IEEE 802.15.3 無線多媒體網路之資源管理

Abstract

Recent progress in wireless technologies (e.g., Ultra-Wideband) has made it possible for people to enjoy high-quality wireless multimedia services at home. The IEEE 802.15.3 standard for high-rate wireless personal area networks (WPANs) is an emerging wireless technology that combines low cost and low power with high data rates and robust quality of service (QoS). Although the IEEE 802.15.3 MAC layer can provide a QoS supporting framework, it does not specify the functions of resource management such as bandwidth allocation, admission control and scheduling. In order to meet QoS requirements for future wireless multimedia services, especially for real-time multimedia services, the following problems are the main challenges of resource management for IEEE 802.15.3 multimedia networks. 1. (P1) To predict bandwidth requirements adaptively for real-time VBR videos. 2. (P2) To design an effective admission control scheme which can guarantee the QoS properties of multimedia traffics and improve channel utilization for real-time VBR videos. 3. (P3) To schedule VBR video traffics so that the QoS properties of multimedia traffics can be guaranteed and better channel utilization can result. The objective of this dissertation is to develop some functions of resource management for IEEE 802.15.3 multimedia networks, in order to support QoS transmissions for multimedia services and improve channel utilization. For (P1), we introduce a new adaptive VBR video predictor, based on a variable step-size LMS algorithm, which can overcome the problem caused by scene changes. We also propose a dynamic bandwidth allocation scheme using the VBR video predictor. The VBR video predictor is adaptive to rapid traffic variation while scene changes occur. Rather than using the fixed step-size adaptive LMS-type predictor, which is difficult to determine in advance the optimal parameters for different VBR video traffics, we enable the VBR video predictor to adjust its step size, automatically, according to the statistics of different VBR video traffics. For (P2), we propose an on-line measurement-based admission control (MBAC) scheme for aggregate VBR video traffics. A linear Kalman filter is to be used in the measurement process to estimate statistical parameters of aggregate VBR videos. The estimated statistical parameters are used to calculate the effective bandwidth for admission decision. The effective bandwidth, which is a measure of resource usage, represents a trade-off between sources of different types. When it is calculated, varying statistical characteristics and QoS requirements should be taken into account. The goal of the MBAC scheme is to achieve QoS guarantee for real-time VBR video traffics and improve channel utilization. Finally, for (P3), we propose an effective scheduling algorithm, which requires the location information provided by ultra-wideband technology and the transmission power control (TPC) supported by IEEE 802.15.3. With it, the system throughput can be maximized and the channel utilization can be enhanced, while the QoS requirements are satisfied.