Scheduling and resource allocation in broadband multimedia wireless local area networks

grantor: University of TorontoTwo main topics of research in modern computer networks are the development of new wireless architectures and technologies, and the addition of new multimedia services. These two topics have converged in the design of multimedia Wireless Local Area Networks (WLANs). The synthesis of wireless and multimedia networks has opened new problem areas in transmission scheduling and resource allocation. Techniques suitable for wireless telephony are unsuitable for a multimedia environment, and techniques for wired multimedia networks are not immediately applicable to a wireless medium. The problems of transmission scheduling and resource allocation are explored in three areas: Time-Division Multiple Access (TDMA), hybrid TDMA/Code Division Multiple Access (CDMA), and multicellular TDMA environments. The problem of scheduling is explored in TDMA networks through Distributed Fair Queueing (DFQ), a centralized scheduling protocol. The necessary concepts of Fair Queueing are reviewed, and the resource allocation problem for multimedia services is addressed. The DFQ architecture is then introduced, and the problems due to physical and error control overhead are studied. Behaviour of a mix of multimedia services is simulated to determine average system performance. The problems of Quality-of-Service (QoS) delivery in hybrid TDMA/Code Division Multiple Access (CDMA) are addressed by introducing differential power control for QoS preservation. The optimal power levels are determined in order to maximize the capacity of the network. Two scheduling methodologies are introduced, differing in efficiency and complexity. Finally, the problem of channel allocation in an unlicensed, distributed-architecture environment is explored through a simple interference avoidance protocol named Active Channel Avoidance (ACA). The ACA protocol attempts to minimize interference between unrelated networks in an environment while allowing communication between cells of multicellular networks. The performance of simple network models under ACA is calculated, in order to estimate performance for real-world networks and provide a theoretical framework for further refinement.Ph.D