Packet switched wireless networks have become increasingly popular due to improvements in transmission speed, ease of deployment and mobility. Wireless technologies such as the IEEE 802.11 Wireless Local Area Networks provide transmission speeds capable of supporting multimedia applications. However, wireless channels suffer from short term effects such as interference and fading, and long term effects such as signal strength changes that are caused by user mobility. In multi-rate networks, stations can adapt to the channel variations by adjusting their physical transmission rates. This introduces resource management problems as resource usage depends on the application's bit rate as well as the physical transmission rate used. Multimedia applications demand consistent Quality of Service (QoS) performance from the network. This does not fit well with the dynamic nature of wireless networks. In this thesis, we propose a link layer resource manager to maintain application QoS requirements in multi-rate wireless networks. It consists of two components - Resource reservation and Medium Access Control (MAC) parameters selection. The resource reservation algorithm determines the current and future amount of channel resources required by a multimedia application and performs the function of admission control. This prevents any new traffic or physical transmission rate changes from degrading the QoS of the admitted traffic. The design of the MAC parameters selection algorithm is based on the IEEE 802.11e Enhanced Distributed Channel Access (EDCA) scheme. The algorithm enables the provision of QoS to individual multimedia applications with the prioritised service of EDCA. Analytical and simulation studies were performed to demonstrate the efficiency and effectiveness of the algorithms. The results highlighted the ability of the algorithms to mitigate the QoS provision problem in multi-rate wireless networks introduced by channel variations.

This thesis presents several decentralized, learning-based algorithms for on-line routing of bandwidth guaranteed paths. The presented routing algorithms do not need any a-priori knowledge of traffic demand; they use only their locally observed events and update their routing policy using learning schemes. The employed learning algorithms are either learning automata or the multi-armed bandit algorithms. We investigate the asymptotic behavior of the proposed routing algorithms and prove the convergence of one of them to the user equilibrium. Discrete event simulation results show the merit of these algorithms in terms of improving the resource utilization and increasing the network admissibility compared with shortest path routing. / We investigate the performance degradation due to decentralized routing as opposed to centralized optimal routing policies in practical scenarios. The system optimal and the Nash bargaining solutions are two centralized benchmarks used in this study. We provide nonlinear programming formulations of these problems along with a distributed recursive approach to compute the solutions. An on-line partially-decentralized control architecture is also proposed to achieve the system optimal and the Nash bargaining solution performances. Numerical results in some practical scenarios with well engineered networks, where the network resources and traffic demand are well matched, indicate that decentralized learning techniques provide efficient, stable and scalable approaches for routing the bandwidth guaranteed paths. / In the context of on-line learning, we propose a new algorithm to track the best action-selection policy when it abruptly changes over time. The proposed algorithm employs change detection mechanisms to detect the sudden changes and restarts the learning process on the detection of an abrupt change. The performance analysis of this study reveals that when all the changes are detectable by the change detection mechanism, the proposed tracking the best action-selection policy algorithm is rate optimal. On-line routing of bandwidth guaranteed paths with the potential occurrence of network shocks such as significant changes in the traffic demand is one of the applications of the devised algorithm. Simulation results show the merit of the proposed algorithm in tracking the optimal routing policy when it abruptly changes.

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The convergence of recent technology advances opens the way to new ubiquitous environments, where network-enabled devices collectively form invisible pervasive computing and networking environments around the users. These users increasingly require extensive applications and capabilities from these devices. Recent approaches propose that cooperating service providers, at the edge of the network, offer these required capabilities (i.e services), instead of having them directly provided by the devices. Thus, the network evolves from a plain communication medium into an endless source of services. Such a service, namely an overlay application, is composed of multiple distributed application elements, which cooperate via a dynamic communication mesh, namely an overlay association. The Quality of Service (QoS) perceived by the users of an overlay application greatly depends on the QoS on the communication paths of the corresponding overlay association. This thesis asserts and shows that it is possible to provide QoS to an overlay application by using alternate Internet paths resulting from the compositions of independent consecutive paths. Moreover, this thesis also demonstrates that it is possible to discover, select and compose these independent paths in a distributed manner within an community comprising a limited large number of autonomous cooperating peers, such as the fore-mentioned service providers. Thus, the main contributions of this thesis are i) a comprehensive description and QoS characteristic analysis of these composite alternate paths, and ii) an original architecture, termed SPAD (Super-Peer based Alternate path Discovery), which allows the discovery and selection of these alternate paths in a distributed manner. SPAD is a fully distributed system with no single point of failure, which can be easily and incrementally deployed on the current Internet. It empowers the end-users at the edge of the network, allowing them to directly discover and utilize alternate paths.

Quality of service differentiation has never achieved much attention and relevance until the advent of the convergence of mobile wireless network and the fixed Internet, that is, Internet Protocol ( IP ) based mobile wireless networks, or wireless Internet. These networks are poised to support multimedia applications ' traffic with diverse QoS sensitivities. To date, most traffic transferred over the Internet still undergo best - effort forwarding, which does not guarantee whether or not traffic sent by a source gets to the intended destination, let alone loss and timing bounds. The major contribution of this thesis is three - fold. First, the thesis proposes a QoS - enabled wireless Internet access architecture, which leverages the micromobility in wireless standards to reduce mobile IP weaknesses, such as long handoff delay, to achieve effective interworking between mobile wireless networks and the global, fixed Internet. Although the idea here is applicable to any wireless standard, the design examples in this thesis are based on the IEEE 802.11b wireless local area network ( WLAN ) standard. Second, it proposes a framework for a class of wireless channel state dependent packet scheduling schemes, which consider the QoS requirements of the applications ' traffic ; the wireless channel state ( reflected in instantaneous data rate or noise level ) ; and optimises the usage of the expensive wireless resource. The operation of the QoS - enabled, channel state - dependent packet scheduler is analysed using optimisation theory, eigenanalysis and stochastic modelling. Third, the thesis analyses the effects of wireless channel properties on differentiated QoS ( DQoS ) schemes, using two - dimensional, channel - state - dependent queuing theory, matrix analytic methods to stochastic modelling and eigenanalysis. The ana - lytical model of DQoS schemes, especially models accounting for user scenarios such as speed of motion and wireless channel properties, such as fading, spatio - temporarily varying quality and low rate, is not properly covered in the open literature, and hence was a motivation for this part of the thesis. The wireless channel is discretized into discrete - time Markovian states based on the received signal - to - noise plus interference ratio ( SNIR ), which also reflects on the instantaneous link quality. The link quality, in turn, influences the QoS experienced by the transported applications sitting on top of the ISO / OSI protocol hierarchy. The parameters of the Markovian states are evaluated using realistic physical channel noise models and transceiver characteristics, such as modem. [ Different modems ( modulator / demodulator ) yields different transceiver properties such as sensitivity. The analysis in the thesis adopts QPSKand BPSK modulation. ] Source traffic models are used in the analysis. Lastly, the thesis provides an extensive introduction to, and provides a detailed background material for the new area of mobile wireless Internet systems, upon which considerable future research can be based. / Thesis (Ph.D.)--School of Electrical and Electronic Engineering, 2003.

Quality of service differentiation has never achieved much attention and relevance until the advent of the convergence of mobile wireless network and the fixed Internet, that is, Internet Protocol ( IP ) based mobile wireless networks, or wireless Internet. These networks are poised to support multimedia applications ' traffic with diverse QoS sensitivities. To date, most traffic transferred over the Internet still undergo best - effort forwarding, which does not guarantee whether or not traffic sent by a source gets to the intended destination, let alone loss and timing bounds. The major contribution of this thesis is three - fold. First, the thesis proposes a QoS - enabled wireless Internet access architecture, which leverages the micromobility in wireless standards to reduce mobile IP weaknesses, such as long handoff delay, to achieve effective interworking between mobile wireless networks and the global, fixed Internet. Although the idea here is applicable to any wireless standard, the design examples in this thesis are based on the IEEE 802.11b wireless local area network ( WLAN ) standard. Second, it proposes a framework for a class of wireless channel state dependent packet scheduling schemes, which consider the QoS requirements of the applications ' traffic ; the wireless channel state ( reflected in instantaneous data rate or noise level ) ; and optimises the usage of the expensive wireless resource. The operation of the QoS - enabled, channel state - dependent packet scheduler is analysed using optimisation theory, eigenanalysis and stochastic modelling. Third, the thesis analyses the effects of wireless channel properties on differentiated QoS ( DQoS ) schemes, using two - dimensional, channel - state - dependent queuing theory, matrix analytic methods to stochastic modelling and eigenanalysis. The ana - lytical model of DQoS schemes, especially models accounting for user scenarios such as speed of motion and wireless channel properties, such as fading, spatio - temporarily varying quality and low rate, is not properly covered in the open literature, and hence was a motivation for this part of the thesis. The wireless channel is discretized into discrete - time Markovian states based on the received signal - to - noise plus interference ratio ( SNIR ), which also reflects on the instantaneous link quality. The link quality, in turn, influences the QoS experienced by the transported applications sitting on top of the ISO / OSI protocol hierarchy. The parameters of the Markovian states are evaluated using realistic physical channel noise models and transceiver characteristics, such as modem. [ Different modems ( modulator / demodulator ) yields different transceiver properties such as sensitivity. The analysis in the thesis adopts QPSKand BPSK modulation. ] Source traffic models are used in the analysis. Lastly, the thesis provides an extensive introduction to, and provides a detailed background material for the new area of mobile wireless Internet systems, upon which considerable future research can be based. / Thesis (Ph.D.)--School of Electrical and Electronic Engineering, 2003.

Siu Chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 66-68). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Thesis Overview --- p.3 / Chapter 2 --- Background and Related work --- p.4 / Chapter 2.1 --- Emergence of IP-over-ATM --- p.4 / Chapter 2.2 --- ATM architecture --- p.5 / Chapter 2.3 --- Scheduling issues in output-queued switch --- p.6 / Chapter 2.4 --- Scheduling issues in input-queued switch --- p.18 / Chapter 3 --- The Deadline-ordered Burst-based Parallel Scheduling Strategy --- p.23 / Chapter 3.1 --- Introduction --- p.23 / Chapter 3.2 --- Switch and queueing model --- p.24 / Chapter 3.2.1 --- Switch model --- p.24 / Chapter 3.2.2 --- Queueing model --- p.25 / Chapter 3.3 --- The DBPS Strategy --- p.26 / Chapter 3.3.1 --- Motivation --- p.26 / Chapter 3.3.2 --- Strategy --- p.31 / Chapter 3.4 --- The Deadline-ordered Burst-based Parallel Iterative Matching --- p.33 / Chapter 3.4.1 --- Algorithm --- p.34 / Chapter 3.4.2 --- An example of DBPIM --- p.35 / Chapter 3.5 --- Simulation results --- p.33 / Chapter 3.6 --- Discussions --- p.46 / Chapter 3.7 --- Future work --- p.47 / Chapter 4 --- The Quasi-static DBPIM Algorithm --- p.50 / Chapter 4.1 --- Introduction --- p.50 / Chapter 4.2 --- Quasi-static path scheduling principle --- p.51 / Chapter 4.3 --- Quasi-static DBPIM algorithm --- p.56 / Chapter 4.4 --- An example of Quasi-static DBPIM --- p.59 / Chapter 5 --- Conclusion --- p.63 / Bibliography --- p.65

Indiana University-Purdue University Indianapolis (IUPUI) / The contribution of this thesis focuses on addressing the challenges of improving and integrating the UniFrame Discovery Service (URDS) and Multi-level Matching (MLM) concepts. The objective was to find enhancements for both URDS and MLM and address the need of a comprehensive discovery service which goes beyond simple attribute based matching. It presents a detailed discussion on developing an enhanced version of URDS with MLM (proURDS). After implementing proURDS, the thesis includes details of experiments with different deployments of URDS components and different configurations of MLM. The experiments and analysis were carried out using proURDS produced MLM contracts. The proURDS referred to a public dataset called QWS dataset. This dataset includes actual information of software components (i.e., web services), which were harvested from the Internet. The proURDS implements the different matching operations as independent operators at each level of matching (i.e., General, Syntactic, Semantic, Synchronization, and QoS). Finally, a case study was carried out with the deployed proURDS. The case study addresses real world component discovery requirements from the earth science domain. It uses the contracts collected from public portals which provide geographical and weather related data.