Adaptive quality-of-service provisioning in wireless and mobile networks

The problem of adaptive QoS provisioning in wireless and mobile networks is studied in this thesis. A mathematical model is established to analyze the impact of adaptive bandwidth allocation on both system performance and user-perceived QoS. With this model, network service providers can dynamically adjust---based on the network load or available network capacity---user bandwidth with controllable degradation on user-perceived QoS. To facilitate adaptive QoS support in time-division multiplexed wireless networks (such as the IEEE 802.11 wireless LANs), a distributed airtime usage control is also developed. By using the proposed airtime control, wireless stations using the contention-based medium access method are shown to be able to provide users the parameterized QoS, which can only be achieved by using the polling-based medium access method in the current IEEE 802.11e standard. The proposed distributed airtime usage control is also shown to be able to provide QoS support in ad hoc IEEE 802.11 wireless LANs.; In order to further improve the user's QoS, the concept of "spectral agility" is introduced to wireless networks (especially, the IEEE 802.11 wireless LANs). An analytical model is established in order to derive the achievable improvement gained by using spectral agility. To fully exploit spectral agility, a comprehensive framework for spectral-agile networks is also developed. This framework and the associated functionalities are integrated with the IEEE 802.11 wireless LAN in the ns-2 simulator to demonstrate the effectiveness of the resulting spectral-agile wireless networks. Finally, the mobility support for QoS provisioning in the IEEE 802.11 wireless LAN is investigated, and a unified smooth-and-fast handoff is developed for both intra- and inter-subnet handoffs based on the Inter-Access Point Protocol.