Power control based QoS provisioning for wireless multimedia networks.

摘要

Multimedia support is an outstanding feature of third generation wireless communication systems, and Wideband Code Division Multiple Access (W-CDMA) is an outstanding candidate as the underlying air interface technology. Quality of Service (QoS) is a crucial issue as in any networking environment, and the wireless last hop is major bottleneck. Supporting multiple rates in the CDMA environment introduces power assignment problem, for bandwidth and error provisioning. Multimedia traffic flows should be classified and serviced in such a way to provision delay guarantees, and to maximize throughput. In this thesis a QoS framework, namely Dynamic Resource scheduling (DRS), has been proposed to handle the last hop QoS issues in W-CDMA systems. Power optimization is applied on a radio frame basis, and dynamic updates provide flexibility and statistical multiplexing. A family of nine algorithms has been developed within the DRS framework. They can be distinguished by single or prioritized queuing architectures, fixed or variable rate bandwidth and power assignment, and variable spreading gain or multiple code spreading strategies. Power control ensures efficient and optimal use of W-CDMA resources in all of the algorithms. Power savings on each terminal not only provides individual benefits on battery life, but it increases the system capacity as well. Prioritized queuing performs service classification to provision delay QoS on guaranteed services. Variable bandwidth improves the throughput of best effort traffic, due to variable resource allocation. Variable rate can be applicable on the data services only, or on all services in the general sense. Performance of the DRS algorithms have been compared with conventional, S-CDMA and proposed W-CDMA power control schemes, to evaluate QoS provisioning performance. The performance for error, delay and throughput QoS provisioning and power control dynamics are explored. The advantages, disadvantages and limitations of the algorithms are discussed. DRS framework is concluded to be a promising QoS architecture, with a simple, flexible, scalable structure, that can be configured according to the traffic scenario. It is also generic to be applied over any kind of network technology, IP or ATM.