Controlling the mobility and enhancing the performance of multiple message ferries in delay tolerant networks

In einem drahtlosen Netzwerk mit isolierten und stationären Knoten können Adhoc und verzögerungstolerante Netzwerk Routing-Protokolle nicht verwendet werden. Message Ferry Netzwerke sind die Lösung für diese Fälle, in denen ein (oder mehrere) Message Ferry Knoten den store-carry-forward Mechanismus verwendet und zwischen den Knoten reist, um Nachrichten auszutauschen. In diesem Fall erfahren die Nachrichten für gewöhnlich eine lange Verzögerung. Um die Performance der Message Ferry Netzwerke zu verbessern, kann die Mobilität der Message Ferry Knoten gesteuert werden. In dieser Doktorarbeit werden zwei Strategien zur Steuerung der Mobilität der Message Ferry Knoten studiert. Die Strategien sind das on-the-fly Entscheidungsverfahren in Ferry Knoten und die offline Wegplanung für Ferry Knoten. Für die on-the-fly Strategie untersucht diese Arbeit Decision-maker in Ferry Knoten, der die Entscheidung auf Grundlage der lokalen Observation eines Ferry Knoten trifft. Zur Koordinierung mehrerer Ferry Knoten, die keine globale Kenntnis über das Netzwerk haben, wird eine indirekte Signalisierung zwischen Ferry Knoten vorgeschlagen. Zur Kooperation der Ferry Knoten für die Zustellung der Nachrichten werden einige Ansätze zum Nachrichtenaustausch zwischen Ferry Knoten vorgeschlagen, in denen der Decision-maker eines Ferry Knotens seine Information mit dem verzögerungstoleranten Router des Ferry Knoten teilt, um die Effizienz des Nachrichtenaustauschs zwischen Ferry Knoten zu verbessern. Umfangreiche Simulationsstudien werden zur Untersuchung der vorgeschlagenen Ansätze und des Einflusses verschiedener Nachrichtenverkehrsszenarien vorgenommen. Außerdem werden verschiedene Szenarien mit unterschiedlicher Anzahl von Ferry Knoten, verschiedener Geschwindigkeit der Ferry Knoten und verschiedener Ansätze zum Nachrichtenaustausch zwischen Ferry Knoten studiert. Zur Evaluierung der offline Wegplanungsstrategie wird das Problem als Multiple Traveling Salesmen Problem (mTSP) modelliert und ein genetischer Algorithmus zur Approximation der Lösung verwendet. Es werden verschiedene Netzwerkarchitekturen zur Pfadplanung der Ferry Knoten vorgestellt und studiert. Schließlich werden die Strategien zur Steuerung der Mobilität der Ferry Knoten verglichen. Die Ergebnisse zeigen, dass die Performance der Strategien in Bezug auf die Ende-zu-Ende-Verzögerung von dem Szenario des Nachrichtenverkehrs abhängt. In Szenarien, wie Nachrichtenverkehr in Sensor-Netzwerken, in denen ein Knoten die Nachrichten zu allen anderen Knoten sendet oder von allen anderen Knoten empfängt, zeigt die offline Wegplanung, basierend auf der mTSP Lösung, bessere Performance als die on-the-fly Strategie. Andererseits ist die on-the-fly Stratgie eine bessere Wahl in Szenarien wie Nachrichtenaustausch zwischen Rettungskräften während einer Katastrophe, in denen alle drahtlose Knoten die Nachrichten austauschen müssen. Zudem ist die on-the-fly Strategie flexibler, robuster als offline Wegplanung und benötigt keine Initialisierungszeit.In a wireless network with isolated and stationary nodes, ad hoc and delay tolerant routing approaches fail to deliver messages. Message ferry networks are the solution for such networks where one or multiple mobile nodes, i.e. message ferry, apply the store-carry-forward mechanism and travel between nodes to exchange their messages. Messages usually experience a long delivery delay in this type of network. To improve the performance of message ferry networks, the mobility of ferries can be controlled. In this thesis, two main strategies to control mobility of multiple message ferries are studied. The strategies are the on-the-fly mobility decision making in ferries and the offline path planning for ferries. To apply the on-the-fly strategy, this work proposes a decision maker in ferries which makes mobility decisions based on the local observations of ferries. To coordinate multiple ferries, which have no global view from the network, an indirect signaling of ferries is proposed. For cooperation of ferries in message delivery, message forwarding and replication schemes are proposed where the mobility decision maker shares its information with the delay tolerant router of ferries to improve the efficiency of message exchange between ferries. An extensive simulation study is performed to investigate the performance of the proposed schemes and the impact of different traffic scenarios in a network. Moreover, different scenarios with different number of ferries, different speed of ferries and different message exchange approaches between ferries are studied. To study the offline path planning strategy, the problem is modeled as multiple traveling salesmen problem (mTSP) and a genetic algorithm is applied to approximate the solution. Different network architectures are proposed and studied where the path of ferries are planned in advance. Finally, the strategies to control the mobility of ferries are compared. The results show that the performance of each strategy, in terms of the average end-to-end delay of messages, depends on the traffic scenario in a network. In traffic scenarios same as the traffic in sensor networks, where only a single node generates messages to all nodes or receives messages from all node, the offline path planning based on mTSP solution performs better than the on-the-fly decision making. On the other hand, in traffic scenarios same as the traffic in disaster scenarios, where all nodes in a network may send and receive messages, the on-the-fly decision making provides a better performance. Moreover, the on-thy-fly decision making is always more flexible, more robust and does not need any initialization time

Evangelical Friend, January 1974 (Vol. 7, No. 5)

News of Friends Northwest conference - Faith and Life,Unity of concern marks meeting of Superintendents. Page 2 Editorials So, you want it calm in \u2774, \u27And they walked no more with him.\u27 Page 5 Through the uncertain with the unfailing In order to make 1974 a wonderful year, we need to expect great things and put our lives in God\u27s hands. Page 6 1973 - The end was not yet Norman B. Rohrer of the EPA brings into focus the events of 1973 in his annual Religion in Review. Page 7 East Whittier Friends and President Nixon Pastor Eugene Coffin writes an exclusive report on East Whittier Friends Church and the membership of Richard M. Nixon. Page 8 A declaration of evangelical social concern Fifty evangelical Christian leaders explore the importance of social concern for biblical faith. Page 9 Missionary Voice A visit to Friends in Bolivia 13Missions in the next ten years 15 What\u27s New! What about Senior Adults? Here\u27s a story of how three churches provide creative programs for this segment of our church. Page 17 Regular Features The Face of the World 4Friends Write 4The Children\u27s Page 18Friends Concerns 19Friends Gather 22Friends Record 25Books 26Over the Teacup 27https://digitalcommons.georgefox.edu/nwym_evangelical_friend/1072/thumbnail.jp

Congestion Control and Routing over Challenged Networks

This dissertation is a study on the design and analysis of novel, optimal routing and rate control algorithms in wireless, mobile communication networks. Congestion control and routing algorithms upto now have been designed and optimized for wired or wireless mesh networks. In those networks, optimal algorithms (optimal in the sense that either the throughput is maximized or delay is minimized, or the network operation cost is minimized) can be engineered based on the classic time scale decomposition assumption that the dynamics of the network are either fast enough so that these algorithms essentially see the average or slow enough that any changes can be tracked to allow the algorithms to adapt over time. However, as technological advancements enable integration of ever more mobile nodes into communication networks, any rate control or routing algorithms based, for example, on averaging out the capacity of the wireless mobile link or tracking the instantaneous capacity will perform poorly. The common element in our solution to engineering efficient routing and rate control algorithms for mobile wireless networks is to make the wireless mobile links seem as if they are wired or wireless links to all but few nodes that directly see the mobile links (either the mobiles or nodes that can transmit to or receive from the mobiles) through an appropriate use of queuing structures at these selected nodes. This approach allows us to design end-to-end rate control or routing algorithms for wireless mobile networks so that neither averaging nor instantaneous tracking is necessary

Elimination of doubt : methods for a predictive design to direct and optimize the flow of visitors

Ympäristömme globaalistuu ja monimutkaistuu kaiken aikaa. Prosessi näkyy muun muassa kansainvälisen liikenteen solmukohdissa. Esimerkiksi lentokentät ovat kyseisiä eri kulttuurien keskinäisen vuorovaikutuksen kohtia. Eri kulttuureista tulevien ihmisten pitää osata orientoitua vieraassa ja usein sekavassa ympäristössä. Jotta toiminta olisi sujuvaa näissä solmukohdissa, on suunnistamiseen tarvittavan tiedon oltava nopeasti omaksuttavaa ja ymmärrettävää. Monet muotoilijat ja suunnittelijat ajattelevat, että opastejärjestelmät ovat reduktionistisia ja mekanistisia syy-seuraus systeemejä. On kuitenkin ilmeistä, että kansainvälisesti harmonisoimattomien piktogrammien kyky välittää informaatiota on epäonnistunutta. Nykyiset kognitiotieteen havainnot osoittavat, että visuaalisen havaitsemisen ja tilallisen orientaation aikaisemmat mallit ovat vain osittain toimivia. Siispä oli syytä kysyä ”onko mahdollista tuottaa ennakoiva malli jonka avulla voi kehittää, toteuttaa ja varmistaa suunnitteluratkaisuja, jotka ohjaavat ja optimoivat vierailijoiden virtaa laajoissa julkisissa tiloissa.“ Tutkimuksen keskiössä on tästä syystä tilallisessa orientoitumisessa tapahtuva kulttuurinen merkityksellistäminen ja paikkatietoisuuden lisääminen (situation awareness). Juuri tuo yksilöllinen merkityksen tuottaminen voi tarkoittaa laajaa kirjoa erilaisia tulkintoja. Paikkatietoisuuden syntymisen erilaiset mahdollisuudet yhdessä erilaisten menetelmien kanssa voivat tuottaa ratkaisuja suunnitteluprosessiin. Suunnitteluprosessissa voidaan ottaa huomioon myös havaintopsykologisia näkökulmia. Kaiken kaikkiaan tämä johtaa systeemis-holistiseen ja käyttäjäkeskeiseen ajatteluun julkisten tilojen opastejärjestelmien suunnittelun kehityksessä. Esitän myös käytännöllisen ratkaisun opastejärjestelmien suunnitteluun ja arviointiin tarkastelemalla olemassa olevien järjestelmien rakennetta ja parametreja sekä niiden kehitystyötä. Työ sisältää yhteensä yhdeksän tapaustarkastelua. Tutkimusmenetelminä käytin laadullista havainnointia ja kvantitatiivista analyysiä. Havainnoin ja tulkitsin etnisiä tottumuksia ja henkilökohtaisia näkemyksiä. Tekemäni kyselyjen perusteella näyttää siltä, että konstruoimaani mallia voitaisiin käyttää kehittämisen ja todentamisen välineenä.The rapid development of international traffic characterizes our increasingly globalized and ever more complex world. Nodal points (for example, airports) have formed where people from various cultural backgrounds and with differing levels of educational attainment need to reorient themselves in a unfamiliar and often confusing environment. A key condition to ensure everything works smoothly in such an international junction is the extremely fast reception and processing of information by everyone involved. The dominant school of thought among many designers and planners of guidance and routing systems is still a reductionist and mechanistic one (cause - effect). It has become apparent that the use of non-internationally harmonized pictograms as information carriers has failed completely. Recent findings in the field of cognitive science demonstrate convincingly that previous models of visual perception and spatial orientation can only highlight partial aspects. For these aspects, the question has arisen: “Is there a possibility to evolve a predictive system to develop, implement and verify design solutions to direct and optimize the flow of visitors in large public spaces?” Therefore, the moment of semiosis of the orientation seekers moved into the focus of the investigation. This moment of meaning-making, which is perceived by every individual differently, spans the entire spectrum of the perception of the designated item (the optical characteristic of the character substrate) between manifold interpretation or absolute certainty. The various viewing options of “situational awareness” with the help of various methodologies provide solutions for the design process. Taking the aspects of perceptual psychology into account leads to the development of a systemic/holistic and user-centred design of orientation systems in public spaces. Identifying and consulting the predictive parameters in a systematic process could show a practicable solution for the planning and evaluation of guidance and routing systems. In various national and international case studies, the process reliability and processing quality of this solution were demonstrated. Involving mixed research methodologies of qualitative observation and quantitative analysis, it was possible to develop a workable model. Through observation and interpretation, ethnic habits and personal views were taken into account to develop the methods. The use of questionnaires or surveys created statistics to prove or disprove the hypothetical model. The capacity of the presented model and the operationalization of the research demonstrated an effective method for overcoming barriers of age, language and culture. The publication satisfies, therefore, the criteria of the academic quality of a practice-based Ph.D