Browse Theses

During the last few years there has been a great demand for multimedia applications with Quality of Service (QoS) in wireless/mobile networks. QoS provisioning and guarantee for multimedia services have become more and more important partially due to the users' requirements. The tasks are more challenging than those in the wired networks due to channel fading and mobility. Although channel fading can be improved with better transmission and reception systems, mobility would cause severe fluctuations of resources. Thus, the existing QoS components need to be enhanced and redesigned in order to apply to wireless/mobile networks. In this research, many aspects of QoS provisioning and guarantee for multimedia services in wireless/mobile networks will be addressed. Firstly, the layered coding multimedia traffic model is adopted to mitigate the fluctuations of resources. In such a model, the multimedia receivers can selectively choose a subset of the hierarchical coding depending on its capacity and the network traffic condition. Secondly, we classify services into three categories. For each of the above three categories, traffic descriptors and QoS parameters are defined and specified. We abstract these three categories into a general traffic model. Thirdly, under the general traffic model, optimal Call Admission Control (CAC) schemes are presented analytically to guarantee the QoS parameters' requirements and traffic descriptors from a service user's point of view, and maximize the revenue from a service provider's point of view. Fourthly, two novel QoS parameters are proposed for adaptive multimedia traffic model to provide better QoS for adaptive multimedia users. These QoS parameters characterize both the frequency of degradation and the degree of degradation. Fifthly, based on new proposed QoS parameters, we propose a measurement-based CAC scheme and two Bandwidth Adaptation Algorithms to guarantee QoS for single class of adaptive multimedia services in wireless/mobile networks. The proposed CAC scheme measures the observed history of the system, and reflects more weights on the current system status. Finally, we propose proportional degradation services for multiple classes of adaptive multimedia services in wireless/mobile networks including two measurement-based CAC schemes and a K-Level Proportional Bandwidth Adaptation algorithm to fairly adapt calls' bandwidth, to minimize the degradation ratio and the degradation degree, and to guarantee the predefined ratios of service degradation among classes. The proposed approaches are innovative and will greatly aid mobile cellular network providers.