Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

In the CDMA cellular networking system, power control is a very important issue because it is an interference limited system. In order to reduce the near-far problem and improve the battery life of mobile station, the transmit power of mobile stations must be controlled to limit interference. In this paper, we study the effect of power control on system performance. Different power control rates may have influence on the performance. Meanwhile, we take the consideration of different call admission control algorithm. By introducing soft handoff waiting queue and guard channel into the soft handoff algorithm, we compare the power control influence on a base case (which is similar to IS95 algorithm, but with perfect power control) and proposed call admission control algorithm. The simulation shows that increasing power control rate and combination of power control and soft handoff prioritization can greatly reduce the blocking rates and refuse rates of new/soft handoff calls, thus the system performance is improved.

Les systèmes de génétique inverse permettent de manipuler les génomes viraux et se sont révélés essentiels pour étudier les virus à ARN. Récemment, une méthode basée sur la PCR, la méthode ISA (Infectious Subgenomic Amplicons), a été développée. La première partie de cette thèse se concentre sur la simplification de la méthode ISA. La principale contrainte d'ISA est l'exigence de produire des fragments génomiques modifiés qui nécessite un promoteur de transcription à l’extrémité 5’ du premier fragment et un ribozyme du virus de l'hépatite delta, suivi du signal de polyadénylation du virus simien 40 (HDR / SV40pA) à l’extrémité 3’ du dernier fragment. Ici, nous proposons une nouvelle méthode simplifiée "Haiku", dans laquelle sont fournis ces deux séquences en tant qu'amplicons séparés. Cette technique améliorée a été appliquée avec succès à une large gamme de virus dans des cellules de moustiques et de mammifères. La deuxième partie de cette thèse est axée sur la caractérisation de la population virale issue de divers systèmes de génétique inverse en utilisant le HRV-B14 comme modèle.Nos résultats montrent que le choix de la méthode a influencé la diversité génétique des populations virales mais quelle que soit la méthode utilisée, la fitness réplicative était similaire. En outre, nos données ont révélé que le poly(A)25 est la longueur optimale pour récupérer le HRV-B14 avec une efficacité élevée. La dernière partie du présent travail a examiné le potentiel de la méthode «ISA» pour conserver le spectre mutant présent dans l'échantillon viral d'origine. Nous avons montré que cette méthode récapitule au moins partiellement les quasi-espèces de la population virale native. / Reverse genetics systems allow manipulating viral genomes and have proved to be essential for studying RNA viruses. Recently, a PCR-based method, named ISA (Infectious Subgenomic Amplicons), was developed to facilitate the study of single-stranded positive-sense RNA viruses. The first part of the present work focused on simplifying the ISA method. The main constraint of the canonic protocol of the ISA method is the requirement to produce modified genomic fragments encompassing the transcription promoter and the terminator. Here, we propose the ultimately simplified "Haiku" design in which the promoter and the terminator are provided as additional separate DNA amplicons. This improved procedure was successfully applied to the rescue of a wide range of viruses in mosquito and mammalian cells. The second part of this work assessed the viral population issued from different reverse genetics systems. Using HRV B-14 as a model, we compared the genetic diversity and the replicative fitness of viruses generated using the most commonly used reverse genetics methods. Our results showed that the choice of the method influenced the genetic diversity of viral populations but whatever the method used, the replicative fitness was similar. In addition, Our data revealed that poly(A)25 is the optimal length to recover HRV-B14 with high efficiency and could be used to recover polyadenylated RNA viruses other than HRV-B14. The last part of the present work investigated the potential of the “ISA” method to conserve the mutant spectrum present in the original viral sample. We have showed that this method recapitulate at least partially the quasispecies of the native viral population.

Current congestion control approaches that attempt to provide fair bandwidth allocation among competing flows primarily consider only data rate when making decisions on which packets to drop. However, responsive flows with high round trip times (RTTs) can still receive significantly less bandwidth than responsive flows with low round trip times. This paper proposes a congestion control scheme called WHITE that addresses router unfairness in handling flows with significantly different RTTs. Using a best-case estimate of a flow's RTT provided in each packet by the flow source or by an edge router, WHITE computes a stabilized average RTT. The average RTT is then compared with the RTT of each incoming packet, dynamically adjusting the drop probability so as to protect the bandwidth of flows with high RTTs while curtailing the bandwidth of flows with low RTTs. We present simulation results and analysis that demonstrate that WHITE provides better fairness than other rate-based congestion control strategies over a wide-range of traffic conditions. The improved fairness of WHITE comes close to the fairness of Fair Queuing without requiring per flow state information at the router.

There are several approaches for creating double-ended heaps from the single-ended heaps. We build on one of them, the leaf correspondence heap, to create a generic double ended heap scheme called L-correspondence heap. This will broaden the class of eligible base single-ended heaps (e.g. by Fibonacci heap, Rank-pairing heap) and make the operations Decrease and Increase possible. We show this approach on specific examples for three different single-ended base heaps and give time complexity bounds for all operations. Another result is that for these three examples, the expected amortized time for Decrease and Increase operations in the L-correspondence heap is bounded by a constant.

Made available in DSpace on 2016-04-28T20:19:18Z (GMT). No. of bitstreams: 1 2007- Eliezer de Oliveira Figueiredo.pdf: 1961844 bytes, checksum: de32c223ac9f98f50331aa303f3973b7 (MD5) Previous issue date: 2007-08-27 / This paper is about Queue Management and Organizational Culture. Its study subject was the Campo Grande Branch of Banco do Brasil, located in the West District of the City of Rio de Janeiro, Brazil. Its general purpose is to investigate and interpret, on a day-to-day basis, how the Organizational Culture, or Subculture, influences Queue Management in a Banking Branch. As specific purposes its aims are: to verify if the existing theory on Queue Perception Management is applied; to present waiting time as a feature that must receive special attention from Bank Managers; to experience, first hand, the displeasure of waiting in line; to compile the gathered information and to suggest measures to mitigate the negative effects on the waiting client, when reducing or eliminating the wait is not possible. Methodologically, the research is classified on its ends as explanatory, whereas as its means it is classified as bibliographic, documental, of case study and field research. The ethnographic method was used on the field work, where the author immersed himself in the researched group, in the context where the social phenomena occurred, for a better understanding of the native point of view , through the process of interactive observation and semi-structured interview. Resulting data, including snapshots of the researched location, were recorded on the field journal. Data from the interviews of 14 customer contact personnel were recorded and fully transcripted. Obtained data went through a non digital analysis process according to a predefined script. The analysis of the speech concluded: concerning Queue Management, that there is a lack of distractions to entertain the client, that the clients notice available resources not being used for their benefits and that there are lonely waits; concerning Organizational Culture, that stress, selfishness, lack of punishment, the cult to foreign culture and the attachment to the internal rules are traits of the internal culture in Banco do Brasil that may be related to Queue Management. The paper concludes that the Bank culture is not concerned with the management of the perceptions of those waiting in line. A complete lack of knowledge about the Queue Management solutions could be easily verified on the customer contact personnel. It is noticed that this research has no signs of duality. The online pool brought to light and the ethnographic research made clear that waiting in line is a major factor on the clients level of satisfaction. The most urgent suggested measure is the implementation of distractions, along with the review of all processes related to customer contact, in order to reduce their duration. The conclusions of this paper are subject to the methodological limitations proper to ethnographic studies. / Esta disserta??o abordou o tema gest?o da fila sob a perspectiva da cultura organizacional. Teve como objeto de estudo a Ag?ncia Campo Grande RJ, do Banco do Brasil, localizada na Zona Oeste da cidade do Rio de Janeiro (RJ). Seu objetivo geral consistiu em interpretar e/ou investigar, na rotina di?ria, como a cultura (ou subcultura) organizacional est? influenciando a gest?o das percep??es nas filas de espera de uma ag?ncia banc?ria. Como objetivos espec?ficos procurou: verificar se h? aplica??o, na pr?tica, da teoria existente sobre a gest?o da percep??o do cliente na fila de espera; apontar o tempo de espera como um atributo que precisa merecer aten??o especial dos gestores das institui??es financeiras; vivenciar ou experimentar, no cotidiano, o desconforto da espera numa fila; compilar as informa??es obtidas sobre o assunto; e, por fim, propor sugest?es para, quando n?o for poss?vel a redu??o ou elimina??o, mitigar os efeitos negativos no cliente que espera na fila. Metodologicamente, a pesquisa foi classificada como explorat?ria, quanto aos fins, e bibliogr?fica, documental, de estudo de caso e de campo, quanto aos meios. No trabalho de campo, utilizou-se um m?todo com inten??o etnogr?fica, onde o pesquisador fez uma imers?o no dia-a-dia do grupo pesquisado, no contexto onde o fen?meno social acontecia, com a finalidade de compreender o chamado ponto de vista nativo , atrav?s do processo da observa??o participante e da entrevista semi-estruturada. Os dados provenientes da observa??o participante, inclusive foto retirada do ambiente, foram registrados no di?rio de campo do pesquisador. Os provenientes das entrevistas, realizadas com os 14 funcion?rios do atendimento (caixas e atendentes), foram gravados e transcritos em sua totalidade. Os dados obtidos foram, ent?o, submetidos ? an?lise de conte?do (sem o aux?lio de software), seguindo rotina definida. Foi apreendido, atrav?s da an?lise do discurso, que: sob o prisma da gest?o da fila, h? aus?ncia de distra??es que entretenham o consumidor, que h? recursos que n?o est?o atendendo aos consumidores ? vista deles e que h? esperas solit?rias; sob o prisma da cultura organizacional, o estresse, o esp?rito individualista, a impunidade, o culto ao estrangeiro e o apego ? norma est?o entre os tra?os culturais percebidos no Banco do Brasil que podem guardar alguma rela??o com a gest?o da fila. Como considera??es e conclus?es ficou evidente que n?o existe na cultura do banco uma preocupa??o com a gest?o das percep??es dos que esperam na fila; verificou-se uma quase completa ignor?ncia, por parte dos atendentes, dos conhecimentos existentes a cerca da gest?o das percep??es nas filas; registrou-se que a pesquisa n?o deixou marcada nos seus resultados a quest?o da dualidade; a pesquisa on line demonstrou, mas foi na viv?ncia do trabalho etnogr?fico que ficou bem caracterizado, que a espera na fila ? fator de grande insatisfa??o por parte dos clientes. Como sugest?o mais urgente, al?m da revis?o, para redu??o, dos tempos de todos os processos que envolvem o atendimento das pessoas, ficou a instala??o de distra??es. Finalmente, sublinhou-se que as conclus?es apresentam as limita??es metodol?gicas pr?prias dos estudos de cunho etnogr?fico.

Improving network performance in terms of efficiency, fairness in the bandwidth, and system stability has been a research issue for decades. Current Internet traffic control maintains sophistication in end TCPs but simplicity in routers. In each router, incoming packets queue up in a buffer for transmission until the buffer is full, and then the packets are dropped. This router queue management strategy is referred to as Drop Tail. End TCPs eventually detect packet losses and slow down their sending rates to ease congestion in the network. This way, the aggregate sending rate converges to the network capacity. In the past, Drop Tail has been adopted in most routers in the Internet due to its simplicity of implementation and practicability with light traffic loads. However Drop Tail, with heavy-loaded traffic, causes not only high loss rate and low network throughput, but also long packet delay and lengthy congestion conditions. To address these problems, active queue management (AQM) has been proposed with the idea of proactively and selectively dropping packets before an output buffer is full. The essence of AQM is to drop packets in such a way that the congestion avoidance strategy of TCP works most effectively. Significant efforts in developing AQM have been made since random early detection (RED), the first prominent AQM other than Drop Tail, was introduced in 1993. Although various AQMs also tend to improve fairness in bandwidth among flows, the vulnerability of short-lived flows persists due to the conservative nature of TCP. It has been revealed that short-lived flows take up traffic with a relatively small percentage of bytes but in a large number of flows. From the user’s point of view, there is an expectation of timely delivery of short-lived flows. Our approach is to apply artificial intelligence technologies, particularly fuzzy logic (FL), to address these two issues: an effective AQM scheme, and preferential treatment for short-lived flows. Inspired by the success of FL in the robust control of nonlinear complex systems, our hypothesis is that the Internet is one of the most complex systems and FL can be applied to it. First of all, state of the art AQM schemes outperform Drop Tail, but their performance is not consistent under different network scenarios. Research reveals that this inconsistency is due to the selection of congestion indicators. Most existing AQM schemes are reliant on queue length, input rate, and extreme events occurring in the routers, such as a full queue and an empty queue. This drawback might be overcome by introducing an indicator which takes account of not only input traffic but also queue occupancy for early congestion notification. The congestion indicator chosen in this research is traffic load factor. Traffic load factor is in fact dimensionless and thus independent of link capacity, and also it is easy to use in more complex networks where different traffic classes coexist. The traffic load indicator is a descriptive measure of the complex communication network, and is well suited for use in FL control theory. Based on the traffic load indicator, AQM using FL – or FLAQM – is explored and two FLAQM algorithms are proposed. Secondly, a mice and elephants (ME) strategy is proposed for addressing the problem of the vulnerability of short-lived flows. The idea behind ME is to treat short-lived flows preferably over bulk flows. ME’s operational location is chosen at user premise gateways, where surplus processing resources are available compared to other places. By giving absolute priority to short-lived flows, both short and long-lived flows can benefit. One problem with ME is starvation of elephants or long-lived flows. This issue is addressed by dynamically adjusting the threshold distinguishing between mice and elephants with the guarantee that minimum capacity is maintained for elephants. The method used to dynamically adjust the threshold is to apply FL. FLAQM is deployed to control the elephant queue with consideration of capacity usage of mice packets. In addition, flow states in a ME router are periodically updated to maintain the data storage. The application of the traffic load factor for early congestion notification and the ME strategy have been evaluated via extensive experimental simulations with a range of traffic load conditions. The results show that the proposed two FLAQM algorithms outperform some well-known AQM schemes in all the investigated network circumstances in terms of both user-centric measures and network-centric measures. The ME strategy, with the use of FLAQM to control long-lived flow queues, improves not only the performance of short-lived flows but also the overall performance of the network without disadvantaging long-lived flows.

L'objectif de cette thèse est d'étendre une méthode d'estimation des paramètres d'une loi stable dans Rd aux lois à queue régulière dans un cône arbitraire. La méthode d'échantillonnage par paquets est modifiée afin d'optimiser la vitesse de convergence des estimateurs. Un nouvel estimateur de la masse totale de mesure spectrale est proposé. Des résultats sur les statistiques d'ordre des lois à queue régulière dans un cône et la loi des grands nombres pour le schéma triangulaire sont établis. La consistance et la normalité asymptotique des estimateurs sont démontrées. La performance des estimateurs est étudiée par simulation. On compare ces estimateurs avec quelques estimateurs connus. Les tableaux de performance sont fournis. La méthode de noyau est utilisée pour estimer la densité d'une mesure spectrale absolument continue d'une loi à queue régulière. On prouve la consistance de l'estimateur dans notre cas particulier. Pour augmenter le nombre de points utilisés dans l'échantillon, on propose une méthode d'estimation utilisant les permutations aléatoires de l'échantillon. La variation régulière a la propriété d'être préservée par plusieurs opérations et transformations. On considère trois sortes de transformations. Des conditions suffisantes pour cette préservation sont proposées et quelques contre-exemples sont présentés. Les modèles de lois stables et de lois à queue lourde sont très utilisés dans plusieurs domaines d'application. On considère deux jeux de données réelles : les cours des 30 valeurs de l'indice DJIA et les perturbations planétaires des comètes du nuage de Oort. En appliquant la méthode d'estimation présentée on obtient des descriptions statistiques de ces données.

Le modèle auto-régressif linéaire (AR) en temps discret et à coefficients aléatoires englobe de nombreuses classes de modèles très utilisés en modélisation statistique. Sous des hypothèses simples, ce modèle a une unique solution stationnaire. Le comportement à l'infini de sa queue a été étudié par H. Kesten, E. LePage puis C. Goldie lorsque les coefficients sont indépendants. Cette thèse étend leurs résultats dans deux directions. Dans une première partie, on étudie le modèle AR scalaire à régime markovien introduit par J. D. Hamilton en économétrie. On obtient un résultat similaire au cas indépendant qui s'étend aussi au temps continu. Dans une deuxième partie, on s'intéresse au modèle multidimensionnel à coefficient indépendants. On étend les résultats existants à une vaste classe de coefficients vérifiant une condition d'irréductibilité et de proximalité. Les techniques utilisées dans les deux parties font appel à la théorie du renouvellement et des opérateurs markoviens.

<p>In the past 10 years, the bandwidths and processing capabilities of the networks have increased dramatically. The number of real-time applications using these networks has also increased. The large number of real-time packets might, in a switched multi-hop network, lead to unpredictable traffic patterns. This is not a problem when the traffic intensity is low, but if the same network is used by a large number of users simultaneously, the overall performance of the network degrades. In fact, unpredictable delays in the delivery of the message can adversely affect the execution of the tasks dependent on these messages, even if we take into account the soft real-time performance.</p><p>In this paper, we investigate the effect of traffic shapers on soft real-time performance. We will consider a switched multi-hop network with FCFS queues. We will implement two versions of the network simulator. One version will be without traffic shaper and the other version will use a traffic shaper. By comparing the results (for average delay, deadline miss ratio etc.) from both the versions, we will try to conclude if it is really beneficial to use traffic shapers for soft real-time performance. Leaky bucket and token bucket algorithms are the most popular ones for traffic shaper implementation. We will consider leaky bucket algorithm for our analysis. We analyse different versions of the leaky bucket and present the trade-off’s involved.</p>