Scalable and flexible location-based services for ubiquitous information access

In mobile distributed environments applications often need to dynamically obtain information that is relevant to their current location. The current design of the Internet does not provide any conceptual models for addressing this issue. As a result, developing a system that requires this functionality becomes a challenging and costly task, leading to individual solutions that only address the requirements of specific application scenarios. In this paper we propose a more generic approach, based on a scalable and exible concept of location-based services, and an architectural framework to support its application in the Internet environment. We describe a case study in which this architectural framework is used for developing a location-sensitive tourist guide. The realisation of this case study demonstrates the applicability of the framework, as well as the overall concept of location-based services, and highlights some of the issues involved.To the GUIDE team, and especially to Keith Mitchell and Matthias Franz, for their collaboration in the preparation of this case study. To Adrian Friday for his comments on a draft version of this paper. To the anonymous reviewers for their attentive reading and valuable comments. This work was carried out as part of the PRAXIS funded AROUND project (PRAXIS/P/EEI/14267/1998) and supported by grant PRAXIS XXI/BD/13853/97

Inter Vehicle Distance based connectivity aware routing in vehicular adhoc networks

Connectivity in vehicular traffic environment has witnessed significant attention due to the direct impact on the performance of most of the traffic safety applications of intelligent transport system. Various parameters such as density, speed, direction, link quality and inter vehicle distance (IVD) have been utilized for measuring connectivity. IVD has greater impact on connectivity and controls the impact of other parameters. Usage of real time IVD for measuring connectivity has not received sufficient attention in VANETs. This paper proposes IVD based connectivity aware routing (Ivd-CAR) for enhancing connectivity aware data dissemination. IVD calculation is robust and can effectively handle instantaneous GPS failure. Two localization techniques; namely, cooperative localization and Geometry based Localization are developed. Standard deviation of real time IVDs of a forwarding path is derived. Distribution of IVDs of a forwarding path is employed for estimating connectivity. Segment vehicle based next hop vehicle selection is utilized for incorporating network load, link quality and direction into consideration while selecting forwarding path. Simulations are carried out in ns2 to evaluate the performance of Ivd-CAR in realistic traffic environment. Comparative analysis of simulation results attests the superiority of Ivd-CAR to the state-of-the-art techniques: CSR and A-CAR

A fine-grained addressing concept for GeoCast

GeoCast provides the functionality of sending messages to everyone in a specific area. So far, only the addressing of larger two-dimensional areas was possible. For the use in an urban environment it is crucial that small and three-dimensional areas can be addressed. For example, GeoCast can then be used to send lecture notes to all in a classroom. In this paper we describe a fine-grained addressing concept for GeoCast that supports such areas. In addition we present an architecture that allows the use of that addressing concept together with the GeoRouting-approach developed by Navas and Imielinski. We also present some modifications necessary to enhance the scalability of GeoCast

Internet-wide geo-networking problem statement

This document describes the need of specifying Internet-wide location-aware forwarding protocol solutions that provide packet routing using geographical positions for packet transport

Algoritmi di routing per Vehicular Ad-hoc NETworks (VANETs)

La tesi si propone di presentare la situazione attuale delle reti veicolari mobili. Vengono analizzate brevemente le reti MANET (Mobile Ad-hoc NETwork) e poi presentate le VANET (Vehicular Ad-hoc NETwork) come sottoinsieme delle prime. Si analizzeranno poi le differenze rispetto alle reti infrastrutturate e si individueranno i problemi che possono insorgere nelle trasmissioni. Viene infine presentata una suddivisione dei protocolli di routing presenti in letteraturaope

Adressierung und Semantik von geographischen Nachrichten

In den letzten Jahren haben mobile Computer eine große Verbreitung gefunden. Zur gleichen Zeit wurden Systeme zur Ortsbestimmung (z.B. GPS) auch für normale Anwender verfügbar. Schnell wurde klar, daß eine Kombination dieser beiden Technologien einen deutlichen Mehrwert für die Nutzer bieten kann. Wenn die Information über den aktuellen Aufenthaltsort des Nutzers vorhanden ist, liegt es nahe diese auch für die Kommunikation zu verwenden. Ähnlich wie beim Multicast ist es auch beim sogenannten GeoCast möglich, mehreren Empfängern eine Nachricht zukommen zu lassen. Nur müssen die Empfänger beim GeoCast keiner Gruppe beitreten. Der Sender spezifiziert viel mehr das Zielgebiet der Nachricht, und alle potentiellen Empfänger, die sich in diesem Gebiet befinden, erhalten die Nachricht. Im Bereich GeoCast sind vor allem zwei Bereiche noch nicht intensiv betrachtet worden. Zum einen ist die Frage der Adressierung des Zielgebietes noch offen. Also wie sehen die Adressierungskonzepte aus, mit denen ein Sender das Zielgebiet spezifizieren kann. Die andere Frage die noch nicht sauber betrachtet wurde, ist die Semantik. Welche Semantik hat eine geographische Nachricht. Was sind Alternativen, und warum sind welche Alternativen am sinnvollsten. Diese Fragen sollen in dieser Arbeit näher betrachtet werden

Nopea tiedonsiirto asennusjärjestelmissä

Tässä tutkielmassa esitellään, miten ryhmälähetystekniikkaa voidaan käyttää hyväksi suurien datamäärien kopioinnissa sekä käydään lävitse ryhmälähetystekniikkaa soveltavan ohjelmiston suunnittelu, toteutus ja arviointi. Ohjelmistoa arvioidaan kahdella erilaisella testillä, datan siirtonopeustestillä ja ohjelmiston asennusnopeustestillä. Ohjelmiston tuomia etuja tarkastellaan niin yrityksen kuin ohjelmaa käyttävän henkilön näkökulmasta. Huomioitavia laatukriteereitä ovat esimerkiksi varmuus, käytettävyys ja taloudellisuus

Overlay networks for intelligent transportation systems

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores - Major de Telecomunicações. Faculdade de Engenharia. Universidade do Porto. 200

Spatiotemporal Multicast and Partitionable Group Membership Service

The recent advent of wireless mobile ad hoc networks and sensor networks creates many opportunities and challenges. This thesis explores some of them. In light of new application requirements in such environments, it proposes a new multicast paradigm called spatiotemporal multicast for supporting ad hoc network applications which require both spatial and temporal coordination. With a focus on a special case of spatiotemporal multicast, called mobicast, this work proposes several novel protocols and analyzes their performances. This dissertation also investigates implications of mobility on the classical group membership problem in distributed computing, proposes a new specification for a partitionable group membership service catering to applications on wireless mobile ad hoc networks, and provides a mobility-aware algorithm and middleware for this service. The results of this work bring new insights into the design and analysis of spatiotemporal communication protocols and fault-tolerant computing in wireless mobile ad hoc networks