The IEEE 802.16 standard popularly known as WiMAX is at the forefront of the technological drive. Achieving high system throughput in these networks is challenging due to interference which limits concurrent transmissions. In this thesis, we study routing and link scheduling inWiMAX mesh networks. We present simple joint routing and link scheduling algorithms that have outperformed most of the existing proposals in our experiments. Our session based routing and links scheduling produced results approximately 90% of a trivial lower bound. We also study the problem of quality of service (QoS) provisioning in WiMAX mesh networks. QoS has become an attractive area of study driven by the increasing demand for multimedia content delivered wirelessly. To accommodate the different applications, the IEEE 802.16 standard defines four classes of service. In this dissertation, we propose a comprehensive scheme consisting of routing, link scheduling, call admission control (CAC) and channel assignment that considers all classes of service. Much of the work in the literature considers each of these problems in isolation. Our routing schemes use a metric that combines interference and traffic load to compute routes for requests while our link scheduling ensures that the QoS requirements of admitted requests are strictly met. Results from our simulation indicate that our routing and link scheduling schemes significantly improve network performance when the network is congested. / ix, 77 leaves : ill. ; 29 cm

Today, the fulfillment of customer demands and user experience requirements are becoming the main differentiators for gauging the effectiveness of telecom operators and service providers. In this competitive market, the poor Quality of Experience (QoE) leads to a chain reaction of negative word of mouth, pushing customers into the arms of waiting competitors. Therefore it is important for service providers to ensure superior quality of experience in order to avoid customer disloyalty and negative reputation. QoE is a fast emerging multi-disciplinary field focused on understanding overall human quality requirements from different angles such as technology, business and context of use. The first and foremost challenge is to understand how different influencing characteristics related to business, technology, and context influence human behavior. In this thesis, initial work addresses this challenge of understanding the influence of disparate domains over QoE. A consolidated QoE interaction model is proposed which links disparate domains (human, business, technology, and context) to understand overall human quality of experience requirements. Then taxonomy is presented for QoE interaction model. Second contribution in this thesis is based on the first and its main objective is to capture and analyze QoE data through user studies. Based on user data, the influence of technological, contextual and business parameters over QoE are evaluated. Different multimedia services were selected for user study such as video streaming service, telephony (VoIP and PSTN), and 3D audio teleconferencing service. Depending upon multimedia service, different aspects were considered during each user study such as types of multimedia service parameters (QoS, content, context), the types of QoE metrics (subjective, objective cognitive or both), human characteristics (age, gender etc), and human roles (user, or customer). These findings help in understanding the link between QoE and other influencing domains. The third contribution is based upon ongoing work of developing QoE based tools for video streaming services. Two QoE based tools for the assessment of multimedia services have been presented in this thesis, their main functions are to capture, analyze and report QoE metrics in real time. These QoE tools are useful for real time measurement of QoE metrics

Magistro darbe yra suformuluotos Lietuvos Notariato veiklos optimizavimo problemos, remiantis moksline literatūra bei kitais šaltiniais, išanalizuoti Lietuvos Notariato 1990 – 2010 m. laikotarpyje įvykusius pokyčius įtakoję veiksniai ir atskleisti, kokie sprendimai neigiamai, kokie teigiamai paveikė institucijos veiklą. Darbe iškeltos 4 hipotezės. Remiantis atliktu tyrimu, pirmoji hipotezė, kad Lietuvos Notariatui iš Valstybinio tapus Lotyniškuoju pagerėjo atliekamų paslaugų kokybė bei išaugo pasitikėjimas šios profesijos atstovais, buvo patvirtinta tik iš dalies; antroji hipotezė, kad Lietuvos tapimas Europos Sąjungos nare lotyniškojo tipo notarui atvėrė kelius integracijai į Europos teisinį tinklą - į patikimesnį profesinį bendradarbiavimą, buvo patvirtinta; trečioji hipotezė, kad sėkmingam Notariato veiklos optimizavimui būtinas elektroninių sistemų diegimas, buvo patvirtinta; ketvirtoji hipotezė, kad notarinių paslaugų vartotojai notarų veiklos optimizavimą vertina pagal gaunamų paslaugų kokybę bei jų kainodarą, buvo patvirtinta. / This master’s final paper formulates the problems of optimization of Lithuania’s Notary activity. Based on scientific literature and other sources, factors, which influenced the changes of Lithuania Notary in 1990 – 2010, were analyzed, and reveal, which decisions negatively or positively have affected the performance of the institution. There are four hypotheses raised in the master’s final paper. According to a study carried out, the first hypothesis says that when Lithuania’s Notary has changed to the Latin type, the quality of services has improved and the trust of the employees has increased. This hypothesis was only confirmed partially. The second hypothesis which says that after Lithuania became a member of the European Union, the notary of Latin was able to integrate into the European legal network, which meant stronger professional cooperation, was confirmed. The third hypothesis, which says that electronic systems are necessary for successful optimization of Notary activity, was confirmed. The fourth hypothesis, which says that customers of Notary service assess the optimization according to the quality of service and their pricing, was confirmed.

Magistro darbe yra iškelta bankų teikiamų paslaugų kokybės problema. Darbe išanalizuota ir susisteminta įvairių tiek Lietuvos, tiek ir užsienio autorių publikuota medžiaga bei atlikti tyrimai, susiję su paslaugų kokybe, klientų lojalumu. Darbe išsamiai išanalizuota paslaugų koncepcijos esmė, lojalumas ir jį įtakojantys veiksniai, stadijos. Darbe plačiai analizuojama paslaugų kokybė teoriniu aspektu, atlikta paslaugų kokybės modelių analizė, analizuojamas lojalumas, kas jį įtakoja, lojalumo stadijos ir lojalumo klientų kategorijos. Atlikta bankų teikiamų paslaugų kokybės ir klientų lojalumo analizė pagal komercinių bankų klientų lojalumo formavimo modelį. Nepasitvirtina autorių suformuluota hipotezė, kad bankų teikiamų paslaugų kokybė, netenkina daugelio klientų poreikių. / In this master's work analyze the quality of service in the bank’s problem. The material of the foreign authors and Lithuanian ones has been analyzed and structured. However, the research, involving service, quality and loyalty of customer is made. Has been analyzed the essence of the service conception, loyalty, and its influencing factor stage. Moreover, the paper theoretically analyzes the quality of the service, and there is maid the analysis of the service quality modals analyses of the loyalty of customers, who it affects, the stage of loyalty and categories of customer loyalty. There was performed the analysis of the banks of the quality of accommodation services and loyalty of customers provided by commercial banks and the forming of the model of customer loyalty. There does not prove a hypothesis formulated by the authors that the quality of accommodation services provided by banks does not satisfy the needs of most clients.

Šiame magistro baigiamajame darbe ištirta ir įvertinta Lietuvos hidrometeorologijos tarnybos teikiamų paslaugų efektyvumas, kokybė, vertinimas bei tobulinimo galimybės, iškeltos paslaugų kokybės vertinimo problemos bei pateikti pasiūlymai šių problemų sprendimui. Pirmoje dalyje tiriamos paslaugų sampratos, paslaugų ypatumai, vieša ir meteorologijos paslauga bei vartotojų pasitenkinimo indeksas. Išanalizuoti šeši pagrindiniai paslaugų kokybės modeliai. Antroje dalyje pateikta tyrimų metodologija. Aprašytas instrumentarijus dviejų atliktų tyrimų. Pirmasis tyrimas - hidrometeorologijos tarnybos vieša vartotojų pasitenkinimo apklausa atlikta tarnybos tinklalapyje. Antrasis tyrimas - hidrometeorologijos tarnybos paslaugų kokybės vertinimas, paslaugų vartotojų anketavimo būdas. Trečiojoje dalyje aprašoma hidrometeorologijos tarnybos charakteristika, atliktų tyrimų rezultatai. Aptartos tobulinimo galimybės. Pateikiami paslaugų kokybės gerinimo būdai. / This master's thesis investigates and assesses the efficiency of services, services‘ quality, assessment and improvement opportunities, raises the problems of services‘ quality and provide suggestions for solving these problems in Lithuanian Hydrometeorological Service. The first part explores the concept of services, services’ features, public meteorological service and customer satisfaction index. There are analyzed six main service quality models. The second part is intended to explain the methodology. There are described two instrumentations used for analysis. The first analysis aims to investigate public users’ satisfaction with Hydrometeorological Service and was implemented in the Authority's website. The second analysis covers Hydrometeorological Service services’ quality assessment and was implemented by questioning service’ customers. The third part describes basic characteristics of Hydrometeorological Service and examines research results. There are possibilities for improvements discussed and methods how to improve the quality of services explained.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

In this thesis we deal with the application of Network Coding to guarantee the Quality of Service (QoS) for wireless multi-hop networks. Since the medium is shared, wireless networks suffer from the negative interference impact on the bandwidth. It is thus interesting to propose a Network Coding based approach that takes into account this interference during the routing process. In this context, we first propose an algorithm minimizing the interference impact for unicast flows while respecting their required bandwidth. Then, we combine it with Network Coding to increase the number of admitted flows and with Topology Control to still improve the interference management. We show by simulation the benefit of combining the three fields: Network Coding, interference consideration and Topology Control. We also deal with delay management for multicast flows and use the Generation-Based Network Coding (GBNC) that combines the packets per blocks. Most of the works on GBNC consider a fixed generation size. Because of the network state variations, the delay of decoding and recovering a block of packets can vary accordingly degrading the QoS. To solve this problem, we propose a network-and content-aware method that adjusts the generation size dynamically to respect a certain decoding delay. We also enhance it to overcome the issue of acknowledgement loss. We then propose to apply our approach in a Home Area Network for Live TV and video streaming. Our solution provides QoS and Quality of Experience for the end user with no additional equipment. Finally, we focus on a more theoretical work in which we present a new Butterfly-based network for multi-source multi-destination flows. We characterize the source node buffer size using the queuing theory and show that it matches the simulation results.

The issue of providing Quality of Service (QoS) in the Internet is becoming more and more important because of two phenomena: (1) the growth of the value added services that require QoS (e.g., VPNs, IPTV) and (2) network convergence towards a unified IP-based architecture, for voice, image and data services. In this context, the limitations of existing QoS technologies emerge: it is currently difficult for an operator to guarantee that its network can offer a specific level of service. Furthermore, it is hard to ensure a consistent treatment of end-to-end QoS-sensitive flow that cross networks controlled by several operators. Indeed, the control on such traffic flows is shared between all the traversed operators. In the thesis, we have studied these issues. Specifically, we have addressed the problems of routing and dynamic traffic engineering at inter-domain level. We have proposed several algorithmic solutions to compute paths subject to multiple performance constraints. Analytical studies and simulations show that our algorithms are efficient and scalable. Finally, we have integrated our solutions into an architecture that is under ongoing standardization by the IETF and we have studied the protocol adaptations required for the deployment of our algorithms. Our work represents an important step towards more effective inter-domain traffic management in traffic engineered networks

Ultra-wideband (UWB) technologies with higher data rates and lower transmission power over shorter ranges, have enabled a new set of applications in Wireless Personal Area Networks (WPANs). For example, UWB can offer data rates 50 to 500 times higher than the current WPAN technologies such as Bluetooth. This property makes UWB a primary candidate for indoor high-speed multimedia applications such as whole-house Internet Protocol Television (IPTV) and Personal Video Recorder (PVR). Lower power emission brings less interference to other devices, and larger bandwidth makes UWB less affected by interference from others, which are very attractive attributes in a household environment. However, the effective and efficient utilization of such high data rate wireless channel represents a new challenge to WPAN Media Access Control (MAC), especially for high quality video streaming applications. To meet the minimum bandwidth and maximum delay requirement for Quality-of-Service (QoS) guarantee, high-definition IPTV and PVR services usually need to reserve a certain amount of channel time for exclusive access in a dynamic manner, since the number of video flows may change over time in a piconet. WiMedia Alliances MAC protocols for UWB-based WPANs have become an international standard. The Distributed Reservation Protocol (DRP) is part of this standard that reserves the wireless channel on a slot-by-slot basis for different flows. However, not much work has been done on DRP reservation algorithms and their performance. In this research, we propose, analyze and evaluate two application-aware reservation algorithms. One algorithm allocates time slots based on the first-fit idea whereas the other takes one step further by doing a best-fit reservation according to the maximum tolerable delay bound. Our proposed algorithms try to find the best possible time slots for any requests with respect to the existing reservations in the piconet and those arriving later. With these algorithms, devices in the same piconet that have data to transmit can negotiate and reserve time slots based on their traffic specification and QoS requirement while following WiMedia MAC reservation policies. We analyze the reservation algorithms and policies with a tiered overflow model, and evaluate their performance with Network Simulator (NS-2 ) and an MPEG-4 video traffic generator. We further discuss the ways of improving video streaming quality and system resource utilization in UWB networks.

With the convergence of the wireless networks and the Internet and the booming demand for multimedia applications, the next-generation (beyond the third generation, or B3G) wireless systems are expected to be all IP-based and provide real-time and non-real-time mobile services anywhere and anytime. Powerful and efficient mobility support is thus the key enabler to fulfil such an attractive vision by supporting various mobility scenarios. This thesis contributes to this interesting while challenging topic. After a literature review on mobility support architectures and protocols, the thesis starts presenting our contributions with a generic multi-layer mobility support framework, which provides a general approach to meet the challenges of handling comprehensive mobility issues. The cross-layer design methodology is introduced to coordinate the protocol layers for optimised system design. Particularly, a flexible and efficient cross-layer signalling scheme is proposed for interlayer interactions. The proposed generic framework is then narrowed down with several fundamental building blocks identified to be focused on as follows. As widely adopted, we assume that the IP-based access networks are organised into administrative domains, which are inter-connected through a global IP-based wired core network. For a mobile user who roams from one domain to another, macro (inter-domain) mobility management should be in place for global location tracking and effective handoff support for both real-time and non-real-lime applications. Mobile IP (MIP) and the Session Initiation Protocol (SIP) are being adopted as the two dominant standard-based macro-mobility architectures, each of which has mobility entities and messages in its own right. The work explores the joint optimisations and interactions of MIP and SIP when utilising the complementary power of both protocols. Two distinctive integrated MIP-SIP architectures are designed and evaluated, compared with their hybrid alternatives and other approaches. The overall analytical and simulation results shown significant performance improvements in terms of cost-efficiency, among other metrics. Subsequently, for the micro (intra-domain) mobility scenario where a mobile user moves across IP subnets within a domain, a micro mobility management architecture is needed to support fast handoffs and constrain signalling messaging loads incurred by intra-domain movements within the domain. The Hierarchical MIPv6 (HMIPv6) and the Fast Handovers for MIPv6 (FMIPv6) protocols are selected to fulfil the design requirements. The work proposes enhancements to these protocols and combines them in an optimised way. resulting in notably improved performances in contrast to a number of alternative approaches.