One of the challenging issues for mobile ad hoc network (MANET) applications is data replication. Unreliable wireless communication, mobility of network participators and limited resource capacities of mobile devices make conventional replication techniques useless for MANETs. Frequent network divisions and unexpected disconnections should be handled. In this thesis work, a novel mobility and power aware, data interest based data replication strategy is presented. Main objective is to improve data accessibility among a mission critical mobility group. A clustering approach depending on mobility and data interest patterns similarities is introduced. The investigated replica allocation methodology takes care of data access frequency and data correlation values together with mobile nodes&rsquo / remaining energy and memory capacities. Performance of the proposed approach is analyzed in terms of data accessibility / cache hit ratio and traffic metrics. Improvements are observed by data interest based clustering in addition to mobility awareness over sole mobility aware clustering. Advantages of power aware replica allocation are demonstrated by experimental simulations.

I många nätverk antas det att någon form av fix infrastruktur existerar och att nätverkets olika noder kan använda denna för att kommunicera med varandra. I ett ad hoc-nätverk antar man att det inte finns någon fix infrastruktur och att noderna måste använda varandra för att kunna kommunicera. Ett exempel på ett ad hoc-nätverk kan vara bärbara datorer sammankopplade med infraröda länkar under ett möte. När ad hoc-nätverket är mobilt innebär det att noderna rör sig. I detta arbete har de tre protokollen Epidemic, GeoMean och GeoMove tillsammans med de två rörelsemodellerna Waypoint och den utökade slumpmässiga vandringen implementerats i en nyskriven simulator för denna typ av nätverk. De två Geo-protokollen är nyutvecklade och syftar till att använda geografisk information för att underlätta kommunikationen i denna kategori av nätverk tillsammans med den nya utvidgade slumpmässiga vandringsmodellen. / In many networks, some kind of fix infrastructure is assumed to exist and the nodes of the network can use this infrastructure to communicate with each other. In an ad hoc network one assumes that there don't exist any kind of fix infrastructure and that the nodes must use each other to be able to communicate. One example of an ad hoc network could be laptops connected together with infrared links during a meeting. When an ad hoc network is mobile it implies that the nodes are moving. In this work, the three protocols Epidemic, GeoMean and GeoMove together with the two mobility models Waypoint and Extended Random Walk, have been implemented in a newly written simulator for this kind of network. The two Geo-protocols are newly developed and aim to use geographical information to aid communication in this category of networks together with the new Extended Random Walk model.

Thesis (MSc (Mathematical Sciences)--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In this thesis, a pricing mechanism to stimulate cooperation between nodes in ad hoc networks is explored. The model incorporates incentives for users to act as transit nodes and carry the traffic between other nodes on multi-hop paths, and to be rewarded with their own ability to send traffic. The thesis investigates the consequences of this pricing model by means of simulation of a network and illustrates the way in which network resources are allocated to users according to their geographical position. Moreover, since modelling node movements is an important aspect in ad hoc network simulation, a collective mobility model, the adaptive mobility model, is used to maximise the area coverage of the nodes. / AFRIKAANSE OPSOMMING: In hierdie tesis word ’n koste meganisme gebruik om samewerking te stimuleer tussen nodusse in ad hoc netwerke. Die model inkorporeer trekpleisters deur gebruikers te beloon om verkeer te stuur deur op te tree as transito nodusse, en verkeer tussen nodusse op multi-skakel paaie te dra. Die tesis ondersoek die ge- volge van die koste model deur die simulering van ’n netwerk, en demonstreer die manier waarop die netwerk hulpbronne geallokeer word aan gebruikers gebaseer op hulle geografiese posisie. Siende dat die modellering van nodus bewegings ’n belangrike aspek is in ad hoc netwerk simulasie, word ’n kollek- tiewe mobiliteits model sowel as ’n veranderlike mobiliteits model gebruik om die dekkings areas van die nodusse te maksimeer.

Submitted by LEONEL DA FONTOURA MATTOSO NEGREIROS FARIA (leonelfaria@hotmail.com) on 2018-07-15T15:53:43Z No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 927107 bytes, checksum: fbf14b67a7c420c60157bbeed1c4cc49 (MD5) / Rejected by Thais Oliveira (thais.oliveira@fgv.br), reason: Boa tarde, Leonel, Para que possamos aprovar seu trabalho, serão necessárias as seguintes alterações: ´- O nome GETULIO, da capa, não tem acendo; - A Lista de Figuras, Tabelas e Sumário devem estar em páginas separadas; - Adicionar o número na página da Introdução. Por gentileza, alterar e submeter novamente. Para qualquer dúvida, entre em contato. Thais Oliveira - SRA mestradoprofissional@fgv.br - 3799-7764 on 2018-07-18T17:30:17Z (GMT) / Submitted by LEONEL DA FONTOURA MATTOSO NEGREIROS FARIA (leonelfaria@hotmail.com) on 2018-07-18T22:55:50Z No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 932254 bytes, checksum: d4565924757aebfd1ccca3560e3eccea (MD5) / Rejected by Thais Oliveira (thais.oliveira@fgv.br), reason: Boa tarde, Leonel, Conforme conversado, a Data da Aprovação deve estar em branco para que possamos aprovar. Por gentileza, alterar e submeter novamente. Obrigada! on 2018-07-19T16:35:52Z (GMT) / Submitted by LEONEL DA FONTOURA MATTOSO NEGREIROS FARIA (leonelfaria@hotmail.com) on 2018-07-20T00:45:37Z No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 930936 bytes, checksum: d20eac773c3509c258654a88ab69baf5 (MD5) / Approved for entry into archive by Thais Oliveira (thais.oliveira@fgv.br) on 2018-07-20T16:47:53Z (GMT) No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 930936 bytes, checksum: d20eac773c3509c258654a88ab69baf5 (MD5) / Approved for entry into archive by Suzane Guimarães (suzane.guimaraes@fgv.br) on 2018-07-20T17:12:16Z (GMT) No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 930936 bytes, checksum: d20eac773c3509c258654a88ab69baf5 (MD5) / Made available in DSpace on 2018-07-20T17:12:16Z (GMT). No. of bitstreams: 1 EVIDÊNCIAS DE AJUSTES NO LANCE MÉDIO DE ADVERTISERS EM UMA AD EXCHANGE DADO A PERCEPÇÂO DE FRAUDE.pdf: 930936 bytes, checksum: d20eac773c3509c258654a88ab69baf5 (MD5) Previous issue date: 2018-06-27 / Este trabalho tem como objetivo identificar se lances médios de anunciantes sofrem algum impacto dado a um aumento na popularidade de termos de busca no Google referentes a fraude na indústria ou devido a notícias de casos de fraude. Para isto, são analisados dados mensais de Janeiro de 2014 a Janeiro de 2018 de lances médios de uma Ad Exchange, (construído a partir do valor faturado e volume de instalações do aplicativo fim), popularidade mensal de termos de busca no Google (Ad Fraud, Mobile Ad Fraud e Mobile Advertising) bem como datas de notícias sobre fraudes para encontrar evidências de que um aumento na popularidade do termo 'Ad Fraud' impacta negativamente no lance médio, um aumento no termo 'Mobile Advertising' impacta positivamente no lance médio, e uma notícia de fraude de 2016 também têm efeito negativo sobre o lance médio dos Advertisers. / This work checks for empirical evidence that Advertisers’ bids are impacted by fraud related search terms popularity in Google regarding the mobile advertising industry and by fraud related news. For this to be accomplished, monthly data from January 2014 to January 2018 from an Ad Exchange regarding Advertisers’ monthly bid (calculated based on spend and app installs) is gathered and compared with 'Ad fraud', 'Mobile Ad Fraud' and 'Mobile Advertising' search terms popularity in Google as well as fraud volume related news dates, to find evidence that an increase in 'Ad Fraud' term popularity has a negative impact in the average bid, an increase in 'Mobile Advertising' term popularity has a positive impact in the average bid and a 2016 fraud related news also has a negative impact in Advertisers average bid.

Wireless communication has grown very popular, and communication is the key to success in many situations. However, most of the common technologies today rely on infrastructure and in disaster situations infrastructure might be lost or get severely overloaded. This master thesis concerns intermittently connected mobile ad hoc networks. A network in which the devices may move freely in any direction and still be able to communicate. To be able to demonstrate a network protocol called random-walk gossip-based manycast (RWG) my assignment has been to implement this protocol using off-the-shelf hardware and software. RWG is a multi-hop and partition-tolerant mobile ad hoc manycast network protocol. Multi-hop refers to information being able to hop between more than two nodes in a network and partition-tolerant means that the protocol works even though a network is partitioned. Manycast means that the information should be successfully delivered to K of all the potential nodes in the area. The RWG protocol makes use of four different packet types, request to forward (REQF), ac- knowledgement (ACK), ok to forward (OKTF) and be silent (BS). The actual data being sent is carried by REQFs, and is referred to as messages. When a message is sent it takes what could be described as a random walk among the nodes in the network, hence the name. The implementation of the RWG protocol resides in user-space and depends on the IEEE 802.11b standard and the raw socket that is specified in the BSD socket API. It is written in C and was developed on a machine running Ubuntu. It runs on systems that use Linux 2.6 kernels and it supports cross-compiling for ARM based devices such as the Nokia N810 internet tablet and the Android dev phone 1. To be able to demonstrate the protocol I developed my own client application. Moreover, an already existing application for Android, Portable Open Search and Identification Tool (POSIT), was successfully extended to run on top of the RWG implementation. The extension was developed by people in the POSIT project and tested in a physical experiment covering five devices. The report covers the RWG protocol, the system choice, the implementation and the testing of the implementation.

Internet and mobile communications have had a profound effect on today’s society. New services are constantly being deployed, in which an increasing amount of personal data is being processed in return for personally tailored services. Further, the use of electronic surveillance is increasing. There is the risk that honest citizens will have their privacy invaded for “the greater good”. We argue that it is of uttermost importance to retain the individuals’ control over their personal spheres. One approach for enhancing the users’ privacy is to deploy technical measures for safeguarding privacy, so-called Privacy-Enhancing Technologies (PETs). This thesis examines a set of PETs for enabling anonymous communication, so-called anonymous overlay networks,which eliminate the processing of personal data altogether by allowing the users act anonymously when communicating in a networked environment. This thesis focuses mainly on mobile networks. These are of great interest because on the one hand they lay the groundwork for new innovative applications, but on the other hand they pose numerous novel challenges to privacy. This thesis describes the implementation and performance evaluation of mCrowds – an anonymous overlay network for mobile Internet that enables anonymous browsing. It also describes the ongoing investigation on how to design anonymous overlay networks in order to make them suitable for mobile ad hoc networks, a required building block for ambient intelligence.

No description available.

A mobile ad hoc network (MANET) is an infrastructure-less multi-hop network where each node communicates with other nodes directly or indirectly through intermediate nodes. Thus, all nodes in a MANET basically function as mobile routers participating in some routing protocol required for deciding and maintaining the routes. Since MANETs are infrastructure-less, self-organizing, rapidly deployable wireless networks, they are highly suitable for applications such as military tactical operations, search and rescue missions, disaster relief operations, and target tracking. Building such ad-hoc networks poses a significant technical challenge because of energy constraints and specifically in relation to the application of wireless network protocols. As a result of its highly dynamic and distributed nature, the routing layer within the wireless network protocol stack, presents one of the key technical challenges in MANETs. In particular, energy efficient routing may be the most important design criterion for MANETs since mobile nodes are powered by batteries with limited capacity and variable recharge frequency, according to application demand. In order to conserve power it is essential that a routing protocol be designed to guarantee data delivery even should most of the nodes be asleep and not forwarding packets to other nodes. Load distribution constitutes another important approach to the optimisation of active communication energy. Load distribution enables the maximisation of the network lifetime by facilitating the avoidance of over-utilised nodes when a route is in the process of being selected. Routing algorithms for mobile networks that attempt to optimise routes while at- tempting to retain a small message overhead and maximise the network lifetime has been put forward. However certain of these routing protocols have proved to have a negative impact on node and network lives by inadvertently over-utilising the energy resources of a small set of nodes in favour of others. The conservation of power and careful sharing of the cost of routing packets would ensure an increase in both node and network lifetimes. This thesis proposes simultaneously, by using an ant colony optimisation (ACO) approach, to optimise five power-aware metrics that do result in energy-efficient routes and also to maximise the MANET's lifetime while taking into consideration a realistic mobility model. By using ACO algorithms a set of optimal solutions - the Pareto-optimal set - is found. This thesis proposes five algorithms to solve the multi-objective problem in the routing domain. The first two algorithms, namely, the energy e±ciency for a mobile network using a multi-objective, ant colony optimisation, multi-pheromone (EEMACOMP) algorithm and the energy efficiency for a mobile network using a multi-objective, ant colony optimisation, multi-heuristic (EEMACOMH) algorithm are both adaptations of multi-objective, ant colony optimisation algorithms (MOACO) which are based on the ant colony system (ACS) algorithm. The new algorithms are constructive which means that in every iteration, every ant builds a complete solution. In order to guide the transition from one state to another, the algorithms use pheromone and heuristic information. The next two algorithms, namely, the energy efficiency for a mobile network using a multi-objective, MAX-MIN ant system optimisation, multi-pheromone (EEMMASMP) algorithm and the energy efficiency for a mobile network using a multi-objective, MAX- MIN ant system optimisation, multi-heuristic (EEMMASMH) algorithm, both solve the above multi-objective problem by using an adaptation of the MAX-MIN ant system optimisation algorithm. The last algorithm implemented, namely, the energy efficiency for a mobile network using a multi-objective, ant colony optimisation, multi-colony (EEMACOMC) algorithm uses a multiple colony ACO algorithm. From the experimental results the final conclusions may be summarised as follows:<ul><li> Ant colony, multi-objective optimisation algorithms are suitable for mobile ad hoc networks. These algorithms allow for high adaptation to frequent changes in the topology of the network. </li><li> All five algorithms yielded substantially better results than the non-dominated sorting genetic algorithm (NSGA-II) in terms of the quality of the solution. </li><li> All the results prove that the EEMACOMP outperforms the other four ACO algorithms as well as the NSGA-II algorithm in terms of the number of solutions, closeness to the true Pareto front and diversity. </li></ul> / Thesis (PhD)--University of Pretoria, 2010. / Computer Science / unrestricted

No / Trust management in mobile ad hoc networks (MANETs) has become a significant issue in securing routing protocols to choose reliable and trusted paths. Trust is used to cope with defection problems of nodes and stimulate them to cooperate. However, trust is a highly complex concept because of the subjective nature of trustworthiness, and has several social properties, due to its social origins. In this paper, a friendship-based trust model is proposed for MANETs to secure routing protocol from source to destination, in which multiple social degrees of friendships are introduced to represent the degree of nodes' trustworthiness. The model considers the behaviour of nodes as a human pattern to reflect the complexity of trust subjectivity and different views. More importantly, the model considers the dynamic differentiation of friendship degree over time, and utilises both direct and indirect friendship-based trust information. The model overcomes the limitation of neglecting the social behaviours of nodes when evaluating trustworthiness. The empirical analysis shows the greater robustness and accuracy of the trust model in a dynamic MANET environment.

Ensuring trustworthiness through mobile nodes is a serious issue. Indeed, securing the routing protocols in Mobile Ad Hoc Network (MANET) is of paramount importance. A key exchange cryptography technique is one such protocol. Trust relationship between mobile nodes is essential. Without it, security will be further threatened. The absence of infrastructure and a dynamic topology changing reduce the performance of security and trust in mobile networks. Current proposed security solutions cannot cope with eavesdroppers and misbehaving mobile nodes. Practically, designing a key exchange cryptography system is very challenging. Some key exchanges have been proposed which cause decrease in power, memory and bandwidth and increase in computational processing for each mobile node in the network consequently leading to a high overhead. Some of the trust models have been investigated to calculate the level of trust based on recommendations or reputations. These might be the cause of internal malicious attacks. Our contribution is to provide trustworthy communications among the mobile nodes in the network in order to discourage untrustworthy mobile nodes from participating in the network to gain services. As a result, we have presented an Elliptic Curve Diffie-Hellman key exchange and trust framework mechanism for securing the communication between mobile nodes. Since our proposed model uses a small key and less calculation, it leads to a reduction in memory and bandwidth without compromising on security level. Another advantage of the trust framework model is to detect and eliminate any kind of distrust route that contain any malicious node or suspects its behavior.