critical data. This paper elaborates on the problem of performance, related to the discovery and maintenance of such overlay networks in a mobile ad hoc context. We analyze SLOT, an overlay selected based on a Relative Neighbour Graph (RNG) scheme. We then apply SLOT to a standard IP protocol: OSPF, a popular routing protocol which has recently been extended, with RFC 5449 and RFC 5614, to work also on mobile ad hoc networks, and which makes use of a similar overlay synchronization subgraph. This paper compares the performance of these existing OSPF mechanisms with that of SLOT-OSPF, a novel OSPF extension for mobile ad hoc networks using SLOT. Simulations show that SLOT-OSPF produces drastically less control traffic than RFC 5449 or RFC 5614, allowing SLOT-OSPF to function correctly while the other existing approaches stall, when the number of routers in the domain is large

Modeling, Designing, and Implementing an Ad-hoc M-Learning Platform that Integrates Sensory Data to Support Ubiquitous Learning

Learning at any-time, at anywhere, using any mobile computing platform learning (which we refer to as “education in your palm”) empowers informal and formal education. It supports the continued creation of knowledge outside a classroom, after-school programs, community-based organizations, museums, libraries, and shopping malls with under-resourced settings. In doing so, it fosters the continued creation of a cumulative body of knowledge in informal and formal education. Anytime, anywhere, using any device computing platform learning means that students are not required to attend traditional classroom settings in order to learn. Instead, students will be able to access and share learning resources from any mobile computing platform, such as smart phones, tablets using highly dynamic mobile and wireless ad-hoc networks. There has been little research on how to facilitate the integrated use of the service description, discovery and integration resources available in mobile and wireless ad-hoc networks including description schemas and mobile learning objects, and in particular as it relates to the consistency, availability, security and privacy of spatio-temporal and trajectory information. Another challenge is finding, combining and creating suitable learning modules to handle the inherent constraints of mobile learning, resource-poor mobile devices and ad-hoc networks. The aim of this research is to design, develop and implement the cutting edge context-aware and ubiquitous self-directed learning methodologies using ad-hoc and sensor networks. The emphasis of our work is on defining an appropriate mobile learning object and the service adaptation descriptions as well as providing mechanisms for ad-hoc service discovery and developing concepts for the seamless integration of the learning objects and their contents with a particular focus on preserving data and privacy. The research involves a combination of modeling, designing, and developing a mobile learning system in the absence of a networking infrastructure that integrates sensory data to support ubiquitous learning. The system includes mechanisms to allow content exchange among the mobile ad-hoc nodes to ensure consistency and availability of information. It also provides an on-the-fly content service discovery, query request, and retrieving data from mobile nodes and sensors

Konzeption und Realisierung eines kontextsensitiven Routingverfahrens

Communication and information services both depend on the individual needs of the users and on the possibilities of the used network techniques. To provide an optimal service level adapted to the user, his context must be considered. Thereby, service access should be carried out as flexibly and independently from the network as possible. Infrastructure networks, due to their topology, cannot give mobile access to such services everywhere. Mobile ad hoc networks are not bound to any infrastructure and are therefore very flexibly applicable. As a result of their dynamic topology, there are special requirements to routing and service discovery compared to conventional networks. Conventional methods usually are neither usable in ad hoc networks, nor suitable in heterogeneous environments. Especially because of the progressive convergence of the networks a network-wide solution is inevitable. This work therefore is concerned with the topics of ad hoc networks as well as routing protocols and procedures which are used for these. Possibilities for service discovery are described and compared. Based on this, an architectural concept is developed, which permits service discovery both in ad hoc networks and in conventional infrastructure networks. Service discovery is combined with a routing protocol especially extended for this purpose. Why this kind of service discovery on network level is advantageous is described and well founded. Principal components of the developed architecture are the so-called context-routers, which support service discovery independently of the address of a service provider. Thus, the user does not need to know such an address. Service discovery is, therefore, depending on the service itself and on the available information about the context of the user. Hence, a service optimally adapted to the user is selected. The concept supports rerouting data messages to an alternative server, if the original server breaks down, and offers the possibility for the provider to control service discovery and communication. A verification of the presented concept is carried out with practical implementations. The demonstrator network developed for this is used for a set of tests to verify the functions and the efficiency of the architecture. The results prove that the concept can meet the requirements. Finally, suggestions for future advancements conclude this dissertation.Das Angebot von Kommunikations- und Informationsdiensten richtet sich einerseits nach den individuellen Bedürfnissen der Nutzer andererseits aber auch nach den Möglichkeiten der verwendeten Netztechniken. Um einen optimal auf den Nutzer angepassten Dienst bereitstellen zu können, muss dessen Kontext berücksichtigt werden. Ein Dienstzugriff soll dabei möglichst flexibel und unabhängig vom Netz erfolgen. Den mobilen Zugriff auf solche Dienste können Infrastrukturnetze, durch ihre Topologie bedingt, nicht überall bedienen. Mobile Ad-hoc-Netze sind dagegen an keine Infrastruktur gebunden und deshalb sehr flexibel einsetzbar. Durch deren dynamische Topologie ergeben sich jedoch gegenüber den herkömmlichen Netzen auch spezielle Anforderungen an die Routen- und Dienstsuche. Konventionelle Verfahren sind hierbei in der Regel weder nutzbar, noch für einen Einsatz in heterogenen Umgebungen geeignet. Gerade mit der fortschreitenden Konvergenz der Netze ist aber eine netzübergreifende Lösung unumgänglich. Die vorliegende Arbeit befasst sich deshalb mit den Themen Ad-hoc-Netze sowie den hierbei eingesetzten Routingprotokollen und -verfahren. Es werden Möglichkeiten zur Dienstsuche erläutert und gegenübergestellt. Mit den Erkenntnissen daraus wird ein Architekturkonzept entwickelt, das die Dienstsuche sowohl in Ad-hoc- als auch in herkömmlichen Infrastrukturnetzen erlaubt. Die Dienstsuche erfolgt dabei in Verbindung mit einem für diesen Zweck erweiterten Routingverfahren. Warum diese Art einer Dienstsuche auf Netzwerkebene vorteilhaft ist, wird erläutert und begründet. Kernstück der entwickelten Architektur bilden die so genannten Kontextrouter, die eine Dienstsuche unabhängig von der Adresse eines Dienstanbieters unterstützen. Auch der Nutzer benötigt keine Kenntnis über eine solche Adresse. Eine Suche erfolgt lediglich über den Dienst und den zur Verfügung stehenden Informationen über den Kontext des Nutzers. Damit wird ein auf den Nutzer optimal angepasster Dienst ausgewählt. Das Konzept unterstützt die Weiterleitung von Daten zu einem alternativen Server, sofern der ursprüngliche Server ausfällt, und bietet Providern die Möglichkeit, steuernd auf die Dienstsuche und -kommunikation einzuwirken. Das Verifizieren des vorgestellten Konzeptes erfolgt auf Basis praktischer Realisierungen. Das dazu aufgebaute Demonstratornetzwerk dient für eine Reihe von Tests zum Nachweis der Funktionen und der Leistungsfähigkeit der Architektur. Die daraus resultierenden Ergebnisse beweisen, dass das Konzept den gestellten Anforderungen genügen kann. Abschließend werden in der Arbeit Vorschläge für zukünftige Weiterentwicklungen unterbreitet

Achieving Coordination Through Dynamic Construction of Open Workflows ** PLEASE SEE WUCSE-2009-14 **

Workflows, widely used on the Internet today, typically consist of a graph-like structure that defines the orchestration rules for executing a set of tasks, each of which is matched at run-rime to a corresponding service. The graph is static, specialized directories enable the discovery of services, and the wired infrastructure supports routing of results among tasks. In this paper we introduce a radically new paradigm for workflow construction and execution called open workflow. It is motivated by the growing reliance on wireless ad hoc networks in settings such as emergency response, field hospitals, and military operations. Open workflows facilitate goal-directed coordination among physically mobile agents (people and host devices) that form a transient community over an ad hoc wireless network. The quintessential feature of the open workflow paradigm is the ability to construct a custom context-specific workflow specification on the fly in response to unpredictable and evolving circumstances by exploiting the knowhow and services available within a given spatiotemporal context. This paper introduces the open workflow approach and explores the technical challenges (algorithms and architecture) associated with its first practical realization

Using Relative Neighborhood Graphs for Reliable Database Synchronization in MANETs

International audienceAchieving reliable communication of critical data on mobile ad hoc networks is a must before MANETs can be considered practical for standard mobile and vehicular commu- nications. This paper thus focuses on schemes that complement existing ad hoc broadcast mechanisms (inherently unreliable), which can guarantee the full diffusion of critical messages, when necessary. An interesting approach in this domain is the use of an overlay network, over which critical messages are acknowledged peer to peer, in order to verify the actual dissemination. This paper elaborates on the problem of performance, related to the discovery and the maintenance of such an overlay network, in a mobile ad hoc context. We present an analysis of a novel algorithm, SLOT (Synchronized Link Overlay - Triangular), an overlay selected based on a Relative Neighborhood Graph (RNG) scheme, and we compare its performance with that of other existing algorithms, in the context of the industry-standard IP routing protocol OSPF, which uses alternative overlay algorithms to synchronize link state databases of routers. The results presented in this paper show that SLOT outperforms other existing overlays by necessitating drastically less control traffic in order to function, enabling OSPF to scale to larger mobile ad hoc topologies

BeFriend: platforma za kontekstno-svjesno ad-hoc društveno umrežavanje

Ad-hoc social networks, focused on managing user social relationships in a novel fashion based on establishment of temporary social connections among users with mutual interests and/or needs, provide an innovative medium for upgrading existing, as well as developing new social relationships. This paper describes the BeFriend, a context-aware ad-hoc social networking platform based on Facebook and Google+ social graphs. The BeFriend platform is for mobile users equipped with a smartphone -- after installing and activating the BeFriend client, they are able to receive push notifications when a certain rule is triggered (e.g. it is Friday evening, Ewan and Luke are drinking beer in a bar and one of their Facebook/Google+ friends passes nearby). Personal agents within the BeFriend platform provide autonomous decision-making in the platform, decrease the need for user input and enable automated social discovery of new community members. The proof of-concept BeFriend platform presented in this paper is available in form of BeFriend application for users possessing Android-based smartphones.Ad-hoc društvene mreže su usmjerene na novi pristup upravljanju društvenim odnosima koji se temelji na uspostavi privremene društvene povezanosti među korisnicima sa zajedničkim interesima i/ili potrebama. Na taj način ad-hoc društvene mreže predstavljaju inovativni medij za nadogradnju postojećih te razvoj novih društvenih odnosa. Ovaj rad opisuje platformu za kontekstno-svjesno ad-hoc društveno umrežavanje BeFriend, koja je zasnovana na društvenim grafovima Facebook i Google+. Platforma BeFriend je namijenjena korisnicima pametnih pokretnih uređaja te omogućuje, nakon instalacije i aktivacije klijenta BeFriend, primanje push-obavijesti potaknuto aktiviranjem određenog pravila (primjerice, Ewan i Luke piju pivu u kafiću u petak navečer te njihov Facebook/Google+ prijatelj upravo prolazi pokraj kafića). Osobni agenti koji su dio platforme BeFriend omogućuju samostalno donošenje odluka unutar platforme, što smanjuje potrebu za korisničkim akcijama ili intervencijama i omogućuje automatski pronalazak novih članova društvene zajednice. Prototip platforme BeFriend koji je opisan u ovome radu dostupan je kao aplikacija BeFriend korisnicima koji posjeduju pametne pokretne uređaje zasnovane na operacijskom sustavu Android